ASYMMETRIC ALLYLATION REACTION OF IMINES WITH CHIRALLY MODIFIED ALLYLMETALS

尽管通过有机金属试剂的亲核加成反应合成光学活性胺的不对称合成是当前的研究热点，但与记录在案的不对称加成羰基化合物相比，烯丙基金属与C=N双键的不对称加成反应还很不发达。本研究项目旨在设计亚胺的不对称烯丙基离子反应，我们发现N-金属亚胺，如N-硅基、N-铝和N-溴亚胺与烯丙基硼试剂进行烯丙化反应，以较高的产率得到相应的高烯丙基胺。从高烯丙基胺中脱除N-取代基相当容易。因此，该方法是合成光学活性伯烯丙基胺的一种新的有效方法。例如，N-水飞蓟亚胺与手性改性烯丙基硼试剂对映体选择性地进行了反应，得到了几乎定量的高烯丙基胺，对映体选择性很高(&gt；90%ee)。据我们所知，这个…首次报道了烯丙基硼试剂对亚胺的不对称诱导。尽管烯醇化醛衍生的N-水飞蓟亚胺与烯丙基离子形成络合物，但含有α-质子的N-铝亚胺可以烯丙化得到高烯丙基胺。在N-铝亚胺和N-硼基亚胺的对映选择性烯丙化反应中，高烯丙基胺以较高的选择性得到了对映体丰富的高烯丙基胺。值得注意的是，即使在室温下，当这些亚胺发生烯丙化反应时，也能获得很高的对映体选择性(&gt；80%ee)。聚合物支载的手性试剂和催化剂在不对称合成领域具有重要意义，因为这些手性试剂可以多次循环使用。在某些情况下，使用聚合物支载的手性催化剂可以实现连续流动体系。我们制备了聚合物支载的手性改性烯丙基硼试剂。研究了上述N-金属亚胺与聚合物支载试剂的不对称烯丙化反应。由D-樟脑或去甲麻黄碱衍生的聚合物负载N-磺酰氨基醇是非常适合于亚胺烯丙化反应的手性配体。尽管使用这种聚合物进行多相反应，但仍获得了足够的反应活性和较高的对映体选择性。这也是首次发现使用聚合物试剂对亚胺的对映选择性烯丙基化反应。较少

Although the enantioselective synthesis of optically active amines by nucleophilic addition of organometallic reagents is a topic of current interest, the enantioselective addition of allylmetals to C=N double bond is quite underdeveloped in comparison to the effort on record in the area of asymmetric addition to carbonyl compounds. This research project aimed at design of asymmeric allylat ion reaction of imines, We have found that N-metallo imines such as N-silyl, N-aluminum, and N-borylimines were allylated with allylboron reagents to give the corresponding homoallylamines in good yield. Removal of N-substituents from the homoallylamines were quite easy. This approach is thus a novel efficient method for the synthesis of optically active primary homoallylamines. For example, N-silylimines were enantioselectively allylated with chirally modified allylboron reagent to give the homoallylamines in almost quantitative yield with high enantioselectivity (> 90% ee). To our knowledge, this … More is the first report of high level of asymmetric induction realized in the enantioselective addition of allylboron reagent to imines. Although N-silylimines derived from enolizable aldehydes resulted in the formation of complexed mixture as the product of allylat ion, N-alumino imines having alpha-proton could be allylated to give the homoallylamine. In the cases of the enantioselective allylation of N-alumino imines and N-boryl imines afforded the enantioenriched homoallylamines in good yield with high selectviity. It is noteworthy that high enantioselectivty (>80% ee) was attained even at room temperature when these imines were allylated.Polymer-supported chiral reagents and catalysts are of interest in the field of asymmetric synthesis, since the chiral reagents can be recycled many times. In some cases, continuous flow system is possible by using polymer-suppored chiral catalyst. We have prepared polymer- supported chirally modified allylboron reagents. Asymmetric allylation of N-metallo imines described above with the polymer-supported reagents have been investigated. Polymer- supported N-sulfonylaminoalcohols derived from D-camphor or norephedrine were quite suitable chiral ligands for the allylation of imines. In spite of heterogeneous reaction using such polymers, sufficient reactivity and high enantioselelctivity was attained. This is also the first finding of the enantioselective allylation of imines using polymeric reagent. Less