Synthesis of methyl ethers of methyl (methyl α-D-mannopyranosid)-uronate

Methyl (methyl -D-mannopyranosid)uronate (I) has been obtained by the catalytic oxidation of methyl -D-mannopyranoside with oxygen in the presence of platinum carbon with a yield of 20%. The partial methylation of (I) and preparative column chromatography on silica gel has provided a convenient method of obtaining all the methyl ethers of (I) in the individual state.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 203–205, March–April, 1987.     

Synthesis of methyl ethers of methyl (methyl α-D-glucopyranosid)uronate

Methyl (methyl -D-glucopyranosid)uronate (I) has been obtained by the catalytic oxidation of methyl -D-glucopyranoside with oxygen in the presence of platinum on carbon with a yield of 31%. The partial methylation of (I) followed by preparative liquid column chromatography on silica gel has provided a convenient method of obtaining all the methyl ethers of (I) in the individual state.Pacific Ocean Institute of Bioorganic Chemistry, Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 35–37, January–February, 1987.     

Synthesis of methyl ethers of methyl (methyl β-D-galactopyranosid)uronate

The oxidation of methyl -D-galactopyranoside with oxygen in the presence of platinum and carbon gave methyl (methyl -D-galactopyranosid)uronate (I) with a yield of 20%. The partial methylation of (I) with methyl iodide in the presence of silver oxide followed by preparative liquid chromatography on silica gel provided a convenient method for obtaining all the methyl ethers in the individual state.Pacific Ocean Institute of Bioorganic Chemistry. Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 37–39, January–February, 1987.     

A comparative ab initio study of methyl formate, methyl thiolformate and methyl thionoformate

Ab initio SCF-MO calculations have been carried out for HCOOCH₃, HC(=O)SCH₃ and HC(=S)OCH₃. Relative stabilities of s-trans/s-cis conformers are reported and discussed in terms of specific intramolecular interactions. The energy difference between the s-trans and the s-cis form increases in the order methyl thiolformate < methyl thionoformate < methyl formate. The major stabilizing factors of the s-cis forms are the bond dipolar interaction and the mesomeric delocalization through the five member ring involving both the X=C---Y---C (X, Y = O, S) skeleton and the out-of-plane hydrogen atoms. These effects are used to explain the trends mentioned. The non-planarity previously proposed for the thionoester is reinvestigated. Our calculations show that this molecule is planar. Molecular atomic charges, dipole moments and ionisation potentials are determined and compared with available experimental values.     

Ion-molecule reactions involving methyl isocyanide and methyl cyanide

Ion-molecule reactions involving methyl isocyanide and methyl cyanide have been performed in a new rf-only hexapole collision cell inserted in a large-scale tandem mass spectrometer. Beside protonation processes, N-methyl cyanogen ions (CH(3)N(+)CCN) and 1-methyleneiminium-1- ethylenium ions (CH(2)CN(+)CH(2)) have been produced in high yield and fully characterized by high-energy collisional activation. The unimolecular chemistry of the molecular ions of caffeine (1,3,7-trimethyl xanthine) has been revisited on the basis of these new results.     

Photoinitiated polymerization of methyl methacrylate and methyl acrylate with 14C-labeled benzoin methyl ethers

Three ¹⁴C-labeled benzoin methyl ether (α-methoxy-α-phenylacetophenone) derivatives were utilized as photoinitiators in the polymerization of methyl methacrylate (MMA) and methyl acrylate (MA). The results of polymer end-group analysis are in accord with a mechanism of benzoin ether photocleavage into initiator radicals and dispute earlier labeling studies which were interpreted as evidence for copolymerization of excited-state benzoin ethers with reactive monomers. In MMA polymerization, the results indicate a preference for termination by disproportionation (～60%) and provide evidence for primary radical termination at 0.041M photoinitiator (optically dense solutions) in neat MMA. Evidence for chain branching by initiator radical hydrogen abstraction from poly(methyl acrylate) (PMA) is also presented. The benzoyl and α-methoxybenzyl radicals, produced on photolysis of benzoin methyl ether, appear to be equally effective in both initiation and hydrogen-abstraction processes. Quantum yields at 366 and 313 nm indicate the absence of a wavelength effect.     

Studies on pyrrolidones. Convenient syntheses of methyl,methyl N-methyl- and methyl N-methoxymethylpyroglutamate

Facile methods to prepare methyl pyroglutamate ( 2 ), methyl N-methylpyroglutamate ( 1 ) and methyl N-methoxymethylpyroglutamate ( 7 ) in one-step from pyroglutamic acid are described.     

