2-Amino-6-nitro-benzoic acid → 2-methyl-5-nitro-4H-benzo[d][1,3]oxazin-4-one

Participants

Reaction Steps

In yet another embodiment, provided herein is a method for preparing 3-(5-amino-2-methyl-4-oxoquinazolin-3(4H)-yl)piperidine-2,6-dione, or an enantiomer or a mixture of enantiomers thereof; or a pharmaceutically acceptable salt, solvate, hydrate, or polymorph thereof; comprising the steps of (a) reacting 2-amino-6-nitrobenzoic acid with activated acetic acid in a solvent to form 2-methyl-5-nitro-4H-benzo[d][1,3]oxazin-4-one; (b) reacting 2-methyl-5-nitro-4H-benzo[d][1,3]oxazin-4-one with 3-aminopiperidine-2,6-dione or a salt thereof in a solvent in the presence of a coupling reagent to form 3-(2-methyl-5-nitro-4-oxoquinazolin-3(4H)-yl)piperidine-2,6-dione; and (c) reducing 3-(2-methyl-5-nitro-4-oxoquinazolin-3(4H)-yl)piperidine-2,6-dione via transfer hydrogenation in a solvent to form 3-(5-amino-2-methyl-4-oxoquinazolin-3(4H)-yl)piperidine-2,6-dione, or an enantiomer or a mixture of enantiomers thereof; or a pharmaceutically acceptable salt, solvate, hydrate, or polymorph thereof. In one aspect of the embodiment, the molar ratio of the activated acetic acid versus 2-amino-6-nitrobenzoic acid is ranging from about 1 to about 10, from about 1 to about 5, from about 1.5 to about 5, or from about 1.5 to about 2.5; and wherein steps (a), (b), and (c) are each as described herein elsewhere.

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