Concise synthesis of (+)-machaeriols A, B, C, and their enantiomers

ORGN 672

Xin Li, xinxin2019@hotmail.com1, Hee Jin Lee, devil5425@hotmail.com2, Likai Xia, xialikai@hotmail.com1, and Yong Rok Lee, yrlee@yu.ac.kr2. (1) School of Chemical Engineering and Technology, Yeungnam University, Gyeongsan, 712-749, South Korea, (2) School of Chemical Engineering and Technology, Yeungnam University, Gyeongsan, 712-749, South Korea
Machaeriols A, B, C, and D bearing the cannabinoid structure,were recently isolated from the bark of the Machaerium multiflorum spruce. They have been reported to have potential in vitro antimicrobial activity against Staphylococcus aureus and methicillin-resistant S. aureus. They also showed potent in vitro antimalarial activity against Plasmodium falciparum D6 and W2 clones. These important biological activities have led to the development of a variety of synthetic approaches to these natural products. Total synthesis of biologically interesting (+)-machaeriols A, C, and their enantiomers has been achieved from a readily available aryl aldehyde or aryl ester, respectively. The key steps are stilbene formation by a Horner-Wadsworth-Emmons reaction and trans-hexahydrodibenzopyran formation by domino reaction. The concise synthesis of (+)-machaeriol B and its enantiomer has been also accomplished from o-phenylhydroxyamine in 4 steps. The key strategies in the syntheses of (+)-machaeriol B and its enantiomer involved benzofuran formation through a [3,3]-sigmatropic rearrangement and trans-hexahydrodibenzopyran formation by a domino reaction.