Synthesis of 5-methylene-1,3-cyclohexadienes (o-isotoluenes) via electrocyclization of (4Z)-1,2,4,6-heptatetraenes

Article abstract of DOI:10.1016/0040-4039(96)00774-5

Treatment of alkenyldicyclohexylborane 5 with 1-lithio-3,4-pentadien-1- ynes derived from 10 followed by trimethyltin chloride and acetic acid furnished o-isotoluenes 13 in a single operation. The reaction proceeded through an initial formation of diene-allenes 11, which underwent facile electrocyclizations to produce 12 leading to o-isotoluenes 13.