Alkylation of n-methylpyrrole with tert-butanol in the presence of amberlyst 15 ion exchanger

The 2- and 3-tert-butylderivatives of 1-methylpyrrole, hitherto unknown, have been obtained by a single-stage method. The process is characterized by a low positional selectivity with asomewhat predonminating -substitution. The results have been compared with data, obtained by the quantum-chemical calculation of the molecules of pyrrole, N-methylpyrrole, and also of their -complexes with protons, introduced in the - and -position of the rings.Latvian Institute of Organic Synthesis, Riga LV-1006.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 163–167, February, 1995. Original article submitted January 17, 1995.     

Alkylation of furan,thiophene, and pyrrole with furfuryl alcohol in the presence of the strongly acidic Amberlyst 15 sulfo cation-exchange resin

The corresponding 2-furylhetarylmethanes were obtained by the reaction of furan, thiophene, or pyrrole with furfuryl alcohol in the presence of the strongly acidic Amberlyst 15 cation-exchange resin in the H⁺ form. The alkylation of furan and thiophene takes place regiospecifically in the 2 position, whereas 2-furyl-2-pyrrolyl- and 2-furyl-3-pyrrolylmethane in a ratio of 6.21 are formed in the case of pyrrole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 746–749, June, 1989.     

Synthesis of 2-(pyridylazo)-2-furyl-and 2-(pyridylazo)-2-thienylmethines and other heterocyclic Schiff bases in the presence of molecular sieves

The reactions of 2-furaldehyde, 2-thiophenecarbaldehyde, and their 5-methyl derivatives with 2-aminopyridines and some other amines in the presence of molecular sieves as a dehydrating agent and acid catalyst have been studied. A series of new heterocyclic azomethines was synthesized. Proposals were made for the mechanism of the condensation involving 2-aminopyridines and the structure of the intermediates in these processes.Latvian Institute of Organic Synthesis, Riga LV-1006, Latvia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 890–897, July, 2000.     

Synthesis of pyridyl(trichloromethyl)carbinols under interphase-catalysis conditions

The corresponding pyridyl(trichloromethyl)carbinols were obtained by reactions of 2- and 3-formylpyridine and 6-methyl-2-formylpyridine with chloroform in the presence of aqueous or solid alkali and an interphase catalyst. It is shown that carrying out the reaction in a liquid-solid system is more efficient than in a liquid-liquid system.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 46–49, January, 1990.     

Asymmetric reduction of aromatic and hetero cyclic ketones by hydrosilylation and hydrogen transfer in the presence of optically active rhodium catalysts

A study has been made of enantioselective hydrosilylation and reduction, by hydrogen transfer, of prochiral alkyl phenyl ketones or alkyl hetaryl ketones over various optically active catalysts. A total of 14 aromatic and heterocyclic carbinols were synthesized with preparative yields of 54–100%. The most effective catalytic systems were found to be complexes of RhCl₃ and [Rh(cod)Cl]₂ with the known optical inductor (S,S)-i-Pr-Pybox, with which we have obtained for the first time a series of heterocyclic secondary alcohols with an enantioselectivity of 20–63%.Latvian Institute of Organic Synthesis, Riga, LV-1006. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 342–358, March, 1996. Original article submitted December 11, 1995.     

1-(pyridylmethoxy)silatranes

A series of 1-(pyridylmethoxy)silatranes was obtained by the dehydrocondensation of pyridinemethanols with 1-hydrosilatrane catalyzed by potassiumtert-butylate.     

Free radical chlorination of methyl derivatives of pyridine,pyrazine, and thiazole by N-chlorosuccinimide

When methylazines (2-, 3-, and 4-methylpyridines, methylpyrazine) are treated with N-chlorosuccinimide they undergo successive chlorination of the methyl group to give 2-chloromethylpyridine, 2-dichloromethylpyridine, and dichloromethylpyrazine in preparative yields. 3-Dichloromethylpyridine was synthesized from pyridine-3-aldehyde and PC1₅. The primary chlorination products of 4-methylthiazole are 4-methyl-5-chlorothiazole and 5-chloro-4-chloromethylthiazole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 543–546, April, 1989.     

Hydroxymethylation and alkylation of compounds of the furan, thiophene, and pyrrole series in the presence of H+ cations (review)

Published data and the results of the authors' own investigations on the transformations of O-, S-, and N-heterocyclic compounds under the conditions of acid-catalyzed hydroxymethylation and alkylation are summarized. The mechanisms and the directions of the reactions taking place under the influence of weakly and strongly acidic ion exchangers are discussed.The authors consider it their duty to mention that the work on the review was initiated by Prof. M. V. Shimanskaya.Latvian Institute of Organic Synthesis, Riga. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 3–16, January, 1998.