Patent ID: 8258299

Claim:
A process for preparation of Temsirolimus having a structural formula (1) as below-illustrated: wherein, n=1, the steps comprising: A. acylating the rapamycin (compound 4b) or rapamycin 31-sily ether (compound 4d) with Isopropylidene-2,2-bis(methoxy)propionic acid anhydride (compound 11a) in the presence of organic base to give rapamycin 42-ester of 2,2,5-trialkyl[1,3-dioxane]-5-carboxylic acid (compound 12b) or rapamycin 42-ester of 31-0-trialkylsily ether of 2,2,5-trimethyl[1,3-dioxane]-5-carboxylic acid (compound 12d) and B. treating said rapamycin 42-ester of 2,2,5-trialkyl[1,3-dioxane]-5-carboxylic acid (compound 12b), or said rapamycin 42-ester of 31-0-trialkylsily ether of 2,2,5-trimethyl[1,3-dioxane]-5-carboxylic acid (compound 12d) in a mild acidic condition to obtain Temsirolimus.