Synthesis of protected norcysteines for SPPS compatible with Fmoc strategy
摘要:
We report the synthesis of racemic Alloc-Ncy(Tmob)-OH, the resolution of its methyl ester and demonstrate its application to form a norcystine bridge in octreotide-amide using the Fmoc strategy on solid phase. N-Alloc and S-Tmob protections of norcysteine (Ncy) were found to be a preferred choice for Fmoc strategy over three other protected norcysteines synthesized, that is, Fmoc-Ncy(tBu)-OH, Alloc-Ncy(tBu)-OH, and Alloc-Ncy(Trt)-OH. (C) 2007 Elsevier Ltd. All rights reserved.
Synthesis of racemic .alpha.-amino carboxamides via Lewis acid-mediated reactions of .alpha.-methoxyglycinamide derivatives with allylsilanes: enzymic resolution to optically active .alpha.-amino acids
摘要:
A short and expedient synthetic route to optically active, saturated and gamma,delta-unsaturated alpha-amino acids is reported. The key step is a BF3.OEt2-mediated reaction of allylsilanes with N-(alkoxycarbonyl)-alpha-methoxyglycinamides 11-15, leading to the corresponding gamma,delta-unsaturated alpha-aminocarboxamides. The genuine S(N)1-character of this process with iminium ion 6 as intermediate is proven in the case of the glycine ester 10. Thus, reaction of enzymatically resolved 10 with pi-nucleophiles leads to racemic products. The most useful iminium precursors are the N-methoxyamides 12-14 providing good yields of coupling products. The most convenient N-protective group is the allyloxycarbonyl group. Deprotection proceeds via a Pd(0)-catalyzed transprotection to the corresponding BOC-protected analogues. Four examples of the enzymatic resolution of alpha-amino carboxamides, by using an L-specific aminopeptidase from Pseudomonas putida, are described in detail. Most notably, secondary N-methoxyamides are good substrates for the enzyme to provide the desired a-amino acids in high optical purity.
Improvements in or relating to benzothienylglycyl cephalosporin derivatives
申请人:ELI LILLY AND COMPANY
公开号:EP0122154A2
公开(公告)日:1984-10-17
7-(3-Benzothienyl)glycylamido cephalosporins provided by this invention possess favorable pharmacokinetics and are orally-effective against gram positive microorganisms.
Orally absorbable cephalosporin antibiotics. 1. Structure-activity relationships of benzothienyl- and naphthylglycine derivatives of 7-aminodeacetoxycephalosporanic acid
作者:Stjepan Kukolja、Susan E. Draheim、Janice L. Pfeil、Robin D. G. Cooper、Bernard J. Graves、Richard E. Holmes、David A. Neel、George W. Huffman、J. Alan Webber
DOI:10.1021/jm00150a022
日期:1985.12
A structure-activity relationship study of a number of orally absorbed cephalosporins together with their syntheses is described. These new cephalosporins are benzothienyl- and naphthylglycine derivatives of 7-aminodeacetoxycephalosporanic acid. Several different synthetic methods for the glycine side chains, their protection, and the final acylations are reported. Several of these analogues were more active than cephalexin both in vitro and in vivo against commonly encountered Gram-positive bacteria. (R)-7-(3-Benzothienylglycylamido)-3-methyl-3-cephem-4-carboxylic acid (1R) has emerged as a potent antibacterial agent and is currently undergoing preclinical evaluation.