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Synthesis of Endothiopeptides and Their Cyclization to 1,3‐Thiazol‐5(4 H )‐imines
Author(s) -
Lehmann Jürg,
Heimgartner Heinz
Publication year - 1999
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(19991110)82:11<1899::aid-hlca1899>3.0.co;2-m
Subject(s) - chemistry , thioamide , epimer , imine , yield (engineering) , stereochemistry , organic chemistry , materials science , metallurgy , catalysis
Abstract Further investigations of the synthesis of endothio analogues of the segment 1 – 10 ( 8 ) of an apolar analogon of zervamicin IIA are described. The endothiodecapeptide Boc‐Trp‐Ile‐Ala‐Aib‐Ile‐Val‐Aib‐Leu‐Aib‐ Ψ (CS)‐Pro‐OMe ( 10 ) has been prepared in good yield by our novel methodology. On the other hand, all attempts to prepare endothio analogues of 8 with the thioamide group at position 3 (Ala t ) gave not the expected linear endothiopeptides but led to epimerized 1,3‐thiazol‐5(4 H )‐imine derivatives as the main products. The mixture of epimers of the thiazolimines 27 , 30 , and 31 have been separated by means of preparative HPLC, and their structures have been established by 2D‐NMR experiments.