Promotion effect of ButOK on the reaction of bromolithiocarbenoids at low temperatures
Abstract
Lithium carbenoids prepared from 7,7-dibromonorcarane or (2,3-benzocyclohex-2-en-1-ylidene)dichloromethane with butyl-lithium at –85 °C were unreactive at this temperature in tetrahydrofuran (THF) but reacted rapidly with the addition of a stoicheiometric amount of ButOK to give the insertion product with THF, or the addition product with cyclohexane in high yields.