Ring Expansion Reactions of Electron-Rich Boron-Containing Heterocycles

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• 作者：Juan F. Araneda ; Warren E. Piers ; Michael J. Sgro ; Masood Parvez
• 刊名：Organometallics
• 出版年：2015
• 出版时间：July 13, 2015
• 年：2015
• 卷：34
• 期：13
• 页码：3408-3413
• 全文大小：484K
• ISSN：1520-6041

文摘

The potassium salts of the dianions of isomeric compounds bis-benzocycloborabutylidene, 1, and the ladder diborole 2 were reacted with carbon dioxide (CO₂) and carbon monoxide (CO) and the ring expansion products fully characterized. Both dianions 1 and 2 react rapidly with carbon dioxide to form the same insertion product, 3, in which the boron-containing rings are expanded to six-membered rings. Compound 3 is a B鈥揙 analogue of binaphtholate. Only dianion 2 reacts cleanly with the weaker electrophile CO, producing a product (4) in which only one of the boron-containing rings is expanded through formal insertion of CO into a B鈥揅 bond. The X-ray structures of both 3 and 4 are reported, and reasonable paths to their formation are proposed.