金属锌促进羰基化合物水相嚬呐偶合反应

报道了一种简便、有效的水相嚬呐偶合反应。在含有少量季铵盐或季磷盐的氯化铵水溶液中,用金属锌促进羰基化合物进行水相嚬呐偶合反应,其中加入的少量季铵盐或季磷盐有助于显著提高反应产率,嚬呐醇产率由53%提高到87%。但嚬呐偶合反应的产率受羰基周围环境的立体位阻影响较大,在此条件下,金属锌可有效地促进芳香族醛化合物进行水相嚬呐偶合反应,得到产率较高的嚬呐醇,但非对映异构体选择性差,而脂肪族醛化合物得到的嚬呐醇产率较低,在同样条件下,酮类化合物不能顺利进行嚬呐偶合反应。

Coupling Reaction of Carbonyl Compounds Mediated by Zinc in Aqueous Media

A convenient,efficient pinacol coupling of carbonyl compounds mediated by zinc in good yields was carried out in water in the presence of NH4Cl and tiny Bu4NCl or Bu4PBr.It was highly effective to enhance yields of pinacol by adding a small amount of Bu4NCl or Bu4PBr,the yield of pinacol was increased from 53% to 87%,and it was strongly affected by the steric environment surrounding the carbonyl group.The pinacol coupling of aromatic aldehydes was also completed with high yields under above conditions.However,the diastereoselectivities of pinacols were not effective,and the ketones and most aliphatic aldehydes appeared to be inert under the same reaction conditions.