Hydrazine → benzyl spiro[1H-chromeno[4,3-c]pyrazole-4,4'-piperidine]-1'-carboxylate

Participants

Reaction Steps

A solution of benzyl 3-(hydroxymethylene)-4-oxo-spiro[chromane-2,4′-piperidine]-1′-carboxylate (1.95 g, 5.10 mmol) and hydrazine (161 μL, 5.10 mmol) in EtOH (39 mL) was stirred at room temperature for 1 hour and then at 50° C. for 3 hours. The reaction mixture was concentrated and the residue was purified by silica gel chromatography (10-100% ethyl acetate in hexane) to afford benzyl 1H-spiro[chromeno-[4,3-c]pyrazole-4,4′-piperidine]-1′-carboxylate (1.11 g, 58%). ESI-MS m/z calc. 375.2. found 376.3 (M+1)+; Retention time: 1.71 minutes (3 min run).

Provenance & Evidence