344765-12-4Relevant academic research and scientific papers
Highly efficient enantioselective synthesis of 1,3-disubstituted 2,5-diketopiperazine derivatives via microwave irradiation
Han, Si Yeon,Gong, Young-Dae
supporting information, p. 3426 - 3434 (2019/11/03)
Chiral 2,5-diketopiperazine (2,5-DKP) derivatives have a broad range of biological activities in the medicinal field. The synthetic protocols of 1,3-disubstituted 2,5-DKPs via base-catalyzed cyclization of chloroacetamide have been reported. However, there are several drawbacks, such as an overly long reaction time, low to moderate yield, and racemization of the products. The sequence modified herein of 1,3-disubstituted 2,5-DKPs involves microwave-assisted cyclization. It increases yields and reduces reaction time. Furthermore, employing N-PMB protection prevents racemization, which frequently occurs in the base-catalyzed cyclization reaction. Consequently, the rapid synthetic method of enantiomerically pure 1,3-disubstituted 2,5-DKPs via microwave reaction was established successfully.
β-Lactams derived from phenylalanine and homologues: effects of the distance between the aromatic rings and the α-stereogenic reactive center on the memory of chirality
Bonache, M. Angeles,Cativiela, Carlos,García-López, M. Teresa,González-Mu?iz, Rosario
, p. 5883 - 5887 (2007/10/03)
The enantioselectivity in the base-promoted cyclization of N-chloroacetyl derivatives of Phe, Phg, and Hph is dependent on the side-chain length, with the best results for Phg analogues (up to 74% ee). In contrast, shortening of the N-substituent, from a
Amino acid-derived 4-alkyl-4-carboxy-2-azetidinones. New insights into β-lactam ring formation and n-deprotection
Gerona-Navarro, Guillermo,Bonache, MaAngeles,Reyero, Nuria,Garcia-Lopez, MaTeresa,Gonzalez-Muiz, Rosario
, p. 501 - 513 (2007/10/03)
The preparation and N-deprotection of a series of phenylalanine-derived 2-azetidinones incorporating 2,4-dimethoxybenzyl (Dmb), 2,3,4-, 2,4,6- and 3,4,5-trimethoxybenzyl (Tmb) groups at 1 position are described. The base-promoted cyclization of the corresponding methoxy-substituted Nαbenzyl-Nα-chloroacetyl derivatives to the 1,4,4-trisubstituted azetidinones proceeded with moderate to good yields, except for the 2,4,6-Tmb analogue. In spite of the number and position of the OMe groups, N-unsubstituted β-lactams were obtained by oxidative debenzylation using potassium peroxodisulfate. Alternatively, debenzylation of Pmb, Dmb and Tmb 2-azetidinones with TFA/anisole resulted in concomitant β-lactam opening to α-benzylaspartic acid derivatives.
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.
