Asperparaline A: biosynthetic studies and synthetic efforts
Date
2008
Authors
Gray, Chandele Ramsey, author
Williams, Robert M., advisor
Kennan, Alan, committee member
Szamel, Grzegorz, committee member
Parkinson, Bruce, committee member
Brennan, Patrick, committee member
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Abstract
Asperparaline A, a fungal metabolite isolated from Aspergillus japonicus, is of interest due to anthelmintic activity and structural similarities to the paraherquamides and brevianamides owing to the presence of bicyclo [2.2.2] diazaoctane core proposed to be derived from a biosynthetic [4+2] cycloaddition. This communication details two aspects of research regarding asperparaline A. The first goal involves the elucidation of asperparaline A as being biosynthetically composed of dimethylallylpyrophosphate and the amino acids, tryptophan and L-isoleucine, analogous to the paraherquamides. The second goal addresses the desire to develop synthetic methodology amenable to the introduction of isotopic labels for further biosynthetic studies. The proposed retrosyntheses envision the spiro-succinimide ring of asperparaline A being introduced by the photooxidation of a suitably oxidized pyrrole ring. Synthetic approaches toward asperparaline A presented include peptide coupling of β-methylproline with a prenylated pyrolylalanine, and Horner-Wadsworth-Emmons olefination of a diketopiperazine phosphonate with various aldehydes designed to allow for late stage pyrrole synthesis.
Description
Rights Access
Subject
Fungal metabolites
Anthelmintics
Biosynthesis
Indole alkaloids