Investigation on radical polymerization of 2-methylene-1,3-dioxolanes and 2-methylene-1,3-oxazolidines

The reaction of 2-methylene-1,3-dioxolanes and 2-methylene-1,3-oxazolidines with benzoyl peroxide (acceptor radical) and with N-ethylmaleimide (acceptor) was investigated. It was shown that benzoyl peroxide adds to monomers 1a and 1b , giving the corresponding linear diester amides 1a and 1b respectively. The oxazolidine 1c adds benzoyl peroxide, without ring opening, by addition to the exomethylene group. Together with N-ethylmaleimide the oxazolidines 1a or 1b produce deep-colored charge transfer complexes, resulting in high molecular poly-N-ethylmaleimides probably via a radical mechanism. The 1,3-dioxolanes 2a and 2b were radically polymerized to produce polyacetals by vinyl polymerization. 2c was polymerized to produce randomly containing acetal units and ester units. The mechanism of polymerization of 2e is complex, affording polymers of nonuniform character. 2-Methylene-4-phenyl-1,3-dioxolane polymerization leads to polyester as the main structure, and to a lesser degree polyacetal structures. The chemical structures of the polymers were confirmed by NMR spectra and elemental analysis. © 1996 John Wiley & Sons, Inc.     

Acetals and ethers,XVII. One- or two-step syntheses of 2-(2-alkoxyethyl)-1,3-dioxacyclanes

2-(2-Alkoxyethyl)-1,3-dioxanes (1) were prepared by ap-toluenesulfonic acid-catalyzed, one-step reaction of propenal with a mixture of aliphatic alcohol and trimethylene glycol in good yields. The transacetalization reaction of 1,1,3-trialkoxypropanes (3) with ethylene glycol or propylene-(1,2)glycol afforded good yields of pure 2-(2-alkoxyethyl)-1,3-dioxolanes (5 or6), respectively. This reaction proceeds through an intermediate 1,3-dialkoxy-1-(2-hydroxyalkoxy)-propane.

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Ein- oder Zweistufensynthese von 2-(2-Alkoxyethyl)-1,3-dioxacyclanen

Zusammenfassung In der durchp-Toluolsulfonsäure — katalysierten, direkten Reaktion von Propenal mit einem Gemisch von aliphatischem Alkohol und Trimethylenglykol wurden die entsprechenden 2-(2-Alkoxyethyl)-1,3-dioxane (1) in guten Ausbeuten erhalten. Die Umacetalisierung von 1,1,3-Trialkoxypropanen (3) mit Ethylenglykol oder 1,2-Propylenglykol lieferte 2-(2-Alkoxyethyl)-1,3-dioxolane (5 oder6) in guten Ausbeuten. Die Umacetalisierungsreaktion von 1,1,3-Trialkoxypropanen verläuft über 1,3-Dialkoxy-1-(2-hydroxyalkoxy)-propane als Zwischenprodukte.

     

Fragmentation Pathways of Singly- and Doubly-charged Ions in the Mass Spectra of Si-, N- and C-Substituted 1,3-Dioxa-6-aza-2-silacyclooctanes

The fragmentation pathways of singly- and doubly-charged ions in the mass spectra of Si-, N-, and C-substituted 1,3-dioxa-6-aza-2-silacyclooctanes upon electron impact have been studied. The directions for the fragmentation of the singly- and doubly-charged molecular ions differ markedly. All the doubly-charged fragmentation ions are formed by the loss of neutral molecules from M⁺⁺ and contain nitrogen and silicon atoms.     

Rh2(oac)4-catalyzed reactions of methyl diazoacetate with 1,3-oxazolidines and 1,3-oxathiolanes

Methoxycarbonylcarbene generated by catalytic decomposition of methyl diazoacetate in the presence of Rh₂(OAc)₄, is regioselectively inserted into the C(2)-O bond of 3-alkyl-2-phenyl-1,3-oxazolidines and into the C(2)-S bond of 2-phenyl-1,3-oxathiolane. Study by the competitive reaction method demonstrated that the relative reactivity toward the insertion of the methoxycarbonylcarbene fragment into the C-heteroatom bond increases in the series of 1,3-dioxolane, 1,3-oxazolidine, and 1,3-oxathiolane. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1411–1415, August, 2006.     

