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 $\text{1}$.     

Isolation of sterols with cyclopropyl-containing side chains from the cultured marine alga peridiniumfoliaceum

The sterol fraction of the cultured dinoflagellate $\text{Peridinium}$$\text{foliaceum}$ contains in addition to cholesterol, 24-methylcholesterol, 4,24-dimethylcholesterol and dinosterol ($\text{3c}$) small amounts of the cyclopropyl-containing sterols gorgosterol ($\text{1a}$) and 5α-gorgostanol ($\text{1b}$) as well as 4α-methylgorgostanol ($\text{1c}$) and E-4α,22ξ,23ξ (or 24ξ)-trimethylcholest-17(20)-en-3β-ol ($\text{6c}$ or $\text{7c}$). The biosynthetic implications of the first isolation of such sterols from a free-living alga are emphasized.     

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.     

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.     

Four novel C28 sterols from lobophytum depressum

Four novel polyoxygenated C₂₈-sterols have been identified from the soft coral $\text{L. depressum}$ (the Gulf of Eilat, the Red Sea): the 22,28-lactol of 24-methylcholest-5-en-3β,22(R),25-triol-28-al ($\text{1}$), 24-methylcholest-5-en-3β,22(R),25,28-tetraol($\text{2}$) and the corresponding 5,6β-epoxides ($\text{3}$ and $\text{4}$).     

Stereoselective synthesis of (25R)-25,26-dihydroxy-23-oxovitamin D3 and its enzymatic conversion to (25R)-1α,25,26-trihydroxy-23-oxovitamin D3, a putative metabolite of vitamin D3

(25$\text{R}$)-25,26-Dihydroxy-23-oxovitamin D₃ was synthesized efficiently and stereoselectively, and it was converted enzymatically to (25$\text{R}$)-1α,25,26-trihydroxy-23-oxovitamin D₃, a putative metabolite of 1α,25-dihydroxyvitamin D₃. The spectral and chemical properties of (25$\text{R}$)-25,26-dihydroxy-23-oxovitamin D₃ and its 1α,hydroxylated derivative disagree with those reported for the isolated metabolite.     

A synthetic approach to (+)-aldosterone and its relatives (2)- a stereoselective synthesis of (+)-trans-4,5-(4-methoxybenzo)- 1β , 7aβ - ( 2α-methoxymethyl- 5 -oxofuro) hydrindane

A stereoselectivity in an intramolecular cycloaddition of the olefinic $\text{o}$-quinodimethanes 13 and 23 generated $\text{in}$$\text{situ}$ from the thermolysis of optically active 4β-[2-(4-methoxybenzocyclobutenyl)ethyl] -5α-methoxymethyl-3-phenyl-thio-methylenefuran-2-ones 12 and 22, respectively, is studied and a stereoselective synthesis of (+)-$\text{trans}$-4,5-( 4-methoxybenzo) -1β,7aβ-(2α-methoxymethyl-5-oxofuro)hydrindane 1 is also described.     

Chiral aminoacid containing macrocycles

Optically active macrocycles (R, R)-$\text{8}$-$\text{10}$ and diastereomeric mixtures of (±)-$\text{8}$-$\text{10}$ and meso-(R, S)-$\text{8}$-$\text{10}$ were prepared containing two (R)- or (S)-α-phenylglycine units as sources of chirality.     

Cyanosugars III : The reaction of trimethylsilyl cyanide with keto,epoxy and acetal derivatives of carbohydrates

Reaction of methyl 2-acetamido-4,6-$\text{O}$-benzylidene-2-deoxy-α-$\text{D}$-$\text{ribo}$-hexopyranosid-3-ulose with Me₃SiCN afforded methyl 2-acetamido-4,6-$\text{O}$-benzylidene-3-$\text{C}$-cyano-2-deoxy-3-$\text{O}$-trimethylsilyl-α-$\text{D}$-$\text{allo}$- Reaction of ethyl 4,6-di-$\text{O}$-acetyl-2,3-anhydro-α-$\text{D}$-mannopyranoside with Me₃SiCN gave the corresponding ethyl 4,6-di-$\text{O}$-acetyl-2-$\text{C}$-cyano-2-deoxy-α-$\text{D}$-glucopyranoside. Reaction of methyl 4,6-$\text{O}$-benzylidene-2,3-anhydro-α-$\text{D}$-allopyranoside or methyl 4,6-$\text{O}$-benzylidene-2,3-di-$\text{O}$-tosyl-α-$\text{D}$-glucopyranoside with Me₃SiCN at - 75° or - 50° gave the corresponding methyl 6-$\text{O}$-[(R)-cyano phenyl methyl]-α-$\text{D}$-glyco-pyranosides with high or total regio and stereoselectivity.     

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.     

The stereochemistry of guggulsterol-1

The steroechemistry of guggulsterol-1, a component of the exudate of $\text{Commiphora}$$\text{mukul}$, is shown to be 20(R), 22(R)($\text{3}$).     

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.     

5,12-dihydro-6,11-didehydronaphthacene,A derivative of 1,4-didehydronaphthalene

Treatment of the di-lithium derivative of 1,2-diethynyl-benzene ($\text{1}$) with $\text{o}$-xylene-α,α′-diol di-$\text{p}$-toluenesulphonate ($\text{2}$) in tetrahydrofuran led to 5,12-dihydronapthacene ($\text{5}$) as the only identifiable product. This reaction presumably involves 5,12-dihydro-6,11-didehydronaphthacene ($\text{4}$) as an intermediate, and this was confirmed by the formation of 5,12-dihydro-6,11-dideuterio-naphthacene when the reaction was carried out in tetrahydrofuran-$\text{d}$₈.     

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.     

Stereocontrolled synthesis of either (22S)- or (22R)-hydroxy-23-acetylenic steroid side chains via [2,3]-Wittig sigmatropic rearrangement

A unified approach to either (22$\text{S}$)- or (22$\text{R}$)-hydroxy-23-acetylenic steroid side chains is described which relies on the concept of the stereochemical transmission via the [2,3]-Wittig sigmatropic rearrangement.     

Stereoselective synthesis of 3-(1-Hydroxyethyl)-2-azetidinonesfrom 3-hydroxybutyrates

Addition of dianions of 3-hydroxybutyrates to benzylideneaniline results in direct formation of $\text{trans}$$\text{S*}$-3-(l-hydroxyethyl)-1,4-diphenyl-2-azetidinone with 95% diastereoselectivity. Inversion of the configuration at Cα, gives the desired $\text{trans}$$\text{R*}$-2-azetidinone in high yield.     

Novel (4 + 1) fragment combination approach to chiral cyclopentanoids from tartaric acid

A $\text{chiral}$ cyclopentanoid building block $\text{29}$ has been synthesized in “one pot” cyclization process from epoxides $\text{22}$ - $\text{25}$ (which are readily accessible from (R,R)-(+) tartaric acid) with the carbanion derived from phenylthioacetonitrile (PhS-CH₂-CN).     

Regioselective intramolecular asymmetric cyclization of symmetrical open chain triketone

The title reactions performed with (S)-α-amino acids or their derivatives as chiral sources were found to regioselectively give enantiomeric pairs of optically active 4-acetyl-3, 4-dimethyl-2-cyclohexenone (R)(+)- and (S)(?)-$\text{4}$), 16–25% e.e., and those of optically active 6-acetyl-3,6-dimethyl-2-cyclohexenone((R)(+)- and (S)(?)-$\text{5}$, 54–59% e.e., from the open chain triketone($\text{3}$).