García-Domínguez P, Lorenzo P, Álvarez R, de Lera AR. Total Synthesis of the Proposed Structure of (-)-Novofumigatamide, Isomers Thereof, and Analogues. Part I.
J Org Chem 2022;
87:12510-12527. [PMID:
36137268 PMCID:
PMC9552234 DOI:
10.1021/acs.joc.2c01227]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The total synthesis of the suggested structure of (−)-novofumigatamide,
a natural product containing a C3-reverse prenylated N-acetyl-exo-hexahydropyrrolo[2,3-b]indole motif fused to a 10-membered ring lactam, was achieved using
the macrolactam formation in advance of a diastereoselective bromocyclization
and reverse prenylation steps. Since the NMR data of the synthetic
sample did not match those of the natural product, the endo-bromo precursor of a N-Boc analogue and additional
diastereomers derived from l-Trp were also synthesized. Five
alternative synthetic routes, which differed in the order of final
key steps used for the construction of the 10-membered ring lactam
and the hexahydropyrrolo[2,3-b]indole framework within
the polycyclic skeleton and also in the amide bond selected for the
ring-closing of the macrolactam, were thoroughly explored. Much to
our dismay, the lack of spectroscopic correlations between the proposed
structure of natural (−)-novofumigatamide and the synthetic
products suggested a different connectivity between the atoms. Additional
synthetic efforts to assemble alternative structures of the natural
product and isomers thereof (see accompanying paper; DOI: 10.1021/acs.joc.2c01228) further highlighted the frustrating endeavors toward the identification
of a natural product.
Collapse