Triethylamine → Benzyl 1'-methylspiro[indoline-3,4'-piperidine]-1-carboxylate

Participants

Reaction Steps

A solution of 99 g (489 mmol) of 1'-methylspiro(indoline-3,4'-piperidine) (prepared according to Ong, H. H. et al, J. Med. Chem., 1983, 26, 981-986) in 1 L of CH2Cl2 and 82 mL (539 mmol) of Et3N was cooled to 0-5° C. with an ice bath and 77 mL (539 mmol) of benzyl chloroformate was added over 30 min keeping the reaction temperature below 10° C. After stirring for 2 h 19 mL (136 mmol) of Et3N and 15 mL (105 mmol) of benzyl chloroformate were added since the reaction was incomplete and stirred for 2 h. At this time, additional 19 mL (136 mmol) of Et3N and 15 mL (105 mmol) of benzyl chloroformate were added. After 1 h, when a TLC indicated a complete reaction, the solution was concentrated in vacuo and the residue was partitioned between ether and saturated NaHCO3. The layers were separated, the organic layer was washed with saturated NaHCO3 and brine, and dried over MgSO4. The filtrate was concentrated and the residue was chromatographed on 2 kg of silica gel using 1-5% MeOH/CH2Cl2 to obtain 117 g (71%) of 1-benzyloxycarbonyl-1'-methylspiro(indoline-3,4'-piperidine) as a yellow oil.

Provenance & Evidence