Ethanol → Tert-butyl 5-chlorospiro[indole-3,4'-piperidine]-1'-carboxylate

Participants

Reaction Conditions

Reaction Steps

TFA (2.2 ml, 28 mmol) was added to a stirred solution of tert-butyl 4-formylpiperidine-1-carboxylate (2.00 g, 9.38 mmol), 1-(4-chlorophenyl)hydrazine hydrochloride (1.68 g, 9.38 mmol) and ethanol (0.2 mL) in CHCl3 (200 mL) at about 0° C. The reaction mixture was then stirred at about 50° C. overnight. After cooling, the reaction was quenched by the addition of 10% NH4OH (20 mL) and ice (60 mL). The organic layer was separated. The aqueous layer was extracted with DCM. The combined organic layers were washed with brine, dried over MgSO4, filtered and concentrated to yield tert-butyl 5-chlorospiro[indole-3,4′-piperidine]-1′-carboxylate which was used in the next step without further purification (2.57 g, 85%). LCMS (APCI+) m/z 221, 223 [M+H-Boc]+; Rt=3.67 min.

Provenance & Evidence