The Preparation of Two, Preclinical Amino-quinazolinediones as Antibacterial Agents

This paper describes the synthesis of two amino-quinazolinediones which are potent gyrase/topoisomerase inhibitors and useful as antibacterial agents. The early scale-up work to prepare a chiral side chain on multigram scale and two different amino-quinazolinedione cores is detailed. The enabling synthesis for the side chain employed a previously reported Michael addition of MeNO2 to an enantiomerically enriched δ-amino-enoate and a two-step de-oxygenation of a lactam. Key synthetic steps for core preparation and completion of the amino-quinazolinediones include dianion-promoted cyclization via intramolecular, nucleophilic aromatic substitution, electrophilic amination, nucleophilic aromatic substitution of the side chain to the core, deprotection and isolation of the hydrochloride salt in acceptable yield.