Conjugate Addition of gem-Borazirconocene Alkenes to Michael Acceptors

Article abstract of DOI:10.1016/0040-4039(95)00148-6

gem-Borazirconocenes, 1, readily add across Michael acceptors in the presence of Cu(I)Br*SMe2, to afford 1,4-addition products in good to excellent yilds.In the case of cycloalkenones diastereomers are produced, with the anti product favored.The selectivity with cyclopentenone is high (9:1), while with cyclohexenone it is less (3:1).In the present context, gem-borazirconocene alkanes can be regarded as α-hydroxyl anion equivalents.