Combined epimerisation and acylation: Meerwein-Ponndorf-Verley-Oppenauer catalysts in action.
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.
Klomp
Dirk
D
Gebouw voor Scheikunde, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands.
Djanashvili
Kristina
K
Svennum
Nina Cianfanelli
NC
Chantapariyavat
Nuttanun
N
Wong
Chung-Sing
CS
Vilela
Filipe
F
Maschmeyer
Thomas
T
Peters
Joop A
JA
Hanefeld
Ulf
U