<b>On Cysteine and Cystine Peptides. I. New S-Protecting Groups for Cysteine</b>
作者:Leonidas. Zervas、Iphigenia. Photaki
DOI:10.1021/ja00879a019
日期:1962.10
Titanium(IV)-Mediated Tandem Deprotection−Cyclodehydration of Protected Cysteine <i>N</i>-Amides: Biomimetic Syntheses of Thiazoline- and Thiazole-Containing Heterocycles
作者:Prakash Raman、Hossein Razavi、Jeffery W. Kelly
DOI:10.1021/ol000178q
日期:2000.10.1
[GRAPHICS]The scope and limitations of TiCl4-mediated Delta(2)-thiazoline synthesis via tandem deprotection-dehydrocyclization of trityl-protected cysteine N-amides is presented. While chemical yields are acceptable (53-96%), the stereochemical outcomes vary on the basis of structural considerations and reaction conditions (22-99% ee). Racemization at the C(2)-exomethine position limits the utility of this method for the formation of a thiazoline within a peptide. Treatment of a tritylated Cys-Cys dipeptide with TiCl4 afforded the corresponding thiazole-thiazoline heterocycle 12 (38% yield, 97% ee).
A Biomimetic Synthesis of Thiazolines Using Hexaphenyloxodiphosphonium Trifluoromethanesulfonate
The use of phosphonium anhydrides for the synthesis of 2-oxazolines, 2-thiazolines and 2-dihydrooxazine under mild conditions
作者:Maria J. Petersson、Ian D. Jenkins、Wendy A. Loughlin
DOI:10.1039/b818310d
日期:——
β-Hydroxy amides6 and 7 were treated with triphenylphosphonium anhydride trifluoromethane sulfonate (3), or the cyclic analogue 4, to generate 2-oxazolines 5 and 8 under mild conditions. The reaction was optimised by examining the number of equivalents of reagents 3 or 4, or diisopropylethyl amine required to best effect cyclisation. The effects of altering the reaction temperature, reaction time,