Die Reaktion von E-ß-Nitro-styrolen mit Pyrazolidon-(3)-azomethiniminen – eine nicht-cisoide 1,3-dipolare Cycloaddition

The Reaction of E-ß-Nitro-styrenes with 3-Pyrazolidone-azomethinimines – a Non-cisoid 1,3-Dipolar Cycloaddition Normal flipping at both ring-N-atoms postulated, the thermal addition of E-β-nitro- 5a or E-(4-chloro-β-nitro)-styrene 5b to 3-pyrazolidone-azomethinimine-1,3-dipoles 4a or 4b formally can yield 8 isomeric pairs of enantiomers, 4 of which are “permitted”(cisoid) and 4 of which are “forbidden” according to the concerted [_π4_s + _π2_s]-mechanism. If the addition of 5 to 4 is regiospecific, 2 “permitted”(cisoid) ( 1 and 6 ) and 2 “forbidden”( 3 and 10 ) isomers are conceivable. From pure 5a and 4a we regiospecifically got 1ref,3trans-diphenyl-2cis-nitro- 6a (75%) and 1ref,3trans-diphenyl-2trans-nitro-5-oxo-perhydropyrazolo[1,2-a]pyrazol 10a (25%), from 5b and 4b the corresponding bis(4-chloro-phenyl)-isomers 6b and 10b . The sodium salts 8a, b , gained from 6a, b and 10a, b , are identical. With H⊕ (D⊕) in water (D₂O) 8a, b give 6a, b (2-deutero- 6a, b = 7 a, b ). The ¹H-n.m.r. spectra of 6a, b, 7a, b, 8a, b, 10a, b , and of the 2-amino-isomers 11a/12a , corresponding to 6a/10a , are discussed. For the first time products of a non-cisoid 1,3-dipolar cycloaddition ( 10a, b ) were isolated. In the discussion (E ⇌ Z)-isomerization of 5a , and conceivable mechanisms of isomerizations 6a → 10a are excluded. Theoretical consequences are suggested.     

Bornane with integrated push–pull butadienes

The {3-[bis(alkylthio)methylene]-1,7,7-trimethyl-bicyclo[2.2.1]hept-2-ylidene}malononitriles ((1R,4S)- 2 , (1S,4R)- 2 and (1R,4S)- 3 ) were prepared starting from 1,7,7-trimethyl-bicyclo[2.2.1]hept-2-ylidenemalononitriles (1R, 4R)- 1 and (1S,4S)- 1 ) arisen from (+)-, (–)-camphor. The reaction of (1R,4S)- 2 with bromine yielded the (1S,8R)-8,11,11-trimethyl-3-methylthio-5-oxo-4-thiatricyclo-[6.2.1.0^2,7]undeca-2,6-diene-6-carbonitrile ( 8 ) after hydrolysis of the initially formed (1S,8R)-6-cyano-8,11,11-trimethyl-3-methylthio-4-thia-tricyclo[6.2.1.0^2,7]undeca-2,6-diene-5-iminium bromide ( 7 ).     

Domino imine condensation/intramolecular polar [4π+ + 2π]-cycloaddition of anilines and ω-unsaturated aldehydes: A versatile tool for the highly diastereoselective synthesis of 1,2,3,4,4a,9,9a,10-octahydroacridines

The highly diastereoselective synthesis of substituted 1,2,3,4,4a,9,9a,10-octahydroacridines 7 , 8 with five stereogenic centers has been achieved by domino imine condensation/intramolecular polar [4π⁺ + 2π]-cycloaddition of anilines 3 and ω-unsaturated aldehydes 4 . The transformations which can be performed under mild reaction conditions using 0.3 eq. BF₃·Et₂O as a Lewis acid give the cycloadducts 7 , 8 with yields ranging from 63–76%. The relative configuration of 7 , 8 was assigned by ¹H- and ¹³C-NMR spectroscopy. For 7a , an X-ray crystal structure analysis was obtained. Experimental as well as semiempirical results support a polar [4π⁺ + 2π]-cycloaddition under kinetic control. It is assumed that the diastereoselectivity of the process is governed by decalin-like exo-E-anti-transition state structures 24 , 25 with equatorial arrangement of the bulky substituents R².     

