Steric- and Electronic-Controlled Intramolecular [2 + 2]-Cycloaddition of Cyclohexadienone-Containing 1,7-Enynes
Anandarao Munakala1, Tarun Nallamilli1, Jagadeesh Babu Nanubolu1
1Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
Abstract:
Herein we have developed the silver-catalyzed electronic- and steric-controlled intramolecular formal [2 + 2]-cycloaddition of alkyne-tethered cyclohexadienones. Substrates with electron-rich alkynes and a less hindered quaternary carbon center afford tricyclic fused cyclobutenes through 1,7-enyne cyclization. In contrast, the formation of dihydrofurans was observed from electron-deficient alkynes via proton abstraction/C-O bond cleavage. The synthetic potential of this method was also broadened with a gram-scale reaction and various transformations on cyclobutene.
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