Field of the Invention The present invention provides ketolide derivatives, which can be used as anti-bacterial agents. Compounds disclosed herein can be used for the treating or preventing conditions caused by or contributed to by gram positive, gram negative or anaerobic bacteria, more particularly against, for example. Staphylococci, Streptococci, Enterococci, Haemophilns, Moraxalla spp., Chlumydia spp., Mycoplasm, Legionella spp., Mycobacterhim, Helicobacler, Clostridium, Bacteroides. Corynebaclerium, Bacillus, Enterobactericeae or any combination thereof. Also provided are processes for preparing compounds disclosed herein, intermediates used in their synthesis, pharmaceutical compositions thereof, and methods of treating bacterial infections. Background of the Invention First generation macrolides, such as erythromycin A and early derivatives, can be characterized by bacteriostatic or bactericidal activity for most gram-positive bacteria, atypical pathogens and many community-acquired respiratory infections, particularly in patients with penicillin allergies. However, erythromycin A causes numerous drug-drug interactions, has relatively poor absorption, poor local tolerance, loses its antibacterial activity under acidic conditions by degradation and the degraded products are known to cause undesired side effects (Itoh. Z el cil.. Am. J. Physiol, 1984, 247:688; Omura, S el al., J. Med. Chem., 1987, 30:1943). Various erythromycin A derivatives have been prepared to overcome the acid instability and other problems associated with it. Roxithromycin, clarithromycin and azithromycin were developed to address the limitations of erythromycin A. Both clarithromycin and azithromycin are reportedly important drugs in the treatment and prophylaxis of atypical mycobacterial infections in patients with HIV. Macrolides are reportedly effective drugs in the treatment of many respiratory tract infections. However, increasing resistance among S. pneumonias has prompted the search for new compounds that retain favorable safety profiles, retain a spectrum of activity and are confined to respiratory pathogens. Consequently, numerous investigators have prepared chemical derivatives of erythromycin A in an attempt to obtain analogs having modified or improved profiles of antibiotic activity. Ketolides exhibit greater efficacy and safety, have broader spectrum of activities, and are particularly effective against resistant pathogens; hence, ketolides have been developed as next generation macrolides. U.S. Patent No. 5.635,485 discloses erythromycin compounds that are reportedly useful in the treatment of bacterial infections in warm-blooded animals. U.S. Patent No. 5.866,549 discloses novel semi-synthetic macrolides reportedly having antibacterial activity, more particularly, 6-O-substituted erythromycin ketolide derivatives and a method of treating bacterial infections. U.S. Patent No. 6,472,372 discloses 6-O-carbamoyl ketolide antibacterials and a method of treating bacterial infections. PCT Publication No. WO 2004/029066 discloses bitunctional heterocyclic compounds that are reportedly useful as anti-infective, anti-proliferative, anti-inflammatory and prokinetic agents. PCT Publication No. WO 00/62783 discloses ketolide antibacterials that are reportedly useful in the treatment of bacterial and protozoa! infections and in the treatment of other conditions involving gastric motility. PCT Publication No. WO 00/44761 discloses ketolide antibiotics reportedly useful as antibacterial and antiprotozoal agents in mammals. U.S. Patent No. 5,747,467 discloses novel antibacterial composition and method of treating bacterial infections of gram positive bacteria in warm-blooded animals. U.S. Patent No. 6.433.151 discloses demethylated ketolide derivatives and their use as medicament for the treatment of infection caused by gram positive bacteria, Haemophilus influenzae, Moraxalla spp. U.S. Patent Nos. 6,458.771 and 6,399,582 disclose ketolide antibacterials that are reportedly useful in the treatment of bacterial and protozoa! infections and in the treatment of other conditions involving gastric motility. U.S. Patent Application Nos. 2002/0115621 and 2003/0013665 disclose macrolide compounds that are reportedly useful as antibacterial and antiprotozoal agents in mammals, including man. as well in fish and birds. European Patent No. 1 114 826 discloses macrolide compounds that are reportedly useful antibacterial, antiprotozoal and/or prokinetic agents, also, it relates to a method of treating cancer or atherosclerosis. U.S. Patent Nos. 6.313,101 and 6,407,257 disclose derivatives of erythromycin that reportedly have good antibiotic activity on gram-positive bacteria. Other ketolide compounds have also been reported. A. Denis and A. Bonnefoy. Drugs of the Future, 26(10):975-84 (2001), Champney W. S., at al., Current Microbiology. 