Synthesis of 2-Oxazolines by <i>in Situ</i> Desilylation and Cyclodehydration of β-Hydroxyamides
作者:Marco Brandstätter、Fabian Roth、Nathan W. Luedtke
DOI:10.1021/jo5016695
日期:2015.1.2
A powerful method for the synthesis of 2-oxazolines from silyl-protected β-hydroxyamides is reported. Using diethylaminosulfur trifluoride (DAST) or its tetrafluoroborate salt (XtalFluor-E), silyl-protected β-amidoalcohols can be in situ deprotected and dehydrated to give 2-oxazolines in good yields. The utility of this approach was demonstrated by preparing the first reported oligomer of [2,4′]-coupled
The invention provides compounds of formula I:
wherein A, B, D, E, R
1
, R
2
, R
3
, R
4
, R
5
, X, and ----- have any values defined herein, as well as salts thereof. The compounds have activity as G-quadruplex DNA stabilizers and as anti-proliferative agents.
“Customizable” Units in Di- and Tripeptides: Selective Conversion into Substituted Dehydroamino Acids
作者:Carlos J. Saavedra、Alicia Boto、Rosendo Hernández
DOI:10.1021/ol301676z
日期:2012.7.20
The selective conversion of serine or threonine units of di- and tripeptides into substituted dehydroamino acids is reported. Thus, these common α-amino acids undergo a scission–phosphorylation process to give α-amino phosphonate residues. A Horner–Wadsworth–Emmons reaction with aldehydes or ketones follows to afford the final products with excellent Z-stereoselectivity (Z:E > 98:2). In this way, a
Novel polyoxazole-based cyclopeptides from Streptomyces sp. Total synthesis of the cyclopeptide YM-216391 and synthetic studies towards telomestatin
作者:Jon Deeley、Anna Bertram、Gerald Pattenden
DOI:10.1039/b802477d
日期:——
hepta-oxazole 30en route to telomestatin 1. Likewise, neither the hexa-oxazole 47 or application of an intramolecular Hantzsch oxazole ring-forming reaction from 44b allowed access to the advanced polyoxazole-macrolactam intermediates 48 and 30a, respectively, towards telomestatin. Combination of the tris-oxazole based methylamine 70 with the dipeptide carboxylic acid 71 derived from D-valine and L-isoleucine
An improved protocol for the SmI2-promoted C-alkylation of peptides: degradation and functionalization of serine residues in linear and cyclic peptides
The utility of the samarium diiodide promoted C-alkylation of peptides for the introduction of new side chains on peptide strands is dramatically enhanced by the initial oxidative degradation of serine residues in small peptides. In this way, cyclic peptides may also be included in this repertoire as a method for the preparation of peptide libraries. (C) 2004 Elsevier Ltd. All rights reserved.