Asymmetric Synthesis based on Carbonyl-Ene Reaction

本工作的目的是发展基于羰基-烯反应的不对称合成新方法。（1）内不对称诱导研究发现，羰基烯与氟醛反应生成赤型三氟甲基氰醇离子的选择性大于90%。(2)相对不对称诱导羰基-烯与b-氨基醛的反应表现出大于99%的非对映选择性。此外，用非手性取代的烯组分的反应仅提供单一的区域异构体（>99%区域选择性）。(3)对映体选择性诱导手性（修饰）联萘酚衍生的钛配合物与前手性羰基亲烯体如乙醛酸、氟醛和共轭炔醛催化羰基烯的不对称反应，发现对映体过量超过95%。此外，不对称催化的羰基-烯反应即使在非前手性亲烯体如甲醛的存在下也能提供高水平的不对称诱导。

The purpose of this work is to develop the new method for asymmetric synthesis based on carbonyl-ene reaction. A summary of the research results is as follow :(1) Internal Asymmetric InductionThe carbonyl-ene reaction with fluoral is found to afford the erythro-trifluoromethylcsarbinol ion more thasn 90% selectivity.(2) Relative Asymmetric inductionThe carbonyl-ene reaction with b-amino aldehyde is found to exhgiobit the-diastereofacial selectivity in more than 99% selectivity. Furthermore, the reavcti0n with un-symmetricallyt substituted ene component provides only sngle regioisomer (>99% regioselectivity).(3) Enantiofacial Selective InductionThe asymmetric catalysis of carnbonyl-ene reaction catalyzed by chiral (modified) binaphthol-derived titanium complexes with prochiral carbonyl enophiles such as glyoxylate, fluoral, and conjugate ynals is found to give more than 95% enantiomeric excesses. Furthermore, the asymmetric catalytic carbonyl-ene reaction even with non-prochiral enophile such as formaldehyde afford the high levle of asymmetric induction.