Regiocontrolled synthesis of ring-fused thieno[2,3-c]pyrazoles through 1,3-dipolar cycloaddition of nitrile imines with sulfur-based acetylenes

Article abstract of DOI:10.1002/ejoc.201001048

1,3-Dipolar cycloadditions of C-carboxymethyl-N-arylnitrile imines with substituted acetylenes bearing thiol or sulfone groups were studied. The sulfur controls the regiochemistry of the reaction, and this protocol was applied to the synthesis of ring-fus