Pyridylsilanes in the synthesis of heterocycles (review)

The desilylation of pyridylsilanes and pyridylmethylsilanes is one of the most characteristic reactions of organosilicon derivatives of pyridine, and it has been shown to be possible to utilize this reaction in organic synthesis. In many instances, desilylation affords difficultly-accessible pyridine derivatives, which have also been synthesized by insertion of aldehydes into the Si-C bond in pyridylsilanes and reactions of organosilicon pyridinium compounds. 2-Trimethylsilylmethylpyridine has been found to undergo the largest number of reactions leading to the formation of a variety of compounds containing the pyridine ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 5–13, January, 1987.     

Carbenes in the synthesis of heterocycles (review)

The syntheses of heterocyclic compounds by reactions of carbenes with carbon-heteroatom multiple bonds, isomerization of unstable adducts of carbenes to carbon-carbon bonds, and the incorporation of carbenes in C-H, C-N, and C-O bonds are examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1443–1464, November, 1976.     

Catalytic synthesis of nitrogen-containing heterocycles (a review)

The process of the catalytic synthesis of a number of nitrogenous heterocyclic compounds based on the utilization of reactions involving the amination of oxygen-containing heterocycles, the dehydration cyclization of amino alcohols, the deamination of di- and polyamines, and the intermolecular dehydration cyclization of glycols with diamines have been considered.     

Free radical intramolecular cyclization in the synthesis of heterocycles (review)

The possibilities of homolytic cyclization for the synthesis of heterocyclic compounds are examined. Factors affecting the yield and structure of the resulting products are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1011–1034, August, 1993.     

Three-membered heterocycles in the synthesis of crown compounds and cryptands (review)

The cyclo-oligomerization of oxirane and aziridine and their derivatives in the presence of BF₃ leads to the corresponding macroheterocydic compounds. Crown compounds with exocyclic alkyl, aryl, or functional substituents are formed in the reaction of alkyl-, aryl-, and functionally substituted oxiranes or aziridines with dinucleophilic reagents with subsequent intramolecular cyclocondensation of the reaction products. Methods for the synthesis of cryptands that are based on the reaction of diazacrown compounds with diglycidyl ethers of oligoethyleneglycols are described. The reaction of tosylaziridine with ,-alkylenediamines leads to tetrakis(p-toluenesulfamidoethyl)alkylenediamines, the cyclocondensation of which in the presence of 1,2-dibromomethane under interphase-catalysis conditions gives the corresponding cryptands.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1299–1315, October, 1990.     

Furan and its derivatives in the synthesis of other heterocycles (review)

Data on methods of transforming furans into heterocycles containing oxygen, nitrogen, sulfur, and selenium are discussed and summarized.Scientific-Research Institute, N. G. Chernyshevskii Saratov State University. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1034–1052, August, 1995. Original article submitted November 24, 1994, revision submitted February 20, 1995.     

Aza-1,3-butadienes in synthesis of nitrogen-containing six-membered heterocycles (review)

We review and generalize literature data in recent years on application of heterodiene synthesis to obtain azines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1299–1307, October, 1992     

Utilization of aminomercuration and hydroxymercuration reactions in the synthesis of heterocycles (review)

The cyclization of ethyleneamines by the action of mercury salts to give five- and six-membered nitrogen heterocycles is examined. The mechanism and stereochemistry of this reaction and the chemical and three-dimensional structures of the intermediate organomercury compounds and some chemical properties of the latter are discussed.     

Electrophilic heterocyclization of unsaturated amino compounds in the synthesis of nitrogen-containing heterocycles (review)

The literature data on the electrophilic heterocyclization reactions of unsaturated amines, enamines, amidines, amides, and urethanes are correlated. The factors that affect the reactivities of unsaturated amino compounds in electrophilic intramolecular-cyclization reactions are discussed. The problems involved in the regioselectivity of the addition of electrophiles and the stereochemistry of the resulting products are examined, and kinetic data are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 435–449, April, 1985.     

Hydrofurans in the synthesis of heterocycles — A review

The use of hydrofurans in the synthesis of heterocyclic compounds is reviewed.Deceased.Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 723–746, June, 1997.     

Perfluoro(1,2-epoxycyclohexane) in the synthesis of fluorinated heterocycles

Perfluoro(1,2-epoxycyclohexane) readily reacts with bifunctional nucleophiles (urea, thiourea, and benzene-1,2-diamine) via opening of the oxirane ring and subsequent heterocyclization to give fluorinated benzimidazole, 1,3-benzothiazole, and phenazine derivatives, respectively.     

