Tunable Synthesis of Pyrazolo Oxepines, Pyrazolo Thiophenes and 1 H ‐Indazoles Using Alkylation, Aldol Condensation and Thermal Rearrangement

Abstract Base‐mediated alkylation of 1‐alkyl/aryl‐5‐hydroxy/mercapto‐1 H ‐pyrazole‐4‐carbaldehydes with functionalized 3‐bromo‐prop‐1‐enes and 3‐bromo‐1‐(arylsulfonyl)propenes followed by intra‐molecular cyclization afforded regioselective pyrazolo oxepines, pyrazolo thiophenes, and 1 H indazoles respectively, with good to excellent yields. This protocol paves the way for the development of syntheses of interesting biologically active scaffolds.