Reactions with 5,6-Diphenyl-2,3-dihydro-imidazo[2,1-b]thiazol-3-ones and 6,7-Diphenyl-2,3-dihydro-4H-imidazo[2,1-b]1,3-thiazin-4-one

2-Methyl-5,6-diphenyl-2,3-dihydro-imidazo[2,1-b]thiazol-3-one 5 and 6,7-diphenyl-2,3-dihydro-4H-imidazo[2,1-b]1,3-thiazin-4-one 6 are prepared from 4,5-diphenyl-2-mercapto-imidazole 1 . Compounds 5 and 6 react with amines or hydrazines to give the 2-(4,5-diphenyl-imidazol-2-ylthio)acet(or propan) amides (hydrazides) 7a – g and the 3-(4,5-diphenyl-imidazol-2 ylthio) propanamides(hydrazides) 8a – e , respectively. The hydrazides 7a, 7b and 8a are condensed with aromatic aldehydes to the hydrazones 9a – h and 10a – d . Compound 5 couples with aryldiazonium salts to give 2-arylazo-2-methyl-5,6-diphenyl-2,3-dihydro-imidazo[2,1-b]thiazol-3-ones 11a – d .     

Umwandlung von (20S)-20-(Hydroxymethyl)pregna-1,4-dien-3-on in (20S)-20-(p-Toluolsulfonyloxymethyl)pregna-1,5-dien-3β-ol und -3α-ol: Zwischenprodukte für Vitamin D-Derivate

Transformation of (20S)-20-(Hydroxymethyl)pregna-1,4-dien-3-one into (20S)-20-(p-Toluene-sulfonyloxymethyl)pregna-1,5-dien-3β-ol and -3α-ol: Intermediates of Vitamin D Derivatives Efficient three-step approaches to the two 3-epimeric 22-tosylated 1,5-diene-3,22-diols 6 and 7 starting with (20S)-20-(hydroxymethyl)pregna-1,4-dien-3-one ( 1 ) were developed and optimized. Isomerization of 1 to the 1,5-dien-3-one 3 and subsequent tosylation furnished the deconjugated 3-ketone 4 . The 3β-alcohol 6 was available from 4 by means of in situ generated calcium borohydride. Treatment of 4 with lithium trisiamylborohydride (LS-Selectride) afforded the highest yield of the hitherto unknown 3α-epimer 7 . Following the optimized synthesis, 6 and 7 were obtained from 1 in 60 % and 50 % overall yield, respectively.     

Cobalt(II)‐Catalyzed Electrophilic Alkynylation of 1,3‐Dicarbonyl Compounds To Form Polysubstituted Furans via π–π Activation

Polysubstituted furans were obtained with excellent yields via the electrophilic alkynylation of 1,3‐dicarbonyl compoundsws with phenyl‐ or ester‐substituted brominated alkynes. The reaction is catalyzed by the inexpensive and readily available catalyst, cobalt(II) chloride, and has a wide substrate scope. The C(sp) C(sp³) coupling occurs under mild conditions with short reaction times and does not require an inert atmosphere or ligands. It is proposed that the reaction proceeds through a chelation complex of cobalt(II) with the deprotonated 1,3‐dicarbonyl compound.

     

Spiegelsymmetrische Hexahydro-1,2,4,5-tetrazine aus Pyrazolidon-(3)-N,N-betainen – ein Beitrag zur „thermischen Dimerisierung”︁ von 1,3-Dipolen

Mirror-symmetric Hexahydro-1,2,4,5-tetrazines from Pyrazolidine-3-one-N,N-betaines—a Contribution to the „Thermal Dimerization”︁ of 1,3-Dipoles Chemical reactions, i.r., ¹H-n.m.r., and ¹³C-n.m.r. data show that the “thermal dimers” of pyrazolidine-3-one azomethinimines 2 , which till now accidentally formed during the synthesis of 2 from pyrazolidine-3-ones 5 and aldehydes 6 , are 5,11-diaryl-perhydro-dipyrazolo[1,2-a; 1′,2′-d][1,2,4,5]-tetrazine-1,9-diones 3 , i.e. mirror-symmetric hexahydro-1,2,4,5-tetrazines with (C-5) and (C-11) placed on the mirror plane. From DREIDING models and from the nonequivalence, concerning ¹³C-n.m.r., of the pairs of carbon atoms in the o- resp. m-positions of the aryl substituent I at (C-5) of the “dimers” 3 is derived that the rotation of I is sterically hindered (ΔG = 16,3 kcal/mole for 3b ), and that the preferred arrangement of I is perpendicular to the plane of the hexahydrotetrazine ring. The “thermal dimerization” of the 1,3-dipoles 2 is a complex series of two addition and elimination steps proceeding in the presence of catalytical amounts of pyrazolidine-3-one 5 and of H^⊕. The mechanism is rationalized, consequences are suggested concerning known “dimerizations” of 1,3-dipoles.     

