Enantioselective construction of novel chiral spirooxindoles incorporating a thiazole nucleus

Abstract

Asymmetric cascade Michael/cyclization reaction between 2-substituted thiazol-4-ones and 2-(2-oxoindolin-3-ylidene)malononitriles was investigated using a series of chiral bifunctional hydrogen-bonding organocatalysts. Good yields (up to 91%) and excellent enantioselectivities (up to 98% ee) were achieved by using a (1R,2R)-1,2-diphenylethane-1,2-diamine derived thiourea catalyst. This method provides an elegant synthetic route to access novel thiazole-fused spirooxindoles with potential bioactivity.