Regiocontrolled Synthesis of Ring‐Fused Thieno[2,3‐<i>c</i>]pyrazoles through 1,3‐Dipolar Cycloaddition of Nitrile Imines with Sulfur‐Based Acetylenes

Abstract

Abstract 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‐fused thieno[2,3‐ c ]pyrazoles.