Synthesis of Monoacylated Derivatives of 1,2- Cyclohexanediamine. Evaluation of their Catalytic Activity in the Preparation of Wieland−Miescher Ketone
摘要:
Ureas, carbamoyl derivatives, amides, and sulfonamides can be easily prepared from the strained (R,R)-cylohexanediamine urea (1) in high yield, leaving a free amino group that shows good catalytic activity in intramolecular aldol condensations. The preparation of Wieland-Miescher ketone has been studied with these catalysts.
Chiral amine organocatalysts for the syn-aldol reaction involving substituted benzaldehydes and hydroxyacetone
作者:Dhruba Sarkar、Kurt Harman、Subrata Ghosh、Allan D. Headley
DOI:10.1016/j.tetasy.2011.05.021
日期:2011.5
A new series of cyclohexanediamine organocatalysts that contain the primary amine functionality has been designed, synthesized and tested as catalysts for the asymmetric aldol reaction involving hydroxyacetone and a variety of substituted benzaldehydes. High enantioselectivites and diasteroselectivites were obtained using catalyst la for these reactions. A key step in this reaction for the formation of the syn-product is the formation of a stable intramolecular hydrogen bonded Z-enamine isomer, which in addition to the steric bulk of the catalyst, serve to dictate the course of the stereochemical outcome of the reaction. (C) 2011 Elsevier Ltd. All rights reserved.