Photosonosynthesis of 1,2,4-tris(methylthio)-3-H-hexafluoro-n-butane

The preparation of neat 1,2,4-tris(methylthio)-3-H-hexafluoro-n-butane is described. The mechanism, which involves the elimination of hydrogen fluoride with the subsequent isomerization in forming the $\text{cis}$- and $\text{trans-}$ 1,2,4-tris(methylthio)hexafluoro-l-butene, is discussed. This study also supports the presence of methanethiol as an intermediate during the photosonoreaction of bis(methylthio)hexafluoro-2-butene with an excess of methyl disulfide.     

Preparation and reactivity of mesoionic 1,2,4-triazolo-[4,3-b]-1,2,4-triazole derivatives

A number of mesoionic compounds (2) derivatives of the 1,2,4-triazolo[4,3-$\text{b}$]-1,2,4-triazole ring system have been prepared from 4-amino-1 -methyl -3,5-bis(methylthio)- 1,2,4-triazolium cation and aryl isothiocyanates. Compounds ((2) react with methyl iodide to give the methiodides ((3) which undergo ring opening to the monocyclic compounds ((4) through sulfur extrusion under thermal conditions. Methiodides ((3) by sequential treatment with malononitriIe and hydrochloric acid lead to the pyrazolo[5,1-$\text{c}$]-1,2,4-triazole (6).     

Synthesis of 9-(2,3-dihydroxy-1-propoxymethyl)guanine - a new potential antiviral agent

Coupling of tris(trimethylsilyl)guanine (4) with 1,2-di-$\text{O}$-acetyl-3-$\text{O}$chloromethyl glycerol (3), followed by removal of the protecting groups afforded 9-(2,3-dihydroxy-1-propoxy)guanine (1). Compound 1 exhibited potent antiviral activity.     

Synthesis of the chiral acyclonucleoside antiherpetic agent (S)-9-(2,3-dihydroxy-1-propoxymethyl)guanine

A new synthesis of the potential antiviral agent, (S)-9-(2,3-dihydroxy-1-propoxymethyl)guanine is described, starting from the readily available methyl 2,3,4-tri-$\text{O}$-benzyl-α-(=D)-glucopyranoside. The sequence utilizes the absolute configuration defined by carbons 4, 5 and 6 of the (=D)-glucose ring and provides a ready synthesis of the single enantiomer without recourse to many chromatographic separations.     

A route to prostaglandin precursors from 1-(phenylthio)-2-octenyllithium.

The enolates generated by the conjugate addition of 1-(phenylthio)-2-octenyllithium to 4-$\text{tert}$-butoxycyclopent-2-en-1-one and <-crotonolactone react with methyl 7-halohept-5-ynoates in the presence of Ph₃SnCl to deliver products which may be converted into prostaglandin precursors.     

(E)- and (Z)-1-benzenesulfonyl-4-trimethylsilyl-2-butenes as (E)-1-(1,3-butadienyl) synthons

(E)- and (Z)-1-benzenesulfonyl-4-trimethylsilyl-2-butenes (E/Z=9), prepared from 4-trimethylsilyl-1-buten-3-ol, $\text{n}$-butyllithium and benzenesulfenyl chloride and oxidation of the intermediate (E)- and (Z)-1-benzenesulfinyl-4-trimethylsilyl-2-butenes with hydrogen peroxide, react with $\text{n}$-butyllithium and then primary halides to give 4-benzenesulfonyl-1-trimethylsilyl-2-alkenes which are rapidly 1,4-debenzenesulfonyltrimethylsilated to (E)-1,3-alkadienes by tetra-$\text{n}$-butylammonium fluoride at O°C.     

