Combined epimerisation and acylation: Meerwein–Ponndorf–Verley–Oppenauer catalysts in action
Dirk Klomp,Kristina Djanashvili,Nina Cianfanelli Svennum,Nuttanun Chantapariyavat,Chung-Sing Wong,Filipe Vilela,Thomas Maschmeyer,Joop A. Peters,Ulf Hanefeld
Organic & Biomolecular Chemistry Pub Date : 12/17/2004 00:00:00 , DOI:
10.1039/B413944EAbstract
A practical racemisation–epimerisation method for chiral secondary alcohols has been developed. Meerwein–Ponndorf–Verley-Oppenauer catalysts such as neodymium(III) isopropoxide are able to racemise these alcohols with retention of other stereocentres in the molecule. This is particularly useful for the recycling of the undesired products of kinetic resolutions of alcohols. By combination of such a racemisation with an acylation using isopropenyl or ethoxyvinyl esters as acyl donors, a fast straightforward recycling of starting materials may be achieved. The combined epimerisation and acylation process is demonstrated for the steroid estradiol methyl ether.