A comparative study of the aggregation, rotational side-chain isomerism and side-chain/side-chain interactions in the cyclic dipeptides c/Phe, Pip/ and c/Phe, (s)Pip/

✍ Scribed by Rik Schrooten; Satish Joshi; Marc J. O. Anteunis

• Publisher: Wiley (John Wiley & Sons)
• Year: 2010
• Weight: 409 KB
• Volume: 89
• Category: Article
• ISSN: 0037-9646
• DOI: 10.1002/bscb.19800890804

✦ Synopsis

Abstract

We compare in this contribution the aggregation and the rotational side‐chain isomerism of the diastereomeric cyclodipeptides phenylalanine‐pipecolic acid (1, 2) with those previously observed^1^ in the parent DKP's, containing the 4‐thiapipecolic acid moieties instead. Concomitantly with dimerisation (C~8~‐dimer) an increasing folding with concentration of the aromatic nucleus over the DKP‐ring is observed in aprotic solvents. The greater tendency for stacking in the cis‐isomer than in the trans‐isomer is thus reflected by a larger dimerisation capacity of the former. In the carbocyclic congeners the stabilisation of the folded form in the cis‐isomer is less pronounced than for the thia‐analog, thus confirming the surmise that an attractive interaction would occur when sulfur approaches a π‐system in space.