5-(1,3-Dioxolan-2-yl)-2-furanylzinc bromide; direct preparation, and its application for the synthesis of 5-substituted furan derivatives

5-(1,3-Dioxolan-2-yl)-2-furanylzinc bromide was easily prepared by the direct insertion of active zinc to 2-bromo-5-(1,3-dioxolane)furan under mild conditions. Of interest, the resulting organozinc was successfully coupled with aryl halides and acid chlorides affording the corresponding coupling products in good to excellent yields.     

Synthesis and structure of novel 2-amino-l,3-dicyano-4-cyclopropyl-6-aryl-1,3-cyclohexadienes

The reaction of arylmethylenedicyanoacetates with 1,1-dicyano-2-cyclopropylpropene was studied and found to give 2-amino-1,3-dicyano-4-cyclopropyl-6-aryl-1,3-cyclohexadienes. The structure of 2-amino-6-(2-nitrophenyl)-1,3-dicyano-4-cyclopropyl-1,3-cyclohexadiene was corroborated by means of X-ray analysis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 355–358, February, 1993.     

Borylation of saturated heterocycles with several heteroatoms. (Review)

New examples of the borylation of a series of five-and six-membered saturated 1,3-and 1,3,2-heterocycles with the formation of cyclic boric esters are described. The probable mechanism of the reaction is discussed. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 643–654, May, 2006.     

Cationic polymerizations of substituted 2-methylene-1,3-dioxocyclic acetals, 2-methylene-1,3-dithiolane and copolymerization of 2-methylene-1,3-dithiolane with 4-(t-butyl)-2-methylene-1,3-dioxolane1

Carbon black-supported sulfuric acid or BF₃·Et₂O-initiated polymerizations of 2-methylene-4,4,5,5-tetramethyl-1,3-dioxolane (1), 2-methylene-4-phenyl-1,3-dioxolane (2), and 2-methylene-4-isopropyl-5,5-dimethyl-1,3-dioxane (3) were performed. 1,2-Vinyl addition homopolymers of 1–3 were produced using carbon black-supported H₂SO₄ initiation at temperatures from 0°C to 60°C whereas both ring-opened and 1,2-vinyl structural units were present in the polymers using BF₃·Et₂O as an initiator. Cationic polymerizations of 2-methylene-1,3-dithiolane (4) and copolymerization of 4 with 2-methylene-4-(t-butyl)-1,3-dioxolane (5) were initiated with either carbon black-sulfuric acid or BF₃·Et₂O. Insoluble 1,2-vinyl addition homopolymers of 4 were obtained upon initiation with the supported acid or BF₃·Et₂O. A soluble copolymer of 2-methylene-1,3-dithiolane (4) and 4-(t-butyl)-2-methylene-1,3-dioxolane (5) was obtained upon BF₃·Et₂O initiation. This copolymer is composed of three structural units: a ring-opened dithioester unit, a 1,2-vinyl-polymerized 1,3-dithiolane unit, and a 1,2-vinyl polymerized 4-(t-butyl)-1,3-dioxolane unit. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2823–2840, 1999     

Cleavage of 1,3-oxathiol-2-one rings withn-butyllithium a new route to alkyl thiolates

1,3-Oxathiol-2-ones are converted byn-butyllithium into alkynyl thiolates.

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Spaltung von 1,3-Oxathiazol-2-on-Ringen mitn-Butyllithium. Ein neuer Weg zu Alkylthiolaten (Kurze Mitteilung)

Zusammenfassung 1,3-Oxathiol-2-one werden mitn-Butyllithium zu Alkinylthiolaten umgesetzt.

