Diastereoselective Cyclopropanation of Ketone Enols with Fischer Carbene Complexes
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- 作者：José ; Barluenga ; Marcos G. Suero ; Ivá ; n Pé ; rez-Sá ; nchez ; Josefa Fló ; rez
- 刊名：Journal of the American Chemical Society
- 出版年：2008
- 出版时间：March 5, 2008
- 年：2008
- 卷：130
- 期：9
- 页码：2708 - 2709
- 全文大小：48K
- 年卷期：v.130,no.9(March 5, 2008)
- ISSN：1520-5126
文摘
Treatment of aryl/heteroaryl methoxycarbene complexes of chromium with G SRC="/images/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-substituted ketone lithium enolates between -78 
ges/entities/deg.gif">C and room temperature resulted in the diastereoselective synthesis of 1,2,2,3-tetrasubstituted cyclopropanols. An exception has been observed in the reaction with cyclohexanone lithium enolate that yielded a bicyclic 2-buten-4-olide. 1,2-Dimethoxycyclopropanes and 1-methoxy-2-trimethylsilyloxycyclopropanes were isolated by quenching the reactions with MeOTf or Me3SiCl, respectively. This novel cyclopropanation process involves formation of lithium (3-oxoalkyl)pentacarbonylchromate intermediates which on warming undergo intramolecular addition to the carbonyl group. This cyclization is equivalent to the cyclopropanation in smooth conditions of electron-rich alkenes with Fischer carbene complexes.
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