A new carotenoid,halocynthiaxanthin from the sea squirt, halocynthiaroretzi

A new carotenoid, halocynthiaxanthin (5,6-epoxy-3,3′-dihydroxy-7′,8′-didehydro-5,6,7,8-tetrahydro-β,β-caroten-8-one) has been isolated from the Japanese sea squirt, $\text{Halocynthia}$ roretzi.     

Herpetetradione,nouveau lignoide tetramere isole d'Herpetospermum caudigerum wall.

The title compound, a new tetramer of coniferyl alcohol, has been isolated from seeds of $\text{Herpetospermum caudigerum}$ Wall. (Cucurbitaceae). Its structure was elucidated by spectroscopic means as $\text{rel}$-(7′S, 8′S, 7″S, 8″)-4,9,4′,4″,4″′,9″′-hexahydroxy-5,5′5″,5″′-tetramethoxy-7,7″′-dioxo-8.3′, 7′.0.9″,8′.8″,9′.0.7″,3″.8″′ -lignoïd.     

Ophioxanthin,a new marine carototenoid sulphate from the ophiuroid ophioderma longicaudum

A new carotenoid sulphate, Ophioxanthin, has been isolated from the ophiuroid $\text{Ophioderma longicaudum}$; ophioxanthin is the second known naturally occurring carotenoid sulphate and was shown to be 5,6,5′,6′-tetrahydro-β,β-carotene-3,4,3′,4′-tetraol 4,4′-disulphate ($\text{1}$).     

Synthesis of N-benzoyl-L-daunosamine from D-threonine

The synthesis of N-benzoyl-$\text{L}$-daunosamine (14) from the C₄$\text{threo}$ aldehyde (2b), prepared from $\text{D}$-threonine, through the intermediacy of the C₇ adduct (7a) is reported     

The sterepolides: new isolactaranes from stereumpurpureum

Sterepolide and dihydrosterepolide, new sesquiterpenes isolated from the fungus $\text{Stereum}$$\text{purpureum}$, are assigned structures $\text{4}$ and $\text{7}$, respectively. The assignments are based mainly on spectroscopic studies and similarities to isolactarorufin ($\text{5}$). A possible mode of biogenesis of these isolactarane type sesquiterpenes is discussed.     

Steroidal antifeedants from the dorid nudibranch Aldisasanguineacooperi

Two steroids, 3-oxo-chol-4-ene-24-oic acid ($\text{2}$) andi ts unsaturated analog $\text{4}$ have been isolated from the dorid nudibranch $\text{Aldisa}$$\text{sanguinea}$$\text{cooperi}$, and the acid $\text{2}$ has been shown to have antifeedant properties.     

O- versus N-methanesulphonylation and N-(methanesulphonyl)-methanesulphonylation with methanesulphonyl chloride

Depending upon the experimental conditions, t-butyl (1$\text{SR}$,5$\text{SR}$,7$\text{RS}$,8$\text{RS}$)-1-ethoxycarbonyl-8-hydroxy-2-oxa-6-azabicyclo[3.2.0]octane-7-carboxylate (2a) reacts with methanesulphonyl chloride to give predominantly the $\text{O}$-methanesulphonyl derivative (2b), the $\text{N}$-methanesulphonyl derivative (3a), or the $\text{N}$-(methanesulphonyl)methane-sulphonyl derivative (6a).     

Electronic spectra of 12-S-CIS conformationally locked retinals

The electronic absorption spectra of the four new 12-$\text{s}$-$\text{cis}$-locked retinals (1a–1d) bearing 7-$\text{trans}$, 11-$\text{trans}$ double bond geometries are described and compared with those of analogous 7-$\text{trans}$, 11-$\text{cis}$-geometries (1e–1h) and parent retinals (2a-h).     

Synthesis of N-benzoyl L- and D-2,3,6-trideoxy-3-aminoxylo-hexose from non-carbohydrate precursors

The enantiomeric alcohols ($\text{2}$) and ($\text{11}$), obtained from (2$\text{R}$,3$\text{R}$) tartaric acid and, respectively, $\text{L}$-threonine, have been used to construct the C₆, enantiomeric deoxy amino sugar derivatives ($\text{7}$) and ($\text{12}$)     

Synthesis of (1s,5r)-karahana ether and (1s,5r)-karahana lactone,the optically active forms of unique monoterpenes wit

(1$\text{S}$,5$\text{R}$)-(-)-Karahana ether (8,8-dimethyl-2-methylene-6-oxabi-cyclo[ 3.2.1]octane) and (1$\text{S}$,5$\text{R}$)-(-)-karahana lactone (8,8-dimethyl-2-methylene-6-oxabicyclo [3.2.1]octan-7-one) were synthesized from ($\text{S}$)-3-hydroxy-2,2-dimethylcyclo-hexanone. The natural karahana lactone was shown to be almost racemic ($\text{ca}$. 1.3 % e.e.).     

A new steroidal lactone with plant growth-regulatory activity from dolichoslablab seed

A new plant growth-promoting sterol was isolated from immature seeds of $\text{Dolichos}$$\text{labla}$. The structure was elucidated as (22$\text{R}$, 23$\text{R}$-2α, 3α, 22, 23-tetrahydroxy-B-homo-7-oxa-5α-ergost-24(28)-en-6-one $\text{1}$.     

