Organic Syntheses Utilizing Titanium Carbene Complexes
Organic Syntheses Utilizing Titanium Carbene Complexes
复制标题
利用钛卡宾配合物的有机合成
DOI：
10.1002/chin.200522256
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
T. Takeda*
中科院分区：
文献类型：
--
作者：
T. Takeda*
利用钛卡宾络合物的合成反应，通过硫代缩醛和相关的有机硫化合物与二茂钛（II）物种[Cp 2 Ti{P（OEt）3 } 2 ]的脱硫钛化制备。包括羧酸衍生物在内的羰基化合物与钛卡宾络合物的Wittig型烯化反应提供了多种烯烃化合物。该反应成功地应用于羧酸衍生物的分子内羰基烯化反应，得到各种碳环和杂环。通过用二茂钛（II）物质处理偕二卤化物和某些烷基卤化物产生的有机钛物质也可用于将羰基化合物转化为高度取代的烯烃或转化为带有大取代基的烯烃。由硫代缩醛生成的亚烷基二茂钛与烯烃以分子间和分子内的方式反应，得到烯烃复分解产物。由具有末端烯烃的硫代缩醛形成的卡宾络合物的闭环烯烃复分解提供了多种不饱和杂环化合物。另一方面，当末端烯烃用烯基-和炔基-卡宾络合物处理时，环丙烷化进行。环丙烷也可以通过处理具有末端碳碳双键的宝石二卤化物获得。碳烯配合物对三键也具有高度反应性。它们与腈类反应，中间体乙烯亚胺钛络合物水解后得到酰化产物。通过形成钛环丁烯中间体的卡宾配合物与内部炔的反应提供具有高立体选择性的共轭二烯，而复分解聚合进行时，得到反式聚乙炔的卡宾配合物用过量的乙炔处理。碳烯配合物还与叔烷基卤化物和第14族金属卤化物反应。
Synthetic reactions utilizing titanium carbene complexes prepared by the desulfurizative titanation of thioacetals and related organosulfur compounds with the titanocene(II) species [Cp 2 Ti{P(OEt) 3 } 2 ] are described. TheWittig type olefination of carbonyl compounds including carboxylic acid derivatives with the titanium carbene complexes affords a variety of olefinic compounds. The reaction is successfully applied to the intramolecular carbonyl olefination of carboxylic acid derivatives, giving various carbo- and hetero-cycles. The organotitanium species generated by the treatment of gem-dihalides and certain alkyl halides with the titanocene(II) species are also useful for the transformation of carbonyl compounds into highly substituted olefins or into olefins bearing a bulky substituent. The alkylidenetitanocenes generated from thioacetals react with olefins in both inter- and intramolecular fashions to give olefin metathesis products. The ring-closing olefin metathesis of the carbene complexes formed from thioacetals having a terminal olefin provides a variety of unsaturated heterocyclic compounds. On the other hand, cyclopropanation proceeds when terminal olefins are treated with alkenyl- and alkynyl-carbene complexes. Cyclopropanes are also obtained by treatment of gem-dihalides having a terminal carbon-carbon double bond. The carbene complexes are also highly reactive toward triple bonds. Their reactions with nitriles afford the acylation products after hydrolysis of intermediary titanium vinylimido complexes. The reactions of the carbene complexes with internal alkynes via the formation of titanacyclobutene intermediates afford conjugated dienes with high stereoselectivity, whereas metathesis polymerization proceeds to give trans-polyacetylene when the carbene complexes are treated with excess acetylene. The carbene complexes also react with t-alkyl halides and group 14 metal hydrides.