CARBON-CARBON BOND FORMATION BY USE OF ORGANOZIRCONIUM COMPLEX UNDER TRANSITION-METAL CATALYST

有机茂锆氯化物配合物是一种弱亲核试剂，在过渡金属催化条件下表现出较强的亲核性。在Rh（I）催化下，烯基二茂锆氯化物与α，β-不饱和羰基化合物发生1，4-加成反应。将反应扩展到含有手性酰胺类助剂的α，β-不饱和化合物，发现产物具有高的非对映选择性，因此是光学纯的。酰基二茂锆氯化物配合物，这已被我们确定为一个酰基阴离子供体，进一步显示出有用的碳环化合物的形成。因此，在钯催化下，酰基二茂锆氯化物与ω-烯基或ω-炔基α，β-烯酮反应，立体选择性地得到了双环[3.3.0]化合物。有趣的是，不含α，β-烯酮官能团的α，ω-不饱和化合物在Ni催化剂的催化下反应生成双环[3.1.0]化合物，对二氯二茂锆与正丁基锂反应生成低价茂锆配合物的化学研究表明，低价茂锆与邻烷氧基甲基苯乙烯反应生成苄型茂锆配合物是有效的。在铜催化剂的存在下，由由此生成的二茂锆配合物形成碳-碳键，从而通过我们的二茂锆/金属催化剂化学有效地生成用于制备雌酮的重要中间体。因此，我们继续有机二茂锆化学以发现新的和稀有的碳-碳形成反应。

Organozirconocene chloride complex, which is known to be a poor nucleophile, showed the enhanced nucleophilicity under transition-metal catalyzed conditions. Thus, alkenylzirconocene chloride complex reacted with α,β-unsaturated carbonyl compounds to give 1,4-addition products in the presence of Rh(I) catalyst. The reaction was extended to α,β-unsaturated compounds, which have a chiral amides auxiliary, and we found that the product was obtained in high diastereoselectivity, thus in optically pure state. Acylzirconocene chloride complex, which has been established as an acyl anion donor by us, showed further usefulness for the formation of carbocyclic compounds. Thus, the Pd-catalyzed reactions of acylzirconocene chlorides with co-alkenyl or-alkynyl α,β-enones afforded bicyclo[3.3.0]compounds, stereoselectively. Interestingly, the reaction of α,w-unsaturated compounds, which possess no α,β-enone functionality, was catalyzed by Ni catalyst to give bicylo[3.1.0] compounds.The continuing study on the chemistry of low valent zirconocene complex, which can be generated by treating zirconocene dichloride with n-BuLi, indicated that an efficient formation of benzylic zirconocene complex by treating o-alkoxymethl styrene with low valent zirconocene. Formation of carbon-carbon bond from thus generated zirconocene complex was carried out in the presence of Cu catalyst, and thus the important intermediate for the preparation of estrone was efficiently generated by our zirconocene/metal catalyst chemistry.Elucidations on the nucleophilic reactivity and the synthetic application of organozirconocene complex are our current very active research project, thus we continue the organozirconocene chemistry to find a new and noble carbon-carbon forming reaction.