Asymmetric synthesis of spiro[chroman-3,3′-pyrazol] scaffolds with an all-carbon quaternary stereocenter<i>via</i>a oxa-Michael–Michael cascade strategy with bifunctional amine-thiourea organocatalysts

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.