Microwave-Assisted Organocatalytic Enantioselective Intramolecular aza-Michael Reaction with α,β-Unsaturated Ketones
摘要:
AbstractAn organocatalytic enantioselective intramolecular aza‐Michael reaction of carbamates bearing conjugated ketones as Michael acceptors is described. By using 9‐amino‐9‐deoxy‐epi‐hydroquinine as the catalyst and pentafluoropropionic acid as a co‐catalyst, a series of piperidines, pyrrolidines, and the corresponding benzo‐fused derivatives (indolines, isoindolines, tetrahydroquinolines, and tetrahydroisoquinolines) can be obtained in excellent yields and enantioselectivities. In addition, the use of microwave irradiation at 60 °C improves the efficiency of the process giving rise to the final products with comparable yields and enantiomeric excesses. Some mechanistic insights are also considered.
Enantioselective Synthesis of Piperidines through the Formation of Chiral Mixed Phosphoric Acid Acetals: Experimental and Theoretical Studies
作者:Zhankui Sun、Grace A. Winschel、Paul M. Zimmerman、Pavel Nagorny
DOI:10.1002/anie.201405128
日期:2014.10.13
of unsaturated acetals has been utilized for the synthesis of functionalized chiral piperidines. The chiral enol ether products of these cyclizations undergo subsequent in situ enantioenrichment through acetalization of the minor enantiomer. A new computational reaction exploration method was utilized to elucidate the mechanism and stereoselectivity of this transformation. Rather than confirming the