【文章名】Organocatalytic Asymmetric Tandem Michael-Henry Reactions: A Highly Stereoselective Synthesis of Multifunctionalized Cyclohexanes with Two Quaternary Stereocenters.
Organocatalytic Asymmetric Tandem Michael-Henry Reactions: A Highly Stereoselective Synthesis of Multifunctionalized Cyclohexanes with Two Quaternary Stereocenters.
[摘要]：A novel organocatalytic asym. tandem Michael-Henry reaction catalyzed by 9-amino-9-deoxyepiquinine (I) was developed. The reaction was efficiently catalyzed by I to give highly functionalized cyclohexanes with four stereogenic carbons including two quaternary stereocenters in excellent enantioselectivities (97 to >99% ee) and high diastereoselectivities (93:7-99:1 dr). Thus, reaction of MeCOCH2CH2CH(COMe)CO2Et with trans-PhCH:CHNO2 in Et2O contg. 15 mol % I at room temp. for 16 h gave 93% nitrocyclohexanecarboxylate II with 98:2 diastereoselectivity and >99% enantioselectivity. This is the first organocatalytic asym. Henry reaction of common ketones.
