A Fit-for-Purpose Synthesis of a Chiral Oxa-azaspiro Building Block

A seven-step enantioselective route for the synthesis of benzyl ( R )-10-oxo-2-oxa-7-azaspiro[4.5]decane-7-carboxylate ( 1 ) with >99% ee is reported on a multi-hundred-gram scale in 42% overall yield. The synthesis features an asymmetric allylic alkylation to establish the quaternary stereocenter on a piperidine ring, followed by an oxidation/reduction and Mitsunobu conditions sequence to construct the tetrahydrofuran ring within the chiral oxa-azaspirocycle.