We Claim:
1. A process for the preparation of Valbenazine tosylate (1) having purity greater than 99.0% by HPLC comprising:
a) reacting 6,7-dimethoxy-3,4-dihydroisoquinoline (10) with 2-acetyl-N,N,N,4-tetramethylpentan-l-aminium iodide (9) to obtain 3-isobutyl-9,10-dimethoxy-3,4,6,7-tetrahydro-lH-pyrido [2,1-a]isoquinoIin-2(llbH)-one (8);
b) reducing 3-isobutyl-9,10-dimethoxy-3,4,6,7-tetrahydro-lH-pyrido [2,l-a]iso quinolin-2(llbH)-one (8) in the presence of a reducing agent to form 3-isobutyl-9,10-dimethoxy-2,3,4,6,7,1 lb-hexahydro-lH-pyrido[2, l-a]isoquinolin-2-ol (7);
c) reacting 3-isobutyl-9,10-dimethoxy-2,3,4,6,7,l lb-hexahydro-lH-pyrido[2,l-a]isoquinolin-2-ol (7) with a chiral resolving agent to form (2R3R1 lbS)-34sobutyl-9,10-dimethoxy-2,3,4,6,7,l lb-hexahydro-1 H-pyrido[2,1 -a] isoquinolin-2-ol S-(+)-camphor sulfonate (6);
d) converting (2R,3R,llbS)-3-isobutyl-9,10-dimethoxy-2,3,4,6,7,llb-hexahydro -lH-pyrido[2,l-a]isoquinolin-2-ol S-(+)-camphor sulfonate (6) to form (2R,3R,llbS)-3-isobutyl-9,10-dimethoxy-2,3,4,6,7,1 lb-hexahydro -lH-pyrido[2,l-a]isoquinolin-2-ol (5) in the presence of a base;

e) reacting (2R3R,llbS)-3-isobutyl-9,10-dimethoxy-2,3,4,6,7,llb-hexahydro-lH-pyrido[2,l-a]isoquinolin-2-ol (5) with (S)-2-(tert-butoxycarbonylamino)-3-methylbutanoic acid (4) in the presence of a coupling agent and an aprotic solvent to form (S)-((2R,3R,1 lbS)-3-isobutyl-9,10-dimethoxy-2,3,4,6,7,llb-hexahydro-lH-pyrido[2,l-a]isoquinolin-2-yl) 2-(tert-butoxy carbonylamino)-3-methylbutanoate (3);
f) deprotecting (S)-((2R,3R,llbS)-3-isobutyl-9,10-dimethoxy-2,3,4,6,7,1 lb-hexahydro-lH-pyrido[2,l-a]isoquinolin-2-yl) 2-(tert-butoxycarbonylamino)-3-methylbutanoate (3) in an aprotic solvent

and in the presence of an acid to form (S)-((2R,3R,1 lbS)-3-isobutyl-9,10-dimethoxy-2,3,4,6,7,llb-hexahydro-lH-pyrido[2,l-a]isoquinolin-2-yl) 2-amino-3-methylbutanoate (2); and g) converting (S)-((2R,3R,llbS)-3-isobutyI-9,10-dimethoxy-2,3,4,6 ,7,1 lb-hexahydro-lH-pyrido[2,l-a]isoquinolin-2-yl) 2-amino-3-meth ylbutanoate (2) to (S)-((2R,3R,llbS)-3-isobutyl-9,10-dimethoxy-2,3,4,6,7,llb-hexahydro-lH-pyrido[2,l-a]isoquinolin-2-yl) 2-amino-3-methylbutanoate di(4-methylbenzenesulfonate) (Valbenazine tosylate) (1) in an aprotic solvent.
2. The process according to claim 1, wherein the reducing agent used in step b) is selected from lithium aluminium hydride, sodium borohydride, lithium borohydride.
3. The process according to claim 1, wherein the chiral resolving agent used in step c) is S- (+)-camphor sulfonic acid.
4. The process according to claim 1, wherein the coupling agent used in step e) is selected from the group comprising of N,N'-Dicyclohexylcarbodiimide (DCC), Diisopropyl carbodiimide (DIC), N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC.HC1), l,l'-Carbonyldiimidazole (CDI).
5. The process according to claim 1, wherein the acid used in step f) is selected from para-toluene sulfonic acid, trifluoroacetic acid, hydrochloric acid.
6. A process for the purification of Valbenazine tosylate (1), which comprises of:

a) providing a solution of Valbenazine tosylate (1) in a solvent;
b) heating to a suitable temperature; and
c) isolating pure Valbenazine tosylate (1).

7. The process according to claim 7, wherein the solvent used in step a) is selected from the group comprising of methanol, ethanol, water, isopropanol and mixtures thereof.
8. A process for the preparation of crystalline form 1 and form 2 of Valbenazine tosylate (1), which comprises of;

a) providing Valbenazine tosylate (1) in a suitable aprotic solvent or mixtures;
b) filtering the reaction mass;
c) cooling the filtrate to a suitable temperature; and
d) isolating and drying crystalline forms of Valbenazine tosylate (1) using a suitable technique.
9. A process for the preparation of crystalline form 3 and form 4 of
Valbenazine tosylate (1), which comprises of;
i. providing Valbenazine tosylate (1) in a suitable aprotic solvent or
mixtures; ii. optionally, providing a solution of Valbenazine tosylate (1) in a
suitable organic acid 25-30 °C; iii. stirring and filtering the reaction mass; iv. adding the filtrate to a suitable pre-cooled aprotic solvent; v. stirring the reaction mass at -60 to -20 °C; vi. optionally, heating the reaction mass to 25-35°C; and vii. isolating and drying crystalline forms of Valbenazine tosylate (1)
using a suitable technique.
10. A process for the preparation of solid dispersions of Valbenazine tosylate
(1) with a suitable excipient, which comprises of;
1. providing Valbenazine tosylate (1) in a suitable protic solvent;
2. adding a suitable pharmaceutically acceptable excipient;
3. optionally, heating the reaction mixture to a suitable temperature;
4. stirring and filtering the reaction mixture; and
5. isolating and drying amorphous solid dispersion of Valbenazine tosylate (1) using a suitable technique