42 :203-10 (2001). However, there remains a need for novel ketolide derivatives that are useful in treating or preventing bacterial infections. Summary of the Invention The present invention provides ketolide derivatives, which can be used in the treatment or prevention of bacterial infections, and processes for the synthesis of these compounds. Pharmaceutically acceptable salts, pharmaceutically acceptable solvates, stereoisomers, metabolites, prodrugs, polymorphs of these compounds having same type of activity are also provided. Pharmaceutical compositions containing the disclosed compounds together with pharmaceutically acceptable carriers, excipients or diluents, which can be used for the treatment of bacterial infection. Thus in one aspect, provided herein are compounds having the structure of Formula I,pharmaceutically acceptable salts, pharmaceutically acceptable solvates, stereoisomers, prodrugs, metabolites and polymorphs thereof, wherein: R can be hydrogen, hydroxyl protecting group; R and R can independently be hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl. aryl, (heterocyclyl)alkyl or -COR11, wherein R" can be hydrogen, alkyl, aryl, NR9R10 or alkoxy; R and RH)can independently be hydrogen, alkyl, alkenyl or alkynyl; and with the proviso that R~ and R are not simultaneously methyl: W can be -NH or -(CHi)™-, wherein in can be an integer of from 2 to 6; -(CH2)m- group can optionally be interrupted by one or more of unsaturated bond, oxygen, sulfur, -NRa- or combination thereof, wherein Ra can be hydrogen, alkyl, cycloalkyl, alkenyl, heterocyclyl, (heterocyclyl)alkyl, alkynyl or aryl; one of the hydrogen atoms of -(CH2)m- group can optionally be replaced by halogen, alkyl, hydroxyl or alkoxy; and with the proviso that R2 is hydrogen when W is -(CH?),,,-, wherein m is an integer of from 2 to 6; R can be hydrogen, hydroxy, alkyl, aryl, heterocyclyl, cycloalkyl or cycloalkenyl; R4 can be hydrogen, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocyclyl, amidoarylalkyl or amidoarylalkynyl; R' can be hydrogen, aryl, alkyl or -(CH2)r-U; wherein r can be an integer of from 1 to 4; and U can be alkenyl, alkynyl, alkylalkenyl, alkylalkynyl, arylalkenyl, arylalkynyl, heterocyclylalkenyl or heterocyclylalkynyl; or OR' can be replaced by hydrogen; Y can be hydrogen, halogen, cyano, alkyl, aryl, heterocyclyl, hydroxy, amino, PhSe. alkenyl, alkynyl or -NRl)R10, wherein R9 and R10 are the same as defined earlier; and Z can be oxygen, sulphur or NOR11, wherein R11 is the same as defined earlier. The compounds described herein can include one or more of the following embodiments. For example. R1 can be hydrogen; R2 can be hydrogen or alkyl; R4 can be alkyl; Y can be halogen; R' can be alkyl or alkenyl; R' can be alkyl; Z can be oxygen or NOR11; W can be -NH or -(CH2)4-, wherein the -(CH2)4- group can be interrupted by oxygen, nitrogen or unsaturated bond or one of the hydrogen atoms of -(CH2)4- group can be replaced by alkyl; and R is hydrogen, aryl, substituted aryl or heterocyclyl. In another example, R1 can be hydrogen; R can be hydrouen or methyl; R4 can be ethyl; Y can be fluorine; R3 can be ethyl or allyl; R1 can be * ^ J ^ ^ J *f ^ methyl; Z can be oxygen or -NOCH3; W can be -NH-, -(CH2)3O-, -NH-(CH2)3-. - NHCH2CH=CH- or -NH(CH2)2-CH(CH3)- and R can be phenyl, 3-(pyridine-3-yl)-phenyl. 