69748-52-3Relevant academic research and scientific papers
Facile and simple synthesis of ring C aromatic diterpenes: Synthesis of (+)-13-hydroxypodocarpa-8,11,13-triene and (+)-7-deoxynimbidiol
Villamizar, Jose E.,Gamez, Carlos,Alcala, Antonio,Salazar, Franklin,Tropper, Eleonora,Angarita, Ana,Canudas, Nieves
, p. 1733 - 1741 (2011/06/21)
A convenient synthesis of the natural (+)-13-hydroxypodocarpa-8,11,13- triene 1 and (+)-7-deoxynimbidiol 2 from (+)-manool 4 has been achieved in good overall yield.
Enantio- and diastereoselective stepwise cyclization of polyprenoids induced by chiral and achiral LBAs. A new entry to (-)-ambrox, (+)-podocarpa-8,11,13-triene diterpenoids, and (-)-tetracyclic polyprenoid of sedimentary origin
Ishihara, Kazuaki,Ishibashi, Hideaki,Yamamoto, Hisashi
, p. 3647 - 3655 (2007/10/03)
An enantio- and diastereoselective stepwise cyclization of polyprenoids induced by Lewis acid-assisted chiral Bronsted acids (chiral LBAs) and achiral LBAs is described. In particular, the absolute stereocontrol in the initial cyclization of polyprenoids to form an A-ring induced by chiral LBAs and the importance of the nucleophilicity of the internal terminator in polyprenoids for the relative stereocontrol in subsequent cyclization are demonstrated. (-)-Ambrox was synthesized via the enantioselective cyclization of (E,E)-homofarnesyl triethyrsily ether with triethylsilyl ether with tin(IV) chloride-coordinated (R)-2-(o-fluorobenzyloxy)-2′-hydroxy-1,1′-binaphthyl ((R)-BINOL-o-FBn) and subsequent diastereoselective cyclization with CF3CO2H·SnCl4 as key steps. Protection of (E,E)-homofarnesol by a triethylsilyl group increased the enantioselectivity of chiral LBA-induced cyclization and both the chemical yield and diastereoselectivity in the subsequent cyclization. The enantioselective cyclization of homo(polyprenyl)arenes possessing an aryl group was also induced by (R)-BINOL-o-FBn·SnCl4. Several optically active podocarpa-8,11,13-triene diterpenoids and (-)-tetracyclic polyprenoid of sedimentary origin were synthesized (75-80% ee) by the enantioselective cyclization of homo(polyprenyl)benzene derivatives induced by (R)-BINOL-o-FBn·SnCl4 and subsequent diastereoselective cyclization induced by BF3-Et2O/EtNO2 or CF3CO2H·SnCl4.
The synthesis and antibacterial activity of totarol derivatives. Part 1: Modifications of ring-C and pro-drugs
Evans, Gary B.,Furneaux, Richard H.,Gravestock, Michael B.,Lynch, Gregory P.,Scott, G.Kenneth
, p. 1953 - 1964 (2007/10/03)
A series of analogues of, and potential pro-drugs derived from, the potent antibacterial diterpene totarol (1) were synthesized in order to elucidate the minimum structural requirements for antibacterial activity and to seek compounds with good bioavailability in vivo. These analogues varied in the structural features of their aromatic rings and the prodrugs were O-glycosylated derivatives. They were tested in vitro against three Gram-positive bacteria: β-lactamase-positive and high level gentamycin-resistant Enterococcus faecalis, penicillin-resistant Streptococcus pneumoniae, and methicillin-resistant Staphylococcus aureus (MRSA); and against the Gram-negative multi-drug-resistant Klebsiella pneumoniae. None of the analogues was more potent than totarol itself, which is effective against these Gram-positive bacteria at MIC values of 7 μM. The results were evaluated in terms of a structure-activity relationship and this showed that a phenolic moiety was essential for potent antibacterial activity. Amongst the pro-drugs, totaryl α-D-mannopyranoside (22) proved the most active in vitro (MIC 18 μM). The in vivo antibacterial activities of compounds 1, 22 and totarol β-lactoside (23) were assessed in a mouse model of infection, but they were found to be ineffective. Compounds 1 and 22 were shown to be cytotoxic towards proliferating human cell cultures, CH 2983, HeLa, and MG 63, but only at concentrations of > 30 μM.
