Synthesis of 2β-fluoro-1α-hydroxyvitamin D3

2β-Fluoro-1α-hydroxyvitamin D₃($\text{3}$) was prepared from 1,2α-epoxy-cholest-5-en-3β-yl tetrahydropyranyl ether($\text{1a}$ via 2β-fluorocholest-5-ene-1α, 3β-diol($\text{2}$).     

Shinjulactone C,a new quassinoid ith a 1α, 12α:5α, 13α-dicyclo-9βH-picrasane skeleton from ailanthus altissima SWINGLE

A new non-bitter quassinoid, named shinjulactone C ($\text{1}$), was isolated from the root bark of $\text{Ailanthus altissima}$ SWINGLE and shown to be 1α, 12α:5α, 13α-dicyclo-1β, 12β, 20-trihydroxy-9β$\text{H}$-picras-3-ene-2, 11, 16-trione by X-ray diffraction method.     

The Neutral Part of the Bark of Pinus Taiwanensis Hayata

The neutral part of the acetone extract from the bark of Pinus taiwanensis Hayata has been Investigated and found to consist of alkanes (C₁₄-C₃₃), longifolene, aliphatic esters (C₄₂, C₄₄, C₄₉), aliphatic alcohols (C₂₄, C₂₆), 3β-21α-dimethoxyserrat-14-enc, 3β-methoxyserrat-14-en-21-one, β-sitosterol, 3β-methoxyserrat-14-en-21ã-ol and 3β-hydroxyserrat-14-en-21-one.     

Hydroxylation of dammarane type triterpenes with m-chloroperbenzoic acid

Dammaran-20(S)-ol and 20(S)-hydroxydammaran-3β-yl acetate were reacted with $\text{m}$-CPBA to give the corresponding 5α-ol, 7β-ol, 12β-ol, 25-ol, 2α-ol, and 5α,25-diol.     

Studies on the stereochemical course of intramolecular cycloaddition reactions of olefinic o-quinodimethanes-stereoselective synthesis of 8α, 9α, 14β-estranes

The stereoselective synthesis of 3-O-methyl-7α-$\text{p}$-toluenesulphonyl-8α, 9α, 14β-estradiol ($\text{25}$) and its 11-oxo derivative ($\text{26}$) $\text{via}$ thermolysis of 1β-$\text{tert}$-butoxy-2α-[2-(4-methoxybenzocyclobutenyl)ethyl]-2β-methy1-3α-[2-($\text{p}$-toluenesulphonyl)ethenyl] cyclopentane ($\text{22}$) and its oxo derivative ($\text{24}$), which were derived from condensation product ($\text{9}$) of optically active aldehyde ($\text{8}$) and 1-cyano-4-methoxybenzocyclobutene through $\text{10}$ and $\text{11}$ to selenides $\text{16}$ and $\text{21}$, is described.     

Two New Daucane Sesquiterpenoids from <em>Daphne aurantiaca</em>

Two new daucane sesquiterpenoids 1β,2β-epoxy-10(H)α-dauca-11(12)-ene-7α,14-diol (1) and 1α,2α-epoxy-10(H)α-dauca-11(12)-ene-7α,14-diol (2) were isolated from the plateau medicinal plant Daphne aurantiaca Diels. (Thymelaeceae). Their structures were elucidated by 1D and 2D NMR spectroscopy, as well as HR-ESI-MS data.     

New antimicrobial diterpenes from the sponge spongia officinalis

The methanol extract of the sponge Spongia officinalis from Pt. Guimar, Tenerife (Canary Islands) contained new diterpenoids which inhibited the growth of microbes. The structures of the new diterpenes isolated were determined as; 11β-hydroxyspongi-12-en-16-one ($\text{2}$), 11β-acetoxyspongi-12-en-16-one ($\text{3}$), 7β,11β-dihydroxy8pongi-12-en-16-one ($\text{5}$), and 7β,11α-dihydroxy-spongi-12-en-16-one ($\text{6}$), by spectral and chemical degradation studies. The previously reported diterpenes isoagatholactone ($\text{1}$) and aplysillin ($\text{4}$) were also found in the extract.     

