Development of Highly Efficient Methods for the Construction of Carbon Frameworks Utilizing Titanium-Carbene Complexes

本研究探索了利用二茂钛（II）脱硫制备硫缩醛的钛-碳配合物构建基本碳框架的新方法。钛-羰基配合物的分子间反应羰基配合物与腈的反应是通过氮合基环丁烯的形成而得到收率高的酰化产物。乙烯基羰基配合物与叔卤化物的处理得到乙烯基钛，它与末端炔和醛反应生成相应的加合物。以具有三烷基硅基甲基的1,3-二（苯硫代）丙烯为原料，合成了各种烯丙基硅烷。钛-碳配合物的分子内反应带有碳-碳双键的硫缩醛与二茂钛（II）进行合环复分解反应，生成不饱和环化合物。该反应已成功地应用于环胺、醚、硫化物等杂环化合物的合成。含硅醚部分的不饱和硫缩醛的合环复分解和随后的氧化裂解得到了具有高立体选择性的z - 1,5 -烯烃二醇。结果表明，含硫缩醛部分的酯类和硫酯类是分子内羰基烯化反应的良好底物，可生成多种不饱和环化合物。利用该方法，实现了环酮烯醇醚的区域选择性制备、二氢噻吩的合成以及羧酸转化为邻羟基酮。有机卤化物与二茂钛反应生成有机钛（II）与二茂钛（II）具有末端碳碳双键的宝石二卤化物处理生成双环丙烷。以1,3-二卤化物与二茂钛（II）试剂反应，制备了具有高反式选择性的1,2-二取代环丙烷。少

In this study, new methods for the construction of fundamental carbon frameworks utilizing titanium-carbene complexes, prepared by the desulfurizarion of thioacetals with titanocene(II) species, were explored.1. Intermolecular reactions of titanium-carbene complexesThe reaction of carbene complexes with nitriles proceeded via the formation of azatitariacyclobutene to produce acylation products in good yields. The treatmant of vinylcarbene complexes with tert-halides gave the vinyltitanium species, which reacted with terminal alkynes and aldehydes to produce the corresponding adducts. Various allylsilanes were prepared by the reaction of the carbene complexes generated from 1,3-bis(phenylthio)propenes possessing a trialkylsilylmethyl group.2. Intramolecular reactions of titanium-carbene complexesThioacetals bearing a carbon-carbon double bond afforded the unsaturated cyclic compounds via the ring-closing metathesis process when being treated with titanocene(II) species. This reaction wa … More s successfully applied to the synthesis of various heterocycles such as cyclic amines, ethers, and sulfides. The ring-closing metathesis and subsequent oxidative cleavage of unsaturated thioacetals possessing a silyl ether moiety gave the Z-1 ,5-olefmic diols with high stereoselectivity. It was found that the esters and thiolesters bearing a thioacetal moiety were good substrates for the intramolecular carbonyl olefination giving a variety of unsaturated cyclic compounds. Using this method, regioselective preparation of enol ethers of cyclic ketones, synthesis of dihydrothiophenes, and transformation of carboxylic acids into o-hydroxy ketones have been achieved.3. Reaction of organotitanium species generated from organic halides and titanocene(II)The treatment of gem-dihalides having a terminal carbon-carbon double bond with the titanocene(II) species produced the bicyclic cyclopropanes. The 1,2-disubstituted cyclopropanes were also produced with high trans-selectivity by the reaction of 1,3-dihalides with the titanocene(II) reagent. Less