Organocatalytic asymmetric [3 + 2] annulation of 1,4-dithiane-2,5-diol with azlactones: access to chiral dihydrothiophen-2(3H)-one derivatives

Abstract

Herein, the first organocatalyst-mediated enantioselective [3 + 2] annulations of 1,4-dithiane-2,5-diol with various azlactones utilizing C4 and C5 reactivity using squaramide as the catalyst in a ring-opening manner have been reported. This protocol provides convenient access to enantioenriched substituted dihydrothiophen-2(3H)-one derivatives. Excellent isolated yields and moderate to good enantioselectivities have been achieved.