Concise total synthesis and structural revision of (+)-pestalazine B.
A convergent synthesis of the proposed structure of (+)-pestalazine B has been achieved in 4 steps using the N-alkylation of an unprotected tryptophan diketopiperazine with a 3a-bromopyrrolidinoindoline as the key step. Although its structure was confirmed by X-ray analysis, the spectroscopic data did not match those of the natural product. The versatility of the methodology allowed the preparation of several diastereomers, and the database generated led to the proposal of an isomeric structure for the natural alkaloid where the d-leucine and d-phenylalanine residues exchanged positions, which was corroborated by total synthesis.
Pérez-Balado
Carlos
C
Departamento de Química Orgánica, Facultade de Química, Universidade de Vigo, Lagoas-Marcosende, 36310 Vigo, Spain.
de Lera
Angel R
AR
D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry*; D000478:Alkylation; D002625:Chemistry, Organic / Q000379:methods*; D054659:Diketopiperazines / Q000138:chemical synthesis* / Q000737:chemistry*; D007202:Indicators and Reagents; D026121:Indole Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D013237:Stereoisomerism; D014364:Tryptophan / Q000737:chemistry
D000470:Alkaloids; D054659:Diketopiperazines; D007202:Indicators and Reagents; D026121:Indole Alkaloids; D007211:Indoles; C555617:pestalazine B; D014364:Tryptophan