Expedient synthesis of nitrovinyl substituted bicyclo[2.2.2]octenone scaffolds

Abstract

A simple and rapid oxidative acetalization and Diels–Alder protocol of nitrovinyl substituted guaiacols has been developed to synthesize nitrovinyl-bearing bicyclo[2.2.2]octenone derivatives. The electron-deficient nature of the in situ generated ortho-quinone monoketals renders [4 + 2] cycloaddition facile with electron-rich and conjugative dienophiles. The 4-alkenyl masked o-benzoquinone is relatively more reactive than its 3-alkenyl counterpart. The 3-alkenyl masked o-benzoquinone undergoes dimerization partially even in the presence of an external dienophile.