Isolation ofΔ9(11)-sterols from the sea cucumber psolusfabricii. Implications for holothurin biosynthesis

- 14α-Methyl-5α-cholest-9(11)-en-3β-ol ($\text{2}$) and 4α,14α-dimethyl-5α-cholest-9(11)-en-3β-ol ($\text{3}$) have been isolated from the sea cucumber $\text{Psolus}$$\text{fabricii}$ and characterised by ¹H NMR, ¹³C NMR and mass spectrometry. Lanost-9(11)-en-3β-ol ($\text{4}$) has also been tentatively identified. The relevance of this series of Δ⁹⁽¹¹⁾-sterols to holothurin biosynthesis is briefly discussed.     

Chemical synthesis of phosphorylated fundamental structure of lipid a

1-α-Monophosphate ($\text{2}$), 4′-monophosphate ($\text{3}$), and 1-α, 4′-diphosphate ($\text{4}$) of 6-0-(2-deoxy-2-tetradecanoylamino-6-0-tetradecanoyl-β-D-glucopyranosyl) -2-deoxy-2-tetradecanoylamino-3, 4-di -0-tetradecanoyl-D-glucopyranose were prepared in order to elucidate the role of phosphate moieties in endotoxic activity of lipid A.     

A convenient synthesis of flindersine,atanine and their analogues

A new synthesis of the pyranoquinolone alkaloids flindersine ($\text{8a}$), 8-methoxyflindersine ($\text{8c}$), N-methylflindersine ($\text{9a}$), zanthobunglanine ($\text{9c}$) oricine ($\text{9d}$) and veprisine ($\text{9e}$) and the prenylquinolone alkaloids atanine ($\text{13a}$), preskimmianine ($\text{13e}$) N-methylatanine ($\text{14a}$), O-methylglycosolone ($\text{14c}$) and N-methylpreskimmianine ($\text{14e}$) is described.     

Plectranthoic acid A & B, two new triterpenoids from Plectranthus rugosus

Two new triterpenoid acids, designated as plectranthoic acid A and plectranthoic acid B, have been isolated from P. rugosus and are characterised as (20-S)-3α-hydroxy-18α,19α-$\text{H}\text{-}$-urs-12-en-30β-oic acid and (14-S)-3α-hydroxy-18α, 19α $\text{H}\text{-}$-urs-12-en-27α-oic acid.     

Ritter-reaction on steroids: Ring expansion of steroid oxethans into dihydrooxazines

The 3β-acetoxy-16β,17β-epoxymethyleneandrost-5-ene ($\text{1}$) transforms into the dihydrooxazine condensed to the sterane skeleton ($\text{4}$$\text{a}$,$\text{b}$,$\text{c}$,$\text{e}$,$\text{g}$,$\text{i}$) in a ring-expansion reaction with alkyl and aryl nitriles in the presence of HBF₄— diethyletherate The 3β-acetoxy-16α, 17α-epoxymethyleneandrost-5-ene ($\text{9}$) undergoes a Wagner-Meerwein rearrangement under similar conditions.     

Synthesis,structure, and reactions of thiocarbonic acid derivatives new pentathiodipercarbonates, (RSS)2 CS, α,α,α-tris(disulfides), and the first α,α,α-tris(trisulfide)

Novel bis(perhaloalkyl) pentathiodipercarbonates $\text{5b-d}$ have been synthesized by reaction of sulfenyl chlorides with metal trithiocarbonates, and the heptathio analog $\text{21a}$ was prepared similarly. Lenthionine $\text{19}$ is the main product when diiodomethane is treated with sodium tetrathiopercarbonate. A rearrangement of bis(alkyldithio)chloromethanesulfenyl chlorides $\text{22}$ to alkyldithio) (alkyltrithio)dichloromethanes $\text{24}$ has been observed. Additions of sulfenyl chlorides and of thiosulfenyl chlorides to the thiocarbonyl compounds $\text{5}$ and $\text{21a}$ were achieved in acetonitrile. The structures of the first crystalline pentathiodipercarbonate $\text{5a}$ and α,α,α-tris(disulfide) $\text{29a}$, and of the first reported α,α,α-tris(trisulfide)$\text{31a}$ have been determined by X-ray crystallography.     