3- (thienyl-3-yl)-phenyl, pyridin-3-yl, imidazo[4,5-b]pyridin-3-yl, pyrrolo[2,3 b]pyridin-l-yl, isoquinoline-5-yl and benzimidazol-1-yl, 3-(lH-imidazol-4-yl)-pyridine, 4-phenyl-lH-imidazole or 4-thiophen-3-yl-l H-imidazole. In another aspect, provided herein are compounds selected from: 2-a-Fluoro-5-O-(3'-N-didesmethyl-3'-N-ethyl)-l l,12-dideoxy-3-O-decladinosyl-6-O-methyl-3- oxo-12.1 l-[oxycarbonyl-((4-imidazol[4,5-b]pyridin-3-yl)-butyl)-imino] erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-ethyl)-11,12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12,1 l-[oxycarbonyl-((3-(3-pyridin-3-yl-phenoxy)-propyl)-imino)] erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-allyl)-ll,12-dideoxy-3-O-decladinosyl-6-0-methyl-3-oxo- 12.1 l-[oxycarbonyl-((3-(3-pyridin-3-yl-phenoxy)-propyl)-imino)] erythromycin A, , 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-ethyl)-ll,12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12,1 l-[oxycarbonyl-((3-(pyridin-3-yloxy)-propyl)-imino)]erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-ethyl)-11.12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12.1 l-[oxycarbonyl-((3-(3-thiophen-3-yl-phenoxy)-propyl)-imino)] erythromycin A. 2-a-Fluoro-5-O-(3' -N-desmethyl-3' -N-ethyl)-11,12-dideoxy-3-O-decladinosyl-6-O-methyl-3- oxo-12.1 l-[oxycarbonyl-hydrazo]erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-allyl)-l l,12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12.1 l-[oxycarbonyl-hydrazo]erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-allyl)-11,12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12.1 l-[oxycarbonyl-((3-pyrrolo[2,3-b]pyridin-l-yl)-propyl)-hydrazo)] erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-allyl)-11,12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12.11 -[oxycarbonyl-((3-phenylpropyl)-hydrazo)]erythromycin A, 2-cx-Fluoro-5-O-(3'-N-desmethyl-3'-N-allyl)-l l,12-dideoxy-3-O-decladinosyl-6-0-methyl-3-oxo- 12,11 -[oxycarbonyl-((3-isoquinolin-5-yl-propyl-hydrazo)]erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-ethyl)-ll,12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12.11 -[oxycarbonyl-((3-phenylpropyl)-hydrazo)]erythromycin A. 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-allyl)-lK12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12.1 l-[oxycarbonyl-((3-(4-phenyl-imidazol-l-yl)-propyl)-hydrazo)]erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-ethyl)-11.12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12.1 l-[oxycarbonyl-((3-(4-phenyl-imidazol-l-yl)-propyl)-hydrazo)] erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-ethyl)-ll,12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12.1 l-[oxycarbonyl-((3-benzoimidazol-l-yl)-propyl)-hydrazo)] erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-ethyl)-11.12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12,1 l-[oxycarbonyl-((3-(4-pyridyl-3-yl-imidazol-l-yl)-propyl)-hydrazo)] erythromycin A. 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-allyl)-11,12-dideoxy-3-O-decladinosyl-6-0-methyl-3-oxo- 12,1 l-[oxycarbonyl-((3-(4-pyridyl-3-yl-imidazol-l-yl)-propyl)-hydrazo)] erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-allyl)-l l,12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12,1 l-[oxycarbonyl-((3-benzoimidazol-l-yl)-propyl)-hydrazo)] erythromycin A. 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-allyl)-11.12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12,1 l-[oxycarbonyl-((3-(4-thiophen-3-yl-imidazol-l-yl)propyl)-hydrazo)] erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-allyl)-ll,12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12,1 l-[oxycarbonyl-((3-(4-phenyl-imidazol-l-yl)-propyl)-hydrazo)] erythromycin A-9-(Omethyl) oxime. 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-ethyl)-l 1.12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12.1 l-[oxycarbonyl-((3-(4-pyridyl-3-yl-imidazol-l-yl)-propyl)-hydrazo)] erythromycin A-9-(Omethyl) oxime. 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-allyl)-11,12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12,ll-[oxycarbonyl-((3-(4-thiophen-3-yl-imidazol-l-yl)propyl)-hydrazo)] erythromycin A-9-(Omethyl) oxime, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-allyl)-11.12-dideoxy-3-O-decladinosyl-6-0-methyl-3-oxo- 12.1 l-[oxycarbonyl-((3-(4-pyridyl-3-yl-imidazol-l-yl)-butyl)-hydrazo)] erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-allyl)-ll,12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12.1 l-[oxycarbonyl-((3-(4-phenyl-imidazol-l-yl)-butyl)-hydrazo)] erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-ethyl)-ll,12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12,11 -foxycarbonyl-((3-phenyl-allyl)-hydrazo)]erythromycin A, 2-a-Fluoro-5-O-(3'-N-desmethyl-3'-N-ethyl)-ll,12-dideoxy-3-O-decladinosyl-6-O-methyl-3-oxo- 12.11-[oxycarbonyl-((3-(4-(2-chloro-pyrimidin-5-yl)-imidazol-l-yl)-propyl)-hydrazo)] erythromycin A, or pharmaceutically acceptable salts, pharmaceutically