Pyryliumverbindungen. 36. Substituierte Benzoesäureester aus 2,4,6-Triaryl-pyryliumsalzen und α-Ketocarbonsäureestern

Pyrylium Compounds. 36. Substituted Benzoic Acid Esters from 2,4,6-Triarylpyrylium Salts and α-Ketocarboxylic Acid Esters 2,4,6-Triarylpyrylium salts 1 react with α-ketocarboxylic acid esters 2 in the presence of two equivalents of an appropriate condensing agent (e.g. dialkylamine salts of weak acids, triethylamine/acetic acid, or sodium acetate) to give 2-aroyl-3,5-diarylbenzoic acid esters 3 . However, using only one equivalent of the condensing agent, the formation of 3,5-diarylbenzoic acid esters 5 predominates. Alkaline saponification of the new esters 3 and 5 yields the corresponding substituted benzoic acids 4 and 6 , respectively. – I.r., u.v., n.m.r. and mass spectroscopic data of the novel products 3 – 6 are reported.     

Pyryliumverbindungen. XXIX [1] Substituierte Benzophenone aus 2,4,6-Triaryl-pyryliumsalzen und Methyl(en)ketonen

Pyrylium Compounds. XXIX. Substituted Benzophenones from 2,4,6-Triarylpyrylium Salts and Methyl(ene) Ketones In the presence of piperidine acetate (or similar salts of certain dialkylamines), 2,4,6-triarylpyrylium perchlorates 5 react with methyl(ene) ketones 6 to give benzophenones 7 , the structure of which was proved by spectroscopic methods as well as by independent synthesis. Besides acetone and other acyclic ketones (e. g. alkyl methyl ketones, phenylacetone, desoxybenzoin, dibenzyl ketone) cyclic ketones (e. g. cyclopentanone, cyclohexanone, cycloheptanone, acenaphthenone) can also be used as ketone component 6 ; acetophenones react differently leading to hydrocarbons of the 1,3,5-triarylbenzene type 15 . The varying efficiency of the diverse amine salts and the mode of incorporation of the unsymmetrically substituted ketones suggest the intermediate formation of enamines 10 as crucial step of the ring transformations observed. This assumption is supported by isolation of the iminium salt 18 on reacting 3,5-dimethyl-2,4,6-triphenylpyrylium perchlorate ( 16 ) with acetone/piperidine acetate.     

Pyryliumverbindungen. 42. Benzocycloalkenone und Dihydro-2H,7H-1-benzopyranone aus 2,4,6-Triaryl-pyryliumsalzen und Cycloalkan-1,2-dionen

Pyrylium Compounds. 42. Benzocycloalkenones and Dihydro-2H,7H-1-benzopyranones from 2,4,6-Triarylpyrylium Salts and Cycloalkane-1,2-diones 2,4,6-Triarylpyrylium salts 1 react with cycloalkane-1,2-diones 2 in the presence of an appropriate condensing agent to yield benzocycloalkenones 3 . Thus, sodium acetate and cyclo-hexane-1,2-dione ( 2a ) lead to the dihydro-2H-naphthalenones 3a – i , whereas with cycloheptane-1,2-dione ( 2b ) and piperidine acetate, triethylamine or sodium acetate the tetrahydro-5H-benzo-cyclohepten-5-ones 3j – r are formed. As shown for the example 3a, j → 4a, b , benzocycloalkenones of type 3 can be converted into phthalazines 4 on heating with hydrazine in ethanol. By reaction of the dione 2a and an equimolar mixture of triethylamine and acetic acid or morpholine acetate with the salts 1 5,6-dihydro-2H,7H-1-benzopyran-8-ones 5 are obtained as a result of a new type of ring transformation. The pyrans 5 can be cleaved with perchloric acid in ethanol to 5,6,7,8-tetrahydro-8-oxo-1-benzopyrylium perchlorates 6 . If the pyrans 5 are heated with sodium acetate in ethanol, a conversion to benzocycloalkenones 3 is achieved (cf. 5a → 3a ). The structure of the new compounds was established by spectroscopic methods.     