Thioimidium salts and the synthesis of heterocycles (Review)

Data on the use of thioimidium salts in the synthesis of heterocycles are classified and analyzed. A brief review of their production methods is given.     

Alpha-(N-carbamoyl)alkylcuprate chemistry in the synthesis of nitrogen heterocycles

The conjugate adducts obtained via coupling of alpha-(N-carbamoyl)alkylcuprates with alpha,beta-ynoates, alpha-allenyl esters, or alpha.beta-enoates or enimides undergo N-Boc deprotection and cyclization onto the ester functionality upon treatment with PhOH/TMSCl, catecholboron bromide, or trimethylsilyl triflate. This two-pot sequence provides synthetic routes to 4-alkylidinepyrrolidine-2-ones, 4-alkylidinepyrrolizidin-2-ones, and 4-alkylidineindolizidin-2-ones via allenyl esters; pyrrolin-2-ones, tetrahydropyrrolizin-2-ones, and tetrahydroindolizin-2-ones via alpha/beta-ynoates; pyrrolidin-2-ones, pyrrolizidin-2-ones, and indolizidin-2-ones via alpha,beta-enoates or alpha.beta-enimides. The reluctance of gamma-carbamoyl-alpha,beta-enoates to undergo E/Z isomerization requires the use of (Z)-beta-iodo-alpha,beta-enoates readily prepared by the addition of HI to the alkynyl esters for the efficient preparation of pyrrolinones, tetrahydropyrrolizinones, and tetrahydroindolizinones. Utilization of omega-functionalized alpha,eta-ynoates or beta-iodo-alpha,beta-enoates allows for cyclization onto the omega-functionality providing for a synthetic route to quinolizidines.     

Acid-base properties of five-membered nitrogen-containing heterocycles (review)

The acid-base properties of five-membered nitrogen-containing heterocycles with one, two, three, and four nitrogen atoms in the ring are discussed. The factors that determine the properties of these compounds as acids and bases are analyzed. The problems that arise in comparing the basicities of heterocycles, the protonation of which is described by different acidity scales are stressed. A significant amount of space is allotted to an examination of the acid-base properties of nitrogen-containing heterocycles in the gas phase and to the use of quantum-chemical methods in the study of the protolytic equilibria of these compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 579–592, May, 1988.     

Molecular design of heterocycles. 4. Utilization of computers in the chemistry of heterocycles (review)

Fundamental principals of the utilization of computers in the design of heterocyclic structures and reactions are examined and systematized in this review. The authors' original GREN program, which lists the recyclizations of heterocycles, and Heterocycland program, which is based on the previously proposed [2] structure-synthesis concept and is used for the retrosynthesis of six-membered heterocycles, are examined concisely.For Communication 3, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1299–1318, October, 1993.     

Reactions involving the formation of five-membered mesoionic heterocycles (review)

The available literature data on reactions involving the formation of five-membered mesoionic heterocycles are systematized and correlated. It is shown that the conversion of linear compounds to mesoionic heterocyclic systems is realized primarily via two pathways, viz., by dehydrocyclization and by protocyclization. These reactions are examined in greatest detail in the case of the formation of sydnones and sydnoneimines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 291–303, March, 1981.     

Catalytic synthesis and reactions of nitrogen heterocycles (Review)

Studies at the Latvian Institute of Organic Synthesis and literature data from 1984–1994 on organic catalysis in the chemistry of N-heterocycles are reviewed. 77 to prospects for further developments in catalytic reactions of N-heterocycles are examined.     

Recent advances in iron(III) chloride catalyzed synthesis of heterocycles

Heterocyclic compounds particularly five, six and seven membered ring containing heterocycles are the most abundant which constitute a staggeringly diverse and important class of molecules that occur ubiquitously in a variety of synthetic drugs, bioactive natural products, pharmaceuticals and agrochemicals. Owing to the glorious past and impressive present of the biologically active heterocyclic scaffolds, these skeletons have long been a subject of immense interest. Hence, substantial efforts have been made to the development of new and innovative synthetic strategies for the synthesis of these heterocycles involving use of different metal catalysts, organic and inorganic reagents etc. Among the different types of metal catalysts used, iron catalysts are one of the cheap and easily available. In recent time, several new and innovative iron(III) chloride catalyzed synthesis of heterocycles with structural diversity are coming in the forefront of the literature by the scientific community. This review highlights the advancements made so far by iron(III) chloride for the synthesis of different assemblies of small heterocycles covering the year 2014–2018.