acceptable solvates, stereoisomers, prodrugs, metabolites or polymorphs thereof. In yet another aspect, provided herein are pharmaceutical compositions comprising therapeutically effective amounts of one or more compounds having the structure of Formula I, pharmaceutically acceptable salts, pharmaceutically acceptable solvates, stereoisomers, prodrugs. metabolites or polymorphs thereof, and optionally together with one or more pharmaceutically acceptable carriers, excipients or diluents, wherein: R1 can be hydrogen, hydroxyl protecting group; R2 and R3 can independently be hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, aryl. (heterocyclyl)alkyl or -COR11, wherein R11 can be hydrogen, alkyl, aryl, NR9R10 or alkoxy; R9and RHlcan independently be hydrogen, alkyl, alkenyl or alkynyl; and ii'/7/7 the proviso that R' and R are not simultaneously methyl: W can be -NH or -(CI-^)™-, wherein in can be an integer of from 2 to 6; -(CH2)m- group can optionally be interrupted by one or more of unsaturated bond, oxygen, sulfur, -NRa- or combination thereof, wherein Ra can be hydrogen, alkyl, cycloalkyl, alkenyl, heterocyclyl, (heterocyclyl)alkyl, alkynyl or aryl; one of the hydrogen atoms of -(CH2)m- group can optionally be replaced by halogen, alkyl, hydroxyl or alkoxy; and with the proviso that R' is hydrogen when W is -(CH2),,,-, wherein m is an integer of from 2 to 6: R can be hydrogen, hydroxy, alkyl, aryl. heterocyclyl, cycloalkyl or cycloalkenyl; R4 can be hydrogen, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocyclyl, amidoarylalkyl or amidoarylalkynyl; R' can be hydrogen, aryl, alkyl or -(CH2)r-U; wherein r can be an integer of from 1 to 4; and U can be alkenyl, alkynyl, alkylalkenyl, alkylalkynyl, arylalkenyl, arylalkynyl. heterocyclylalkenyl or heterocyclylalkynyl; or OR' can be replaced by hydrogen; Y can be hydrogen, halogen, cyano, alkyl, aryl, heterocyclyl, hydroxy, amino, PhSe, alkenyl. alkynyl or -NR9R10, wherein R and R10 are the same as defined earlier; and Z can be oxygen, sulphur or NOR1', wherein R" is the same as defined earlier. In another aspect, provided are methods for treating or preventing a condition caused by or contributed to by bacterial infection in a mammal comprising administering to the mammal in need thereof a pharmaceutical composition described herein. In yet another aspect, provided are methods for treating or preventing a condition caused by or contributed to by bacterial infection in a mammal comprising administering to the mammal in need thereof a therapeutically effective amount of one or more compounds having the structure of Formula I. pharmaceutically acceptable salts, pharmaceutically acceptable solvates, stereoisomers, prodrugs, metabolites or polymorphs thereof, and optionally together with one or more pharmaceutically acceptable carriers, excipients or diluents. wherein: R1 can be hydrogen, hydroxyl protecting group; R2 and R3can independently be hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, aryl, (heterocyclyl)alkyl or -COR11, wherein R" can be hydrogen, alkyl. aryl, NR9R10 or alkoxy; R9and R1(lcan independently be hydrogen, alkyl, alkenyl or alkynyl; and with the proviso thai R2 and R3 are not simultaneously methyl: W can be -NH or -(CH2)m-, wherein m can be an integer of from 2 to 6; -(CH2)m- group can optionally be interrupted by one or more of unsaturated bond. oxygen, sulfur, -NRa- or combination thereof, wherein Ra can be hydrogen, alkyl, cycloalkyl, alkenyl, heterocyclyl, (heterocyclyl)alkyl, alkynyl or aryl; one of the hydrogen atoms of -(CH2)m- group can optionally be replaced by halogen, alkyl, hydroxyl or alkoxy; and with the proviso that R~ is hydrogen when W is -(CH?),,,-- wherein m is an integer of from 2 to 6; R can be hydrogen, hydroxy, alkyl, aryl. heterocyclyl, cycloalkyl or cycloalkenyl; R4 can be hydrogen, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heterocyclyl, amidoarylalkyl or amidoarylalkynyl; R1 can be hydrogen, aryl, alkyl or - ( C H 2 ) ; wherein r can be an integer of from 1 to 4; and LI can be alkenyl, alkynyl, alkylalkenyl, alkylalkynyl, arylalkenyl, arylalkynyl, heterocyclylalkenyl or heterocyclylalkynyl; or OR' can be replaced by hydrogen; Y can be hydrogen, halogen, cyano, alkyl, aryl, heterocyclyl, hydroxy, amino, PhSe, alkenyl, alkynyl or -NR9R10, wherein R9 and R10 are the same as defined earlier; and Z can be oxygen, sulphur or