Pyryliumverbindungen. 43 [1]. Arylsubstituierte 5-(2-Dialkylamino-thiazol-5-yl)-pentadienone aus 2,4,6-Triaryl-pyryliumsalzen und 2-Dialkylamino-4-arylthiazolen

Pyrylium Compounds. 43. Arylsubstituted 5-(2-Dialkylamino-thiazol-5-yl)-pentadienones from 2,4,6-Triarylpyrylium Salts and 2-Dialkylamino-4-aryl-thiazoles 2,4,6-Triarylpyrylium salts 1 react with 2-dialkylamino-4-aryl-thiazoles 7 (used in substance or prepared in situ from α-thiocyanato-acetophenones 9 ) in the presence of an appropriate acid-binding agent (e.g. piperidine acetate or sodium acetate) to give 5-(2-dialkylamino-4-aryl-thiazol-5-yl)-1,3,5-triaryl-penta-2,4-dien-1-ones 8 . As reaction medium aliphatic alcohols (ethanol, n-propanol), dipolar aprotic solvents (acetonitrile) or chlorinated hydrocarbons (methylene chloride, chloroform) can be used. On the other hand, under the same conditions 2-amino-4-phenyl-thiazole ( 10 ) reacts with salts of type 1 via pyrylium ring transformation yielding 2,4,6-triaryl-1-(4-phenyl-thiazol-2-yl)-pyridinium perchlorates 11 .     

Pyryliumverbindungen. 45 [1]. 4-Aroyl-fluorene aus 2,4,6-Triaryl-pyryliumsalzen und Indan-1-on via 2-(5-Oxo-pent-2-en-1-yliden)-indan-1-one

Pyrylium Compounds. 45. 4-Aroyl-fluorenes from 2,4,6-Triaryl-pyrylium Salts and Indan-1-one via 2-(5-Oxo-pent-2-en-1-yliden)-indan-1-ones 2,4,6-Triarylpyrylium salts 1 react with indan-1-one in the presence of an appropriate buffer system (e.g. piperidine acetate, triethylamine/acetic acid, triethylamine or sodium acetate) to yield the 2-(1,3,5-triaryl-5-oxo-pent-2-en-1-yliden)-indan-1-ones 2 . For the reaction medium aliphatic alcohols (methanol, ethanol), dipolar aprotic solvents (acetonitrile) or chlorinated hydrocarbons (methylene chloride, chloroform, carbon tetrachloride) can be used. On treating 2 with sodium methanolate in methanol, a cyclization reaction occurs giving rise to the 4-aroyl-1,3-diaryl-fluorenes 3 . As by-products 1,3-diaryl-fluorenes 8 (e.g. 1,3-diphenyl-fluorene) are formed. - I.r., n.m.r. and u.v. spectroscopic data of the novel compounds 2 and 3 are reported.     

Pyryliumverbindungen. 30. C-Alkylierung von 1,3,5-Triaryl-penten-1,5-dion-Enolaten: Ein einfacher Zugang zu 3-alkylsubstituierten 2,4,6-Triaryl-pyryliumsalzen

Pyrylium Compounds. 30. C-Alkylation of 1,3,5-Triaryl-pentene-1,5-dione Enolates: A Simple Approach to 3-Alkylsubstituted 2,4,6-Triarylpyrylium Salts 1,3,5-Triaryl-pentene-1,5-dione enolates ( 10 ), obtainable in crystalline form from 2,4,6-triarylpyrylium pseudobases ( 9 ) and sodium methoxide in benzene/ether, react in dipolar aprotonic solvents (e.g. DMSO, DMF) with various types of alkyl iodides to give C-alkylation products ( 11 ) which afford 3-substituted 2,4,6-triarylpyrylium salts ( 12 ) on treatment with perchloric acid. This reaction sequence proved to be a convenient synthetic route to pyrylium salts ( 12 ) having 3-oriented substituents such as normal or branched alkyl groups C_nH_2n+1 (e.g.n = 1–5), isotopically modified alkyl groups (e.g. C[²H₃], C₂[²H₅]), allyl type substituents (e.g. CH₂CHCH₂, MeCHCHCH₂, CH₂, CH₂CMeCH₂) or benzyl groups (e. g. PhCH₂, 4-Br C₆H₄CH₂). Bifunctional alkylating agents (e.g. 1,4-diiodobutane, o-xylylenediiodide) resulted in a novel type of bispyrylium salts ( 14 ) with 3,3′-linkage. The pyrylium salts obtained were characterized by their ¹H-n.m.r. and u.v. spectra as well as, in most cases, by transformation into the corresponding pyridine derivatives ( 13 ) and bispyridines ( 15 ) respectively.     

Zur Acylierbarkeit des Phosphorylsauerstoffs. I. Acyloxyphosphoniumsalze aus Hexamethylphosphorsäuretriamid und Carbonsäurederivaten

On the Acylation of the Phosphoryl Oxygen. I. Acyloxyphosphonium Salts from HMPT and Carboxylic Acid Derivates Acylation equilibria with participation of acyloxyphosphonium ions exist in solutions of HMPT and carboxylic chlorides, or anhydrides, respectively, as can be shown by ³¹P-n.m.r. after trapping the counter ion with SbCl₅. Moderately stable acyloxyphosphonium salts have been isolated for the first time by acylation of HMPT. In the alternative reaction of (Me₂N)₃P with CCl₄ and carboxylic acids, acyloxyphosphonium salts are formed only after prolonged reaction times, due to the stability of the intermediate chlorotris-(dimethylamino)-phosphonium ion.     

