Sesterterpenoids

Abstract

The literature concerning sesterterpenoids is reviewed. They are a group of pentaprenyl terpenoids with diverse biological properties, attractive targets for both biomedical and synthetic purposes.

A Geranylfarnesyl Diphosphate Synthase Provides the Precursor for Sesterterpenoid (C25) Formation in the Glandular Trichomes of the Mint Species Leucosceptrum canum

“…Sesterterpenoids have been reported from widespread sources (vascular plants, lichens, terrestrial fungi, insects, and various marine organisms especially sponges) and have attracted extensive interest due to their novel and complex structures as well as various biological activities (Liu et al, 2007;Wang et al, 2013;Zhang and Liu, 2015). However, their biosynthetic pathways have not been well investigated to date, with only a few related genes and enzymes reported from microorganisms (Tachibana, 1994;Tachibana et al, 2000;Ogawa et al, 2010;Chiba et al, 2013;Matsuda et al, 2015;Qin et al, 2015;Ye et al, 2015).…”

Synthetic approaches toward sesterterpenoids

“…The aldehyde fragment 63 was prepared in a straightforward manner from diol 62, that was in turn obtained from (E,E) farnesyl acetate by chemo and enantioselective dihydroxylation. When the key aldehyde/alkyne coupling step was attempted using Ni(cod) 2 with Et 3 B and Bu 3 P, the reaction exhibited low regioselectivty (1.5 : 1) and no diastereoselectivity (1 : 1). Fortunately, replacing Bu 3 P with a P chiral phosphine ligand 64 enabled the formation of the desired alcohol 65 with enhanced regioselectivity (2 : 1) and modest, but synthetically useful diastereoselectivity (3 : 1).…”

“…Although the authors did not specify the precise identity of the Scheme 18 Kishi's asymmetric synthesis of (+) ophiobolin C using an intramolecular NHK reaction. DHP 3,4 dihydro 2H pyran, PPTS pyr idinium p toluenesulfonate, Saegusa Ito TMS enol ether formation, then Pd(OAc) 2 intermediates in this sequence, it involved a Dieckmann cycli zation that ultimately gave rise to tricyclic ketone 172. An additional four step protocol, including a regio and diaster eoselective reduction of the diketone with LiAl(Ot Bu) 3 H, eventually leading to mesylate 173, the substrate for the key Grob fragmentation reaction.…”

“…12,13 They achieved the synthesis via the chiral auxiliary controlled diastereoselective alkylation of a tetronic acid derivative and a series of standard olefinations to install the double bonds with the required configurations. Similar to the synthesis of okonellin B (1), the isolated allylic stereogenic center bearing a methyl group was incorporated starting from the (R) Roche ester ent (2).…”

“…A b lactone 3 was employed to address the stereoselective synthesis of the highly substituted g butyro lactone within okinonellin B (1). The absolute configuration of the isolated allylic stereocenter bearing a methyl group origi nated from the commercially available (S) Roche ester (2). In 2001, Norizuki and co workers 8 synthesized ( ) idiadione (4) 9 starting from (S) citronellal, establishing the single stereogenic center to be (S) configured ( Recently, Gomez and Fall accomplished the enantioselective synthesis of (+) palinurin (6), which was found to act as a non competitive inhibitor of GSK 3b, a kinase implicated in Alz heimer's desease.…”