NOR11, wherein R11 is the same as defined earlier. Such methods can include one or more of the following embodiments. For example, the condition can be selected from community-acquired pneumonia, upper and lower respiratory tract infections, skin and soft tissue infections, hospital-acquired lung infections or bone and joint infections, mastitis, catheter infection, foreign body, prosthesis infections or peptic ulcer disease. The condition can also be caused by or contributed to by one or more gram positive, gram negative or anaerobic bacteria, wherein the one or more gram positive, gram negative or anaerobic bacteria are selected from Staphylococci, Streptococci, Enterococci, Haemophihis, Morcixalla spp., Chlamydlu spp., Mycoplasm, Legionella spp., Mycobucterhtm, Helicobacter, Clostridhim, Bacleroides, L'orynehacieriiim, Bacillus or Enterobactericeae. The one or more gram positive, gram negative or anaerobic bacteria can be a cocci and in other embodiments, the cocci can be drug resistant. The one or more compounds of Formula I can be concurrently or sequentially administered with one or more additional therapeutic agents selected from benzoyl peroxide, clindamycin, telithromycin, tretinoin, vitamin E, vitamin A and its derivatives, tetracycline, isotretinoin, vitamin C, vitamin D, chaparral, dandelion root, licoric root, Echinacea, kelp, cayenine, sassafras, elder flowers, pantothenic acid, para amino benzoic acid, biotin, cholin, inositol, folic acid, calcium, magnesium, potassium, vitamin BA. zinc, carotenoid orazelaic acid or mixtures thereof. In another aspect, provided are processes for preparing compounds of Formula XIII, pharmaceutically acceptable salts, pharmaceutically acceptable solvates, enantiomers. diastereomers or polymorphs thereof, comprising the steps of: (a) hydrolyzing clarithromycin of Formula II, to form a compound of Formula III, (b) protecting the compound of Formula III with one or more reagents of Formula R'2O or R'X (wherein X is halogen) to form a compound of Formula IV, (Figure Removed) reacting the compound of Formula IV with one or more suitable reagents to form a compound of Formula V, reacting the compound of Formula V with one or more organic bases to form a compound of Formula VI, (e) oxidizing the compound of Formula VI to form a compound of Formula VII, desmethylating the compound of Formula VII at the 3'-N-dimethyl group to form a compound of Formula VIII, (g) alkylating the compound of Formula VIII with one or more reagents of Formula R'CHO. R3 2 CO or R3X to form a compound of Formula IX, (h) fluorinating the compound of Formula IX to form a compound of Formula X, (i) reacting the compound of Formula X with N,N'-carbonyldiimidazole to form a compound of Formula XI, h.rmula XI 0) reacting the compound of Formula XI with a compound of Formula R-W-NFb to form a compound of Formula XII, (k) deprotecting the compound of Formula XII to form a compound of Formula XIII (wherein R, R3 R1 and W are the same as defined earlier), wherein R can be hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, aryl, (heterocyclyl)alkyl or - COR ".wherein R" can be hydrogen, alkyl, aryl, NR9R10 or alkoxy; R9and Rlocan independently be hydrogen, alkyl, alkenyl or alkynyl; and with the proviso that R3 is not methyl; W can be -NH or -(CH2)m-, wherein m can be an integer of from 2 to 6; ™- group can optionally be interrupted by one or more of unsaturated bond, oxygen, sulfur, -NRa- or combination thereof, wherein Ra can be hydrogen, alkyl, cycloalkyl, alkenyl, heterocyclyl, (heterocyclyl)alkyl, alkynyl or aryl; one of the hydrogen atoms of -(CH2)m- group can optionally be replaced by halogen, alkyl, hydroxyl or alkoxy; and R can be hydrogen, hydroxy, alkyl, aryl, heterocyclyl, cycloalkyl or cycloalkenyl; and R1 can be hydrogen, hydroxyl protecting group. In yet another aspect, provided are processes for preparing compounds of Formula XI VA. pharmaceutically acceptable salts, pharmaceutically acceptable solvates, stereoisomers, prodrugs, metabolites or polymorphs thereof comprising the steps of: (a) desmethylating at 3'-N-dimethyl group of a compound of Formula XII to form a compound of Formula XIIIA, (b) deprotecting the compound of Formula XIIIA to form a compound of Formula XIVA, wherein R1 can be hydrogen, hydroxyl protecting group; R3can be hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, aryl, (heterocyclyl)alkyl or - COR ".wherein R" can be hydrogen, alkyl, aryl, NR9R10 or alkoxy; R9and Rl ( lcan independently be hydrogen, alkyl, alkenyl or alkynyl; and W can be -NH or -(CHa)™-, wherein m can be an integer of from 2 to 6; -(CH2)m- group can optionally be interrupted by one or more of unsaturated bond, oxygen, sulfur, -NRa- or combination thereof, wherein Ra can be hydrogen, alkyl, cycloalkyl, alkenyl, heterocyclyl, (heterocyclyl)alkyl, alkynyl or aryl; one of the hydrogen atoms of -(CH2),,!