Iron-modified zeolite BETA: efficient catalyst in methyllaurate, 2-hexyl-1,3-dioxolane, 4-methyl-2-propyltetrahydro-2H-pyran-4-ol and 4-methyl-2-phenyl-tetrahydro-2H-pyran-4-ol synthesis

Research on Chemical Intermediates - Several types of modified zeolite BETA38 with different iron loading were prepared. Prepared materials were characterized using different techniques (XRD, XRF,...     

Prins cyclization for the preparation of 2-isobutyl-4-methyl-tetrahydro-<Emphasis Type="Italic">2H</Emphasis>-pyran-4-ol using supported heteropoly acids

The selective preparation of 2-isobutyl-4-methyl-tetrahydro-2H-pyran-4-ol (also called Florosa or Florol) was performed. Prins cyclization of isoprenol and isovaleraldehyde was used for the preparation of this important fragrant compound. Heteropoly acids (phosphotungstic and phosphomolybdic) were used as a catalyst in homogeneous and also in heterogeneous arrangements (after their immobilization). The only solvent necessary for the reaction was water that enables the increase of the selectivity to the desired product by hydrolysis of catalyst-carbocation intermediates. In a flow, both heteropoly acids were successfully anchored on siliceous MCM-41 and resultant materials were characterized by XRF, XRD, SEM, FTIR, UV–Vis, and nitrogen adsorption. Heterogenization was performed in water as a solvent. Anchored heteropoly acids were used in Prins cyclization under the same conditions (addition of water), and the selectivity was even higher (96 %), comparing the homogeneous arrangement. No leaching of catalyst from solid was observed. Moreover, the catalyst may be reused without loss of activity and selectivity at least four times.     

(4R,6R)-6-(hydroxymethyl)-4-methyltetrahydro-2H-pyran-2-one in the synthesis of polyfunctional compounds with the methyl-branched carbon skeleton

A simple and efficient asymmetrical synthesis was performed of a convenient bifunctional building block, methyl (R)-5,5-dimethoxy-3-methylpentanoate and its (S)-enantiomer. The possibility was shown of its application to the synthesis of insect pheromones.     

Synthesis and aminomethylation of 2-isobutyl-3-and 4-diethoxyphosphorylmethylfurans

Synthetic procedure for preparing 2-isobutyl-3-and 4-furancarboxylic acyl chlorides is developed. Reduction of these compounds with lithium alumohydride leads to corresponding alcohols which under treating with thionyl chloride in the presence of pyridine form chloromethyl derivatives. The latter compounds are phosphorylated with sodium diethyl phosphite under the Michaelis-Becker reaction conditions to give corresponding phosphonates. Reaction of compounds obtained with dimethyl(chloromethyl)amine proceeds at the free α-position of the furan ring and delivers aminophosphonates. These substances do not evolve dimethylamine even under the conditions of vacuum distillation (145–150°C, 1 mm Hg).     

Reactions of 4-Hydroxy-2H-pyran-2-ones with Some N-Nucleophiles

Russian Journal of General Chemistry -     

A diastereoselective route to 2,6-syn-disubstituted tetrahydropyrans: synthesis of the civet compound (+)-2-((2S,6S)-6-methyltetrahydro-2H-pyran-2-yl) acetic acid

A diastereoselective synthesis of 2,6-syn-disubstituted tetrahydropyrans has been developed based on the ability of furanyl-ether chiral centres to epimerise readily under acidic conditions. This novel methodology was applied to the synthesis of (+)-2-((2S,6S)-6-methyltetrahydro-2H-pyran-2-yl) acetic acid, a component of the African civet cat's glandular marking secretion.     

Brominated derivatives of 4-hydroxy- and 4-methoxy-6-methyl-2H-pyran-2-ones

Twenty-five different brominated derivatives of 4-hydroxy-6-methyl-2-pyrone (triacetic acid lactone) and 3-acetyl-4-hydroxy-6-methyl-2-pyrone (dehydroacetic acid) have been prepared. Fifteen derivatives have not been previously described and the preparations of a few known products have been improved. Bromination at C-3, C-5, methyl group at C-6 and deacetylations at C-3 have been the types of reactions used.     

Bis(tetrahydro-2H-pyran-2-ylmethyl)sulfide and -Sulfoxide from Sulfur Dichloride and 5-Hexen-1-ol

The reaction of sulfur dichloride with 5-hexen-1-ol has given bis(tetrahydro-2H-pyran-2-ylmethyl)-sulfide in 87% yield. Oxidation of the latter with NaIO₄ has afforded bis(tetrahydro-2H-pyran-2-ylmethyl)-sulfoxide in 96% yield.

