Flow and Microwave Induced Pellizzari Reactions: Synthesis of Heterocyclic Analogues of the Benzoxazepine Antipsychotic Agents Loxapine and JL-13

Abstract

An expeditious route to fused triazolo-pyrido benzoxazepines has been developed using flow and microwave-mediated cyclization chemistry. A range of substituted aryl hydrazides are coupled with a core chloroimine in good to excellent yield via a Pellizzari type process, producing 1,2,4-triazolo-pyrido [2,3-b] [1,5] benzoxazepines with structural similarity to known antipsychotic agents. Modifications allow for strategically functionalized derivatives, and installation of a fluoro group for use in PET imaging is also demonstrated. Given the affinity of the tricyclic core for 5-HT and dopamine receptors, the derivatives are expected to find utility in CNS research.

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“…This nucleophilic attack on positive center of acetyl chloride derivative causes the internal electron shifting. [38,39] The process of internal electron shifting produces the various intermediates. Finally, the reaction is completed by internal rearrangement and cyclization, which gives the 1,3,4-thiadiazole derivative as product [Figure 12].…”