新型卡宾配体的合成及其在烯丙基烷基化催化反应中的应用

The synthesis of carbene ligands and the application for allylic alkylation reaction

以L-苯丙氨醇为起始原料,经过氨基的氯乙酰基化、与苯并咪唑偶联和噁唑啉构筑等3步反应成功实现了中间体4的合成,总收率达到56.3%,并首次确定了中间体4的绝对构型.最后以乙腈为溶剂,用6种卤代芳烃在不同反应条件下较高产率地合成了5个具有单噁唑啉环和1个具有双噁唑啉环的新型目标配体(5a-5f),最高收率为87.7%,其中双噁唑啉环配体结构具有1个C2轴,此结构是当今此类配体研究的热点.同时,应用所设计的配体催化烯丙基烷基化反应,在最优配体和最优条件下,以1,3-二苯基-2-烯丙基乙酸酯作为底物的反应,配体5a使得反应收到了较好的催化效果,最优收率为73.5%.

A new class of benzimidazole carbine ligands containing oxazoline have been synthesized u- sing L-phenylalaninol as starting materials. In the synthesis,the protection of amino group,the cross- coupling with benzimidazole and the construction of oxazoline were operated. The key intermediate 4 was successfully achieved,in which the yields were 56.3 %. It is the first time to identify the absolute structure of 4. Six new target ligands were successfully synthesized in high yield and the different ar- yl halogenation were used in different temperature conditions. The highest yield reached 87.7%. In the six ligands, there are five compounds with a single oxazoline ring and one compound with a doub- le-oxazoline ring. The ligand with two-oxazoline ring has a C2 axis which was the hotspot in catalytic field. In the application of the designed ligands for the catalytic reaction,the ligands were used in al- lylic alkylation reaction. In the reaction,when 1,3-diphenyl-2-allyl acetate were the substrate,ligand 5a had the optimal yield of 73.5 %.