1,3-Dipolar cycloadditions of silicon and tin alkynes and alkenes. Regiospecific synthesis of silyl and stannylpyrazoles and pyrazolines

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• 关键词：Silicon heterocycles ; Tin heterocycles ; Silylpyrazoles ; Stannylpyrazoles ; Cycloadditions
• 刊名：Tetrahedron
• 出版年：2007
• 期刊代码：107_00404020
• 类别：ch
• 出版时间：1 January 2007
• 卷：63
• 期：1
• 页码：224-231
• 文件大小：484 K

摘要

Silicon and tin 3-, 3,5-, and 3,4,5-metalated pyrazoles have been synthesized by 1,3-dipolar cycloadditions of silyl-, disilyl-, and silylstannylacetylenes with N-phenylsydnone or trimethylsilyldiazomethane. On the other hand, 1- and 2-pyrazolines monometalated and dimetalated in different positions of the heterocycle have been prepared by reaction of vinylsilanes and vinylstannanes with the same 1,3-dipolar reagents. Other interesting products resulting from homologation were obtained by cycloaddition of trimethylsilyldiazomethane with β-silyl enones and esters. Moreover, for the first time a 3-silylpyrazole has been converted into a 3-cyanopyrazole.