187332-62-3Relevant academic research and scientific papers
Construction of quaternary stereogenic centers via [2 + 2] cycloaddition reactions. Synthesis of homochiral 4,4-disubstituted 2-azetidinones and imine substituent effects on β-lactam formation
Palomo, Claudio,Aizpurua, Jesus M.,Garcia, Jesus M.,Galarza, Regina,Legido, Marta,Urchegui, Raquel,Roman, Pascual,Luque, Antonio,Server-Carrio, Juan,Linden, Anthony
, p. 2070 - 2079 (2007/10/03)
A study on the asymmetric construction of quaternary stereogenic centers via [2 + 2] cycloaddition reaction of ketenes with ketimines is described. Reaction of achiral ketenes and chiral α-alkoxy ketone-derived imines resulted in formation of new β-lactams as single diastereomers. The cycloaddition was extended to pyruvate imines, aralkyl ketone-derived imines, and dialkyl ketimines. In these cases the asymmetric induction was satisfactorily achieved using β-silylalkanoyl ketenes and the Evans-Sjogren ketene. C,C-Bis (trimethylsilyl)methylamine ketimines derived from enolizable dialkyl ketones cleanly led to the corresponding C(4) disubstituted β-lactams without deprotonation. Therefore, a general methodology for a convergent asymmetric synthesis of β-lactams in which C(4) exists as a quaternary carbon is provided.
