Synthesis via pummerer intermediates. II.. Disproportionation reactions of 3-(methylsulfinyl)chromones and 3-(methyl-sulfinyl)quinolinones with hydrochloric acid

Sulfoxides ( 1 and 10 ) gave oxidation-reduction products when treated with 5N hydrochloric acid. 8-Methoxy-3-(methylsulfinyl)-4H-benzopyran-4-one (1) gave 8-methoxy-3-(methylthio)-4H-1-benisopyran-4-one ( 4 ) and 8-methoxy-3-(methylsulfonyl)-4H-1-benzopyran-4-one ( 5 ), whereas 1-melhyl-3-(methylsulfinyl)-4(1H)quinolinone ( 10 ) gave 1-methyl-3-(methylthio)-4(1H)-quinolinone ( 12 ) and 1-methyl-4(1H)-quinolinone ( 13 ).     

Synthesis via pummerer intermediates. III. Rearrangements of 3-(methylsulfinyl)quinolinones, 3-(methylsulfinyl)cinnolinones, 3-(methylsulfinyl)chromanones and 3-(methylsulfinyl)chromones with acetic anhydride and with thionyl chloride

The reaction of 1-methyl-3-(methylsulfinyl)-4(1H)quinolinone ( 1 ) with acetic anhydride and thionyl chloride gave 3-[[(acetyloxy)methyl]thio]]-1-methyl-4(1H)quinolinone ( 2 ) and 3-[(chloromethyl)thio]-1-methyl-4(1H)quinolinone ( 3 ) respectively. 3-(Methylsulfinyl)-4(1H)cinnolinone ( 4 ) gave the corresponding products when treated under similar conditions. Treatment of 8-methoxy-3-(methylsulfinyl)-4H-1-benzopyran-4-one ( 11 ) with acetic anhydride and thionyl chloride gave bis addition vinyl Pummerer products 2,3-bis(acetyloxy)-2,3-dihydro-8-methoxy-3-(methylthio)-4H-1-benzopyran-4-one ( 12 ) and 2,3-dichloro-2,3-dihydro-8-methoxy-3-(methylthio)-4H-1-benzopyran-4-one ( 13 ), respectively.     

A study of the Claisen rearrangement of 7-(3-phenyl-2-propenyloxy)-3-phenyl-(4H)-1-benzopyran-4-one derivatives

Summary The Claisen rearrangement of 7-(3-phenyl-2-propenyloxy)-3-phenyl-(4H)-1-benzopyran-4-one (2 a) gave 7-hydroxy-8-(1-phenyl-2-propenyl)-3-phenyl-(4H)-1-benzopyran-4-one (3 a) and 2,3-dihydro-2,6-diphenyl-3-methyl-(7H)furo[2,3-h]-1-benzopyran-7-one (7 a). 2-Methyl-7-(3-phenyl-2-propenyloxy)-3-phenyl-(4H)-1-benzopyran-4-one (2 b) afforded4 b and7 b. 8-Methyl-7-(3-phenyl-2-propenyloxy)-3-phenyl-(4H)-1-benzopyran-4-one (12) gave only the alkali soluble product 7-hydroxy-8-methyl-6-(1-phenyl-2-propenyl)-3-phenyl-(4H)-1-benzopyran-4-one (13).3 a,4 b, and13 were further cyclized in acidic medium to9 a,10 b, and14 followed by dehydrogenation.This paper is dedicated to Dr. F. M. Dean, Department of Organic Chemistry, Robert Robinson Laboratories, University of Liverpool, Liverpool, U. K., on his retirement     

Synthesis of 5-substituted 2-(4- or 3-methoxyphenyl)-4(1H)-quinolones

5-Substituted 7-methoxy-2-(4- or 3-methoxyphenyl)-4(1H)-quinolones 8-17 have been synthesised in good yields from the corresponding 7-methoxy-2-(4- or 3-methoxyphenyl)-5-trifluoromethanesulfonate-4(1H)-quinolones 7 via palladium-mediated cross-coupling reactions or aromatic nucleophilic substitution (SN_Ar) reactions.     

