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

本研究探索了利用硫缩醛与二茂钛(II)物质脱硫制备的钛卡宾配合物构建基础碳骨架的新方法。 1．钛-卡宾配合物的分子间反应卡宾配合物与腈的反应通过形成氮杂环丁烯进行，以良好的收率产生酰化产物。用叔卤化物处理乙烯基碳烯配合物得到乙烯基钛物质，其与末端炔烃和醛反应生成相应的加合物。通过由具有三烷基甲硅烷基甲基的1,3-双(苯硫基)丙烯生成的卡宾配合物的反应制备了各种烯丙基硅烷。 2．钛-卡宾配合物的分子内反应带有碳-碳双键的硫缩醛在用二茂钛(II)物质处理时通过闭环复分解过程提供不饱和环状化合物。该反应已成功应用于环胺、醚、硫化物等各种杂环的合成。具有甲硅烷基醚部分的不饱和硫缩醛的闭环复分解和随后的氧化裂解得到具有高立体选择性的Z-1,5-烯属二醇。研究发现，带有硫缩醛部分的酯和硫醇酯是分子内羰基烯化反应的良好底物，可生成多种不饱和环状化合物。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向邻羟基酮的转化。 3．由有机卤化物和二茂钛(II)产生的有机钛物质的反应用二茂钛(II)物质处理具有末端碳-碳双键的偕二卤化物产生双环环丙烷。通过 1,3-二卤化物与茂钛 (II) 试剂的反应，也可以高反式选择性生产 1,2-二取代环丙烷。较少的

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