Patent ID: 8710226

Claim:
A process for preparation of buprenorphine, represented by formula 1c wherein the process comprises the steps of (a) reacting a compound of formula 2c with ethylchloroformate in presence of an alkali iodide and Lithium carbonate to yield a compound of formula 3c: (b) subjecting the compound of formula 3c to hydrolysis in presence of potassium hydroxide to obtain a compound of formula 4c (c) reacting the compound of formula 4c with a compound of formula 5c in presence of methanesulfonyl chloride and LiBr, to obtain a compound of formula 6c, d) converting the compound of formula 6c to a compound of formula 1c or salt thereof by reacting with potassium tert-butoxide in presence of an C 1-4 alkyl or an arylthiol and optionally reacting with a mineral acid.