Phosgene → 7-(Pyridin-4-yl)-2H-3,1-benzoxazine-2,4(1H)-dione

Participants

Reaction Steps

It was found that the 2-nitro-4-(4-pyridinyl)benzoic acid prepared in the preceding examples could be converted to 1-ethyl-1,4-dihydro-4-oxo-7-pyridinyl-3-quinolinecarboxylic acid by (a) reducing it to 2-amino-4-(4-pyridinyl)benzoic acid, (b) reacting the 2-amino-4-(4-pyridinyl)benzoic acid with phosgene to form 4-(4-pyridinyl)isatoic anhydride, (c) alkylating the 4-(4-pyridinyl)isatoic anhydride with ethyl bromide to produce N-ethyl-4-(4-pyridinyl)isatoic anhydride, (d) reacting the N-ethyl-4-(4-pyridinyl)isatoic anhydride with the potassium salt of ethyl formyl acetate to form ethyl 1-ethyl-1,4-dihydro-4-oxo-7-pyridinyl-3-quinolinecarboxylate, and (e) hydrolyzing that ester.

Provenance & Evidence