Pyryliumverbindungen. 38. Zur Ringtransformation von 2,4,6-Triaryl-thiopyryliumsalzen mit Essigsäureanhydrid zu Arylbenzenen und Thiobenzophenonen

Pyrylium Compounds. 38. About the Ring Transformation of 2,4,6-Triarylthiopyrylium Salts by Acetic Acid Anhydride to Arylbenzenes and Thiobenzophenones 2,4,6-Triarylthiopyrylium salts 5 react in the presence of an appropriate condensing agent (sodium acetate, carbonate, methoxide, tert-butoxide or potassium acetate) with acetic acid anhydride to yield arylbenzenes 3 and thiobenzophenones 6 . This ring transformation represents the first example of the conversion of the moiety into the thiocarbonyl group Under the same conditions 3,5-dimethyl-2,4,6-triphenylthiopyrylium perchlorate ( 13 ) forms via [1,5]-sigmatropic rearrangement the thiobenzophenone 15 . The structure of the new compounds 6 was proved by spectroscopic methods as well as by degradation reactions. Thus, hydrogen peroxide converts 6a to the known benzophenone 4 . Alkaline saponification gives the 2-hydroxy-benzophenone 8 , whereas heating with hydrochloric acid causes a selective cleavage of the acetoxy group to the 2-hydroxy-thiobenzophenone 7 .     

Pyryliumverbindungen. 33 [1] 2-Dialkylamino-2H-thiopyrane aus 2,4,6-Triaryl-thiopyryliumsalzen

Pyrylium Compounds. 33. 2-Dialkylamino-2H-thiopyrans from 2,4,6-Triaryl-thiopyrylium Salts 2,4,6-Triaryl-thiopyrylium salts 7 react with dialkylamines in diethyl ether to give stable crystalline 2-dialkylamino-2H-thiopyrans 8 , the structure of which is in accordance with their u.v., n.m.r. and mass spectra. The chemical properties of 8 parallel those of structurally analogous 2-alkoxy- and 2-dialkylamino-2H-pyrans and 2-alkoxy-2H-thiopyrans. Thus, on heating 2-dimethylamino-2,4,6-triphenyl-2H-thiopyran ( 8a ) with methanol the corresponding 2-methoxy-2H-thiopyran 9 is formed. Nitromethane and ethyl cyanoacetate give rise to ring transformations yielding 1,3,5-triphenyl benzene ( 10 ) and 2,4,6-benzonitrile ( 11 ), respectively. From 8a electrophiles (e.g. mineral acids, methyl iodide, benzoyl chloride) regenerate the initial thiopyrylium system by taking over the dialkylamino group.     

Pyryliumverbindungen. 41. 7aH-Cyclopenta[b]pyran-7-one durch Ringtransformation von 2,4,6-Triaryl-pyryliumsalzen mit acyclischen 1,2-Diketonen

Pyrylium Compounds. 41. 7aH-Cyclopenta[b]pyran-7-ones by Ring Transformation of 2,4,6-Triarylpyrylium Salts with Acyclic 1,2-Diketones Reaction of 2,4,6-triarylpyrylium salts 1 with acyclic 1,2-diketones 2 (CH₃COCOR, R = Me, Ph) in the presence of an appropriate condensing agent (e.g. piperidine acetate, triethyl-amine/acetic acid, sodium acetate) yields the hitherto unknown 2,4,5,7a-substituted 7aH-cyclopenta[b]pyran-7-ones 3 as a result of a new type of ring transformation (2,5-[C₄O+C]/2,3-[C₂+C₃]). A characteristic feature of compounds 3 is their ability to undergo electrophilic substitutions. Thus, stepwise bromination of the 7a-methyl derivative 3a in acetic acid affords 6-bromo-7a-methyl-2,4,5-triphenyl-cyclopenta[b]pyran-7-one ( 4 ) and 3,6-dibromo-7a-methyl-2,4,5-triphenyl-cyclopenta[b]pyran-7-one ( 5 ); analogously, nitration of 3a leads to 7a-methyl-6-nitro-2,4,5-triphenyl-cyclopenta[b]pyran-7-one ( 6 ), indicating that position 6 is the favoured position for electrophilic substitutions. Contrary to the 3,5-unsubstituted pyrylium salts 1 , the 3,5-dimethyl-2,4,6-triphenyl-pyrylium perchlorate ( 13 ) reacts with 1,2-diketones 2 through a 2,6-[C₅+C] transformation to give arylsubstituted 1,2-diones 14 . The structure of the new compounds was determined by spectroscopic methods and by a single crystal X-ray analysis of the dibromo derivative 5 .     

