Piperazine-2,3,5-triones in the synthesis of constrained peptides
摘要:
Amino acid amides react with diethyl oxalate and sodium ethoxide to yield 6-substituted piperazine-2,3,5-triones, which can be mono-alkylated at N-4, bis-alkylated at N-4 and C-6, or tris-alkylated at N-4, N-1, and C-6 under mild basic conditions; this provides access to i) alpha,alpha-disubstituted cyclic peptide derivatives; ii) constrained peptides via C(alpha)-N bond formation; iii) DKP analogues. (C) 1999 Elsevier Science Ltd. All rights reserved.
Piperazine-2,3,5-triones in the synthesis of constrained peptides
摘要:
Amino acid amides react with diethyl oxalate and sodium ethoxide to yield 6-substituted piperazine-2,3,5-triones, which can be mono-alkylated at N-4, bis-alkylated at N-4 and C-6, or tris-alkylated at N-4, N-1, and C-6 under mild basic conditions; this provides access to i) alpha,alpha-disubstituted cyclic peptide derivatives; ii) constrained peptides via C(alpha)-N bond formation; iii) DKP analogues. (C) 1999 Elsevier Science Ltd. All rights reserved.
Preparation of Hydantoins by Catalytic Oxidative Carbonylation of α-Amino Amides
作者:Seth M. Dumbris、Delmy J. Díaz、Lisa McElwee-White
DOI:10.1021/jo9016138
日期:2009.11.20
Hydantoins can be synthesized from the corresponding amino amides employing oxidative catalytic carbonylation using W(CO)(6) as the catalyst, I-2 as the oxidant, CO as the carbonyl source, and DBU as base. Secondary amides afford the hydantoins in good to excellent yields, which decrease as the steric bulk of the N-alkyl substituent increases.
[EN] CHELATING AGENTS
申请人:NYCOMED IMAGING AS
公开号:WO1992011232A1
公开(公告)日:1992-07-09
(EN) There are provided chelating agents of formula (I) (wherein n is 0 or 1 and at least one R1 group comprises a group NR11R14 where one of R11 and R14 comprises a cyclic lipophilic group) and metal chelates and salts thereof. The chelates with paramagnetic or heavy metal ions are particularly suited for use as hepatobiliary contrast agents.(FR) L'invention concerne des chélateurs de formule (I) dans laquelle n vaut 0 ou 1 et au moins un groupe R1 comprend un groupe NR11R14 dans lequel R11 ou R14 comprend un groupe lipophilique cyclique. L'invention concerne également des chélates métalliques et des sels desdits chélateurs. Les chélates possédant des ions métal de lourd ou paramagnétiques sont particulièrement utiles comme agents de contraste hépatobiliaires.