Synthesis of bispiroheterocyclic systems as antimicrobial agents via the reaction of 2-(cycloalkylidene)-1-thia-4-azaspiro[4.4]-nonan-3-one and/or [4.5] decan-3-one with hydrazines,hydroxylamine, urea and thiourea derivatives

1-Oxa-4-thiaspiro[4.4]nonan-2-one ( 1 ) and/or 1-oxa-4-thiaspiro[4.5]-decan-2-one ( 2 ) reacted with 1-naphthylamine to afford 1-thia-4-(1-naphthyl)-4-azaspiro[4.4]nonan-3-one ( 3 ) and/or 1-thia-4-(1-naphthyl)-4-azaspiro[4.5]decan-3-one (4). Reactions of 3 and/or 4 with cyclopentanone or cyclohexanone gave the corresponding 2-cycloalkylidene-4-(1-naphthyl)-1-thia-4-azaspiro[4.4]nonan-3-ones ( 5 and 6 ) and 2-cycloalkylidene-4-(1-napthyl)-1-thia-4-azaspiro[4.5]-decan-3-ones ( 7 and 8 ). Reaction of compounds 5 – 8 with hydrazine hydrate, phenylhydrazine, hydroxylamine hydrochloride, urea and thiourea afforded the corresponding bispirothiazolopyrazolines ( 9 – 16 ), bispirothiazoloisoxazolines ( 17 – 20 ), bispirothiazolopyrimidinones ( 21 – 24 ) and bispirothiazolothiopyrimidinones ( 25 – 28 ) respectively. All the synthesized bispiroheterocyclic derivatives were identified by conventional methods (IR, ¹H-NMR) and elemental analyses. All the prepared compounds were tested for their antimicrobial activities in comparison with tetracycline as a reference compound.     

Kupfer,Silber, Gold; fixiert in metallorganischen π-Pinzetten

Alkinyl functionalized titanocenes of general type RC≡C-[Ti]-C≡CR and Cl-[Ti]-C≡CR {[Ti] = (η⁵-C₅H₄-SiMe₃)₂Ti}; R = singly bonded organic ligand} can successfully be used as organometallic π-tweezers to stabilize numerous mononuclear MX/R¹ species (M = Cu, Ag, Au; X = singly bonded inorganic group; R¹ = singly bonded organic ligand). The synthesis, manifold reaction chemistry as well as bonding and spectroscopy of {[Ti](C≡CR)₂}MX/R¹ and {[Ti] (C≡CR)(Cl)}CuX complexes is described     

Synthesen von C-Nucleosiden und C-Nucleosidanaloga. I. Darstellung von 1-(D-galacto-2,3,4,5,6-Pentakisacetoxyhexanoyl)-3-alkyl- oder arylamino-6,6-dimethyl-4,5,6,7-tetrahydro-benzo[c]thiophen-4-onen

Syntheses of C-Nucleosides and Analogs of C-Nucleosides. I. Preparation of 1-(D-galacto-2,3,4,5,6-Pentakisacetoxy-hexanoyl)-3-alkyl-or arylamino-6,6-dimethyl-4,5,6,7-tetrahydro-benzo[c] thiophene-4-ones 2-(Alkyl- or Arylamino-mercapto-methylen)-5,5-dimethyl-cyclohexane-1,3-diones 1 react in alkaline medium with 3,4,5,6,7-penta-O-acetyl-1-bromo-1-deoxy-D-galacto-heptulose 2b to give the title compounds 6d-g .     

Gold(I)‐Catalyzed Decarboxylation of Propargyl Carbonates: Reactivity Reversal of the Gold Catalyst from π‐Lewis Acidity to σ‐Lewis Acidity

A cationic gold(I)‐catalyzed decarboxylative etherification of propargyl carbonates to selectively produce propargyl ethers is reported. In the reaction the gold(I) catalyst shows a distinct σ‐Lewis acidity rather than the commonly observed π‐Lewis acidity, and thus catalyzes the decarboxylation of a variety of propargyl carbonates to give the corresponding propargyl ethers with high selectivity. This reaction represents a rare example of the tunable reactivity of cationic gold(I) complexes between σ‐Lewis acidity and π‐Lewis acidity.

