Mechanism of the lanthanum bromide assisted electrochemical aldolization of .alpha.-bromo ketones
作者:Albert J. Fry、Marko Susla
DOI:10.1021/ja00191a019
日期:1989.4
the aldol 2-benzoyl-1-phenylpropanol by electrochemical reduction of alpha}-bromopropiophenone in the presence of benzaldehyde and lanthanum bromide. The aldol condensation occurs by reaction of the free (lithio) enolate with a lanthanum bromide-benzaldehyde-tetrahydrofuran complex. Electrochemical reduction of the bromo ketone forms the Z enolate highly stereospecifically. The erythro aldol is formed
线性扫描伏安法、各种实验条件下的制备电解和捕获实验已被用于探索在苯甲醛存在下通过电化学还原 α}-溴苯丙酮形成羟醛 2-苯甲酰基-1-苯基丙醇的机制和溴化镧。羟醛缩合通过游离(锂硫)烯醇化物与溴化镧-苯甲醛-四氢呋喃络合物的反应而发生。溴酮的电化学还原形成高度立体定向的 Z 烯醇化物。赤型羟醛最初是立体选择性形成的,但缩合是可逆的,并且主要含有苏式异构体的羟醛的平衡混合物从电解中分离出来。
MILLER, R. D.;FICKES, G. N., J. ORG. CHEM., 1985, 50, N 13, 2375-2377