A short synthesis of (±)-laurene: mechanistic reinvestigation in palladium-catalyzed cycloreductions of 1,6-enynes

Cycloisomerization of 1,n‐Enynes: Challenging Metal‐Catalyzed Rearrangements and Mechanistic Insights

“…[37] Enyne 67 was transformed to carbocycle 68 or 69 in moderate to good yields, depending on the conditions used [Eqs. (22) and (23)].…”

“…[53] The cycloisomerization of enyne 122 was carried out in the presence of either [CpRu(CH 3 CN) 3 ]PF 6 or [Cp*Ru(CH 3 CN) 3 ]PF 6 (Cp*: C 5 Me 5 ) In both cases, the N-tosylpyrrolidine 123 was obtained in good yield and high diastereomeric ratio [Eq. (37)]. The relocated double bond was found to have an E configuration.…”

Progress in the Chemistry of Organic Natural Products 102

“…Many snyderanes contain a cyclohexane ring with an acyclic side chain (247)(248)(249)(250)(251)(252)(253)(254)(255)(256)(257)(258)(259)(260)(261)(262)(263)(264)(265), while some of them feature 2,7-epoxy (266-281), 3,7-epoxy (282), or 4,7-epoxy (283-289) rings in their structures, thus forming 6,7-, 6,6-, or 6,5-fused systems. They are monocarbocyclic sesquiterpenes arising from the formation of a six-membered ring between carbons C-6 and C-11 of farnesane.…”

Nonhalogenated organic molecules from Laurencia algae

“…nipponica from Japan was the source of laurane sesquiterpenes 25-30 (Suzuki et al 1982), and the absolute configurations of these compounds as well as 24 (from Australian L. filiformis f. heteroclada) were established based on the chemical conversion to laurene (23) (Kazlauskas et al 1976), which was obtained originally from Japanese L. glandulifera with the absolute configuration being assigned by a series of chiral syntheses (Irie et al 1965(Irie et al , 1967(Irie et al , 1969Oh et al 2000;Nemoto et al 1992Nemoto et al , 1993Kulkarni and Pendharkar 1997;Bailey et al 1995;Sunderbabu 1989, 1990). A hydroxylated derivative (31) and an isomer (33) of laurene were identified from Californian L. subopposita and Greek L. microcladia, respectively (Kladi et al 2007;Wratten and Faulkner 1977), and the latter was previously reported to be a byproduct in the synthesis of laurene using two palladium-catalyzed cycloreduction strategies (Oh et al 2000). Compounds 31 and 32 exhibited higher antibacterial activity and brine shrimp toxicity than laurene, which suggested that the hydroxyl and acetoxyl groups at C-7 could be crucial to these activities (Liang et al 2012;Wratten and Faulkner 1977;Li et al 2012b).…”