Synthese eines daunomycin-modells mit honocyclischem aglycon

By condensation of (1S,3S)-1-acetyl-cyclohex-4-ene-1,3-diol ($\text{6}$) with daunosaminylchlorid $\text{7}$ predominatly the α-L-glycosid $\text{10}$ is obtained. As an anthracycline model containing all structural elements except those appropriate for intercalation this compound requires interest with respect to the elucidation of its complex formation with DNA.     

Vicinal diester dianions. Annelation with ω-bromoesters. A simple preparation of bicyclo[4.4.0] decan-2-one derivatives valuable in sesquiterpene synthesis.

The dianion of dimethyl, cyclohex-4-ene-1,2-dicarboxylate ($\text{1}$) can be annelated with ethyl 4-bromobutyrate ($\text{2}$) to give cis-dimethyl 1,2,3,5-tetrahydro-1-oxo-4a(4H), 8a (8H)-naphthalenedicarboxylate ($\text{5}$), which is readily transformed into $\text{8a}$, a synthetic intermediate for a number of sesquiterpene syntheses.     

Novel Nor and Seco Triterpenoids from Koelpinia linearis

Three novel triterpenoids, C:D seco (8→14) urso-8(26),12(13)-dien-3β-ol, C:D seco (8→14) urso-8(26),13(14)-dien-3β-ol, and C:Dseco (8→14),27 nor-urso-12-ene-3β-20α-diol were isolated from Koelpinia linearis and characterized by spectral and chemical methods.     

A novel synthesis of carbacyclin analogs via a stereoselective introduction of 15α-hydroxy group

(+/-)-6,9α-Methanoprostaglandin I₃, ($\text{2}$) and (+/-)-5,6-dihydro-6,9α-methano-6β-prostaglandin I₃, ($\text{4a}$) have been synthesized using a new method for the stereoselective introduction of the 15α-hydroxy group via a stereoselective electrophilic addition of phenyl-sulfenyl chloride to the enol ether ($\text{6}$) and ($\text{23}$) respectively.     

Total synthesis of Δ9(12)-capnellene-8α,10α-diol

A total synthesis of (11), the 8-epimer of Δ⁹⁽¹²⁾-capnellene-8β,10α-diol (1,RH) found in the soft coral $\text{Capnella imbricata}$ is described.     

Officinatrione: an unusual (17S)-17,18-seco-lupane skeleton,and four novel lupane-type triterpenoids from the roots of Taraxacum officinale

Novel 5 lupane-type of triterpenois, i.e., 3β-acetoxy-18α,19α-epoxylupan-21β-ol (1), 18α,19α-epoxy-21β-hydroxylupan-3-one (2), lup-18-ene-3,21-dione (3), lupa-18,21-dien-3β-yl acetate (4), and (17S)-17,18-seco-lup-19(21)-ene-3,18,22-trione (5), named officinatrione, as well as 16 known compounds from the roots of Taraxacum officinale collected in Takatsuki city, Osaka, Japan. Of the above compounds, 5 was the first lupane-type triterpene, of which the D-ring was open to form a nine-membered ring. Compounds 2 and 5 exhibited moderate cytotoxic activities against L1210 cell line (IC₅₀ 10.5 and 10.1 μM).     

Extended hopane derivatives in sediments: identification by 1H NMR

The sedimentary C₃₂ hopanoic acid $\text{3a}$, one of the most abundant in nature and of probable bacterial origin, has been isolated for the first time as a single component and characterised by ¹H NMR. The 17αH,21βH configuration of the C₃₁ alkane has been similarly confirmed.