A new chiral bicyclic guanidine-catalyzed direct catalytic aldolreaction of 5H-oxazol-4-ones with aldehydes has been developed. The present aldolreaction proceeds smoothly with high enantioselectivity using bicyclic guanidines bearing a hydroxy group at the appropriate position, and various combinations of 5H-oxazol-4-ones and aldehydes are applicable. The method provides synthetically useful alpha
Catalyst-controlled switch of regioselectivity in the asymmetric allylic alkylation of oxazolones with MBHCs
作者:Gongming Zhu、Junxian Yang、Guangjun Bao、Ming Zhang、Jing Li、Yiping Li、Wangsheng Sun、Liang Hong、Rui Wang
DOI:10.1039/c6cc03246j
日期:——
A catalyst-controlled switch of regioselectivity in asymmetric allylicalkylation of oxazolones with MBHCs was described. The proper choice of catalysts could differentiate the SN2'-SN2' and addition-elimination process to yield secondary...
Highly<i>Z</i>-Selective Asymmetric 1,4-Addition Reaction of 5<i>H</i>-Oxazol-4-ones with Alkynyl Carbonyl Compounds Catalyzed by Chiral Guanidines
作者:Tomonori Misaki、Kei Kawano、Takashi Sugimura
DOI:10.1021/ja200283n
日期:2011.4.20
An asymmetric I,4-addition reaction of 5H-oxazol-4-ones with alkynyl carbonyl compounds was developed, and, for the first time, high enantiomeric and geometric control was achieved to afford the thermodynamically unstable Z-isomer predominantly using chiral guanidine catalysts bearing a hydroxy group at the appropriate position. The method provides synthetically useful gamma-butenolide ester bearing a chiral quaternary stereogenic center.