Metallacyclobutene-metallabutadiene (vinylcarbene complex) interconversions : ring opening of titanacyclobutenes
Metallacyclobutene-metallabutadiene (vinylcarbene complex) interconversions : ring opening of titanacyclobutenes
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金属环丁烯-金属丁二烯（乙烯基碳烯络合物）相互转化：二氧化钛环丁烯的开环
DOI：
10.1021/om00036a011
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发表时间：
1993
期刊：
影响因子：
2.8
通讯作者：
Kenneth Zientara
中科院分区：
文献类型：
--
作者：
K. Doxsee;J. Juliette;John K. M. Mouser;Kenneth Zientara
本文报道了在金属酰基环丁烯环的α位上带有乙烯基取代基的钛环丁烯的缩合反应。这种钛-环丁烯的开环预期提供二乙烯基卡宾络合物（或其双自由基类似物）;钛环丁烯环的再闭合然后可以导致起始络合物的再生或异构体钛环丁烯的形成。实验上，观察到的瞬时异构化反应与快速、可逆的开环反应相一致。金属环丁烯与乙烯基卡宾配合物的相互转化（1-金属丁二烯，EQ 1）已被提出作为许多重要的过渡金属络合物介导的转化中的关键机理步骤，包括炔的聚合 * 1和通过炔与Fischer型卡宾配合物的偶联合成复杂的有机分子（Dotz反应）。2
Preparationof titanacyclobutenesbearing vinyl substituents on the a-position of the metallacy-clobutene ring is reported. Ring opening of such titana-cyclobutenes is anticipated to afford divinylcarbene complexes (or their biradical analogs); reclosure of the titanacyclobutene ring then can result in either regeneration of the starting complex or in the formation of an isomeric titanacyclobutene. Experimentally, the in-stantaneous isomerization observed is consistent with rapid, reversible ring opening.Interconversion of metallacyclobutenes and vinylcar-bene complexes (1-metallabutadienes, eq 1) has been proposed as a key mechanistic step in a number of important transition metalcomplex mediated transformations, including the polymerization of alkynes* 1 and the synthesis of complexorganic molecules via the coupling of alkynes with Fischer-type carbene complexes (the so-called Dótz reaction). 2