摘要:
                                [(Trimethylsilyl)ethynyl]-9-BBN undergoes Diels-Alder reactions with acyclic dienes at 100-degrees-C to afford 1,4-cyclohexadienes in high yields. The novel regiochemistry of these reactions is consistent with an ab initio prediction of advanced bonding to boron in a [4 atom + 3 atom transition state.