Lewis acid mediated functionalization of β-lactams: mechanistic study and synthesis of C-3 unsymmetrically disubstituted azetidin-2-ones
作者:Aman Bhalla、Suman Rathee、Sachin Madan、Paloth Venugopalan、Shamsher S. Bari
DOI:10.1016/j.tetlet.2006.05.160
日期:2006.7
A convenient and efficient route to novel unsymmetrically disubstituted azetidin-2-ones is described. β-Lactam carbocation equivalents of type 1 and active aromatic substrates in the presence of a Lewis acid promote a facile and stereoselective C-3 substitution to provide monosubstituted β-lactams (3,4) and symmetrically disubstituted β-lactams (5). cis-3-(4′-Methoxyphenyl)-3-phenylthioazetidin-2-ones
描述了一种新颖的不对称双取代的氮杂环丁烷-2-酮的便捷有效途径。β内酰胺型的碳阳离子当量1在路易斯酸的存在和活性芳香底物促进了容易和立体选择性C-3取代,以提供单取代的β内酰胺类(3,4)和二取代的对称β内酰胺(5)。顺式-3-(4'-甲氧基苯基)-3-苯基硫氮杂环丁烷-2-酮(4)进一步被路易斯酸介导的活性芳族底物取代,得到不对称的双取代的氮杂环丁烷-2-酮(7)。