Substitution Reactions at Tetracoordinate Boron: Synthesis of N-Heterocyclic Carbene Boranes with Boron−Heteroatom Bonds

详细信息    查看全文

• 作者：Andrey Solovyev ; Qianli Chu ; Steven J. Geib ; Louis Fensterbank ; Max Malacria ; Emmanuel Lacte ; Dennis P. Curran
• 刊名：Journal of the American Chemical Society
• 出版年：2010
• 出版时间：October 27, 2010
• 年：2010
• 卷：132
• 期：42
• 页码：15072-15080
• 全文大小：363K
• 年卷期：v.132,no.42(October 27, 2010)
• ISSN：1520-5126

文摘

Boryl halide, carboxylate and sulfonate complexes of 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (dipp-Imd-BH₂X, X = halide or sulfonate) have been prepared from the parent borane dipp-Imd-BH₃ by (1) substitution reactions with R−X (X = halide or sulfonate), (2) reactions with electrophiles (like I₂ or NIS), or (3) acid/base reactions with HX (provided that HX has a pK_a of about 2 or less). Dipp-Imd-BH₂I is most conveniently prepared by reaction with diiodine while dipp-Imd-BH₂OTf is best prepared by reaction with triflic acid. These and other less reactive complexes behave as electrophiles and can be substituted by a wide range of heteroatom nucleophiles including halides, thiolates and other sulfur-based nucleophiles, isocyanate, azide, nitrite, and cyanide. The resulting products are remarkably stable, and many have been characterized by X-ray crystallography. Several are members of very rare classes of functionalized boron compounds (boron azide, nitro compound, nitrous ester, etc.).