Pyrimidine derivatives. IX . Synthesis of bromosubstituted 5-nitro-2,4(1H,3H)-pyrimidinedione derivatives

The following 5-nitro-2,4(1H,3H)-pyrimidinediones possessing bromo substituted side chains at the 1- and 6-positions were prepared by bromination of 3,6-dimethyl-1-(ω-hydroxyalkyl)-5-nitro-2,4(1H,3H)-pyrimidinediones 4a and 4b and its nitrates 2a and 2b . The three of mono-bromo derivatives are: 1-(ω-acetoxyalkyl and ω-hydroxyalkyl)-6-bromomethyl-3-methyl. 6a, 6b, 7a and 7b and 1-(ω-bromoalkyl)-3,6-dimethyl-2,4(1H,3H)- pyrimidinediones 8a and 8b . The one type dibromo derivatives are: 1-(ω-bromoalkyl)-6-bromomethyl-3-methyl-2,4(1H,3H)-pyrimidinediones 5a and 5b .     

The parent of 2-(4,5-dihydro-1H-tetrazol-5-ylidene)-2-cyanoacetate: Synthesis and reactivity X-ray structure of (E)2-[1-(2,2-dimethylpropyl)-4,5-dihydro-1H-tetrazol-5-ylidene]-2-cyanoacetate

Reaction of 3,3-diazido-2-cyanoacrylate 5 with four moles of ammonia gives tetrazolyl-bisammonium salt 7 . The key-intermediate is the amino-vinyl azide 6 which spontaneously undergoes a 1,5′ ring-closure reaction followed by double deprotonation. Treatment of 7 with hydrochloric acid yields the parent of 2-(4,5-dihydro-1H-tetrazol-5-ylidene)-2-cyanoacetate 9 (R = Me, Et) as the only tautomer. Regiospecific monoalkylation of bisammonium salt 7a with dimethyl sulfate and reaction of ammonium salt 12 with hydrochloric acid gives (E)2-(1-methyl-4,5-dihydro-1H-tetrazol-5-ylidene)-2-cyanoacetate ( 13 ) (X-ray structure of derivative 14 ). Compound 13 can also be obtained from vinyl azide 10 and methylamine. This experiment as well as AM1 calculations of 9a, 23 and 24 strongly favour tautomer 9a .     

Zur Struktur der Tetrahydro-4-phenylspiro([1]benzopyran-2,4′(1′H)-pyrimidin)-2′(3′H)-one bzw.-thione Über Heterocyclen, 49. Mitt

The structures of tetrahydro-4-phenylspiro([1]benzopyran-2,4(1H)-pyrimidin)-2(3H)-ones and-thiones4 a, b resp., are proved by synthesis. 3-(2-methoxy-3,5-dimethylphenyl)-3-phenylpropionic acid11 b is prepared from 3,4-dihydro-6,8-dimethyl-4-phenylcoumarin10. The lithium salt of11 b reacts with isobutenyl-lithium to 1-(2-methoxy-3,5-dimethylphenyl)-5-methyl-1-phenyl-4-hexen-3-on12 a. 12 a is transferred with urea in acid medium and NH₄CNS resp. in a mixture of dihydro-6-[2-(2-methoxy-3,5-dimethylphenyl)-2-phenyläthyl]-4,4-dimethyl-2(1H)-pyrimidinone and-thione13 a, b and tetrahydro-6-[2-(2-methoxy-3,5-dimethylphenyl)-2-phenyläthyliden]-4,4-dimethyl-2(1H)-pyrimidinone and-thione14 a, b resp.14 b leads to13 a, b with H₂O₂. Heating of13 a, 14 a and14 b resp. with pyridin-HCl leads to the spiro compounds4 a, b.     

Synthesis of α-(aminomethylene)-9-(methoxymethyl)-9H-purine-6-acetic acid derivatives

α-(Aminomethylene)-9-(methoxymethyl)-9H-purine-6-acetamide and the ethyl acetate, 3 and 8 , have been synthesized by catalytic hydrogenation of 6-cyanomethylene-9-methoxymethylpurine derivatives 2 and 7 which were obtained by the substitution of 6-chloro-9-(methoxymethyl)purine ( 1 ) with α-cyanoacetamide and ethyl cyanoacetate, respectively. Substitution of 3 and 8 with amines gave the corresponding N-substituted α-(aminomethylene)-9-(methoxymethyl)-9H-purine-6-acetamide and the ethyl acetate 4 and 10 . Reaction of 3 with piperidine gave 9-(methoxymethyl)-9H-purine-6-acetamide ( 5 ).     