     

Molecular structure of 1-methyl-1-fluoroquasisilatrane (2-methyl-2-fluoro-1,3-dioxa-6-aza-2-silacyclooctane)

The molecular structure of 1-methyl-1-fluoroquasisilatrane (2-methyl-2-fluoro-1,3-dioxa-6-aza-2-silacyclooctane) MeFSi(OCH₂CH₂)₂NH (I) is determined by single crystal X-ray diffraction at 100 K. The coordination polyhedron of the silicon atom in this molecule is a slightly distorted trigonal bipyramid with an NH group and a strongly electron-withdrawing fluorine atom in the axial positions, and two endocyclic oxygen atoms and a CH₃ group in three vertices of the equatorial plane. The axial angle N→SiF is 171°. The length of the transannular donor-acceptor bond N→Si (2.058 Å) is as small as in 1-fluorosilatrane. The axial bond F-Si (1.660 Å) is longer than that in 1-fluorosilatrane and tetrahedral silicon compounds.     

Synthese und Reaktionsverhalten von 6-sec-Amino-1,3-thiazin-2-thionen

The title compounds3 have been prepared by ring transformation reactions of the isomeric 2-sec-amino-1,3-thiazine-6-thiones1 via ring-opening products2 and by special cyclocondensation reactions with thiocarboxamides8, and with iminium salts10, starting from 2,2-dichlorovinyl ketones6 in all cases. The pathways differ specifically in scope and limitations. On the other hand the intermediates2 react with alkylating agents to 2,6-di-sec-amino-1,3-thiazinium salts4, which are also available via alkylation of3 to 2-methylthio-1,3-thiazinium salts11 and aminolysis. Moreover,11 serve as useful precursors for other 1,3-thiazine derivatives by nucleophilic methylthio displacement (examples12).

     

Synthesis of 2-substituted benzo-1,3-ditelluroles

A method for the synthesis of 2-phenylbenzo-1,3-ditellurole by the reaction of disodiumo-benzeneditellurolate with benzylidene chloride was proposed. 2-Methylbenzo-1,3-ditellurole and benzo-1,3-ditellurole-2-carboxylic acid were prepared by the reaction of 2-lithiobenzo-1,3-ditellurole with MeI and CO₂, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1132–1134, June, 2000.     

Stereoselective synthesis of 4-hydroxymethyl-1,3-oxazolidin-2-one derivatives from novel 2-hydroxymethylaziridines

A stereoselective and simple method for the synthesis of trans-2-hydroxymethyl-N-alkyl-1,3-oxazolidin-2-ones is described. The synthesis involved the reduction of trans-aziridine-2-carboxylates with LiAlH₄, followed by a ring opening and a cyclization reaction in the presence of methyl chloroformate to afford the target trans-oxazolidinones in completely regio- and stereoselective process. A plausible reaction mechanism has been proposed involving an S_N1 pathway and a detailed computational study of this mechanistic process has been carried out using theoretical calculations.     

Stereoselective synthesis of oxazolidine, hexahydropyrrolo [2,1-b] oxazole, and tetrahydro-2H-oxazolo [3,2-c] thiazole grafted macrocycles through intramolecular 1,3-dipolar cycloaddition reaction

A facile one-pot synthesis of oxazolidine, hexahydropyrrolooxazole and tetrahydro-2H-oxazolothiazole grafted macrocycles through intramolecular 1,3-dipolar cycloaddition reaction (1,3-DC reaction) is reported. X-ray diffraction studies and 2D NOESY experiments of the cycloadducts proved the stereo- and regiochemistry of the cycloaddition.     

Synthesis and photochromic properties of 1,2-dihetarylethenes with 1,3-dioxole- and 1,3-oxazole-2-thione bridges

Methods for the synthesis of substituted bis(2,5-dimethyl-3-thienyl)ethenes with 1,3-dioxole- and 1,3-oxazole-2-thione fragments as ethene bridges were developed. These compounds exhibit photochromic properties. Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1299–1301, May, 2005.     

New reaction of the sodium salt of 2-nitroethanol. X-ray analysis of the sodium salt of 2-oxo-3-hydroxypropionic acid oxime, 2-bromo-2-nitropropane-1,3-diol,and the model 2,2-dinitropropane-1,3-diol

A novel reaction of the sodium salt of 2-nitroethanol in aqueous ammonia resulted in the sodium salt of 2-oxo-3-hydroxypropionic acid oxime (1) has been found. Bromination of1 affords 2-bromo-2-nitropropane-1,3-diol (2) with a previously unknown molecular conformation. The formation mechanisms of compounds1 and2 were suggested. X-ray analysis of products1,2 and that of the model compound, 2,2-dinitropropane-1,3-diol, was performed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1217–1221, May, 1996.     

