Dimethyl sulfide induced [3 + 2] annulation strategy: An efficient synthesis of functionalized dihydropyrazole derivatives using the Baylis-Hillman bromides

Abstract

Baylis-Hlllman bromides have been successfully employed as a valuable source of 1,3-dipoles for cycloaddition onto dialkyl azodicarboxylates (dipolarophiles) under the influence of dimethyl sulfide and potassium carbonate to provide functionalized dihydropyrazole derivatives in a simple one-pot [3 + 2] annulation strategy. © 2008 American Chemical Society.