2-((3R,9bS)-5,5-Dioxido-2,3-dihydro-9bH-benzo[4,5]isothiazolo[3,2-b]oxazol-3-yl)-1-phenylethan-1-one

Abstract

A highly efficient method has been developed for preparing 2-((3R,9bS)-5,5-dioxido-2,3-dihydro-9bH-benzo[4,5]isothiazolo[3,2-b]oxazol-3-yl)-1-phenylethan-1-one. This enantioenriched title compound was obtained via an organocatalytic asymmetric [3+2]-cycloaddition of benzo[d]isothiazole 1,1-dioxide with (E)-4-hydroxy-1-phenylbut-2-en-1-one, using a bifunctional squaramide-based chiral catalyst. The reaction yielded 99% of the product with high enantioselectivity and diastereoselectivity (89:11 er and >20:1 dr). The structure of the newly synthesized compound was confirmed by 1H-, 13C-NMR, IR and mass spectral data.