The Michael addition of a chiral amine [(-)- 6] to alpha,beta-unsaturated esters ( 4) was attained and the stereoselectivity was inverted by changing the solvent from diethyl ether to tetrahydrofuran when alpha,beta-unsaturated esters having an aromatic ring at the beta-position were employed. In addition, the chiral auxiliary in the Michael adducts ( 9A) was facilely removed with N-iodosuccinimide
[2.2]Paracyclophane-based carbene–copper catalyst tuned by transannular electronic effects for asymmetric boration
作者:Jianqiang Chen、Wenzeng Duan、Zhen Chen、Manyuan Ma、Chun Song、Yudao Ma
DOI:10.1039/c6ra14404g
日期:——
of planar chiral carbene–copper complexes based on the [2.2]paracyclophane backbone with a pseudo-ortho substitution pattern have been synthesized and applied to asymmetric β-boration of α,β-unsaturatedesters. As a result, transannular electronic effects of the substituent of the chiralcatalyst have significant influence on the catalytic performance. A variety of chiral β-hydroxyl esters were obtained
Multiple contiguous chiralcenters were constructed in one pot using three types of multistep reactions initiated with the Michael addition of N-benzyl-2(R)-methoxy-(+)-10-bornylamide to α,β-unsaturated esters, i.e., asymmetric Michael−aldol reaction, double Michael addition, and double Michael−aldol reaction. The chiral 2-methoxy-10-bornyl group as well as the benzyl group on the amino group of the
A simple synthesis of enantiomerically pure piperidine esters is described, offering a straightforward access to the trans-2,3-disubstituted piperidine skeleton which is present in a broad range of biologically active compounds.