DFT Study on the Biosynthesis of Preasperterpenoid A: Role of Secondary Carbocations in the Carbocation Cascade
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Updated: Dec 22, 2025

Preparation of 6-aminocyclohepta-2,4-dien-1-one Derivatives via Tricarbonyltroponeiron
Published on: August 12, 2019
Hajime Sato1,2, Mami Yamazaki1, Masanobu Uchiyama2,3,4
1Graduate School of Pharmaceutical Sciences, Chiba University.
Abstract:
Preasperterpenoid A, featuring a 5/7/(3)6/5 pentacyclic structure, is a C25 sesterterpenoid produced by Penicillium verruculosum. The results of density functional calculations on putative biosynthetic carbocation cyclization/rearrangements leading to preasperterpenoid A revealed a highly concerted four-step cyclization mechanism. Interestingly, two secondary carbocation structures were obtained as minima, but appeared almost as shoulders in the energy profile, and may represent essentially transient structures during the highly concerted reaction.
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