Total synthesis of selaginellin A

The total synthesis of selaginellin A, isolated from Selaginella tamariscina, was achieved through an eight step process including a Diels-Alder reaction, formation of a quinone methide moiety and dehydrogenative aromatization. The NMR spectra collected for different samples of synthetic selaginellin A initially showed irregular peak shapes and variable chemical shifts for the signals of the phenol-substituted quinone methide moiety under neutral conditions. After detailed NMR analysis, it was found that the addition of a trace amount of trifluoroacetic acid accelerated the tautomerism of the phenol-substituted quinone methide moiety and improved the reproducibility of the chemical shifts of synthetic selaginellin A. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The total synthesis of selaginellin A isolated from Selaginella tamariscina was achieved through an eight-step process, and the study found that the addition of a trace amount of trifluoroacetic acid in NMR analysis can improve the reproducibility of its chemical shifts.