New syntheses of methyl ethers from methyl α-L-fucopyranoside

A method for obtaining methyl esters of methyl -L-fucopyranoside based on the partial methylation of methyl -L-fucopyranoside with the subsequent liquid and gasliquid chromatography of the methyl ethers is described. Their properties are given.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 309–312, May–June, 1985.     

New benzenogenic diene syntheses

3,8-Diphenylpyrene 5 and 3,10-diphenylpyrene 10 were synthesized from 1,5-dibenzylnaphthalene and 1,4-diphenylnaphthalene. Dibenzylnaphthalenes were dehydrogenated to the quinonoid compounds 2 and 7, followed by addition of maleic anhydride and dehydrogenation of the adducts to give the aromatic anhydrides 4 and 9. These were decarboxylated to the corresponding hydrocarbons. By an analogous sequence of reactions 3,9-diphenylanthranthrene and 4,9-diphenyl-1,12-benzoperylene were prepared starting from 3,8-dibenzylpyrene 12 and 3,10-dibenzylpyrene 17 respectively. 1,6-Diphenylcoronene was synthesized by a further benzenogenic diene synthesis starting from 4,9-diphenyl-1,12-benzoperylene.     

Syntheses of marine ochtodane antifeedants via hydrolytic dehalogenation

The syntheses of five naturally occurring antifeedants of the ochtodane ring system (1-ethyl-3,3-dimethylcyclohexane), previously isolated from the marine red alga Ochtodes crockeri, are reported. A key synthetic step involves the hydrolytic debromination of 6-bromo-1,4-ochtodien-3-ol.     

New approaches to syntheses of diethers and haloethers from cyclopentadiene

Cyclopentadiene (CPD) is oxidized by copper(ii) bromide and chloride in alcohol solutions to form dialkoxy- and haloethers and exhibits a higher reactivity than butadiene. Dialkoxy-, chloroalkoxy-, and dichlorocyclopentenes are formed from CPD and CuCl₂ without catalysts. The reaction selectivity (yield of ethers calculated per consumed CuBr₂) reaches 98%. The characteristic feature of the oxidation mechanism is the parallel formation of all reaction products through a common intermediate (presumably, the bromonium cation) and bromine-containing carbocationic intermediates.     

从月桂烯合成梨圆蚧性信息素

梨圆蚧是对果林危害较大的害虫。该虫的性信息素包括三个组分:3-亚甲基-7-甲基-7-辛烯-1-醇丙酸酯(1)、(2Z)-3,7-二甲基-2,7-辛二烯-1-醇丙酸酯(2)和(2E)-3,7-二甲基-2,7-辛二烯-1-醇丙酸酯(3)。本文介绍了通过对月桂烯进行结构改造来合成梨圆蚧性信息素,从月桂烯到1,总产率为19%。工业上从月桂烯制龋萑花醇和香叶醇,再将橙花醇和香叶醇转变为相应的氯烯醇后再还原、丙酰化即得2和3,其总产率分别为30%和28%。(以橙花醇和香叶醇计)。月桂烯可从β-蒎烯裂解而得。我国有丰富的蒎烯资源,所以开辟从月桂烯合成梨圆蚧性信息素的新途径具有重要的意义。     

New heterocyclic syntheses from hydrazidoyl halides. Convenient syntheses of fused pyrimidines,pyridazines, and quinazolines

Aminocyanopyrazole derivatives and pyrazolo[2,3-a]quinazolones were obtained in good yields from hydrazidoyl halides and malononitrile. Pyrazolo[3,4-d]pyridazine and pyridazo[4′,5′: 1,2]pyrazolo[1,5-a]quinazoline derivatives were synthesized in quantitative yields by reaction of hydrazine hydrate with 2 and 16 , respectively. A novel ring system, a 3-substituted tetrahydro derivative of 7-oxo-6H,8H-pyridazo[3′,4′,5′-c'd']-pyrazolo[3,4-d]pyrimidine was prepared by reaction of 6 with dimethyl carbonate. Pyrazolo[3,4-d]pyrimidine-4,6-dithiones were obtained in good yields by reaction of 2 with carbon disulfide. The structures of the products were assigned and confirmed on the basis of their elemental analyses, spectral data, and alternate synthesis wherever possible. The structures of the parent fused heterocyclic systems discussed in this work are summarized in Scheme 1 .     

New syntheses of pentafluorotellurium hypochlorite

Chlorination of pentafluoroorthotelluric acid with either chlorine fluorosulfate or chlorine monofluoride furnishes pentafluorotellurium hypochlorite in new, high yield reactions. Additional characterizing data for this useful hypochlorite are presented.     

