Chiral resolution, absolute configuration of two pairs of unusual monoterpene enantiomers from Eupatorium fortunei. Issue 13 (26th March 2020)

• Record Type: Journal Article
• Authors: Shi, Jing; Yuan, Min; Yu, Yue; Shi, Sheng-Bin; Liu, Yu-Guo
• Is Part Of: Tetrahedron letters. Volume 61:Issue 13(2020)
• Publication Date: 2020-03-26
• Subjects: Eupatorium fortunei -- Monoterpene -- Chiral resolution -- Benzocyclobutene; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2020.151655
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Highlights: Two unusual monoterpene racemates were isolated from Eupatorium fortunei . Subsequent chiral resolution led to the separation of two pairs of enantiomers. The compounds are the first example of monoterpenes possessing benzocyclobutene ring. A plausible biogenetic pathway for them was proposed. Abstract: Two unusual monoterpene racemates, (±)-eupafortin A (1 ) and (±)-eupafortin B (2 ), were isolated from the aerial parts of Eupatorium fortunei . Subsequent chiral resolution led to the separation of two pairs of enantiomers, (+)- (1a ) and (–)-eupafortin A (1b ), (+)- (2a ) and (–)-eupafortin B (2b ), respectively. Their structures including absolute configurations were deduced based on spectroscopic analyses and ECD calculations. The isolated compounds are the first example of monoterpenes possessing benzocyclobutene skeleton in natural products and a plausible biogenetic pathway for them was proposed. These compounds exhibited moderate inhibitory activity against nitric oxide (NO) production in lipopolysaccharide-induced (LPS) RAW 264.7 macrophage cells.