手性噁唑硼烷酮催化不对称Aldol反应的研究

THE STUDY OF ASYMMETRIC ALDOL REACTION CATALYZED BY CHIRAL OXAZABOROLIDINONE DERIVED FROM D-PHENYLGLYCINE

以廉价易得的手性氨基酸为原料合成了一系列氮磺酰化氨基酸配体 ,并将之与硼烷原位制备成手性口恶唑硼烷酮催化苯甲醛与烯醇硅醚的不对称Aldol反应 ,获得了较好的效果。对各种影响反应结果的因素进行了讨论 ,并对其不对称诱导机理进行了探讨。结果表明D 苯基甘氨酸衍生的手性口恶唑硼烷酮催化剂对这种反应的催化效能明显好于L 缬氨酸、L 亮氨酸、L 异亮氨酸等其它脂肪侧链氨基酸衍生的口恶唑硼烷酮催化剂。其所得产物的化学产率和ee值分别为 38.7%和 81.7%

A series of Ts amino acids derived from cheap and easy got amino acids were synthesized.They were used to prepare chiral oxazaborolidine in situ with borane and catalyze asymmetric Aldol reaction between benzaldehyde and silyl enol ether.Some good results were achieved.The factors which may affect the results of the reaction and the mechanism of the asymmetric induction were discussed.The results indicated that the catalytic efficiency of the oxazaborolidine derived from D phenylglycine is much higher than the ones derived from natural amino acids which have aliphatic side chains such as L valine,L leucine,L isoleucine.The chemical yield and ee value of this reaction were 38.7% and 81.7% respectively when it was catalyzed by 5a.