New syntheses of dalbergichromene and dalbergin from vanillin via neoflavene intermediate

In this Letter, naturally occurring dalbergichromene and dalbergin were synthesized from a common neoflavene intermediate, which was derived from vanillin. The giving neoflavene intermediate was debenzylated with AlCl₃ to yield dalbergichromene in 39% total yield, and it was oxidized by DDQ, and subsequently debenzylated by Pd(OH)₂/C and cyclohexene in refluxing ethanol to give dalbergin in 31% total yield.     

New syntheses and chemistry of hexafluorotropone

Two new routes to hexafluorotropone have been developed, one from hexachlorotropone and a superior synthesis from hexafluorobenzene. Hexafluorotropone was found to be a very weak base, with a conjugate acid pK(a) of -6.2 +/- 0.5. The tropone adds in [6 + 4] fashion to cyclopentadiene and photocyclizes to hexafluorobicyclo[3.2.0]hepta-3,6-dien-2-one. Lithium hydroxide in benzene transforms the tropone into pentafluorotropolone, which functions as a bidentate ligand.     

New syntheses of jasmone and 2,3-dihydfojasmone

Starting from 3-silylcyclopent-2-enone, a tandem conjugate addition—nucleophilic alkylation process was used to prepare the title compounds as well as allyl rethrone. 1,2-Dimethoxyethane was found useful in the alkylation of the enolate intermediate whereas β-silyl group facilitated the regeneration of C-C double bond.     

New syntheses of 2,4-diaminopyrroles and aminopyrrolinones

Summary Oxazolin-2-ylidene-malononitriles3a–d, obtainable from thioketenaminals and -halogen-ketones, react with primary and secondary amines to afford 2,4-diamino-pyrroles5a–h. Mercaptobenzen as nucleophilic agent gives the 4-amino-2-phenylthio-pyrrole5j. Analogously, cyano-(3,5-diphenyl-3H-oxazol-2-ylidene)-acetic acid methyl esters were prepared as intermediates for the synthesis of 2-amino-4-oxo-pyrrolines10a–d. The isomeric 4-amino-2-oxo-pyrrolines13a–d can be obtained from 4-amino-2-methoxy-pyrroles, which serves as proof for the position of substituents. The structures were investigated by¹H and¹³C NMR spectroscopy.

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Neue Synthesen von 2,4-Diaminopyrrolen und Aminopyrrolinonen

Zusammenfassung Die Oxazolin-2-yliden-malononitrile3a–d. die aus Thioketenaminalen und -Halogenketonen erhalten wurden, reagieren mit primären und sekundären Aminen zu den 2,4-Diaminopyrrolen5a–h. Mercaptobenzol als nukleophiles Reagens liefert 4-Amino-2-phenylthiopyrrol (5j). Analog wurden Cyan-(3,5-diphenyl-3H-oxazol-2-yliden)-essigsäuremethylester als Zwischenprodukte für die Synthese der 2-Amino-4-oxo-pyrroline10a–d hergestellt. Die isomeren 4-Amino-2-oxo-pyrroline13a–d können aus den 4-Amino-2-methoxy-pyrrolen11a,b erhalten werden, was als Nachweis für die Position der Substituenten dient. Die Verbindungen wurden¹H- und¹³C NMR-spektroskopisch untersucht.

     

New “Gabriel” syntheses of amines

The Gabriel synthesis is generalized as monoalkylation of an ammonia or primary amine derivative with subsequent removal of the derivatizing group(s) from nitrogen. Two new derivatives for this purpose are introduced: phenacylsulfonamides and triflamides, with discussion of their generality and effectiveness.     

New polymer syntheses. XIX. Syntheses of aromatic polyesters from phenoxyterephthalic acid

The synthesis of bisphenol-A phenoxyterephthalate was chosen as model system to find the optimum method for polycondensations of aryloxyterephthalic acids. It is demonstrated that phenoxyterephthalic acid or its acid chloride may cyclize at temperatures above 180°C yielding anthrone-3-carboxyclic acid which causes termination steps. The highest yield and molecular weight was obtained by interfacial polycondensation of phenoxyterephthaloylchloride.     

Olefins syntheses from β-hydroxysulfides

Di-,tri-,tetrasubstituted β-hydroxysulfides readily prepared from α-thioalkyllithiums and carbonyl compounds are easily transformed to di- and trisubstituted olefins on reaction with P₂I₄ or PI₃, and to tetrasubstituted ones with SOCl₂.