Asymmetric synthesis of spiro[chroman-3, 3′-pyrazol] scaffolds with an all-carbon quaternary stereocenter via a oxa-Michael–Michael cascade strategy with bifunctional amine-thiourea organocatalysts. Issue 111 (29th October 2015)

• Record Type: Journal Article
• Authors: Zheng, Weiping; Zhang, Jiayong; Liu, Shuang; Yu, Chengbin; Miao, Zhiwei
• Is Part Of: RSC advances. Volume 5:Issue 111(2015)
• Page Start: 91108
• Page End: 91113
• Publication Date: 2015-10-29
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c5ra17792h
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : The chiral spiro[chroman-3, 3′-pyrazol] derivatives have been synthesized through a catalytic oxa-Michael–Michael cascade reaction of 2-hydroxynitrostyrenes with 4-alkenyl pyrazolin-3-ones in good yields with moderate to high stereoselectivities. Abstract : An efficient chiral bifunctional amine-thiourea catalysed cascade oxa-Michael–Michael addition of 4-alkenyl pyrazolin-3-ones to ( E )-2-(2-nitrovinyl)phenol for the synthesis of chiral heterocyclic systems containing spiro[chroman-3, 3′-pyrazol] scaffolds has been developed. This reaction afforded the desired products in high to excellent yields (up to 98%) with moderate to high enantioselectivities (up to 99%) and diastereoselectivities (up to 20 : 1) under low catalyst (15 mol%) concentration. This catalytic asymmetric reaction provides an efficient route toward the synthesis of chiral spiro[chroman-3, 3′-pyrazol] derivatives containing three contiguous stereocenters which possess potential pharmaceutical activities.