Transformations of diethyl mono- and di(β-chloroallyl)malonates

In the reaction between γ-chloro-δ-hydroxy-γ-valerolactone and potassium phthalimide in dimethylformamide, γ-phthalimido-δ-hydroxyγ-valerolactone is formed, alkaline hydrolysis of which gives δ-hydroxylevulinic acid. It is shown that oxidation of di(β-chloroallyl)malonic acid with hydrogen peroxide in acetic acid gives the dilactone of bis(δ-hydroxy-γ-chloro-γ-hydroxy)malonic acid.     

Synthesis of 2-substituted 3-aroylindenes via palladium-catalyzed carbonylative cyclization of diethyl 2-(2-(1-alkynyl)phenyl)malonates with aryl halides

[reaction: see text] The palladium-catalyzed reaction of readily accessible diethyl 2-(2-(1-alkynyl)phenyl)malonates with aryl halides under a balloon pressure of CO produced 2-substitued 3-aroylindenes in good yields. The reaction is believed to proceed via cyclization of the alkyne containing a proximate nucleophilic center promoted by an acylpalladium complex.     

Reactions of aromatic dithiols with diethyl 2-alkyl-2-(oxiran-2-ylmethyl)malonates

New sulfur-containing butano-4-lactones were synthesized by reaction of diethyl 2-alkyl-2-(oxiran-2-ylmethyl)malonates with biphenyl-4,4′-dithiol, (biphenyl-4,4′-diyl)dimethanethiol, and (2,4,6-trimethylbenzene-1,3-diyl)dimethanethiol. Opening of the oxirane ring in the initial ester followed the Krasuskii rule.     

The thermal degradation of poly(diethyl fumarate)

The kinetics and mechanism of the thermal degradation of poly(diethyl fumarate) (PDEF) were studied by thermogravimetry, as well as by analysis of the thermolysis volatiles and polymer residue. The characteristic mass loss temperatures were determined, as were the overall thermal degradation activation energies of three PDEF samples of varying molar mass. Ethylene and ethanol were present in the thermolysis volatiles at degradation temperatures below 300 °C, while diethyl fumarate was also evidenced at higher degradation temperatures. The amount of monomer increased with increasing degradation temperature. The dependence of the molar mass of the residual polymer on the degradation time and temperature was established and the number of main-chain scissions per monomer unit, s/P₀, calculated. A thermal degradation mechanism including de-esterification and random main-chain scission is proposed. The thermal degradation of PDEF was compared to the thermolysis of poly(ethyl methacrylate) (PEMA), poly(diethyl itaconate) (PDEI) and poly(ethyl acrylate) (PEA).     

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.     

Remarkably mild and efficient intramolecular Friedel-Crafts cyclization catalyzed by In(III)

[structure: see text]. Indium(III) salts were found to be highly effective catalysts for the intramolecular Friedel-Crafts reaction of simple allylic bromides and arenes. In(III) salts appear to be the most general and possess unique halophilic properties as a Lewis acid for this reaction among the catalysts evaluated to date. Deactivated arenes possessing chloride, bromide, and fluoride underwent smooth reaction when activated by InCl3.     

Ru(III)-catalyzed cyclization of arene-alkene substrates via intramolecular electrophilic hydroarylation

[reaction: see text] We herein report that RuCl(3)/AgOTf has proven to be a hydroarylation catalyst with an efficiency and scope superior to previously known methods. This catalyst demonstrated consistent performance with arene-ene substrates of diverse structural features, providing good to excellent yields of cyclization products (chromanes, tetralins, terpenoids, dihydrocoumarins).     

Pt(IV)-catalyzed cyclization of arene-alkyne substrates via intramolecular electrophilic hydroarylation

[reaction: see text] We herein report that PtCl(4) has proven to be a hydroarylation catalyst with an efficiency and substrate scope superior to previously known methods. This catalyst demonstrated consistent performance with arene-yne substrates of diverse structural features, including propargyl ethers, propargylamines, and alkynoate esters, providing good to excellent yields of the 6-endo products (chromenes, dihydroquinolines, and coumarins). In contrast, Pt(II), Pd(II), and Ga(III) salts were shown to be sensitive to the substitution on the alkyne moiety.     

