Synthesis and determination of the absolute configuration of (−)-(5R,6Z)-dendrolasin-5-acetate from the nudibranch Hypselodoris jacksoni

• I. Wayan Mudianta,
• Victoria L. Challinor,
• Anne E. Winters,
• Karen L. Cheney,
• James J. De Voss and
• Mary J. Garson

Beilstein J. Org. Chem. 2013, 9, 2925–2933, doi:10.3762/bjoc.9.329

• , Australia 10.3762/bjoc.9.329 Abstract A small sample of (−)-(5R,6Z)-dendrolasin-5-acetate, which was fully characterized by 2D NMR studies, was isolated from the nudibranch Hypselodoris jacksoni, along with the sesquiterpenes (+)-agassizin, (−)-furodysinin, (−)-euryfuran, (−)-dehydroherbadysidolide and

SF002-96-1, a new drimane sesquiterpene lactone from an Aspergillus species, inhibits survivin expression

• Silke Felix,
• Louis P. Sandjo,
• Till Opatz and
• Gerhard Erkel

Beilstein J. Org. Chem. 2013, 9, 2866–2876, doi:10.3762/bjoc.9.323

• second geminal methyl group (δ 0.97) showed spatial correlations with a methine proton at δ 1.94 and two downfield protons at δ 4.02 and 5.72. Based on the absolute configuration reported for drimane sesquiterpenes [14][15], the trans-decalin core of SF002-96-1 was tentatively assigned the configurations

• promoter and subsequently triggering apoptosis in Colo 320 cells. Drimane sesquiterpenes are widespread in plants, fungi and marine organisms such as algae, sponges and corals and have attracted some attention for their potent antibacterial, antifungal, cytotoxic, antifeedant, phytotoxic, piscicidal and

A concise enantioselective synthesis of the guaiane sesquiterpene (−)-oxyphyllol

• Martin Zahel and
• Peter Metz

Beilstein J. Org. Chem. 2013, 9, 2028–2032, doi:10.3762/bjoc.9.239

• ). Retrosynthetic analysis for (−)-oxyphyllol (1) and structures of the guaiane sesquiterpenes (+)-orientalol E (2) and (−)-englerin A (5). Attempted selective deoxygenation of diol 7. a) 1 mol % K2OsO4, NMO, acetone, water, THF, rt, 97%, diastereomeric ratio = 2:1 (ref. [6]); b) PhOC(S)Cl, pyridine, CH2Cl2, 0 °C

Synthesis of the tetracyclic core of Illicium sesquiterpenes using an organocatalyzed asymmetric Robinson annulation

• Lynnie Trzoss,
• Jing Xu,
• Michelle H. Lacoske and
• Emmanuel A. Theodorakis

Beilstein J. Org. Chem. 2013, 9, 1135–1140, doi:10.3762/bjoc.9.126

• majucin-type sesquiterpenes is described here. This strategy is based on an organocatalyzed asymmetric Robinson annulation and provides an efficient approach for a diversity-oriented synthesis of Illicium natural products that holds remarkable therapeutic potential for neurodegenerative diseases

• the central neural system and considerable manufacturing cost [6][7]. These limitations have stimulated the search for small molecules that can enhance or mimic neurotrophin activity as potential drug leads [8][9][10][11][12]. Majucin-type Illicium sesquiterpenes (Figure 1) [13], such as majucin (1

• to low micromolar concentrations. Thus, to develop an efficient synthetic approach toward the complex core skeleton of these natural products is of paramount importance. Consequently, this family of neurotrophic sesquiterpenes has been the focus of extensive synthetic studies in which asymmetric and

Caryolene-forming carbocation rearrangements

• Quynh Nhu N. Nguyen and
• Dean J. Tantillo

Beilstein J. Org. Chem. 2013, 9, 323–331, doi:10.3762/bjoc.9.37

• formation, applying the principles derived from previous theoretical studies on terpene-forming carbocation rearrangements [8]. In this mechanism, formation of the C1–C11 bond was expected to result in secondary carbocation B, in analogy to previously characterized pathways to sesquiterpenes containing 11

Synthesis of 2,6-disubstituted tetrahydroazulene derivatives

• Zakir Hussain,
• Henning Hopf,
• Khurshid Ayub and
• S. Holger Eichhorn

Beilstein J. Org. Chem. 2012, 8, 693–698, doi:10.3762/bjoc.8.77

• ; ring expansion; Introduction Hydroazulene skeletons provide the basic ring systems of natural products, such as guaianolide sesquiterpenes [1][2] and the so-called furanether B series [3][4]. The stereoselective synthesis of trans-hydroazulene derivatives by a tandem Michael/intramolecular Wittig

Toward an integrated route to the vernonia allenes and related sesquiterpenoids

• Da Xu,
• Michael A. Drahl and
• Lawrence J. Williams

Beilstein J. Org. Chem. 2011, 7, 937–943, doi:10.3762/bjoc.7.104

• . Fragmentation of a suitable decalin derivative gave the simplified germacrane scaffold. Computational analysis of this and related substrates provides insight into the stereoelectronic requirements of C–C fragmentation. The overall strategy to access these and other sesquiterpenes and the key steps in the

Rh(I)-catalyzed intramolecular [2 + 2 + 1] cycloaddition of allenenes: Construction of bicyclo[4.3.0]nonenones with an angular methyl group and tricyclo[6.4.0.0^1,5]dodecenone

• Fuyuhiko Inagaki,
• Naoya Itoh,
• Yujiro Hayashi,
• Yumi Matsui and
• Chisato Mukai

Beilstein J. Org. Chem. 2011, 7, 404–409, doi:10.3762/bjoc.7.52

• the α,β-unsaturated ketones 2. By taking advangage of this newly developed reaction, we have completed the first total syntheses of two tricyclic sesquiterpenes 6a,b, isolated from Jatropha neopauciflora, from the methoxycarbonylallenene 4 via the bicyclo[4.3.0]nonenone derivative 5 [24]. The key step

High stereoselectivity on low temperature Diels- Alder reactions

• Luiz Carlos da Silva Filho,
• Valdemar Lacerda Júnior,
• Mauricio Gomes Constantino,
• Gil Valdo José da Silva and
• Paulo Roberto Invernize

Beilstein J. Org. Chem. 2005, 1, No. 14, doi:10.1186/1860-5397-1-14

• sesquiterpenes, labdanic and hydrophenanthroid diterpenes, steroids, and tetracyclic and pentacyclic triterpenes) [5][6]. The role of the Lewis acid is to produce an extra lowering of the LUMO energy of the carbonyl substrate, through complexation with the carbonyl oxygen thus reducing the electron density of