Callviminols A-E, new terpenoid-conjugated phloroglucinols from the leaves of Callistemon viminalis.

Callviminols A-E ( 1 – 5 ), five rare phloroglucinols bearing a framework embodying a hexahydrodibenzo[ b , d ]furan or 2-phenylcyclohexanol nucleus derived from a phloroglucinol-monoterpene adduct, were isolated from the leaves of Callistemon viminalis . Their structures were established via extensive spectroscopic measurements, with the absolute configuration of 5 determined by electronic circular dichroism (ECD) calculations. The plausible biogenetic pathway suggested that a unique oxidative radical addition and classic cationic cyclization were key biosynthetic steps. [ABSTRACT FROM AUTHOR]