An efficient and convenient highly enantioselective Michaeladdition of malononitrile to enones has been developed by using quinine as the organocatalyst. The adducts were isolated in excellent yield and high asymmetric induction (up to 95% ee). An easy route to difficultly accessible ester derivatives has been also disclosed.
Chloramphenicol base chemistry. Part 11: 1 chloramphenicol base-derived thiourea-catalyzed enantioselective Michael addition of malononitrile to α , β -unsaturated ketones
The first chloramphenicol base-derived thiourea-catalyzed enantioselective Michael addition of malononitrile to alpha,beta-unsaturated ketones is reported. The Michael adducts were obtained in good to excellent yields (up to 98% yield) and enantioselectivities (up to 94% ee). This reaction has a broad substrate scope to various alpha,beta-unsaturated ketones. With this in mind, this methodology was successfully applied to the synthesis of a chiral piperidone, an advanced building block for dihydropyridinone P2X(7) receptor antagonists. (C) 2017 Published by Elsevier Ltd.