Synthesis and reaction of 6-substituted 3-methoxycarbonyl-4-methylthio-2H-pyran-2-one derivatives

Reaction of aryl and styryl methyl ketones 1a-m with dimethyl bis(methylthio)methylenemalonate ( 2 ) in the presence of potassium hydroxide in dimethyl sulfoxide gave the corresponding methyl 6-aryl- and 6-styryl-4-methylthio-2-oxo-2H-pyran-3-carboxylates 3a-m . 6-Aryl derivatives 3a-d,g were treated with sodium methoxide in methanol to give the corresponding 6-aryl-4-methoxy-2H-pyran-2-ones 8a-d and 9. Phenylcoumalin ( 7a ) and paracotoin ( 7b ) were synthesized by the desulfurization of 6-aryl-4-methylthio-2H-pyran-2-ones 4a,b. Similarly, anibine ( 8e ) was also synthesized from 3g . Treatment of 3 with hydrogen peroxide or 3-chloroperoxybenzoic acid gave the corresponding 4-methylsulfiny-2H-pyran-2-ones 10a-f in good yields. Displacement reactions of 10a-f with nucleophilic reagents are also described.     

Synthesis and characterization of novel 2-(1-benzyl-3-[4-fluorophenyl]-1H-pyrazol-4-yl)-7-fluoro-4H-chromen-4-one derivatives

Novel 1-benzyl-3-(4-fluorophenyl)-1H-pyrazole-4-carbaldehydes 3a to 3e were synthesized via Vilsmeier-Haack reaction of the appropriate 1-benzyl-2-(1-(4-fluorophenyl)ethylidene)hydrazines, derived from 4-fluoroacetophenone 1 with substituted 2-benzylhydrazines 2a to 2e . The base catalyzed condensation of 1-benzyl-3-(4-fluorophenyl)-1H-pyrazole-4-carbaldehydes 3a to 3e with 1-(4-fluoro-2-hydroxyphenyl)ethanone 4 gave (E)-3-(1-benzyl-3-(4-fluorophenyl)-1H-pyrazol-4-yl)-1-(4-fluoro-2-hydroxyphenyl)prop-2-en-1-ones 5a to 5e . On cyclization with dimethyl sulfoxide (DMSO)/I₂, compounds 5a to 5e gave 2-(1-benzyl-3-(4-fluorophenyl)-1H-pyrazol-4-yl)-7-fluoro-4H-chromen-4-ones 6a to 6e . Structures of all novel compounds were confirmed by infrared (IR), proton nuclear magnetic resonance (¹H NMR), carbon nuclear magnetic resonance (¹³C NMR), and mass spectral data. All the synthesized compounds were screened for their antibacterial activities.     

Synthesis of 1-(2-hydroxyphenyl)-2,4-imidazolidinedione derivatives through cyclic transformations of ethyl 2-oxo-3(2H)-benzoxazoleacetate derivatives

A series of ethyl 2-oxo-3(2H)-benzoxazoleacetate derivatives 2 have been synthesized. By reaction with ammonia, primary amines or hydrazine, these compounds 2 were transformed into 1-(2-hydroxyphenyl)-2,4-imidazolidinedione derivatives 4, 5 and 6 , respectively. Some of these new hydantoins 4 , treated with phosphorus oxychloride, gave 3H-2-oxoimidazo[2,1-b]benzoxazole derivatives 9 . Ethyl 2-oxo-3(2H)-benzoxazolepropionate ( 10 ) was prepared by a Michaël reaction of ethyl acrylate with 2-benzoxazolone ( 1a ). With 10 , no cyclic transformation was observed in the presence of ammonia or alkylamine.     

Zur Struktur der Tetrahydro-4-phenylspiro([1]benzopyran-2,4′(1′H)-pyrimidin)-2′(3′H)-one bzw.-thione über Heterocyclen, 49. Mitt

The structures of tetrahydro-4-phenylspiro([1]benzopyran-2,4(1H)-pyrimidin)-2(3H)-ones and-thiones4 a, b resp., are proved by synthesis. 3-(2-methoxy-3,5-dimethylphenyl)-3-phenylpropionic acid11 b is prepared from 3,4-dihydro-6,8-dimethyl-4-phenylcoumarin10. The lithium salt of11 b reacts with isobutenyl-lithium to 1-(2-methoxy-3,5-dimethylphenyl)-5-methyl-1-phenyl-4-hexen-3-on12 a. 12 a is transferred with urea in acid medium and NH₄CNS resp. in a mixture of dihydro-6-[2-(2-methoxy-3,5-dimethylphenyl)-2-phenyläthyl]-4,4-dimethyl-2(1H)-pyrimidinone and-thione13 a, b and tetrahydro-6-[2-(2-methoxy-3,5-dimethylphenyl)-2-phenyläthyliden]-4,4-dimethyl-2(1H)-pyrimidinone and-thione14 a, b resp.14 b leads to13 a, b with H₂O₂. Heating of13 a, 14 a and14 b resp. with pyridin-HCl leads to the spiro compounds4 a, b.     

