Stereoselective preparation of mono- and bis-.beta.-lactams by the 1,4-diaza-1,3-diene - acid chloride condensation: scope and synthetic applications
                                
                                    
                                        作者:Benito Alcaide、Yolanda Martin-Cantalejo、Javier Perez-Castells、Julian Rodriguez-Lopez、Miguel A. Sierra、Angeles Monge、Virginia Perez-Garcia                                    
                                    
                                        DOI:10.1021/jo00048a027
                                    
                                    
                                        日期:1992.10
                                    
                                    The dehydrochlorination of a variety of acid chlorides with triethylamine in the presence of 1,4-diaza 1,3-dienes gives in fair to excellent yields, with total stereoselectivity, cis-4-imino beta-lactams 2, cis-4-formyl beta-lactams 3, or C4,C4'-bis-beta-lactams 4, depending on the reaction conditions. The reaction tolerates a wide variety of substituents, including alkoxy, thiophenoxy, amino, aryl, alkyl, alkylidene, and halogen groups, at the ketene moiety. The synthetic versatility of compounds 3 has been demonstrated by their conversion to intermediates in the synthesis of carbapenems PS-5 and PS-6. Base-induced isomerization of compounds 4 to novel bis-gamma-lactams 5, which in turn are aza analogs of glycaric acids, occurred with total retention of the configuration. This process is formally the elongation of glyoxal in four carbons bearing four contiguous stereocenters with total stereoselectivity in only three or four synthetic steps.