Ringtransformationen heterocyclischer Verbindungen. VII. 2,4,5-Triaryl-benzophenone aus 2,4,6-Triaryl-pyryliumsalzen und Arylacetaldehyden: Erste Pyryliumringtransformationen mit Aldehyden als Kohlenstoffnucleophile

Ring Transformations of Heterocyclic Compounds. VII. 2,4,5-Triarylbenzophenones from 2,4,6-Triarylpyrylium Salts and Arylacetaldehydes: First Pyrylium Ring Transformations with Aldehydes as Carbon Nucleophiles 2,4,6-Triarylpyrylium salts 1 react with arylacetaldehydes 2 in the presence of sodium acetate in ethanol by a 2,5-[C₄+C₂] ring transformation to give 2,4,5-triarylbenzophenones 3 in high yield. Besides the sodium acetate, sodium methanolate, triethylamine, triethylamine/acetic acid or piperidine acetate can be applied as condensing agent. The reaction represents the first pyrylium ring transformation initiated by aldehydes.     

Mischpolymer-Latices aus Vinylacetat-Vinylestern von aus Tetrapropylen Hergestellten Carbonsäuren

Copolymer Latices Based on Vinyl Acetate and Vinyl Esters of Carboxylic Acids Derived from Propylene Tetramer Vinyl esters of carboxylic acids prepared from propylene tetramer were obtained by interesterification with vinyl acetate and the parameters for the copolymerization with vinyl acetate were determined. The properties of latices and coating films were evaluated with reference to the composition of the copolymer. Compared to other types of latices, coating films based on the above copolymers exhibit good properties. Especially, the resistance towards diluted alkali is excellent.     

Pyryliumverbindungen. XXI. Struktur und Tautomerie von Pseudobasen unsymmetrisch substituierter 2,4,6-Triarylpyryliumsalze

Pyrylium Compounds. XXI. Structure and Tautomerism of Pseudobases of Unsymmetrically Substituted 2,4,6-Triarylpyrylium Salts Hydrolytic ring opening of unsymmetrically substituted 2,4,6-triarylpyrylium salts 11 results in a mixture of two tautomeric pseudobases, the penten-1,5-diones 13 and 14 . In crystalline state as a rule one of these tautomers markedly predominates, whereas in solution a rapid equilibrium establishment occurs which can be followed by ¹H-n.m.r. and u.v. spectroscopy (equilibrium ratio nearly 1:1). The ¹H-n.m.r. spectroscopic structural assignment of the two isomeric forms was supported by u.v. spectroscopic studies using 1:1 mixtures of the chromophoric partial systems ArCOCHCHPh and ArCOMe or the pseudobases 10 of symmetrically substituted 2,4,6-triarylpyrylium salts 9 as reference systems. From the mass spectra of the pseudobases 10 and 13 / 14 follows that – if hydrolysis of 11 is performed in media containing H₂¹⁸O – mass spectrometric isotopic analysis of the resulting ¹⁸O-labelled pseudobases allows no information to be made about the regioselectivity of the ring opening. – Novel starting pyrylium salts of type 9 and 11 are characterized by u.v./vis data and by transformation into the corresponding pyridine derivatives.     

Pyryliumverbindungen. XXIII. 2-Dialkylamino-2H-pyrane aus tetra- und pentasubstituierten Pyryliumsalzen

Pyrylium Compounds. XXIII. 2-Dialkylamino-2H-pyrans from Tetra- and Pentasubstituted Pyrylium Salts. Tetra- and pentasubstituted pyrylium salts of type 6 react with secondary alkyl amines to give stable crystalline 2-dialkylamino-2h-pyrans 7 . In the case of tetrasubstituted pyrylium salts 6 , R′ = Me, R″ = H the reaction occurs regioselectively leading to 2H-pyrans with Me at C-3 of the heterocyclic ring. The structure of the reaction products was established by n.m.r., i.r., u.v. and mass spectroscopic methods. Electrophilic agents like protons, carboxylic acid chlorides or methyl iodide regenerate the original pyrylium cations from 7 . In refluxing methanol 7a is converted into the 2-methoxy-2H-pyran derivative 8 , whereas in aqueous acetone the pseudobase 9 and with ammonia the pyridine 10 are formed. Reaction of 7a with nitromethane or ethyl cyanoacetate provides the benzene derivatives 11 and 12 , respectively.     