Intramolekulare Diels-Alder-Additionen in 6-(But-3-enyl)-6-methyl-cyclohexa-2,4-dien-1-on-Systemen; eine neue Synthese von Twistanderivaten

Alkylation of the sodium salt of mesitol with 2-bromomethyl-buta-1,3-diene ( 7 ) in benzene and subsequent refluxing of the reaction mixture gave 7% 2-methylene-3-butenyl-mesitylether ( 8 ), 12% 5-methylene-1,3,8-trimethyl-tricyclo[4,3,1,0^3,7]-8-decen-2-one ( 9 ) and 44% 9-methylene-1,3,5-trimethyl-tricyclo[4,4,0,0^3,8]-4-decen-2-one ( 10 ), a twistane derivative. The same procedure, when applied to the sodium salt of 2,6-dimethyl-4-methoxyphenol, gave in 73% yield a 26:18:54 mixture of 2,6-dimethyl-4-methoxyphenyl-(2-methylene-3-butenyl)-ether ( 11 ), 1,3-dimethyl-8-methoxy-5-methylene-tricyclo[4,3,1,0^{3, 7}]-8-decen-2-one ( 12 ), and 1,3-dimethyl-5-methoxy-9-methylene-tricyclo[4,4,0,0^{3, 8}]-4-decen-2-one ( 13 ). The tricyclic ketones 9 and 10 , or 12 and 13 , were also obtained on heating 8 or 11 respectively at 176° in decane solution. Alkylation of the sodium salt of 2,6-dimethylphenol with 3-butenylbromide in boiling toluene gave 1,3-dimethyl-tricyclo[4,3,1,0^3,7]-8-decen-2-one ( 17 ) as the only tricyclic product in 8% yield. The structures of the twistane derivatives 10 and 13 as well as those of the ketones 9, 12 and 17 were mainly deduced from spectroscopic data. Furthermore, the ketones 10 and 13 could be converted to the twistane derivatives 20 and 22 , possessing C₂-symmetry. On the other hand, compounds 9 and 17 gave only the asymmetric derivatives 18 and 21 .     

New synthesis of 7-bromo-1, 3-dihydro-3-hydroxy-5-(2′-pyridyl)-2H-1,4-benzodiazepin-2-one

A new synthesis of 7-bromo-1,3-dihydro-3-hydroxy-5-(2′-pyridyl)-2H-1,4-benzodiazepin-2-one ( 5 ) is described. Starting from bromazepam ( 3 ), C(3) acylation with lead tetraacetate/potassium iodide in acetic acid affords 4 , while its mild hydrolysis according to our recently described method (5) gives 5 . Improved hexamine cyclization of 1 into 3 , via quaternary hexaminium salt 2 , is discussed, and identification of the intermediates 7 and 8 is performed. Compound 5 undergoes on melting, or on brief heating in glacial acetic acid, the thermal rearrangement into quinazolin-2-aldehyde ( 13 ), the structure of which is confirmed by oxidation into the ester 14 , which in turn was hydrolyzed to the acid 15 . The same compound ( 5 ) rearranges on heating with manganese(III) acetate in acetic acid into the 3-amino-2-quinolone derivative 6 . On heating in glacial acetic acid in the presence of lead tetraacetate/potassium iodide (or iodine), compound 4 , in addition to giving the aldehyde 13 , ester 14 and acid 15 rearrangement products, affords 1,2-dihydroquinazolin-2-carboxylic acid 16 .     

