Total Synthesis of Aignopsanes, A Class of Sesquiterpenes: (+)-Aignopsanoic Acid A, (−)-Methyl Aignopsanoate A, and (−)-Isoaignopsanoic A

• Published in: Chemistry : a European journal 2015-01, Vol.21 (1), p.395-401
• Main Authors: Bürki, Cédric, Bonjoch, Josep, Bradshaw, Ben, Villa, Giorgio, Renaud, Philippe
• Format: Article
• Language: English
• Subjects: Alkenes - chemistry; biosynthesis; Circular Dichroism; Crystallography, X-Ray; furanosesquiterpenes; Ketones - chemistry; Molecular Conformation; natural products; Oxidation-Reduction; Sesquiterpenes - chemical synthesis; Sesquiterpenes - chemistry; Stereoisomerism; total synthesis; Wieland-Miescher ketone
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201404766

A general strategy for the synthesis of aignopsanes, a new family of sesquiterpene natural products of marine origin, is presented. The total synthesis of (+)‐aignopsanoic acid A (1), (−)‐methyl aignopsanoate A (2), and (−)‐isoaignopsanoic A (3) has been achieved and their absolute configuration confirmed. (+)‐Microcionin‐1 (4), a structurally related furanosesquiterpene isolated in both enantiomeric forms from marine sponges, was also synthesized and its absolute configuration established in an unambiguous way. Interestingly, we report that (+)‐microcionin‐1 (4), can be converted by a simple oxidation process to aignopsanoic acid A (1). This transformation supports the hypothesis that (+)‐microcionin‐1 (4) may be an intermediate in the biosynthesis of aignopsanes. Nature knows best! Synthesis of (+)‐microcionin‐1, a furanosesquiterpene isolated in both enantiomeric forms from marine sponges, was achieved and its absolute configuration established. (+)‐Microcionin‐1 was subsequently converted by a simple oxidation process to aignopsanoic acid A (see scheme). This transformation supports the hypothesis that (+)‐microcionin‐1 may be an intermediate in the biosynthesis of aignopsanes.