developed. A variety of eight-membered cyclic ethers with two contiguous tertiary stereocenters were obtained in high yields with excellent stereoselectivities. This reaction not only provides a new strategy for constructing enantioenriched eight-membered cyclic ethers but also demonstrates the practicability of ynones as C4-syntons for the synthesis of chiral medium-membered rings.
An efficient bifunctional squaramide-catalyzed Michael addition/cyclization reaction of o-quinone methidesgenerated in situ from 2-(1-tosylalkyl)phenols with active methylene compounds bearing a cyano group has been realized to synthesize chiral 2-amino-4H-chromenes with excellent enantioselectivities and broad substrate scope.
A novel and efficient method for the generation of o-quinone methide intermediates was developed from the readily available 2-tosylalkylphenols under the mildbasicconditions, and their reactions with sulfur ylides were investigated for the stereoselective synthesis of trans-2,3-dihydrobenzofurans.
Bifunctional Amine-Squaramide Catalyzed Friedel-Crafts Alkylation Based on<i>ortho</i>-Quinone Methides in Oil-Water Phases: Enantioselective Synthesis of Triarylmethanes
An efficient enantioselective Friedel–Crafts alkylation reaction of electron‐rich β‐naphthol with in situ generated ortho‐quinone methides catalyzed by chiral bifunctional amine‐squaramide catalysts has been developed. The chiral triarylmethane derivatives were obtained in good to high yields (up to 97% yield) with high enantioselectivities (up to 97% ee) for most substrates under mild conditions.
A Concise Synthesis of 2-(2-Hydroxyphenyl)acetonitriles<i>via</i>the<i>o</i>-Quinone Methides Generated from 2-(1-Tosylalkyl)phenols
作者:Bo Wu、Xiang Gao、Mu-Wang Chen、Yong-Gui Zhou
DOI:10.1002/cjoc.201400463
日期:2014.10
A concise synthesis of 2‐(2‐hydroxyphenyl)acetonitriles has been developed through reaction of trimethylsilyl cyanide and the o‐quinone methides in situ generatedfrom 2‐(1‐tosylalkyl)phenols under basic conditions. In addition, 2‐(2‐hydroxyphenyl)acetonitriles could be conveniently transformed to benzofuranones.