Yield:175277-84-6 76%

Reaction Conditions:

Stage #1: 4-methoxy-3-nitro-benzoic acid amidewith Lawessons reagent in tetrahydrofuran;1,2-dimethoxyethane at 50; for 2 h;
Stage #2: with sodium hydrogencarbonate in tetrahydrofuran;1,2-dimethoxyethane at 20; for 1 h;

Steps:

Lawesson's reagent was added to a stirring mixture of 4-methoxy-3-nitrobenzamide in dimethoxyethane-THF 2:1. The reaction was stirred at 50° C. for 2 h and when completed sodium bicarbonate was added and the mixture was stirred at rt for 1 h. The solvents were removed under reduced pressure and the oily residue was slowly added to a stirring mixture of water and crushed ice (300 mL). The milky mixture was heated to boil and then left to cool to rt. resulting in yellow crystals. (0.9 g, 76% yield).

References:

US2012/316148,2012,A1 Location in patent:Page/Page column 193; 194; 195