Novel [2 + 1] Concerted Reaction Path for Disilacyclobutenes with Acetylene

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• 作者：Yoshihiro Hayashi ; Takafumi Natsumeda ; Shun Otsu ; Ryo Yamada ; Akinobu Naka ; Mitsuo Ishikawa ; Tokio Yamabe ; Susumu Kawauchi
• 刊名：Organometallics
• 出版年：2014
• 出版时间：February 10, 2014
• 年：2014
• 卷：33
• 期：3
• 页码：763-770
• 全文大小：551K
• ISSN：1520-6041

文摘

Thermal reactions of benzodisilacyclobutene (1) and disilacyclobutene (2) with acetylene were investigated theoretically. The reactions are thought to proceed via the conventional Diels鈥揂lder reaction of disilabutadiene, the conrotatory ring-opening product of disilacyclobutene, with acetylene. However, this mechanism is incompatible with the observed similar reactivities of 1 and 2 with acetylene and the retention of stereochemistry during the reaction. In our previous paper, we proposed an alternative [2 + 1] cycloaddition pathway that involved the direct addition of acetylene to the Si鈥揝i 蟽鈥揵ond of 1 without ring opening. In this study, we extensively investigated the reaction pathways for both 1 and 2 on a theoretical basis. We found that charge transfer (CT) played a key role in the [2 + 1] cycloaddition pathway. On the basis of natural bond orbital (NBO) analysis, the interaction of the Si鈥揝i 蟽-bond orbital (donor) with the 蟺* orbital (acceptor) of the acetylene was attributed mainly to the CT process. Finally, an experiment to verify the [2 + 1] cycloaddition mechanism was proposed, in which the use of triacetylene as a terminal alkyne would allow the key intermediate in the pathway to be trapped.