Enantioselective Synthesis of 2,6-cis-Disubstituted Tetrahydropyrans via a Tandem Catalytic Asymmetric Hydrogenation/Oxa-Michael Cyclization: An Efficient Approach to (−)-Centrolobine.

A highly efficient one-pot process via a tandem reaction of catalytic asymmetric hydrogenation and oxa-Michael cyclization for the synthesis of 2,6-cis-disubstituted tetrahydropyrans has been developed (ee up to 99.9%, cis/trans-selectivity up to 99:1). This method provides a concise route to (−)-centrolobine (68.8% yield, three steps). [ABSTRACT FROM AUTHOR]