Organocatalytic Domino Michael–Knoevenagel Condensation Reaction for the Synthesis of Optically Active 3‐Diethoxyphosphoryl‐2‐oxocyclohex‐3‐enecarboxylates

Abstract

Versatile dominoes: A novel, organocatalytic, Michael-Knoevenagel condensation domino reaction of ethyl 4-diethoxyphosphoryl-3-oxobutanoate with various aryl- and aliphatic-substituted alpha,beta-unsaturated aldehydes catalyzed by a chiral diarylprolinol ether has been successfully performed. The reaction proceeds in a highly enantio- and diastereoselective manner giving access to optically active 6-substituted-3-diethoxyphosphoryl-2-oxocyclohex-3-enecarboxylates (see scheme).A novel, organocatalytic, highly enantio- and diastereoselective synthetic approach towards optically active 6-substituted-3-diethoxyphosphoryl-2-oxocyclohex-3-enecarboxylates is presented. Our methodology utilizes a Michael-Knoevenagel domino reaction sequence of ethyl 4-diethoxyphosphoryl-3-oxobutanoate and alpha,beta-unsaturated aldehydes catalyzed by a chiral diarylprolinol ether. The cyclohexenecarboxylates obtained are particularly well suited for the preparation of highly functionalized cyclohexene and cyclohexane derivatives, with up to four chiral centers and high levels of stereocontrol.