Selectivity Control in Alkylidene Carbene-Mediated C鈭扝 Insertion and Allene Formation

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• 作者：Jun-Cheng Zheng ; Sang Young Yun ; Chunrui Sun ; Nam-Kyu Lee ; Daesung Lee
• 刊名：Journal of Organic Chemistry
• 出版年：2011
• 出版时间：February 18, 2011
• 年：2011
• 卷：76
• 期：4
• 页码：1086-1099
• 全文大小：1376K
• 年卷期：v.76,no.4(February 18, 2011)
• ISSN：1520-6904

文摘

Regioselectivity of alkylidene carbene-mediated C鈭扝 insertion was explored utilizing electronic, conformational, steric, and stereoelectronic effects. Relying on these factors, highly regio- and chemoselective carbene insertion reaction of C鈭扝 bonds in different environments could be obtained. The observed selectivity clearly indicates that an electronic effect plays a more important role than steric effect. In general, C鈭扝 bonds in conformationally rigid cyclic environments are less reactive than those in acyclic systems toward carbene insertion, and in this situation, a competing intermolecular reaction between alkylidene carbene and trimethylsilyldiazomethane led to the formation of allenylsilanes. The formation of allenylsilane becomes more favorable as the concentration of reaction becomes higher, as well as the C鈭扝 bonds undergoing insertion becomes electronically and conformationally deactivated.