Methyl Isocyanate → 1-[4-(2,4-dioxo-4H-benzo[d][1,3]oxazin-1-ylmethyl)-pyridin-2-yl]-3-methyl-urea

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Reaction Steps

To a stirred solution of 1-(2-amino-pyridin-4-ylmethyl)-1H-benzo[d][1,3]oxazine-2,4-dione (7.0 g, see preparation 7b) in pyridine (70 ml) was added isocyanatomethane (5 eq.) over 45 minutes. More isocyanatomethane (in total 20 eq.) was added over time until all starting material had been consumed. The solvent was evaporated under reduced pressure. The remaining solid material washed with EtOAc (50 ml) and gave 1-[4-(2,4-dioxo-4H-benzo[d][1,3]oxazin-1-ylmethyl)-pyridin-2-yl]-3-methyl-urea after drying in vacuo. Step 2: This anhydride intermediate was converted into the title compound by reaction with O-(4-cyanobenzyl)hydroxylamine hydrochloride (see preparation 10), using general procedure 1A. 13C-NMR (DMSO-d6) δ 167.4, 155.3, 153.7, 151.2, 148.5, 146.6, 141.8, 132.6, 132.2, 129.2, 128.0, 118.7, 115.1, 114.7, 112.9, 111.5, 110.8, 109.1, 76.0, 45.2, 25.8.

Provenance & Evidence