<i>C</i><sub>2</sub>-Symmetric Chiral Bisoxazolines as Hydrogen-Bond-Acceptor Catalysts in Enantioselective Aldol Reaction of β-Carbonyl Acids with Trifluoroacetaldehyde Hemiacetals
作者:Zhen-Yan Yang、Jun-Liang Zeng、Nan Ren、Wei Meng、Jing Nie、Jun-An Ma
DOI:10.1021/acs.orglett.6b03256
日期:2016.12.16
C2-symmetric chiral bisoxazoline is demonstrated to use hydrogen bonding to catalyze an important family of aldolreactions of trifluoroacetaldehyde hemiacetals with various β-carbonyl acids. This reaction is highly enantioselective, delivering chiral nonracemic trifluoromethylated alcohols with excellent optical purity and good isolated yields. This concept of relaying chiral information via a chiral hydrogen-bond
Organocatalytic asymmetric synthesis of β,β-diaryl ketones <i>via</i> one-pot tandem dehydration/1,6-addition/decarboxylation transformation of β-keto acids and 4-hydroxybenzyl alcohols
作者:Jia-Pan Niu、Jing Nie、Shen Li、Jun-An Ma
DOI:10.1039/d0cc02213f
日期:——
Herein we describe an organocatalytic protocol for the asymmetric synthesis of β,β-diaryl ketones. Under the catalysis of a chiral phosphoric acid, 4-hydroxybenzyl alcohols underwent dehydration to form para-quinone methides, which reacted with β-ketoacids in 1,6-addition reactions. Upon treatment with Et3N in one-pot, decarboxylation proceeded to provide the desired chiral ketones in nearly quantitative