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, 1H, 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 1 N 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