'On water' organocatalyzed enantioselective synthesis of highly functionalized cyclohexanones with an all-carbon quaternary centre from allylidene malononitriles and enones

An organocatalyzed endo [4+2] cycloaddition between enones as pro-diene and allylidene malononitrile as dienophile leading to cyclohexanones with two 1,3-related stereogenic centres and an all-carbon quaternary centre has been developed. The reactions were performed under 'green reaction' conditions using water as the reaction medium and ambient conditions. When allylidene cyanoacetate was used as the dienophile, cyclohexanones with three contiguous stereogenic centres, one of which is an all-carbon quaternary centre, were formed. The products were obtained in high yield and with acceptable diastereo-and enantioselectivity. (C) 2016 Elsevier Ltd. All rights reserved.