344765-29-3Relevant academic research and scientific papers
Entry to new conformationally constrained amino acids. First synthesis of 3-unsubstituted 4-alkyl-4-carboxy-2-azetidinone derivatives via an intramolecular Nα-Cα-cyclization strategy
Gerona-Navarro,Bonache,Herranz,Garcia-Lopez,Gonzalez-Muniz
, p. 3538 - 3547 (2007/10/03)
A systematic study on the base-assisted intramolecular alkylation of N-benzyl-N-chloroacetyl amino acid derivatives is described. This study resulted in the first concise and versatile route to the preparation of 3-unsubstituted 4-alkyl-4-carboxy-2-azetidinones, to be included into the scarce family of β-lactams with quaternary centers at the C4 position. Particularly noteworthy is that the intramolecular Nα-Cα-cyclization of Phe and Leu derivatives afforded the corresponding β-lactam derivatives with moderate enantioselectivity (up to 56%). It is suggested that, in these particular cases, the cyclization reaction proceeds by way of planar enolate intermediates, which possess dynamic chirality. The described sequence of reactions, that is compatible with commonly used protecting moieties for the α-carboxy group, cannot be applied to dipeptides, since the cyclization to the six-membered 2,5-diketopiperazine ring occurrs preferentially.