     

Concave π-prismand hydrocarbon [2.2.2]cyclophanes and their crystalline Ag-triflate complexes

New small concave hydrocarbon cyclophanes were prepared via the well-known HD-2SO₂-method. The cyclophanes obtained are isomers of the very well-known [2.2.2]p,p,p-cyclophane, C₂₄H₂₄, a π-prismand efficiently complexing Ag⁺-ion. X-ray crystal structure determinations showed the bis-sulfide 7 (1,10-dithia[3.3.2]m,p,p-cyclophane) to be helically chiral and that the conformation of the parent hydrocarbon cyclophane 13 ([2.2.2]m,p,p-cyclophane) does not change dramatically upon complexation with the Ag⁺-ion. The 16- and 17-membered [2.2.2]m,m,p- and [2.2.2]m,p,p-cyclophane ( 15 and 16 ) also act as π-prismands and form surprisingly similar crystalline 1:1 Ag-triflate complexes (π-prismates) as the well-known 18-membered p,p,p-isomer proved by the X-ray structure analysis.     

Zur Heck-Reaktion von 1-Chloralk-1-inen – Synthese und Charakterisierung von 1,3-disubstituierten 7-(Prop-2-inyliden)bicyclo[2.2.1]heptanen und anderen Bicyclen

The Heck reaction of cyclohexene with 1-chloroalk-1-ynes ClC≡CR 1 (R = Ph a , c-Hex b , n-Bu c , n-Oct d ) using [Pd(OAc)₂]/NaO₂CH/[NEt₃Bz]Cl as catalyst system (DMF, 25 °C) affords 1,3-disubstituted 7-(prop-2-ynylidene)bicyclo[2.2.1]heptanes 2 as tandem products by reaction of cyclohexene and ClC≡CR in a ratio of 1:2. To a smaller extent, substituted 7-[(cyclohexenyl)methylidene]bicyclo-[2.2.1]heptanes 3 (tandem products by reaction of cyclohexene and ClC≡CR in a ratio of 2:1) and the regular Heck products (alkynylcyclohexenes 4 ) are formed. The homocoupling of 1 to give RC≡C–C≡CR does not take place, except for R = n-Oct where it proceeds as side reaction. The analogous reaction of ClC≡CR with cycloheptene affords the 2:1 products (substitued 8-[(cycloheptenyl)methylidene]biyclo[3.2.1]octanes 6 ) as main products and the 1:2 products (1,3-disubstituted 7-(prop-2-ynylidene)bicyclo[3.2.1]-octanes 5 ) as well as the regular Heck products (alkynylcycloheptenes 7 ) as side products. The ratio 5 : 6 is strongly influenced by the ratio cycloheptene : 1 . The products 2 , 5a and 6 were isolated and characterized by means of ¹H and ¹³C NMR spectroscopy. The molecular structures of 7-(1,3-diphenylprop-2-ynylidene)bicyclo[2.2.1]heptane ( 2a ) and 8-[(cyclo-heptenyl)phenylmethylidene)]bicyclo[3.2.1]octane ( 6a ) (as mixture of the cyclohept-3- and -4-enyl double bond isomers) were determined by single-crystal X-ray structure analysis.     

Desaktivierungsverhalten von Arenen und Heteroarenen. XL. Mechanismus der reversiblen intramolekularen [π4s + π4s]-Photocycloaddition von α, ω-Bis-(9-acridiziniumyl)-alkanen

Deactivation Behaviour of Arenes and Heteroarenes. XL. The Mechanism of the Reversible Intramolecular [_π4_s + _π4_s]-Photocycloaddition Reaction of α,ω-Bis-(9-acridiziniumyl)-alkanes. On electronic excitation the bichromophores deactivate by fluorescence and radiationless photophysical processes from its local excited state. Simultaneously, intramolecular interaction occurs between the excited chromophor and that in the ground state (i.e. by reversible energy migration or intramolecular excimer formation). The excimer rapidly collapses to the cyclomer assuming a common pericyclic transition state for the reversible photocycloaddition. In the pericyclic state the reaction is split into cyclomer formation or backformation of bichromophores in the ground state, respectively. This mechanism of the reversible intramolecular [_π4_s + _π4_s]- photo-cycloaddition reaction is discussed on the basis of a potential correlation diagram.     

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 .     

