Revision of the Structure and Total Synthesis of Altenuisol

• Published in: European journal of organic chemistry Vol. 2012; no. 20; pp. 3863 - 3870
• Main Authors: Nemecek, Gregor, Cudaj, Judith, Podlech, Joachim
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.07.2012; WILEY‐VCH Verlag; Wiley; Wiley-VCH
• Subjects: Biological and medical sciences; Chemistry; Chemistry, Organic; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Heterocyclic compounds; Heterocyclic compounds with o, s, se, te hetero atom and condensed derivatives; Lactones; Microbiology; Mycology; Mycotoxins; Organic chemistry; Pathogenicity, host-agent relations, miscellaneous strains, epidemiology; Physical Sciences; Polyketides; Preparations and properties; Science & Technology; Structure ­elucidation; Total synthesis; Polyketides; METABOLITES; ANALOGS; BIOSYNTHESIS; Mycotoxins; ALTERNARIOL METHYL-ETHER; Total synthesis; Lactones; Structure -elucidation; Molecular structure; Mycotoxin; Lactone; NMR spectrometry; Natural compound; Oxygen heterocycle; Aldehydophenols; Suzuki coupling; Polyketide; Toxin; Spectrophotometry; Chemical synthesis; Structure elucidation; Structural analysis
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201200506

A total synthesis of the reported structure of altenuisol is described. Comparison of the 1H NMR spectra of the synthesized compound and of the natural product revealed that the originally proposed structure was not correct. Consequently, two constitutional isomers were synthesized. The spectra of one of these compounds – a structure originally proposed as the structure of altertenuol – matched perfectly with the spectra of the natural product. The total synthesis of altenuisol was thus achieved starting with phloroglucinic acid and protocatechuic aldehyde in 10 steps and in 23 % yield, where the longest linear sequence consisted of 6 steps. The key step was a Suzuki coupling with concomitant formation of the lactone ring. Whether altertenuol is identical with altenuisol could not be decided. Total synthesis of altenuisol, a minor toxin in ubiquitous Alternaria spp. revealed that the originally proposed structure was not correct. Altenuisol was proved to have an isomeric structure by total synthesis.