Silver-Catalyzed and Base-Mediated Double Cyclization for the Streamlined Synthesis of
Kanokwan Jaithum1, Jumreang Tummatorn1,2, Chatphorn Theppitak2
1Program on Chemical Sciences, Center of Excellence on Environmental Health and Toxicology (EHT), OPS, MHESI, Chulabhorn Graduate Institute, 54 Kamphaeng Phet 6, Laksi, Bangkok, 10210, Thailand.
Abstract:
We report a novel silver-catalyzed and base-mediated double cyclization strategy for the streamlined synthesis of benzo[4,5]imidazo[2,1-b]naphtho[2,3-d]oxazoles from ortho-alkynylarylketones. The transformation proceeds through an initial ketonization step catalyzed by silver trifluoroacetate (AgTFA), generating a reactive 1,5-diketone intermediate, followed by a sequential double cyclization under basic conditions. This method affords a broad range of benzo[4,5]imidazo[2,1-b]naphtho[2,3-d]oxazoles with good functional group tolerance in moderate-to-good yields. Moreover, this methodology also enhances the synthetic utility of ortho-alkynylarylketones, expanding their applicability in constructing diverse fused heterocycles.
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