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

在这项研究中，我们探索了一种新的方法，利用硫代缩醛与茂钛(II)物种进行脱硫反应制备的钛-卡宾络合物来构建基本碳骨架。钛-卡宾络合物的分子间反应卡宾络合物与腈的反应通过生成氮杂环丁烯来进行，以较高的产率生成酰化产物。乙烯基卡宾与三卤化物的络合物处理得到乙烯基钛物种，它与末端的炔和醛反应生成相应的加合物。由含有三烷基硅烷基甲基的1，3-二(苯硫基)丙烯生成的卡宾络合物反应合成了各种烯丙基硅烷。钛-卡宾络合物的分子内反应含碳-碳双键的硫代缩醛在与茂钛(II)物种反应时，通过闭环歧化反应生成不饱和环状化合物。这个反应是Wa…更多的S成功地应用于环胺、醚、硫化物等各种杂环的合成。含有硅醚部分的不饱和硫代缩醛的闭环歧化反应和随后的氧化裂解反应使Z-1，5-烯烃二醇具有较高的立体选择性。研究发现，含硫代缩醛的酯和硫代酯是进行分子内羰基烯化反应的良好底物，可合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合成、二氢噻吩类化合物的合成以及羧酸转化为邻羟基酮的反应。有机卤化物生成的有机钛物种与二茂钛的反应(II)与二茂钛物种具有末端碳-碳双键的宝石二卤化物的处理(II)生成双环环丙烷。1，3-二卤化物与二茂钛试剂反应生成的1，2-二取代环丙烷也具有较高的反式选择性。较少

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