Activation of Olefins with Polarity Inversion and Its Synthetic Application

在碳-碳不饱和键上引入官能团的反应作为构筑有机分子的有效方法，已广泛应用于有机合成中。作为这种转化的一种方法，已经开发了许多使用过渡金属催化剂的反应，但是在许多情况下使用后过渡金属催化剂。利用前过渡金属配合物的特性开发新的催化反应是当前研究的主要目标。在格氏试剂存在下，使用催化量的二氯化二茂锆，通过与氯硅烷反应，使末端烯烃进行甲硅烷基化，得到作为产物的烯基和/或烯丙基硅烷。当使用甲硅烷基硫化物、甲硅烷基硒化物和甲硅烷基碲化物代替氯硅烷时，反应也在温和条件下进行。作为该反应的延伸，以茂锆配合物为催化剂，发展了一种新的芳基烯烃的区域选择性烷基化反应。当使用二茂钛催化剂进行反应时，芳基烯烃在THF中进行双烷基化，得到1，2-vic-二烷基化产物。另一方面，芳基烯烃与烷基溴的Heck型转化在醚中在类似条件下进行。还开发了1，3-丁二烯与氯硅烷和/或烷基溴的甲硅烷基化和双甲硅烷基化。该反应在温和条件下通过使用二茂钛催化剂在1，4-BuMgCl存在下进行<11>，产生1，4-甲硅烷基化或1，4-双甲硅烷基化的2-丁烯。芳基取代的烯烃在类似条件下也得到1，2-甲硅烷基化或1，2-双甲硅烷基化产物。

The reactions which introduce functionalities to carbon-carbon unsaturated bonds have been widely used for organic syntheses as useful methods for the construction of organic molecules. As one methodology for such transformations, there have been developed a number of reactions using a transition metal catalyst, but in many cases the late transition metal catalysts have been employed. The main object of the present studies is to develop new catalytic reactions using the characteristics of early transition metal ate complexes. Terminal alkenes undergo silylation by the reaction with chlorosilanes in the presence of a Grignard reagent employing a catalytic amount of zirconocene dichloride to give alkenyl and/or allylsilanes as the products. The reaction also proceeds under mild conditions when silyl sulfides, silyl selenides, and silyl tellurides are used in place of chlorosilanes. As an extension of this reaction, a new transformation of aryl alkenes via regioselective alkylation using alkyl tosylates, sulfates and bromides having a β-hydrogen has been developed using a zirconocene complex as the catalyst. When the reaction was carried out using tianocene catalyst, double alkylation of aryl alkenes proceeds in THF to give 1,2-vic-dialkylated products. On the other hand, Heck type transformation of aryl alkenes with alkyl bromides proceeds in ether under similar conditions. Carbosilylation and double silylation of 1,3-butadienes with chlorosilanes and/or alkyl bromides were also developed. This reaction proceeds under mild conditions by the use of titanocene catalyst in the presence of ^<11>BuMgCl giving rise to 1,4-carbosilylated or 1,4-double silylated 2-butenes. Aryl substituted alkenes also afford 1,2-carbosilylated or 1,2-double silylated products under similar conditions.