Synthesis 2022; 54(13): 3093-3104
DOI: 10.1055/a-1773-4386
paper

Asymmetric Total Synthesis of Ventilanones A and B, Two Naturally Occurring Pyranonaphthoquinones from Ventilago harmandiana

Pramchai Deelertpaiboon
,
Sopanat Kongsriprapan
,
Suppachai Krajangsri
,
Nolan M. Betterley
,
,
We are grateful for the financial support from the NSRF through the Program Management Unit for Human Resources & Institutional Development, Research and Innovation [B16F640099], the Center of Excellence for Innovation in Chemistry (PERCH-CIC), the Ministry of Higher Education, Science, Research and Innovation, and Mahidol University under the National Research Universities Initiative.


Abstract

The asymmetric synthesis of the novel pyranonaphthoquinones ventilanone A and ventilanone B, isolated from the Thai endemic plant Ventilago harmandiana, is accomplished by employing l-rhamnose and gallic acid as the starting materials. The key reactions are the utilization of a newly introduced reagent, PhSCF2H/SnCl4, for the formyl­ation of sterically hindered aromatics containing an electron-withdrawing methyl ester, and the efficient Hauser annulation of phenyl­thiophthalides with optically active C-1 glycals derived from l-rhamnose. The developed synthetic methodologies solve the long-standing problem of the formylation of sterically hindered aromatics containing electron-withdrawing groups, and are applicable for the synthesis of other analogues with substituents on the aromatic and pyran rings.

Supporting Information



Publication History

Received: 25 January 2022

Accepted after revision: 16 February 2022

Accepted Manuscript online:
16 February 2022

Article published online:
07 April 2022

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