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.
Highly Enantioselective Kinetic Resolution of Michael Adducts through N-Heterocyclic Carbene Catalysis: An Efficient Asymmetric Route to Cyclohexenes
A highly efficient strategy for the kinetic resolution of Michael adducts was realized using a chiral N‐heterocyclic carbene catalyst. The kinetic resolution provides a new convenient route to single diastereomers of cyclohexenes and Michael adducts in good yields with high enantiomeric excesses (up to 99 % ee with a selectivity factor of up to 458). This “two flies with one swat” concept allows the