- group can optionally be replaced by halogen, alkyl, hydroxyl or alkoxy; and R can be hydrogen, hydroxy, alkyl, aryl. heterocyclyl, cycloalkyl or cycloalkenyl; In another aspect, provided are processes for preparing compounds of Formula XVI. pharmaceutically acceptable salts, pharmaceutically acceptable solvates, stereoisomers, prodrugs. metabolites or polymorphs thereof, comprising the steps of: (a) reacting the compound of Formula XI with hydrazine hydrate to form a compound of Formula XIV, (b) deprotecting the compound of Formula XIV to form a compound of Formula XV, and (c) reacting the compound of XV with a compound of Formula R-W-CHO to form a compound of Formula XVI, wherein R1 can be hydrogen, hydroxyl protecting group; R3can be hydrogen, alkyl. alkenyl, alkynyl, cycloalkyl, aryl, (heterocyclyl)alkyl or - COR ".wherein R" can be hydrogen, alkyl. aryl. NRl)R10 or alkoxy; R9and Rl ocan independently be hydrogen, alkyl, alkenyl or alkynyl; and with the proviso that R3 is not methyl: W can be -NH or -(CH2)m-, wherein m can be an integer of from 2 to 6; -(CH:),!!- group can optionally be interrupted by one or more of unsaturated bond, oxygen, sulfur, -NRa- or combination thereof, wherein R., can be hydrogen, alkyl, cycloalkyl, alkenyl, heterocyclyl, (heterocyclyl)alkyl, alkynyl or aryl; one of the hydrogen atoms of-(CH2)m- group can optionally be replaced by halogen, alkyl, hydroxyl or alkoxy; and R can be hydrogen, hydroxy, alkyl, aryl, heterocyclyl, cycloalkyl or cycloalkenyl; In yet another aspect, provided are processes for preparing compounds of Formula XVIII, pharmaceutically acceptable salts, pharmaceutically acceptable solvates, enantiomers, diastereomers or polymorphs thereof comprising the steps of: (a) reacting the compound of Formula XV with a compound of Formula FbNOR to form a compound of Formula XVII, (b) reacting the compound of Formula XVII with a compound of Formula R-W-CHO to form a compound of Formula XVIII, wherein R" can be hydrogen, alkyl, aryl, NR9R10 or alkoxy, wherein R9 and R1 can independently be hydrogen, alkyl, alkenyl or alkynyl; R3 can be hydrogen, alkyl, alkenyl. alkynyl, cycloalkyl, aryl, (heterocyclyl)alkyl or - COR ".wherein R11 can be the same as defined above; and with the proviso that R' is not methyl; W can be -NH or -(CH2),,,-, wherein m can be an integer of from 2 to 6; -(CH2)m- group can be optionally interrupted by one or more of unsaturated bond, oxygen, sulfur, -NRa- or combination thereof, wherein R2, can be hydrogen, alkyl, cycloalkyl. alkenyl, heterocyclyl. (heterocyclyl)alkyl, alkynyl or aryl; one of the hydrogen atoms of -(CH2)nr group can optionally be replaced by halogen, alkyl, hydroxyl or alkoxy; and R can be hydrogen, hydroxy, alkyl, aryl, heterocyclyl, cycloalkyl or cycloalkenyl. In yet another aspect, provided herein are compounds of Formula I, which can also be used as anti-inflammatory and prokinetic agents. Detailed Description of the Invention In accordance with one aspect, provided herein are compounds having the structure of Formula I, pharmaceutically acceptable salts, pharmaceutically acceptable solvates, stereoisomers, prodrugs, metabolites and polymorphs thereof, wherein: R1 can be hydrogen, hydroxyl protecting group; R2 and R3 can be independently hydrogen, alkyl. alkenyl, alkynyl, cycloalkyl, aryl, (heterocyclyl)alkyl or -COR11, wherein R" can be hydrogen, alkyl, aryl or NR9R10, wherein R9and Rl ( lare independently hydrogen, alkyl, alkenyl, alkynyl or alkoxy, with the proviso that R' and R are not simultaneously methyl: W can be -NH or -(CH2)m-- wherein m can be an integer of from 2 to 6, and -(CH2)m- group can be optionally interrupted by one or more of unsaturated bond, oxygen, sulfur, -NR;,- or combination thereof, wherein R.i can be hydrogen, alkyl, cycloalkyl, alkenyl, heterocyclyl. (heterocyclyl)alkyl. alkynyl or aryl and one of the hydrogen atom of-(CH2)™- group can be optionally