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Lithium‐Salt Effects in Peptide Synthesis. Part I. Conditions for the Use of Lithium‐Salts in Coupling Reactions
Author(s) -
Thaler Adrian,
Seebach Dieter,
Cardinaux Francis
Publication year - 1991
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/hlca.19910740319
Subject(s) - chemistry , lithium (medication) , salt (chemistry) , peptide , peptide synthesis , medicinal chemistry , coupling reaction , organic chemistry , combinatorial chemistry , inorganic chemistry , catalysis , medicine , biochemistry , endocrinology
The influence of Li‐salts on the course of peptide‐coupling reactions was investigated. As a model for segment couplings, Ac‐Phe‐OH was coupled to HCl·H‐Ala‐OMe using the mixed anhydride, DCC1, DCCl/HOBt, BOP‐ Castro and TBTU‐ Knorr methods. As a model for stepwise synthesis Z‐Phe‐OH was coupled with HCl·Ala‐O( t ‐Bu), using symmetrical anhydrides and active esters. The effects of salt additives such as LiCl, LiBr, LiC10 4 , and ZnCl 2 on yields, side‐product formation, racemisation, and reaction rates are reported.