Synthesis and intramolecular cyclization of bisthiadiazinylmethane derivatives

Bisthiadiazinylmethane derivatives obtained from 1,2,6-thiadiazine 1,1-dioxides and formaldehyde, undergo unusual intramolecular cyclizations to thiadiazino [4,3-g] [2,1,3] benzothiadiazine tetraoxides. The structures of the newly synthesized compounds are discussed on the basis of ¹H and ¹³C-NMR data and X-ray analysis.     

Catalytic claisen amino rearrangement of N-(cyclo)alkenylarylamines and intramolecular cyclization of ortho-alkenylarylamines

Aromatic Claisenamino rearrangements of N-alkenyl-2-methylindoline under the action of Lewis acids leads to 7-alkenyl-2-methylindolines in high yield. Cyclization of ortho-alkenyl compounds was effected in polyphosphoric acid (PPA) and by UV irradiation. Heating 7-(1-methyl-2-butenyl)-2-methylindoline in PPA is accompanied by 1,3-methyl shift in the alkenyl substituent with subsequent cyclization at the aromatic nucleus.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1342–1346, October, 1992.     

Synthesis of carbazoles via an intramolecular cyclization of 2-(6-substituted 3(Z)-hexen-1,5-diynyl)anilines and their related molecules

Various 2-(6-substituted 3(Z)-hexen-1,5-diynyl)anilines 1a-g were treated with potassium tert-butoxide or potassium 3-ethylpentanoxide in NMP at 60 degrees C for 2 h to give the corresponding 5-substituted carbazoles 2a-g in 36-65% yields together with indoles 9a-g in 21-40% yields, respectively. Exposing the trifluoroacetamide analogues 10h-k under the same reaction conditions gave the carbazoles 2b-e in 37-57% yields and indoles 9b-e in 15-27% yields. Subsequent cyclizations of acetamide analogues 10a-g gave carbazoles 2a-g in 53-86% yields.     

The thermal properties of polysiloxanes poly(dimethyl siloxane) and poly(diethyl siloxane)

New measurements and literature data on polysiloxanes covering heat capacities, transition parameters, enthalpies, entropies and Gibbs energies are presented and critically reviewed. TheATHAS computation method is used to bring heat capacities into agreement with an approximate frequency spectrum. The various crystal and mesophases are discussed. TheATHAS (1990) recommended data are as follows: For poly(dimethyl siloxane) the glass transition is at 146 K with an increase in heat capacity of 29.24 J/(K mol). The completely crystalline sample melts at about 219 K with a heat of fusion of 2.75 kJ/mol. For poly(diethyl siloxane) the glass transition is at 135 K with an increase in heat capacity of 34.48 J/(K mol). The completely crystalline sample changes to a condis crystal at 206.7 K with a heat of disordering of 2.72 kJ/mol. The transition to a poorly characterized viscous crystal with thermodynamic properties close to the melt occurs at 282.7 K with an enthalpy of transition of 1.84 kJ/mol. Final fusion occurs at 308.5 K and a small endotherm of about 231 J/mol. Tables of heat capacities, enthalpies, entropies and Gibbs energies are given from 0 K to 550 K.

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Zusammenfassung Neue Messungen und Literaturangaben von Polysiloxanen über Wärmekapazität, Umwandlungsparameter, Enthalpien, Entropien und Gibbssche Energien werden vorgestellt und kritisch betrachtet. Das Rechenverfahren ATHAS wurde benutzt, um die Wärmekapazitäten mit einem annähernden Frequenzspektrum in Einklang zu bringen. Es wurden die verschiedenen Kristall- und Mesophasen diskutiert. Die von ATHAS (1990) empfohlenen Werte sind wie folgt: Für Poly(dimethylsiloxan) beträgt der Glasumwandlungspunkt 146 K bei Zunahme der Wärmekapazität um 29.24 J/(K.mol). Die vollständing kristalline Probe schmilzt bei etwa 219 K mit einer Schmelzwärme von 2.75 kJ/mol. Für Poly(diethylsiloxan) beträgt der Glasumwandlungspunkt 135 K bei Zunahme der Wärmekapazität um 34.48 J/(K.mol). Die vollständig kristalline Probe wandelt sich bei 206.7 K um, die Fehlordnungswärme beträgt 2.72 kJ/mol. Die Umwandlung in einen wenig verstandenen viskosen Kristall, dessen thermodynamische Eigenschaften denen der Schmelze gleichen, erfolgt bei 282.7 K mit einer Umwandlungsenthalpie von 1.84 kJ/mol. Letztendlich verläuft das Schmelzen bei 308.5 K mit einem kleinen endothermen Effekt von etwa 231 J/mol. Wärmekapazitäten, Enthalpien, Entropien und Gibbssche Energien sind für den Bereich 0 K–550 K tabellarisch angegeben.

