Synthesis of Enniatin‐like Cyclic Depsipeptides via ‘Direct Amide Cyclization’ |
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Authors: | Peter Kttgen Anthony Linden Heinz Heimgartner |
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Institution: | Peter Köttgen,Anthony Linden,Heinz Heimgartner |
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Abstract: | The synthesis of several 18‐membered cyclodepsipeptides with an alternating sequence of α,α‐disubstituted α‐amino acids and α‐hydroxy acids (compounds 14a – 14e ) is described. The ring closure via macrolactonization was accomplished by treatment of a diluted suspension of the corresponding linear precursors 12a – 12e in toluene with HCl gas, i.e., the so‐called ‘direct amide cyclization’. The incorporation of the α,α‐disubstituted α‐amino acids was achieved via the ‘azirine/oxazolone method’ with 2H‐azirin‐3‐amines of type 6 and 9 as building blocks. The structure of the cyclic depsipeptide 14a was established by X‐ray crystallography. |
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Keywords: | Cyclodepsipeptides ‘ Direct amide cyclization’ Azirine/oxazolone method 2H‐Azirin‐3‐amines Peptides X‐Ray crystallography Enniatin |
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