New derivatives of (−)-neocembrene from the soft coral Sarcophyton trocheliophorum

First Total Synthesis and Absolute Configuration of (-)-13-Hydroxy-11,12-epoxy-neocembrene

“…17 Epoxidation of 15 with VO(acac) 2 -TBHP 18 gave 1 as the sole product (by 400 MHz 1 H NMR). 19 Synthetic 1 showed identical spectral data with those of natural product 1 reported, 3 and different spectral data with those of its isomer prepared by epoxidation of 15 with peracetic acid. 3 The optical property of synthetic…”

“…The cyclization precursor 2 was added slowly via a syringe pump to a suspension of low-valent titanium reagent (preformed by in situ reduction of TiCl 4 with zinc in the presence of a trace mount of pyridine 15 ) in DME under reflux over 10 hours to afford the desired cyclized ethers consisting of (-)-(3E,7E,11E)-13-(tert-butyldiphenylsiloxyl)neocembrene and its 3Z-isomer in a ratio of approximately 2.5:1 (by 400 MHz 1 H NMR). 7 Desilylation of the cyclized ether with tetra-n-butylammonium fluoride (TBAF) in THF 16 at 60°C for 24 h gave (-)-13-hydroxyneocembrene (15), 3 which has been synthesized by our group. 17 Epoxidation of 15 with VO(acac) 2 -TBHP 18 gave 1 as the sole product (by 400 MHz 1 H NMR).…”

“…The absolute configuration of C-1 and C-13 of 1 has been defined to be (1S,13S) by chemical transformation, but the absolute configuration of the epoxide function of 1 remains undetermined. 3 In continuation of our on-going program on the asymmetric synthetic studies of cembranoids, we report the first total synthesis of (-)-1.…”

“…Cembranoids, a family of 14-membered cyclic diterpenoid natural products existing in terrestrial and especially in marine organisms, 1 are of great interest to synthetic organic chemists and biologists because of their unique structure and wide range of biological activities. 2 (-)-13-Hydroxy-11,12-epoxy-neocembrene (1), a cembranoid which was isolated in 1988 by Suleimenova et al from the soft coral Sarcophyton trocheliophorum, 3 has been shown to be an effective inductor of the release of labelled glucose from the lecithincholesterol liposomes and has cytostatic activities. 4 Its chemical structure was characterized spectroscopically.…”

Marine natural products

“…Savcophyton trochefiophorum from the Seychelle Islands contains 13S-hydroxy-( -)-neocembrene (377), which was identified by X-ray analysis of the corresponding p-nitrobenzoate, and 13shydroxy-11,12-epoxy-( -)-neocembrene (378). 288 Research on the synthesis of marine cembranolides generally emphasizes methods for the formation of 14-membered rings. A radical cyclization route has been used in a formal of the lactone (379) from Sinufaria mayiZg0 and Lobophytum michaelae.…”