Studies belated to the absolute configuration of cyclocinamide A:: Total synthesis of 4(R),11(R)-cyclocinamide A

Coupling of the fluorenylmethyl ester 3 (R = Fm) of (S)-5-bromotryptophan with N-alpha-BOC-(S)-asn-O-benzoyl-(R)-ise 9 gave rise to tripeptide 10. Cleavage of the BOC group in 10 followed by coupling with N-alpha-BOC-N-beta-Fmoc-(R)-2,3-diamino-propanoic acid afforded tetrapeptide II which was transformed into cyclic peptide 12. Cleavage of the BOC in 12 followed by coupling with the glycine derived side chain 14 gave rise, after removal of the benzoyl group to 4(R),11(R)-cyclocinamide A (2) which was not identical to natural cyclocmamide A (1), suggesting that 1 possesses the 4(S),7(S),11(S),14(S) configuration, (C) 1998 Elsevier Science Ltd. All rights reserved.