The investigation of the reactivity of an α-amido sulfone derived from 2-formyl benzoate under organocatalytic conditions in the presence of acetylacetone allowed the synthesis of a new heterocyclic hybrid isoindolinone-pyrazole with high enantiomeric excess. Dibenzylamine was also used as a nucleophile to afford an isoindolinone with aminal substituent in 3-position in suitable selectivity. The use of Takemoto's bifunctional organocatalyst not only led to observed enantioselectivity but was also important in accomplishing the cyclization step in both cases. Notably, this catalytic system proved to be particularly effective in comparison to widely used phase transfer catalysts.
Keywords: asymmetric synthesis; heterocycles; hybrid molecules; organocatalysis.