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Highly Constrained Linear Oligopeptides Containing Heterocyclic α ‐Amino Carboxylic Acids
Author(s) -
Stoykova Svetlana A.,
Linden Anthony,
Heimgartner Heinz
Publication year - 2013
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.201300062
Subject(s) - chemistry , saponification , oligopeptide , steric effects , synthon , stereochemistry , derivative (finance) , helix (gastropod) , stereocenter , thiopyran , amino acid , peptide , crystallography , organic chemistry , biochemistry , ecology , snail , financial economics , economics , biology , enantioselective synthesis , catalysis
Two spiroheterocyclic 2 H ‐azirin‐3‐amines, 1f and 1g , were shown to be useful synthons for the dipeptides N ‐(4‐aminotetrahydro‐2 H ‐pyran‐4‐yl)prolinate (Thp‐Pro) and the corresponding thiopyran derivative, Tht‐Pro, respectively. By coupling of 4‐bromobenzoic acid with 1f or 1g and saponification, followed by repeating the coupling and saponification steps, oligopeptides of type 4‐BrBz‐(Thp‐Pro) n ‐OMe and 4‐BrBz‐(Tht‐Pro) n ‐OMe were prepared, and their conformations were evaluated in solution by NMR techniques and in the crystalline state by X‐ray crystallography. All of these sterically highly congested oligopeptides adopt fairly rigid helical conformations. It is interesting to note that the hexapeptide with Thp forms a 3 10 ‐helix, whereas the Tht analog has a β ‐bend ribbon spiral confirmation.