Total synthesis of mauritines A, B, C, and F: cyclopeptide alkaloids with a 14-membered paracyclophane unit.
A unified strategy for the synthesis of mauritines A (5), B (6), C (7), and F (10) has been developed based on a key intramolecular nucleophilic aromatic substitution reaction (S(N)Ar) for the formation of the strained 14-membered paracyclophane. It was demonstrated that the outcome of the cycloetherification is independent of the stereochemistry of the peptide backbone and that both (1R)-16 and (1S)-16 cyclized smoothly to provide the corresponding macrocycle. On the other hand, dehydration of the secondary benzylic alcohol, via the phenylselenide intermediate, is configuration dependent. (1R)-25 underwent the two-step syn-elimination much more easily than (1S)-22. A modified reductive deamination procedure via the diazonium intermediate was developed. A complete assignment of proton and carbon NMR spectroscopy signals for these natural products is reported for the first time.
Cristau
Pierre
P
Institut de Chimie des Substances Naturelles, CNRS, 91198 Gif-sur-Yvette Cedex, France.
Temal-Laïb
Taoues
T
Bois-Choussy
Michèle
M
Martin
Marie-Thérèse
MT
Vors
Jean-Pierre
JP
Zhu
Jieping
J
D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D047028:Macrocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D010456:Peptides, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D000470:Alkaloids; D047028:Macrocyclic Compounds; D010456:Peptides, Cyclic