Conversion of 6-protoilludene into illudin-M and -S by omphalotusolearius

Deuterium labeled $\text{dl}$-6-protoilludene ($\text{7}$) was synthesized and fed to the illudin-producing fungus $\text{Omphalotus}$$\text{olearius}$ (ATCC 11719). The hydrocarbon ($\text{7}$) was incorporated into illudin-M ($\text{2}$) and -S ($\text{3}$).     

Synthesis of 6-alkyl and 6-aryl substituted 9-β-D-ribofuranosyl purines via the nickel catalyzed coupling of grignard reagents to 2′,3′,5′-tris-0-(t-butyldimethylsilysl)-9-β-D-ribofuranosyl-6-chloropurine

A series of 6-substituted purine nucleosides have been synthesized in moderate yield by the nickel catalyzed cross coupling reaction between alkyl- and aryl- Grignard reagents and 2′,3′,5′-tris-0-(t-butyldimethylsilyl)-9-β-$\text{D}$-ribofuranosyl-6-chloropurine.     

Herpepentol,nouveau lignoide pentamere isole d'Herpetospermum caudigerum wall.

The title compound, a new pentamer of coniferyl alcohol has been isolated from seeds of $\text{Herpetospermum caudigerum}$ Wall. (Cucurbitaceae). Its structure was established by spectroscopic means as 4,9,9′,9″,9″′,4″″-hexahydroxy-5,5′,5″,5″′,5″″-pentamethoxy-7.0.4′,8.3′,7′.0.4″,8′.3″,7″.0.4 8″.3″′,7″′.0.9″″,8″8′.″″--lignoid.     

[2+2] Cycloaddition of benzyne to cis,trans- and cis,cis-1,5-cyclooctadiene

The relative rates of formation of $\text{cis}$ and $\text{trans}$ [2+2]cycloadducts of benzyne to $\text{cis}$, $\text{trans}$- and $\text{cis}$, $\text{cis}$-1,5-cyclooctadiene, $\text{trans}$- and $\text{cis}$-cyclooctene are discussed and properties of the adducts (e.g., their unusual hydrogenation) are described.     

The synthesis of 3-vinylindoles and 11H-5-cyanobenzol[a]carbazole

The synthesis of 3-vinylindoles through Wadsworth Emmons reactions with 3-formyl and 3-acylindoles is described. Although 3-formylindoles react directly with phosphonate derivatives, 3-acylindoles need prior activation by N-sulphonation. 11$\text{H}$-5-Cyanobenzo[$\text{a}$]carbazole has been prepared by the oxidative cycloaddition of $\text{E}$-3-(indol-3′-yl) propenotrile and benzyne.     

Synthesis and absolute configuration of +-lineatin,the pheromone of trypodendronlineatum

A new synthesis of (±), (+)- and (-)-lineatin (3,3,7-trimethyl-2, 9-dioxatricyclo [3.3.1.0^4,7] nonane, $\text{1}$) was achieved. The stereochemistry of (+)-lineatin was established as 1$\text{R}$, 4$\text{S}$, 5$\text{R}$, 7$\text{R}$ by an X-ray crystallographic analysis of an intermediate $\text{1}$$\text{5}$.     

N-Acylated α-aminonitriles and their conversion into 5-aminooxazole, 5(4h)-oxazolone and 4(5h)-imidazolone derivatives

In contrast with the reaction of α-aminonitriles $\text{1}$a, the corresponding $\text{N}$-acylated α-aminonitriles $\text{1}$b-f and oxalyl chloride do not yield pyrazinone derivatives, but 5-aminooxazoles $\text{9}$-$\text{11}$ or 4(5$\text{H}$)-imidazolones $\text{12}$, the latter being converted in some cases into imidazo [2,1-$\text{a}$]isoquinoline-2,5,6(3$\text{H}$)-triones. Reactions of compounds $\text{1}$b-f and ethyl chlorooxoacetate provide evidence for a 5(4$\text{H}$)-iminooxazole intermediate $\text{7}$, which aromatizes to yield 5-aminooxazoles $\text{9}$-$\text{11}$; however, unaromatizable īntermediates of type $\text{7}$ - isolable as 5(4$\text{H}$)y-oxazolones $\text{13}$ after hydrolysis - undergo a catalyzed Dimroth-type rearrangement to give imidazolone derivatives $\text{12}$.     

Diastereoselective synthesis of N-acetyl-D,L-acosamine and N-benzoyl-D,L-ristosamine

N-Acyl derivatives of $\text{D}$,$\text{L}$-acosamine and $\text{D}$,$\text{L}$-ristosamine were synthesized with high stereo selectivity utilizing intramolecular Michael addition of γ- and δ-carbomoyloxy-α,β-unsaturated esters.     

Spirostane derivatives highly oxygenated at A and B rings from the rhizomes of rohdeajaponica roth and of campylandra aurantiaca baker

Two steroidal compounds BR-1 (I) and ?2 (II) which had been obtained from the rhizomes of $\text{Campylandra aurantiaca}$ Baker, were isolated also from those of $\text{Rohdea japonica}$ Roth. They were identified, respectively, by X-ray analysis and chemical correlation as 1β,2β,3β,4β,5β,7α-hydroxy-spirost-25(27)-en-6-one and its corresponding 6β-hydroxy compound.