Zhu Xue-Feng, Henry Christopher E, Kwon Ohyun
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, USA.
J Am Chem Soc. 2007 May 30;129(21):6722-3. doi: 10.1021/ja071990s. Epub 2007 May 8.
Three-component coupling reactions between trialkylphosphines, methyl propiolates, and aldehydes produced 1:1:1 dipolar adducts in moderate-to-excellent yields. The product phosphonium enolate zwitterions were isolated as crystalline solids. X-ray crystallographic analyses of these single crystals established unequivocally the dipolar structures of these tetravalent phosphonium enolate zwitterions. Because phosphonium enolates are the first key intermediates in the nucleophilic phosphine-mediated catalysis of α,β-unsaturated carbonyl compounds, this study provides crucial insight into the mechanisms of Morita–Baylis–Hillman-type reactions.
三烷基膦、甲基丙炔酸酯和醛之间的三组分偶联反应以中等至优异的产率生成了1:1:1的偶极加合物。产物烯醇磷酸鎓两性离子被分离为结晶固体。对这些单晶进行的X射线晶体学分析明确确定了这些四价烯醇磷酸鎓两性离子的偶极结构。由于烯醇磷酸鎓是亲核膦介导的α,β-不饱和羰基化合物催化反应中的首个关键中间体，本研究为森田–贝利斯–希尔曼型反应的机理提供了重要见解。