replaced by halogen, alkyl. hydroxyl or alkoxy. ir/7/7 the proviso thai R' is hydrogen when W is -(CH2),,,-, wherein m can represent an integer of from 2 to 6: R can be hydrogen, hydroxy, alkyl, aryl, heterocyclyl, cycloalkyl, cycloalkenyl; R4 can be hydrogen, alkyl, alkenyl. alkynyl, aryl, cycloalkyl, heterocyclyl, amidoarylalkyl or amidoarylalkynyl: R' can be hydrogen, aryl, alkyl or -(CH2)r-U, wherein r can be an integer of from 1 to 4, and U can be alkenyl, alkynyl, alkylalkenyl, alkylalkynyl, arylalkenyl, arylalkynyl, heterocyclylalkenyl or heterocyclylalkynyl, or OR' can be replaced by hydrogen; Y can be hydrogen, halogen, cyano, alkyl, aryl, heterocyclyl, hydroxy, amino, PhSe. alkenyl. alkynyl or -NRl)R10, wherein R9 and R10 are the same as defined earlier; and Z can be oxygen, sulphur or NOR11, wherein R" is the same as defined earlier. In one embodiment, R1 can be hydrogen, R2 can be hydrogen or alkyl; R4 can be alkyl; Y can be halogen. R"' can be alkyl or alkenyl; R' can be alkyl; Z can be oxygen or NOR11; W can be -NH or -(Cl (2)4-; -(CH2)_4- group can be interrupted by oxygen, nitrogen or unsaturated bond or one of the hydrogen atom of-(CH2)4- group can be replaced by alkyl; R can be hydrogen, aryl, substituted aryl or heterocyclyl. In another embodiment, R1 can be hydrogen; R2 can be hydrogen or methyl; R4 can be ethyl; Y can be fluorine; R can be ethyl or allyl; R' can be methyl; Z can be oxygen or -NOCH3; W can be -NH-. -(CH2)3O-, -NH-(CH2)3-, -NHCH2CH=CH- or -NH(CH2)2-CH(CH3)-; R can be phenyl. 3-(pyridine-3-yl)-phenyl, 3-(thienyl-3-yl)-phenyl, pyridin-3-yl, imidazo[4,5-b]pyridin-3- yl. pyrrolo[2.3 b]pyridin-l-yl, isoquinolin-5-yl and benzimidazole-1-yl, 3-(lH-imidazol-4-yl)- pyridine. 4-phenyl-lH-imidazole or 4-thiophen-3-yl-lH-imidazole. In accordance with a second aspect, provided herein are methods for treating or preventing a mammal suffering from conditions caused by or contributed to by gram positive, gram negative or anaerobic bacteria comprising administering to a mammal in need thereof therapeutically effective amounts of one or more compounds or one or more pharmaceutical compositions disclosed herein. Bacterial infection may be caused by one or more bacteria, for example. Slaphylococci, Streptococci, Enlerococci, Hcieinophilus, Moraxalla spp., Chlamydia spp., Mycoplasm, LegioneUa spp., Mycobucterium, Hclicobactcr, Closlridhtm, Bacleroides, Corynebacterium, Bacillus or Enlerohuclericeae. The conditions treated or prevented may be, for example, community-acquired pneumonia, upper and lower respiratory tract infections, skin and soft tissue infections, hospitalacquired lung infections or bone and joint infections, or other bacterial infections, for example, mastitis, catheter infection, foreign body, prosthesis infections or peptic ulcer disease. In accordance with a third aspect, provided herein are processes for preparing the described compounds. The term "alkyl," unless otherwise specified, refers to a monoradical branched or unbranched saturated hydrocarbon chain having from 1 to 20 carbon atoms. Alkyl groups can be optionally interrupted by atom(s) or group(s) independently selected from oxygen, sulfur, a phenylene. sulphinyl, sulphonyl group or -NRt,-, wherein Rh can be hydrogen, alkyl, alkenyl, alkynyl cycloalkyl or aryl. This term can be exemplified by groups such as methyl, ethyl, npropyl. iso-propyl, n-butyl, iso-butyl, sec-butyl, t-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, ndecyl. tetradecyl, and the like. Alkyl groups may be substituted further (referred herein as "substituted alkyl") with one or more substituents selected from alkenyl, alkynyl, alkoxy, cycloalkyl. cycloalkenyl, acyl, acylamino, acyloxy, alkoxycarbonylamino, azido, cyano, halogen, hydroxy, keto, oxo, thiocarbonyl, carboxy, carboxyalkyl, aryl, heterocyclyl, heteroaryl, (heterocyclyl)alkyl, cycloalkoxy, -CH=N-O(C|.6alkyl), -CH=N-NH(Ci_6alkyl), -CH=N-NH(C,. (,alkyl)-C|_6alkyl, arylthio, thiol, alkylthio, aryloxy. nitro, aminosulfonyl, aminocarbonylamino, - NHC(=O)RP, -NRpRq. -C(=O)NRpRq, -NHC(=O)NRpRq, -C(=O)heteroaryl, C(=O)heterocyclyl, - O-C(=O)NRpRq {wherein Rp and Rq are independently selected from hydrogen, alkyl, alkenyl, cycloalkyl. alkoxy, cycloalkenyl, aryl, aralkyl, heterocyclyl, heteroaryl. heterocyclylalkyl. heteroarylalkyl}, nitro, hydroxyamino, alkoxyamino or S(O)mR66 (wherein m is an integer from 0- 2 and R6& is alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl, aryl, heterocyclyl, heteroaryl, heteroarylalkyl or heterocyclylalkyl). Unless otherwise constrained by the definition, alkyl substituents may be further substituted by 1-3 substituents selected from alkyl. alkenyl, alkynyl, carboxy, -NRPRC], -C(=O)NRpRq. -OC(=O)NRpRq. -NHC(=O)NRpRq (wherein Rp and Rq are the same as defined earlier), hydroxy, alkoxy, halogen, CF3, cyano, and S(O)mR66 (wherein m is an integer from 0-2 and R60, are the same as defined earlier); or an alkyl group also may be interrupted by 1-5 atoms of groups independently selected from oxygen, sulfur or-NRh- (wherein RI, is selected from hydrogen, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, aryl, acyl. aralkyl,- C(=O)ORp (wherein Rp is the same as defined earlier), S(O)mR66 (wherein m is an integer from 0- 2 and R66 is as defined earlier), or -C(=O)NRpRq (wherein Rp and Rq are as defined earlier)}. Unless otherwise constrained by the definition, all substituents may be substituted further by 1-3 substituents selected from alkyl, carboxy, carboxyalkyl, -NRpRq, -C(=O)NRpRq. -O-C(=O)NRpRq (wherein Rp and Rq are the same as defined earlier) hydroxy, alkoxy, halogen, CF^, cyano, and S(O)mR66 (wherein m is an integer from 0-2 and R66 is same as defined earlier); or an alkyl group as defined above that has both substituents as defined above and is also interrupted by 1-5 atoms or groups as defined above. As used herein the term "alkylene" refers a divalent group derived from a straight or branched chain saturated hydrocarbon having from 1 to 20 carbon atoms by the removal of two hydrogen atoms, for example, methylene, 1,2 ethylene and the like. The term "alkenyl," unless otherwise, specified, refers to a monoradical of a branched or unbranched unsaturated hydrocarbon group having from 2 to 20 carbon atoms with cis, trans, or geminal geometry. It can be optionally interrupted by atom(s) or group(s) independently chosen from oxygen, sulfur, phenylene, sulphinyl, sulphonyl and -NRb-, wherein Rh can be hydrogen, alkyl. alkenyl, alkynyl, cycloalkyl or aryl. In the event that alkenyl is attached to a heteroatom, the double bond cannot be alpha to the heteroatom. Alkenyl groups may be substituted further (referred to herein as "substituted alkenyl") with one or more substituents selected from alkyl, alkenyl, alkynyl, alkoxy, cycloalkyl, cycloalkenyl, acyl, acylamino, acyloxy, -NHC(=O)RP, - NRPR(|. -C(=O)NRpRq, -NHC(=O)NRpRq, -O-C(=O)NRpR(] (wherein Rp and Rq are the same as defined earlier), alkoxycarbonylamino, azido, cyano, halogen, hydroxy, oxo, keto, carboxyalkyl, thiocarbonyl, carboxy, arylthio, thiol, alkylthio, aryl, aralkyl, aryloxy, heterocyclyl, heteroaryl, heterocyclyl alkyl, heteroaryl alkyl, aminosulfonyl, aminocarbonylamino, alkoxyamino, hydroxyamino, alkoxyamino, nitro, or SOiRr^ (wherein R&6 are is same as defined earlier). Unless otherwise constrained by the definition, alkenyl substituents optionally may be substituted further by 1-3 substituents selected from alkyl, carboxy, hydroxy, alkoxy, halogen, -CFj. cyano, - NRpRq. -C(=O)NRpRq, -O-C(=O)NRpRq (wherein Rp and Rq are the same as defined earlier) and - SOiR66 (wherein R66 is same as defined earlier). Groups, such as ethenyl or vinyl (CH=CH2), 1- propylene or allyl (-CH2CH=CH2), iso-propylene (-C(CH3)=CH2), bicyclo[2.2.1] heptene, and the like, exemplify this term. The term "alkynyl," unless otherwise specified, refers to a monoradical of an unsaturated hydrocarbon, having from 2 to 20 carbon atoms. It can be optionally interrupted by atom(s) or group(s) independently chosen from oxygen, sulfur, phenylene, sulphinyl, sulphonyl and -NRt,-, wherein Rh can be hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl or aryl. In the event that alkynyl is attached to a heteroatom, the triple bond cannot be alpha to the heteroatom. Alkynyl groups may be substituted further (referred to herein as "substituted alkynyl") with one or more substituents selected from alkyl, alkenyl, alkynyl, alkoxy, cycloalkyl, cycloalkenyl, acyl, acylamino. acyloxy, alkoxycarbonylamino, azido, cyano, halogen, hydroxy, keto, oxo, thiocarbonyl. carboxy, carboxyalkyl, arylthio, thiol, alkylthio, aryl, aralkyl. aryloxy, aminosulfonyl. aminocarbonylamino, hydroxyamino, alkoxyamino, nitro, heterocyclyl. heteroaryl. heterocyclylalkyl. heteroarylalkyl, -NHC(=O)RP. -NRpRq, -NHC(-O)NRPR