A chemoenzymatic-RCM strategy for the enantioselective synthesis of new dihydroxylated 5-hydroxymethyl-indolizidines and 6-hydroxymethyl-quinolizidines

A direct method for the synthesis of new azasugars-like compounds has been developed, which involves a new biocatalytic protocol based on the use of a lipase from Candida Cylindracea and of a ionic liquid as reaction medium, to prepare the key C1-symmetric piperidine precursor. By subsequent application of RCM reactions and OsO4-catalyzed double bond syn-dihydroxylation, the synthesis of the target compounds could be accomplished in a straightforward and stereocontrolled manner.