1-(1,2,4-Triazolyl-3-azo)-2-naphthol as a spectrophotometric reagent for inorganic ions

The synthesis, characteristics and analytical reactions of 1-(1,2,4-triazoly 1-3-azo)-2-naphthol are described. Coloured complexes are formed with 21 metal ions. For the cadmiuin(II) complex, the molar absorptivity is 2.8 × 10⁴ 1 mol^-1 cm^-1 at 515 nm for 40% ($\text{v}\text{v}$) ethanolic solutions at pH 8.0. For the mercury(II) complex at pH 10, the molar absorptivity is 2.7 × 10⁴ mol^-1 cm^-1 at 530 nm. Complexes of the ML₂ type are formed.     

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.     

Palladium-catalyzed cyclization reactions of 3-propargylthio 1,2,4-triazin-5(2h)-ones to thiazolo-1,2,4-triazinones

Selective transformation of 3-propargylthio-1,2,4-triazin-5(2H)-ones ($\text{1}$) to 6-methylene-6,7-dihydro-4H-thiazolo[2,3-c][1,2,4]-triazin-4-ones ($\text{2}$) and 3-methylene-2,3-dihydro-7H-thiazolo[3,2-b]-[1,2,4]triazin-7-ones ($\text{3}$) is performed under the conditions of Pd(II) salt or sodium hydroxide catalysis, respectively.     

A novel method for the synthesis of 9-[[2-hydroxy-1-(aminomethyl)ethoxy]methyl]guanine - a potential antiviral agent

9-[[2-Hydroxy-1-(aminomethyl)ethoxy]methyl]guanine (1a), an amino analogue of 9-[[2-hydroxy-1-(hydroxymethyl)-ethoxy]methyl]guanine (I) which is a potent antiviral agent, has been synthesized $\text{via}$ a multistep-synthesis.     

Complementary short syntheses of (±)-methyl shikimate

Two syntheses of (±)-methyl shikimate from the adduct of furan and methyl acrylate are described. One requires the regioselective hydroxylation of (±)-5β,6β-dihydroxy-$\text{O}$,$\text{O}$-isopropylidene-2-methoxycarbonylcyclohexa-1,3-diene and the other $\text{cis}$-dihydroxylation of (±)-5-hydroxy-1-methoxycarbonylcyclohexa-1,3-diene.     

An efficient and stereocontrolled synthesis of platelet activating factor from (s)-(−)-malic acid

A stereocontrolled synthesis of C₁₆-PAF ($\text{11}$) from (S)-(?)-malic acid ($\text{1}$), employing regioselective hydrogenolytic cleavage of benzylidene acetal derivatives of (S)-1,2,4-butanetriol ($\text{2}$) with borane-tetrahydrofran complex, is described.     

A short and efficient synthesis of 4-hydroxy-5-(1-hydroxyalkyl)-γ-butyrolactones

The cycloaddition of α,β-epoxyaldehydes or ketones ($\text{2}$) with the ketene acetal MeHC=C(OMe)₂ ($\text{1}$) gives epoxyoxetanes ($\text{3}$) in high yields. Without isolation they can be transformed into 4-hydroxy-5-(1-hydroxyalkyl)-γ-butyrolactones ($\text{6}$) via the epoxy esters $\text{4}$ and trihydroxy esters ($\text{5}$). The lactones $\text{6}$ appear to be valuable precursors for the synthesis of 5-(1-hydroxyalkyl)-3-methyl-2-5H-furanones ($\text{7}$) and 3-methyl-5-ylidene-2-5H-furanones ($\text{8}$)     

Synthesis of (2S,3R,1'R)-stegobinone,the pheromone of the drugstore beetle,with stereocontrol at C-2 and C-1'

(2$\text{S}$,3$\text{R}$,1'$\text{R}$)-Stegobinone [2,3-dihydro-2,3,5-trimethyl-6-(1'-methyl-2'-oxobutyl)-4H-pyran-4-one], the pheromone of $\text{Stegobium}$ $\text{paniceum}$ L., was synthesized with stereocontrol at C-2 and C-1' starting from ethyl ($\text{R}$)-3-hydroxybutanoate and methyl ($\text{R}$)-3-hydroxy-2-methylpropanoate. The dihydro-γ-pyrone ring of the pheromone was constructed by an intramolecular acylation followed by acid-catalyzed cyclization.     

