Asymmetric cyclopropanation reactions catalyzed by carbohydrate-based crown ethers

Add time:07/21/2019    Source:sciencedirect.com

Optically active cyclopropane derivatives were prepared by a novel, simple and green approach in high enantioselectivities using monosaccharide-based chiral crown ethers as phase transfer catalysts. The crown ethers having d-glucopyranoside, d-mannopyranoside and d-altropyranoside units proved to be efficient catalyst in a few asymmetric phase transfer cyclopropanation reactions. The Michael-initiated ring closure (MIRC) reactions of diethyl bromomalonate with chalcones took place with complete diastereoselectivity and up to 99% ee. Using benzylidenemalononitrile, 2-arylidenemalononitriles, 2-benzylidene-1,3-indandione, substituted 2-benzylidene-1,3-indandiones, 2-arylidene-1,3-indandiones and 2-benzylidene-1,3-diphenyl-1,3-propanediones enantioselectivities up to 92%, 99%, 54% 93%, 89% and 72%, respectively, were achieved, in the presence of chiral lariat ethers derived from different monosaccharides. The absolute configuration of a cyclopropane diester product was determined by a combined CD spectroscopic and theoretical study.

We also recommend Trading Suppliers and Manufacturers of methyl-13C ether (cas 149228-22-8). Pls Click Website Link as below: cas 149228-22-8 suppliers

Prev:Synthesis and structures of α-lithiated vinyl ethers
Next:Synthesis of 2′,3′-dideoxy-3′-C-(hydroxymethyl)-4′-thiopentofuranosyl nucleosides as potential antiviral agent)