Nitromethane → methyl [5-chloro-3-(nitromethyl)-2-oxo-2,3-dihydro-1H-indol-3-yl](cyano)acetate

Participants

Reaction Steps

A suspension of methyl (2Z)-(5-chloro-2-oxo-1,2-dihydro-3H-indol-3-ylidene)(cyano)acetate, intermediate 1 (10.000 g; 38.1 mmol) in dry nitromethane (61 ml; 1.14 mol) was treated with piperidine (189 μl; 1.90 mmol). After stirring for 3 hours, the mixture was diluted with ethyl acetate and filtered through silica. Evaporation of the solvent gave methyl [5-chloro-3-(nitromethyl)-2-oxo-2,3-dihydro-1H-indol-3-yl](cyano)acetate as an oil (9.1 g, 73.8%). This was a mixture of diastereomers which was sufficiently pure for subsequent reaction (HPLC purity 97%). MS (ESI+): 324.2; MS (ESI−): 322.2

Provenance & Evidence