Pyryliumverbindungen. XVIII, 2-Alkoxy-2H-pyrane aus tetra- und pentasubstituierten Pyryliumsalzen

Pyrylium Compounds. XVIII. 2-Alkoxy-2H-pyrans from Tetra- and Pentasubstituted Pyrylium Salts Alkali alkoxides add regioselectively to 2,3,4,6-tetrasubstituted pyrylium salts 7 (R' H), affording high yields of colourless crystalline 2-alkoxy-2H-pyrans 9 . The latte are also formed simply on refluxing 7 in the corresponding alcohol with triethylamine as proton acceptor. 3,5-Dialkylsubstituted 2,4,6-triarylpyrylium salts react analogously. The 2H-pyran structure of the adducts obtained follows from their n.m.r., i.r., u.v. and mass spectra as well as from their reaction with tetracyanoethylene to cycloadducts of type 10 . Acids regenerate from 9 the original pyrylium cations, whereas reaction of 9 with nitromethane or ethyl cyanoacetate provides benzene derivatives. -- The novel starting pyrylium salts 7b--o are characterized by u.v./vis data and by transformation into the corresponding pyridine derivatives     

Ringtransformationen heterocyclischer Verbindungen. I. 2-Amino-benzophenone und 7-Oxo-hepta-2,4-diennitrile durch Reaktion von 2,4,6-Triaryl-pyryliumsalzen mit 4-Nitro-benzylcyanid

Ring Transformations of Heterocyclic Compounds. I. 2-Amino-benzophenones and 7-Oxo-hepta-2,4-dienenitriles by Reaction of 2,4,6-Triarylpyrylium Salts with 4-Nitrobenzyl Cyanide 2,4,6-Triarylpyrylium salts 1 react with 4-nitrobenzyl cyanide in the presence of sodium acetate, triethylamine or triethylamine/acetic acid to give 7-oxo-hepta-2,4-dienenitriles 2 . With stronger bases such as sodium methanolate or ethanolate a ring transformation of the salts 1 occurs giving rise to 2-amino-benzophenones 3 which can also be obtained by cyclization of the nitriles 2 . Under the same conditions the 3-methyl-2,4,6-triphenylpyrylium salt 4 forms the 4-methyl-7-oxo-hepta-2,4-dienenitrile 5 by regioselective addition of the 4-nitrobenzyl cyanide at C-2 or it is converted to the 2-amino-5-methyl-benzophenone 6 . The ring transformation of the pyrylium salts 1 / 4 by 4-nitrobenzyl cyanide represents a new and simple method for the preparation of 2-amino-benzophenones. – Spectroscopic data of the novel compounds are discussed; the structure of 5 was confirmed by a single crystal X-ray analysis.     

Oxidatives Verfahren zur Herstellung kurzkettiger Carbonsäuren aus ungesättigten Fettsäuren

Oxidative Procedure for Production of Short-Chain Carbon Acids from Unsaturated Fatty Acids For decades, the oxidation of oleic acid to acelaic and pelargonic acid has been carried out in industrial scale by ozone. The high costs of ozone production are a problematical point in this procedure. Thanks to the high selectivity the procedure is today still economic. Efforts to replace the ozone oxidation by an oxygen one haven't yet led to a procedure which can be applied in industry. In this work the oxygen oxidation of oleic acid with aldehyds as intermediary carrier of oxygen is reported.     

Pyryliumverbindungen. 44 [1]. 2-(2-Hydroxy-3-oxo-cycloalk-1-enyl)-2H-thiopyrane aus 2,4,6-Triaryl-thiopyryliumsalzen und Cycloalkan-1,2-dionen

Pyrylium Compounds. 44. 2-(2-Hydroxy-3-oxo-cycloalk-1-enyl)-2H-thiopyranes from 2,4,6-Triarylthiopyrylium Salts and Cycloalkane-1,2-diones 2,4,6-Triarylthiopyrylium salts 5 react with cyclopentane-1,2-dione ( 2a ) or cyclo-hexane-1,2-dione ( 2b ) in the presence of an appropriate acid binding agent (e.g. sodium acetate, piperidine acetate, triethylamine/acetic acid, triethylamine) to give the hitherto unknown 2-(2-hydroxy-3-oxo-cycloalk-1-enyl)-2H-thiopyranes 6 . – The structure of the novel compounds was established by n.m.r., i.r. and u.v. spectroscopic methods.