The cobalt-catalysed 1,4-hydrovinylation of an aryl-substituted 1,3,5-hexatriene was investigated on a large scale for the synthesis of a double-skipped 1,4,7-triene product. The reaction proceeds via a regioselective C–H activation of the alkene and the exclusive formation of the 4Z-double bond. The cobalt-catalysed 1,4-hexatrienylation of a butadiene derivative led exclusively to the desired all-E tetraene product. Finally, the cobalt-catalysed Diels–Alder reaction with trimethylsilyl-substituted alkynes was investigated. The cycloadducts were generated with excellent chemo- and regioselectivity to give the corresponding stilbene derivative.
Key words
alkenes - alkynes - cobalt - 1,3-dienes - Diels–Alder reaction - 1,3,5-hexatrienes - 1,4-hydrovinylation