Alcyonolide,a novel diterpenoid from a soft coral

A novel diterpenoid acetate named alcyonolide has been isolated from an Okinawan soft coral of the genus $\text{Alcyonium}$ and the absolute stereostructure $\text{1}$ has been assigned on the basis of chemical and physicochemical evidence.     

Studies on highly oxidized cyclohexanes. Constitution of a new key metabolic intermediate.

The absolute stereostructure of (?)1,6 desoxypipoxide ($\text{2}$), a new plant metabolite of biosynthetic significance was assigned by spectral interpretation and chemical correlation with (+)pipoxide ($\text{1}$).     

The isolation and structure of tricyclosolidagolactone,a new diterpene from solidago altissima l.

Tricyclosolidagolactone has been isolated from the leaves of $\text{Solidago altissima}$ L., and its structure also been elucidated on the basis of its spectral data coupled with an X-ray crystallographic analysis of the corresponding trihydroxy compound produced on LiAlH₄ reduction.     

Luteone,a twenty three carbon terpenoid from the dorid nudi branch Cadlina luteomarginata

The structure of luteone ($\text{1}$), a twenty three carbon terpenoid, has been solved by performing a single crystal x-ray analysis on a 3,4-dinitrophenylhydrazone derivative.     

The structure of crotofolin E,A novel tricyclic diterpene from Croton corylifolius

A novel and highly functionalized crotofolane diterpene, crotofolin E ($\text{4}$), has been isolated from Croton corylifolius L. (Euphorbiaceae) and its stereostructure determined from spectral and X-ray crystall crystallographic analyses.     

The structure of ferrudiol. A highly oxidized constituent of uvaria ferruginea

Using spectroscopic and chemical methods, the title compound has been shown to posses stereostructure $\text{1}$ or its mirror image.     

Latrunculins: NMR study,two new toxins and a synthetic approach

A complete ¹H and ¹³C NMR assignment of one of the latrunculins (B) was accomplished with the aid of 2D NMR COSY and CH shift-correlation experiments. The various H-H Coupling constants have been datermined and a conformation of the macrolide and the tetrahydropyran (THP) ring suggested on basis of the J-values and measured NOE's. The absolute configuration of latrunculin-A($\text{1}$) was determined on the grounds of its earlier X-Ray analysis, and a chemical degradation to a known compound. Two novel latrunculins, -C($\text{3}$) and -D($\text{4}$), were isolated from the Red Sea sponge $\text{L. magnifica}$ and their structures elucidated. Starting with L-cysteine a synthon for the latrunculins has been synthesized.     

Structure of swinholide-a,a new macrolide from the marine sponge theonella swinhoei

Swinholide-A ($\text{1}$a) a novel 22-membered macrolide has been isolated from a Red Sea sponge. The structure of the tetraformate ($\text{1b}$) has been determined on basis of spectral data using 2D-NMR correlations.     

Teurilene and thyrsiferyl 23-acetate, meso and remarkably cytotoxic compounds from the marine red alga laurencia obtusa (hudson) lamouroux

Two new cyclic ethers consisting of squalene carbon skeleton have been isolated from the red alga L. obtusa. The absolute stereostructure of teurilene ($\text{1}$) was elucidated by x-ray crystallographic method, and the structure of thyrsiferyl 23-acetate ($\text{2}$) was established from the spectral and chemical evidence.     

Protogenkwanin 4′-glucoside,a new type of natural flavonoid with a non aromatic B-ring

From fertile sprouts of $\text{Equisetum arvense}$ L. (Equisetaceae) a flavonoid has been isolated and called protogenkwanin 4′-glucoside (2-(4-β-D-glucosyloxy-1-hydroxy-2,5-cyclohexadienyl)-5-hydroxy-7-methoxy chromone). Its structure has been established on the basis of chemical and spectroscopical evidences.     

Structure of laurycolactone A and B,new C18 - quassinoids from Eurycoma longifolia and revised structured of Eurycomalactone (X - ray analysis)

Laurycolactone A $\text{2}$ and B $\text{3}$ are new quassinoids with a C₁₈ basic skeleton isolated from the Vietnamese Simaroubaceae, Eurycoma longifolia Jack. The structure of Eurycomalactone, a C₁₉ quassinoid isolated previously from the same plant, has been revised and shown to be $\text{4}$. The structures have been established by spectral means and those of $\text{2}$ and $\text{4}$ confirmed by X-ray diffraction analysis.     