Sulfenocyclization of unsaturated ureas and thioureas

Summary A general method for the formation of cyclic sulfenylated 2-oxazoline, 2-thiazolines, 5,6-dihydro-4H-1,3-oxazines, and 5,6-dihydro-4H-1,3-thiazines is described. The procedure employs arylsulfenyl chloride and ethyldiisopropylamine to generate an episulfonium ion intermediate from which the cyclic products arise by internal nucleophilic displacement.

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Sulfenocyclisierung ungesättigter Harnstoffe und Thioharnstoffe

Zusammenfassung Eine allgemeine Methode zur Herstellung cyclischer sulfenylierter 2-Oxazoline, 2-Thiazoline, 5,6-Dihydro-4H-1,3-oxazine und 5,6-Dihydro-4H-1,3-thiazine wird beschrieben. Aus Arylsulfenylchlorid und Ethyldiisopropylamin entsteht ein Episulfoniumion als Zwischenprodukt; dieses bildet durch nucleophile Umlagerung die cyclischen Produkte.

     

Chemical structure and surface activity

Surface tension measurements on aqueous solutions of 2-alkyl-2-methyl-1,3-dioxolanes, 2-alkyl-4-methyl-1,3-dioxolanes, and 2-alkyl-1,3-dioxanes at a temperature of 293.2 K are presented. The surface tension isotherms obtained were used to calculate some adsorption parameters, i. e. the efficiency of surface tension reduction, pC₂₅, surface excess concentration, , and surface area,A, per molecule in the adsorption layer. The Temkin adsorption isotherm equation was used to calculate standard free energy of adsorption, G ⁰ _=0.5 . The increments for a methylene group in the alkyl chain, G ^o [–CH₂–], and for the residual part of the molecule, G ^o [W], were also determined.The results obtained show that: (i) an increase in alkyl chain length at the C-2 carbon atom of the ring by one methylene unit brings about a marked increase in surface activity; (ii) the introduction of a methyl group into the 1,3-dioxolane ring (i. e., at C-2 or C-4 atom) has a weaker effect on surface activity of alkyl-substituted 1,3-dioxolanes, and (iii) the contribution of the 5- and 6-membered 1,3-dioxacyclane rings to a total surface activity of, respectively, 2-alkyl-1,3-dioxolanes and 2-alkyl-1,3-dioxanes is similar.     

Cationic copolymerization of cyclic ketene acetals: The effect of substituents on reactivity

Cationic copolymerizations of 4-methyl-2-methylene-1,3-dioxane, 2 (M₁), with 2-methylene-1,3-dioxane, 1 (M₂); of 4,4,6-trimethyl-2-methylene-1,3-dioxane, 3 (M₁), with 2-methylene-1,3-dioxane, 1 (M₂); of 4-methyl-2-methylene-1,3-dioxolane, 5 (M₁), with 2-methylene-1,3-dioxolane, 4 (M₂); and of 4,5-dimethyl-2-methylene-1,3-dioxolane, 6 (M₁), with 2-methylene-1,3-dioxolane, 4 (M₂) were conducted. The reactivity ratios for these four types of copolymerizations were r₁ = 1.73 and r₂ = 0.846; r₁ = 2.26 and r₂ = 0.310; r₁ = 1.28 and r₂ = 0.825; r₁ = 2.23 and r₂ = 0.515, respectively. The relative reactivities of these monomers towards cationic polymerization are: 3 > 2 > 1; and 6 > 5 > 4. With both five- and six-membered ring cyclic ketene acetals, the reactivity increased with increasing methyl substitution on the ring. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 861–871, 1998     

Zum Mechanismus der Reduktion von 1,3-Benzodithiol-2-thionen

Carbophilic reaction of 1,3-benzodithiole-2-thione (1) with trideuteroborane · dimethylsulfide, synthesized from NaBD₄ and BF₃ ·Me ₂S inTHF, gave 2,2-dideutero-1,3-benzodithiole (5 b) as well as the minor side-products7 b,8 and9 b.