二氢新茉莉酮酸甲酯和二氢茉莉铜酸甲酯的合成

本文报道了二氢茉莉酮酸甲酯(1)和二氢新茉莉酮酸甲酯(2)的新合成路线,以丙二酸二乙酯为原料,依次与溴代戊烷和烯丙基溴进行烷基化反应,得到α-戊基-α-烯丙基-丙二酸二乙酯(5),5经过水解、脱羧得到γ-烯酸3.酰氯化合物6进行Friendel-Crafts反应得到2-戊基-环戊-4-烯-1-酮(7),7通过Michael加成、水解、脱羧和酯化,得到2,总产率为24.4%.7可以异构化为2-戊基-环戊-2-烯-1-酮(9),9用通常的方法合成了1.1和2可以明显地从核磁共振谱、红外光谱和气相色谱识别。     

Michael additions to acrylonitrile,methyl acrylate and methyl vinyl ketone to Nb-benzylidenetryptophan methyl ester

Michael addition to methyl acrylate and methyl vinyl ketone of N_b-benzylidene-L-tryptophan methyl ester 1 gave 2-(3-indolylmethyl)glutamic dimethyl ester 2a and α-(3-oxobutyl)tryptophan methyl ester 2b respectively. Addition to acrylonitrile of 1 yielded α,N_a-dicyanoethyltryptophan methyl ester 3 .     

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.     

Telomerization of acrylonitrile and methyl acrylate with methyl dichloroacetate

Conclusions The telomerization of acrylonitrile and methyl acrylate with methyl dichloroacetate at the C-Cl bond of the latter was accomplished by initiation with iron pentacarbonyl in combination with either DMF ordimethylaniline.Translated from Izvestiya Akademii SSSR, Seriya Khimicheskaya, No. 6, pp. 1410–1412, June, 1973.     

Mass spectrometry of isomeric methyl phenylpentanoates and methyl phenylnonanoates

The mass spectra of methyl 3-, 4- and 5-phenyl pentanoates, and all the straight-chain methyl phenylnonanoates have been recorded. The major fragmentation patterns have been discussed; when the phenyl group is non-terminal, cleavage was observed at the branching position. It is shown that a mixture of methyl 3-, 4- and 5-phenylpentanoates may be analysed both qualitatively and quantitatively by mass spectrometry; in a methyl phenylnonanoate mixture a similar analysis is possible with the exception of the 8- and 9-phenyl isomers.     

Photodegradation in solution of copolymers of methyl vinyl ketone and methyl isopropenyl ketone with methyl methacrylate

Copolymers of methyl vinyl ketone (MVK) and methyl isopropenyl ketone (MIK) with methyl methacrylate (MMA), have been prepared covering the whole composition range. Reactivity ratios have been estimated as follows: MMA/MVK, r_MMA = 0·63 ± 0·2, r_MVK = 0·53 ± 0·2; MMA/MIK, r_MMA = 0·98 ± 0·2, r_MIK = 0·69 ± 0·2. Number average molecular weights have been measured during the course of photodegradation under 253·7 nm radiation in methyl acetate solution and rates of chain scission calculated. In each system the copolymers are less stable than the corresponding homopolymers, the rate passing through a maximum at 20–30% ketone content. These results have been discussed from a mechanistic point of view.     

Gas-phase protonation and methyl cation transfer from methyl halide ions

The ion-molecule reactions between [CH₃X]⁺˙ [CH₃XH] ⁺, [CH₃XCH₃]⁺ ions (X = F, Cl, Br, I) and a number of nucleophiles have been studied by ion cyclotron resonance techniques. Protonation of the nucleophiles is observed to occur from both the molecular ions [CH₃]X⁺˙ and protonated species [CH₃XH]⁺ whereas dimethylhalonium ions [CH₃XCH₃]⁺ react principally by methyl cation transfer. A notable exception occurs in methyl iodide where the molecular ions [CH₃I]⁺˙ act both as proton and methyl cation donors, whereas dimethyliodonium ions are found unreactive. The results are discussed with reference to the use of alkyl halides as reagent gases in chemical ionization experiments.     

Catalytic chain transfer copolymerization of methyl methacrylate and methyl acrylate

Bis(aqua)bis((difluoroboryl)dimethylglyoximate)cobalt(II) (COBF) has proven to be a very effective catalytic chain transfer agent in the copolymerization of MA and MMA. The chain transfer activity depends on the fraction of MMA in the monomer feed and the total radical concentration. The polymerization can be described by a model that combines features of catalytic chain transfer for MMA homopolymerization and cobalt mediated controlled radical polymerization of MA. According to the model part of the COBF is covalently bonded to MA‐ended polymeric radicals and cannot take part in the chain transfer step. The model can also account for the observed inhibition time that occurs at high chain transfer agent concentration and low fraction of MMA in the monomer feed.