Ring transformation and cyclization reactions of 1,1-dioxo-1,2-thiazines – syntheses of pyridines and benzo[c]thiazines with new substitution pattern

In presence of ammonia/ammonium acetate the 3,5-dimethyl-2-phenyl-1,1-dioxo-1,2-thiazine-4-carbaldehyde ( 1 ) reacts with ethyl cyanoacetate to the ethyl 2-cyano-4-[1-methyl-2-methylthio-2-(N-phenylsulfamoyl)vinyl)-hexa-2,4-dienoate] ( 3 ) and the Knoevenagel condensation product 4-(2-ethoxycarbonyl-2-cyanovinyl)-3,5-dimethyl-6-methylthio-1,1-dioxo-2-phenyl-2H-1,2-thiazine ( 2 a). The 4-(2,2-dicyanovinyl)-3,5-dimethyl-6-methylthio-1,1-dioxo-2-phenyl-2H-1,2-thiazine ( 2b ) is obtained from 1 and malononitril. The masked 1,5-dicarbonyl compound 2a undergoes ring transformation to the 3-cyano-1,6-dimethyl-5-[1-methylthio-2-(N-phenylsulfamoyl)vinyl]pyridin-2-one ( 5 ) with methylamine. With ethanolic ethoxide the condensation products 2a,b afford the 7-amino-6-ethoxycarbonyl-4-methylthio-2,2-dioxo-1-phenyl-benzo[c]1,2-thiazine ( 6a ), respectively the corresponding 6-cyano derivative 6b , while 3 cyclizises to furnish ethyl 2-amino-6-methyl-5-[1-methyl-2-methylthio-2-(N-phenyl-sulfamoyl)vinyl]nicotinate ( 4 ).     

Über neue Pyrazolverbindungen. IV Darstellung und Cyclisierungsverhalten einiger akzeptorsubstituierter N-(Pyrazol-3-yl)-thioharnstoffe

New Pyrazol Derivatives. IV. Preparation and Cyclization of Some Acceptor-Substituted N-(Pyrazol-3-yl)-thioureas . 3-Aminopyrazol-4-carboxylic acid derivatives ( 1 , 2 ) were transformed by reaction with different isothiocyanates R²NCS to N-(pyrazol-3-yl)-N^. -substituted thioureas ( 5 , 6 ). Ethyl 3-amino-1-benzylpyrazol-4-carboxylate reacts with CSCl₂ to form ethyl 1-benzyl-3-isothiocyanatopyrazol-4-carboxylate ( 3 ) which yields with amines the corresponding N-(pyrazol-3-yl)-N^. -substituted thioureas ( 5 ). As a byproduct in the reaction with CSCl₂ N,N^. -di-(pyrazol-3-yl)-thiourea ( 4 ) is formed. With hydrazine or phenylhydrazine N-(pyrazol-3-yl)-thiosemicarbazides ( 7a , b ) are obtained. The thioureas ( 5 , 6 ) can be cyclized in basic solution to 4,5,6,7-tetrahydropyrazolo[3,4-d]pyrimidin-4-on-6-thiones ( 8 ) which on alkylation form 6-alkylthio-4,5-dihydropyrazolo[3,4-d]pyrimidin-4-ones ( 9 ). Methyl-N-(pyrazol-3-yl)-N^.-benzoylisothiourea ( 10 ) reacts with ethylamine to form N-benzoyl-N^. -ethyl-N^‥-(pyrazol-3-yl)-guanidine derivative ( 11 ) which on treatment with NaH in dimethylformamide yields 6-benzoylamino-5-ethyl-4,5-dihydropyrazolo[3,4-d]pyrimidin-4-one ( 12 ). By treatment with sulfuric acid the N-(pyrazol-3-yl)-thiourea derivatives ( 5 , 6 ) form new 6-amino substituted pyrazolo[3,4-d][1,3]thiazin-4-ones ( 13 ).     

