Aurobindo Pharma Limited

Islam Aminul

Sivakumaran Meenakshisunderam

Sukumar Nandi

Sambhu Prasad Sarma Mallela

Shankar Reddy Budidet

Gangadhara Bhima Shankar Nangi

Rani Ananta

Raveendra Reddy Chinta

Balanarasimha Reddy Gona

Naresh Akkina

Mahendar Reddy Nayini

Somappa Somannavar Yallapa

The present invention relates to a process for the preparation of pure Valsartan (I) substantially free from impurities of formulae (Ia), (Ib), and (Ic), which comprises: (i) condensing 2-(4'-bromomethylphenyl)benzonitrile of formula (II) with L-valine methyl ester hydrochloride of formula (V) in the presence of a base in a solvent to produce N-[(2&#x2032;-cyanobiphenyl-4-yl)methyl]-(L)-valine methyl ester of formula (VI); (ii) treating the compound VI of step (i) with acid followed by treating with base to produce pure compound VI substantially free from dimeric impurity of formula (Via); (iii) reacting the pure compound of formula (VI) with n-valeryl chloride in the presence of a base to produce pure N-valeryl-N-[(2&#x2032;-cyanobiphenyl-4-yl)methyl]-(L)-valine methyl ester (VII) substantially free from alkene impurity of formula (Vila); (iv) reacting the compound of formula (VII) with trialkyltin chloride and a metal azide in a solvent at a reflux temperature to produce N-(1-oxopentyl)-N-[[2&#x2032;-(2-tributyltintetrazol-5-yl)-(1,1&#x2032;-biphenyl)-4-yl]methyl]-(L)-valine methyl ester of formula (VHIb) free from thermal degradation impurity (Villa); (v) hydrolyzing the compound of formula (VHIb) in the presence of alkaline conditions to produce Valsartan (I).

Process for the preparation of valsartan

The present invention provides an improved process for the preparation of Dutasteride (I) which comprises: (i) reacting 4-aza-5&#x3b1;-androst-1-en-3-one-17&#x3b2;-carboxylic acid (VII), Formula VII with sulfonic acid anhydride (RSO)O in presence of base to produce an intermediate compound of Formula (XIII), wherein R represents Calkyl, Chalo alkyl, Caryl, halo aryl; (ii) condensing compound of Formula (XIII) with 2,5-bis(trifluoromethyl)aniline (III), Formula (III) in the presence or absence of a base to produce Dutasteride (I). 

Process for the preparation of Dutasteride

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Hyderabad Telangana, India

Islam Aminul