Total synthesis of the proposed structure of Anti-TMV active tabasesquiterpene A

The proposed structure of Tabasesquiterpene A, an illudalane type of sesquiterpene has been synthesized in twelve steps from 2-methoxy-4-methylbenzaldehyde in 40% overall yield. Triflic acid mediated intramolecular Freidel-Crafts acylation allows to develop the critical indanone moiety, a key intermediate of this synthesis. A careful ortho-selective formylation and subsequent Knoevenagel condensation to incorporate three carbon side chain, followed by reduction, formation of tricyclic lactone and DIBAL-H supported reduction of lactone to target were other key transformation involved. The NMR spectroscopic data of the synthetic sample differ from those of natural tabasesquiterpene A. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The proposed structure of Tabasesquiterpene A, an illudalane type of sesquiterpene, has been successfully synthesized in twelve steps with an overall yield of 40%. Key transformations include intramolecular Freidel-Crafts acylation, ortho-selective formylation, Knoevenagel condensation, and reduction of lactone. NMR spectroscopic data of the synthetic sample differs from natural Tabasesquiterpene A.