Catalytic Enantioselective Iodocyclization of γ-Hydroxy-<i>cis</i>-alkenes

Abstract

Enantioselective iodocyclization of gamma-hydroxy-cis-alkenes has been achieved using I2 in the presence of an unprecedented catalyst system generated from (R,R)-t-Bu-salen-Co(II) complex and NCS to produce 2-monosubstituted tetrahydrofurans up to 90% ee. While NCS turned out to be the essential additive, neither (R,R)-salen-Co(II) nor (R,R)-salen-Co(III) by itself is likely to be the active species responsible for the asymmetric intramolecular iodoetherification.