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, , , , . ATHAS , - . . ATHAS (1990) : 146 29,24 / ·. 219 2,75 /. 135 34,48 /·. 206,7 2,72 /. « » 282,7 1,84 /. 308,5 231 /. , , 0–550 .

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This work was supported by the National Science Foundation, Polymers Program, Grant #DMR 83-17097 and early work of J.P.W. was supported by the Am. Chem. Soc. Petroleum Research Found, Grant 12431-AC7. In addition at Oak Ridge National Laboratory the work was sponsored by the Division of Materials Sciences, Office of Basic Energy Sciences, U.S. Department of Energy under contract DE-AC05-84OR21400 with Martin Marietta Energy Systems Inc.     

Ruthenium-catalyzed intramolecular cyclization of hetero-functionalized allylbenzenes

Intramolecular addition of heterofunctionalities to CC double bonds without β-hydride elimination was investigated and catalyzed by ruthenium complexes. The combination of RuCl₃ · nH₂O (10 mol%) and 3 equiv. of AgOTf acted as a catalyst for cyclization of 2-allylphenol (1a) to 2,3-dihydro-2-methylbenzofuran (2a) in good yield in the presence of Cu(OTf)₂ as a co-catalyst and PPh₃ as a ligand. This catalyst system also catalyzed the cyclization of 2-allylbenzoic acid to lactone in 91% yield. Then, a new catalyst system (RuCp¹Cl₂)₂ (1.0 mol%)/4AgOTf/4PPh₃, was found to be more active even in the absence of Cu(OTf)₂. Furthermore, this catalysis was applied to asymmetric reaction of 2-allylphenol (1a). When using TolBINAP as a ligand, over 60% e.e. was achieved.     

Synthesis of pyridone-substituted furan-2(5H)-ones and their intramolecular cyclization to afford furo[3,4-f]isoquinolines

Chemistry of Heterocyclic Compounds - Synthetic approach toward pyridone-substituted furan-2(5H)-ones has been described. Intramolecular cyclization of these compounds leads to novel 7-substituted...     

Structure of pyrrolisidinediones — Products of the intramolecular cyclization of aminoketo-stabilized sulfonium ylides

The structure of three pyrrolisidinediones was determined by x-ray crystallographic analysis. A pseudocentrosymmetrical structure of the dimer crystal with a molecule of water of crystallization close to the inversion center was detected in the oxidation product.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1797–1802, August, 1991.     

Platinum(II)-catalyzed intramolecular cyclization of alkynylbenzonitriles: synthesis of 1-alkoxyisoquinolines and isoquinolones

A facile synthesis of a series of 1-alkoxyisoquinolines and (2H)-isoquinolones by an intramolecular 6-endo-dig cyclization of ortho-alkynylbenzonitriles in the presence of a catalytic amount of hydrido(dimethylphosphinous acid-κP)[hydrogen bis(dimethylphosphinito-κP)]platinum(II) in various alcohols at 65-90 °C is described for the first time.     

Alkali hydrolysis of diethyl malonates: Theoretical conformation analysis for substrates and tetrahedral intermediates

Molecular-mechanics methods have been applied to the conformations of substituted diethyl malonates; models for reaction complexes formed with hydroxide anions have been constructed. The relative preferences for the diastereometric tetrahedral intermediates have been determined for both stages in the alkali hydrolysis. Potential-surface sections give a qualitative interpretation of the steric factors governing the reactivity, which can be evaluated precisely from the steric indices IS_V.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 6, pp. 675–681, November–December, 1990.