Stereoselective synthesis of fully substituted ethylenes via an Ag-catalyzed 1,6-nucleophilic addition/annulation cascade

Chem Commun (Camb). 2020 Jul 18;56(56):7749-7752. doi: 10.1039/c9cc10022a. Epub 2020 Jun 17.

Abstract

A catalytic 1,6-nucleophilic addition/annulation cascade was developed for the first time, and used to produce 27 hitherto unreported ethylene-linked 1-naphthol-imidazole pairs with generally good yields and complete stereoselectivity. An Ag2O-catalyzed reaction of yne-allenone esters with tosylmethyl isocyanide proceeded efficiently, and provided a simple and convergent protocol for the synthesis of fully substituted (Z)-ethylenes whereas tetrasubstituted (E)-ethylenes were obtained when ethyl isocyanoacetate was employed in this transformation. The reaction pathway consists of [2+2] cycloaddition, 1,6-nucleophilic addition and [3+2] cycloaddition, leading to continuous multiple bond-forming events including C-C and C-N bonds to construct complex molecules.