180839-85-4Relevant 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.
Concise synthesis of α-alkyl α-amino acids and their incorporation into peptides via β-lactam-derived α-amino acid N-carboxy anhydrides
Palomo, Claudio,Aizpurua,Ganboa, Inaki,Odriozola, Beatriz,Urchegui, Raquel,Goerls, Helmar
, p. 1269 - 1270 (2007/10/03)
a-Hydroxy β-lactams in which C4 exists as a quaternary carbon are transformed in a single one-pot operation into α,α-dialkyl α-amino acid N-carboxy anhydrides providing a new approach to conformationally restricted peptide segments from non α-a