     

New reaction for the preparation of ethers of 1,1,1-trinitropropan-2-ol

Conclusions On reacting trinitromethane with vinyl acetate in a medium of different alcohols the ethers of these alcohols with 1,1,1-trinitropropan-2-ol are obtained.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2566–2568, November, 1969.     

Synthesis of 2-amino-5-nitro-4H-pyran-3-carbonitriles

Reaction of 2-carbomethoxy-ω-nitroacetophenone with arylmethylenemalononitriles gives the previously unknown 2-amino-4-aryl-5-nitro-6-(2-carbomethoxyphenyl)-4H-pyran-3-carbonitriles. N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. E-mail: muskat@cacr.ioc.ac.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1661–1663, December, 1998.     

Studies of a proposed mechanism for the reaction between 2H-pyran-2-ones and organomagnesium compounds

Part of the reaction between 2H-pyran-2-ones and organomagnesium compounds has been investigated by means of MNDO and ab initio calculations. Criteria for the mechanism of reaction are provided by the stereoselectivity observed and calculations are consistent with this stereoselectivity. Conformations of the reaction intermediates are given.     

Thermal rearrangement of condensed alkoxy-substituted 2-trifluoromethyl-4H-pyran-4-ones to spiroannelated 3(2H)-furanones

Isomerization of the acetates and benzoates of condensed hydroxy-substituted 2-trifluoromethyl-4H-pyran-4-ones at 300–320°C gave the corresponding derivatives of spiroannelated 3(2H)-furanones. Their structure was confirmed by spectral data and by X-ray crystallographic analysis.Belarus State University, Minsk; Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1028–1034, August, 2000.     

The reaction of ethyl 4H-pyran-4-one-2-carboxylate with 1,2-diaminobenzene

Ethyl 4H-pyran-4-one-2-carboxylate was allowed to react with 1,2-diaminobenzene and related diamines. The resulting products were found to be 8H-5,6-dihydro-6,8-dioxopyrido[1,2-a]quinoxaline and derivatives. The synthesis 3H-5,6-dihydrobenzo[g]pyrido[1,2-a]quinoxaline-3,5-dione ( 2c ) constitutes the synthesis of a derivative of previously unknown benzo[g]pyrido[1,2-a]quinoxaline ring system.     

Reaction of 2-isobutyl-5-methyl-4-phenyl-1,3,2-dioxaborinane with acetonitrile

Reaction of 2-isobutyl-5-methyl-4-phenyl-1,3,2-dioxaborinane (a mixture ofcis- andtrans-isomers in a 81 : 19 ratio) with acetonitrile yielded 2,5-dimethyl-4-phenyl-5,6-dihydro1, 3-oxazine as a mixture ofcis- andtrans-forms in a 50 : 50 ratio. The possible mechanism of this transformation is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1297–1298, May, 1996.     

Synthesis of the bis-potassium salts of 5-hydroxy-3-oxopent-4-enoic acids and their use for the efficient preparation of 4-hydroxy-2H-pyran-2-ones and other heterocycles

5-Hydroxy-3-oxopent-4-enoic acid esters can be efficiently transformed into the stable bis-potassium salts of the corresponding 5-hydroxy-3-oxopent-4-enoic acids, from which the sensitive acids are released in situ, the latter being converted into substituted 4-hydroxy-2H-pyran-2-ones, pyrazoles and isoxazoles under mild conditions; the efficiency of this method is demonstrated by the first synthesis of two naturally occurring pyrones.     

CO2 laser-induced decomposition of propan-2-ol,butan-2-ol,pentan-2-ol,pentan-3-ol,and hexan-2-ol

The pulsed CO₂ laser-induced decompositions of propan-2-ol, butan-2-ol, pentan-2-ol, pentan-3-ol, and hexan-2-ol in the gas phase have been investigated. Like ethanol which we examined previously [1] the absorption cross section of propan-2-ol for pulsed 9R14 radiation increases with pressure at low pressures, an effect attributed to rotational hole-filling. In contrast the absorption cross section of butan-2-ol (10R24) has only a small pressure dependence and those of pentan-2-ol (9R26), pentan-3-ol (10R14), and hexan-2-ol (9P20) show little or no variation with pressure in the range 0.1–5.0 torr. Decomposition products have been investigated at low pressure where the excitation of the alkanols was essentially collision free. The observed products for all the alkanols can be rationalized on the basis of primary dehydration and C? C fission channels, with minor contributions from other molecular eliminations. © 1994 John Wiley & Sons, Inc.