3-Bromo-2-(tert-butylsulfonyl)-1-propene. A multi-coupling reagent Part 1.

3-Bromo-2-(tert-butylsulfonyl)-1-propene $\text{4}$ is easily available in two steps from allyl-tert-butylthioether $\text{5}$ (70% overall yield). It reacts with a great variety of carbanions to give functionnalized α, β-unsaturated sulfones of type $\text{7}$ in high yields. A second nucleophile (lithium cuprates) can then be added to compounds $\text{7}$ to furnish functionnalized sulfones of type $\text{3}$ (Y=SO₂-tert-butyl).     

O-silylated ketene acetal chemistry; β-(alkoxycarbonyl)methyl O-silyl enolates,useful synthons for α-substituted-β-(alkoxycarbonyl)methylalkanones

Conjugate addition of O-silylated ketene acetals $\text{2}$ to α,β-unsaturated carbonyl compounds $\text{1}$ in acetonitrile gave quantitative yields of the corresponding β-(alkoxycarbonyl)methyl O-silyl enolates $\text{4}$. Site specific electrophilic substitutions of $\text{4}$ yielded the corresponding α-substituted β-(alkoxycarbonyl)-methylalkanones $\text{5}$, $\text{7}$, and $\text{8}$.     

Backbone rearrangements of methyl (-)-kaur-9(11)-en-19-oate and its epoxide: structures of two diterpenes of a new skeletal type

cleavage of the epoxide ($\text{2}$) of methyl (-)-kaur-9(11)-en-19-oate ($\text{1b}$) with boron trifluoride-ether in benzene and in acetic anhydride yielded ($\text{3a}$) and ($\text{3b}$), respectively. On epoxidation with $\text{m}$-chloroperbenzoic acid in the presence of $\text{N}$-nitrosomethyl urea, ($\text{1b}$) suffered a backbone rearrangement to form ($\text{6}$).     

N-halogeno-compounds. Part 9 [1]. Azoxy- and azo-arenes derived from 4-(dichloroamino)tetrafluoropyridine; crystal structure of trans-2,3,5,6-tetrafluoro-4-(2,4,6-trimethylphenyl-onn-azoxy)pyridine

The nitrosoarenes ArNO (Ar = C₆H₅, 2-MeC₆H₄, 2,4,6- Me₃C₆H₂ and C₆F₅) have been condensed with 4-(dichloroamino)- tetrafluoropyridine to provide the azoxy-compounds py_FN$\text{N}\text{+}$($\text{N}\text{-}$)Ar (py_F = 2,3,5,6-tetrafluoro-4-pyridyl); de-oxygenation of the first three with triphenylphosphine or triethyl phosphite gave the corresponding azo-compounds, and the reverse reaction was achieved in the case of py_FNNC₆H₂Me₃-2,4,6 using peroxytrifluoroacetic acid. Thermolysis of 4-azidotetrafluoropyridine in the presence of pentafluoronitrosobenzene provided the perfluorinated azoxy-compound py_FN$\text{N}\text{+}$($\text{O}\text{-}$)C₆F₅. X-Ray methods have been used to determine the molecular geometry of py_FN$\text{N}\text{+}$($\text{O}\text{-}$)C₆H₂Me₃-2,4,6.     

A practical process for large-scale synthesis of (S)-5-hydroxy-6-trans-8,11,14-cis-eicosatetraenoic acid (5-HETE)

($\text{S}$)-5-Hydroxy-6-$\text{trans}$-8,11,14-$\text{cis}$-eicosatetraenoic acid (5-HETE) (1) and its enantiomer are readily available by a chemical synthesis from arachidonic acid which includes a chromatographic separation of diastereomeric urethanes (3) made from (±)-5-HETE methyl ester and the isocyanate 4 derived from dehydroabietylamine.