Studies on amino acids and peptides-III. 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide,LR, as a new racemization free coupling reagent in peptide synthesis

The easily accessible 2,4-bis (4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide, $\text{LR}$, has been reacted with salts of N-protected amino acids $\text{1}$ (Z-Gly-OH, Boc-Gly-OH, Boc-S-Ser(Bzl)-OH, Boc-S-Tyr(Bzl)-OH, Z-S-Arg(Z₂)-OH, and Z-S-Pro-OH), at room temperature in CH₂Cl₂ to give the intermediates $\text{2}$, mixed anhydrides. When $\text{2}$ is treated with two moles of a base and one mole of the salt of an amino acid ester $\text{3}$ (TosOH·H-Gly-OBzl, HCl·H-Gly-OBzl, HCl·H-Gly-OEt, and HCl·H-S-Phe-OtBu) at 0°C, the expected peptide $\text{4}$ is isolated in high yields. LR is also found to be a useful reagent in a fragment coupling between Z-Gly-S-Ala-OH and TosOH·H-S-Leu-OBzl). This tripeptide was tested by means of HPLC (deprotection and amino acid analysis according to Izumiya was not necessary), and no epimerization (<0.7 %) was observed.     

Muqubilin,a new c24-isoprenoid from a marine sponge

The Red Sea sponge $\text{Prianos}$ sp. contains a cyclic peroxide C₂₄ - nor sesterterpene, Muqubilin ($\text{1}$). The structure of $\text{1}$ was deduced from spectroscopic data and by chemical degradation.     

Senecicannabine,a new pyrrolizidine alkaloid from senecio cannabifolius

The structure of senecicannabine($\text{1}$), a new mcrocyclic pyrrolizidine alkaloid isolated from $\text{Senecio cannabifolius}$, has been established by chemical study and X-ray analysis.     

The intramolecular nitrile oxide cycloaddition (INOC) route to the ergot alkaloids: Use of the isoxazoline to γ-amino alcohol conversion in the total synthesis of (+)-paliclavine

A total synthesis of the ergot alkaloid paliclavine ($\text{20}$), in optically active form is described. The synthesis scheme is based on the intramolecular dipolar cycloaddition reaction of a nitrile oxide to a neighboring olefinic appendage bearing an allylic asymmetric center. The extent of diastereofacial selection in the intramolecular nitrile oxide cycloaddition (INOC) reaction was found to be marginal. A single-crystal X-ray analysis has established the complete stereostructure of the isoxazoline $\text{15}$ prepared from the “major” INOC product. The dependence of the reduction stereochemistry of the isoxazolinium salt $\text{15a}$ on the nature of the reducing agent is discussed.     

Structure of absintholide a new guaianolide dimer of Artemisia absinthium L.

Absintholide $\text{1}$ is a new guaianolide dimer whose structure and stereochemistry has been elucidated on the basis of high resolution n.m.r.     

Ajugareptansin,a new diterpenoid from ajuga reptans (L.)

The structure of a new clerodane diterpene, isolated from $\text{Ajuga}$$\text{reptans}$, has been elucidated by chemical and spectral means and confirmed by X-ray crystallographic studies of the corresponding $\text{p}$-bromobenzoate.     

Structure of aszonalenin,a new metabolite of aspergillus zonatus

Aszonalenin ($\text{1}$) has been isolated from $\text{Aspergillus zonatus}$ together with LL-S490β ($\text{2}$) and the structure of $\text{1}$ has been established by spectroscopic evidences and chemical transformation.     

Caraibical,a new aromatic sesquiterpene from the marine alga laurenciacaraibica

Caraibical, a new aromatic sesquiterpene aldehyde, has been isolated from the marine marine red alga $\text{Laurencia}$$\text{caraibica}$. The structure, which possesses an ether cyclization differing from previous compounds, was defined on the basis of its spectral data.