Die Nitril-Carboxamid-Umlagerung

The Nitrile Carboxamide Rearrangement By reaction of cyclohexanone-2-carboxamide ( 4 ) with cyan amide 1-cyano-cyclohex-1-en-2-yl-urea ( 6 ) is formed via nitrile carboxamide rearrangement. Whilst compound 6 with 1,2-diaminobenzene hydrochloride forms 11-amino-1 H-2,3,4,5-tetrahydrodibenzo[b,e][1,4]diazepin hydrochloride ( 8 and 8a ), compound 6 and 1,2-diaminobenzene form hexahydro-benzimidazo[1,2-c]-quinazolin-6-one ( 12 ). Compound 8 with sodium hydroxide yields 11-amino-1 H-2,3,4,11a-tetrahydrodibenzo[b,e]-[1,4]diazepin ( 9 ). Compound 6 reacts with cyclohexylamine to form N-(1-cyanocyclohex-1-en-2-yl)-N′-cyclohexyl urea ( 10 ). Compound 10 with 1,4- or 1,2-diaminobenzene hydrochloride yields compound 7 and 8 . In alkaline solution 10 cyclises to 4-amino-3-cyclohexyl-2,3,5,6,7,8-hexahydroquinazolin-2-one ( 11 ). Compound 4 and malonitrile form either 3-amino-4-cyano-1,2,5,6,7,8-hexahydro-isoquinol-1-one ( 13 ) or 1-amino-4-cyano-2,3,5,6,7,8-hexahydro-isoquinol-3-one ( 14 ). Compound 13 and alkaline formaldehyde react to cyanooctahydroisoquinoline-[2,3-c] [1,3,5]oxdiazin-6-one ( 17 ). 2-Cyanoethyl-cyclohexan-one-2-carboxamide ( 22 ), prepared by Michael-reaction from 4 and acrylonitrile, forms via nitrile carboxamide rearrangement 10-cyano-1,2,3,4,5,6,7,10-octahydroquinolin-2-one ( 24 ) and 2-(1′-cyano-cyclohexyl-2′-one)-propionic acid ( 25 ). Nucleophilic attack of the NH₂-group at the cyanogroup of compound 22 forms 5-(spirocyclohexan-2′-one)-hexahydropyridin-2,6-dione ( 27 ).     

Synthesis of pyrazolo[4′,3′:5,6]pyrazino[2,3-c]pyrazoles and pyrazolo[4′,3′:5,6]pyrazino[2,3-d]pyrimidines and their application to polyester fibres

4-Nitroso-1-phenyl-3-methyl-5-aminopyrazole ( 1 ) was condensed with ethylcyanoacetate ( 2 ), malononitrile ( 4a ) and 2-cyanomethylbenzimidazole ( 4b ) to yield 6-hydroxy-5-cyano, 6-amino-5-cyano and 6-amino-5-(benzimidazol-2-yl)-3-methylpyrazolo [3,4-b]pyrazines 3, 5a and 5b , respectively. 5-Cyano-6-chloro derivative 6 obtained from 3 was converted to 3-aminopyrazolo[4′,3′:5,6]pyrazino[2,3-c]pyrazoles 8a and 8b by the treatment with hydrazin hydrate ( 7a ) and phenylhydrazine ( 7b ), respectively. Compound 5a was treated with formamide ( 9a ), urea ( 9b ) and thiourea ( 9c ) to give 4-aminopyrazolo[4′,3′:5,6]pyrazino[2′3′-d]pyrimidines 10a–10c. With refluxing acetic anhydride compounds 8a, 8b and 10a gave corresponding acetamido derivatives 8c, 8d and 10d. Compound 5a was treated with ethylorthoformate ( 11 ), acetic anhydride ( 12 ) or benzoylchloride ( 13 ) to give fused benzimidazopyrazolo[4′,3′:5,6]pyrazino[2′,3′-d]pyrimidines, viz., benzimidazol[1,2-c]pyrazolo[4,3-g]pteridines ( 14a–14c ). Some of the compounds 8, 10 and 14 were applied to polyester as disperse dyes and their fastness properties were studied.     

Struktur und Isomerisierung der 1,3-dipolaren Cycloaddukte von Malein- und Fumarsäure-dimethylester an Pyrazolidon-(3)-azomethinimine

Structures and Isomerisation of the 1,3-Dipolar Cycloadducts of Dimethyl Maleate and Fumarate to 3-Pyrazolidone-azomethinimines The 1,3-dipolar cycloaddition of dimethyl maleate 1b and fumarate 5b to the 3-pyrazolidone-azomethinimine 2 is a stereospecific cisoid reaction yielding the perhydropyrazolo[1,2-a] pyrazoles 3b/4b in the molar ratio of 2:1, and 6 b/7b in the molar ratio 1:1. Starting with each of the 4 stereoisomers, epimerization, catalysed by alcoholate, results in all 4 of them 3b, 4b, 6b and 7b with 7b as sterically favoured main product. During the addition reaction no epimerization is occurring. ¹H- and ¹³C-n.m.r. data are discussed.