Phosgene → Methyl 2-isocyanatobenzoate

Participants

Reaction Steps

Phosgene was bubbled through a solution of 10 g (66 mmol) of methylanthranilate in 15 ml of anhydrous toluene for 2 hours at reflux. Then the solvent was distilled off under reduced pressure to give 11.7 g (100%) of 2-methoxycarbonylphenylisocyanate; NMR (CDCl3) 3.89 (s, 3H, CH3); 7.0-7.63 (m, 3H, phenyl H-3,-4,-5); 8.0 (dd, 1 H, phenyl H-6). This was converted to the title compound, in 34% overall yield, by condensation with an equimolar amount of 2-pyridylcarbinol followed by saponification of the resulting ester with 1N sodium hydroxide and acidification of the reaction mixture to pH 4. The crude product was purified by crystallization from ethyl acetate; melting point =172°-175° C.; NMR (DMSO-d6) 5.2 (s, 2H, methoxy CH2); 6.8-8.8 (m, 9H, aromatic, NH); 10.8 (broad s, 1H, OH).

Provenance & Evidence