Nucleosides and nucleotides. 2. Synthesis of both anomers of 1-(5'-O-phosphoryl-2'-deoxy-D-ribofuranosyl)-2(1H)-pyridone

The two anomeric 1-(2′-deoxy-D -ribofuranosyl)-2(1H)-pyridones 6 and 7 were synthesized from 2-pyridone and 3,5-di-(O-p-toluoyl)-2-deoxy-D -ribofuranosyl chloride ( 2 ) via the di-O-p-toluoyl derivatives 3 and 4 using the mercuric halide procedure. Phosphorylation of the nucleosides 6 and 7 by bis-(2,2,2-trichloroethyl)-chlorophosphate gave the phosphate esters 8 and 9 together with some 2-(bis-[2,2,2-trichloroethyl]-phosphoryloxy)-pyridine 10 , which proved to be very labile. Structure and configuration of compounds 6 to 9 were established by spectral methods, the configurations being derived from the chemical shifts of the sugar protons and the splitting patterns of the anomeric protons (‘triplet-quartet rule’). The specific rotations of 3 , 4 , 6 , 7 , 8 and 9 show that the three pairs of anomers represent exceptions to Hudson's rule of isorotation. Reductive removal of the trichloroethyl groups in 8 and 9 with zinc proceeds stepwise, yielding the phosphoro-diesters 13 and 14 and the two desired anomeric 5′-nucleotides 15 and 16 . These latter were purified and characterised as the ammonium salts. Enzymatic cleavage by the 5′-nucleotidase of Crotalus adamanteus venom took place only in the ‘natural’ β-series. The ‘unnatural’ α-anomers were resistent to the enzyme. The structure of 10 was established by spectral methods and confirmed by synthesis.     

Synthesis of obtusinin and 7-(3′-hydroxymethylbut-2′-enyloxy)-6-methoxy-2H-1-benzopyran-2-one

Obtusinin (1) has been synthesised by the reaction of 6-methoxy-7-(3-methylbut-2-enyloxy)-2H-1-benzopyran-2-one (3) with OsO₄. Synthesis of 7-(3-hydroxymethylbut-2-enyloxy)-6-methoxy-2H-1-benzopyran-2-one (2) has been achieved by the regiospecific oxidation of3 with SeO₂ followed by reduction of the formed aldehyde with KBH₄.

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Synthese von Obtusinin und 7-(3-Hydroxymethylbut-2-enyloxy)-6-methoxy-2H-1-benzopyran-2-on

Zusammenfassung Obtusinin (1) wurde über 6-Methoxy-7-(3-methylbut-2-enyloxy)-2H-1-benzopyran-2-on (3) mit OsO₄ synthetisiert. Die Darstellung von 7-(3-Hydroxymethylbut-2-enyloxy)-6-methoxy-2H-1-benzopyran-2-on (2) wurde mittels regioselektiver Oxidation von3 mit SeO₂, gefolgt von Reduktion des gebildeten Aldehyds mit KBH₄, bewerkstelligt.

     

Synthesis of certain 3-alkoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidines structurally related to adenosine,inosine and guanosine

Several 3-alkoxysubstituted pyrazolo[3,4-d]pyrimidine ribonucleosides structurally related to adenosine, inosine and guanosine have been prepared by the direct glycosylation of preformed aglycon precursor containing a 3-alkoxy substituent. Ring closure of 5(3)-amino-3(5)-ethoxypyrazole-4-carboxamide ( 6b ) with either formamide or potassium ethyl xanthate gave 3-ethoxyallopurinol ( 7b ) and 3-ethoxy-6-thioxopyrazolo[3,4-d]-pyrimidin-4(5H,7H)-one ( 10 ), respectively. Methylation of 10 gave the corresponding 6-methylthio derivative 15 . Similar ring annulation of 5(3)-methoxypyrazole-4-carboxamide ( 6a ) with formamide afforded 3-methoxyallopurinol ( 7a ). Treatment of 5(3)-amino-3(5)-methoxypyrazole-4-carbonitrile ( 5a ) with formamidine acetate furnished 4-amino-3-methoxypyrazolo[3,4-d]pyrimidine ( 4 ). High-temperature glycosylation of 7b with 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribofuranose in the presence of boron trifluoride etherate gave a 2:1 mixture of N-1 and N-2 glycosyl blocked nucleosides 11b and 13b . Deprotection of 11b and 13b with sodium methoxide gave 3-ethoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-4(5H)-one ( 12b ) and the corresponding N-2 glycosyl isomer 14b , respectively. Similar glycosylation of either 4 or 7a , and subsequent debenzoylation gave exclusively 4-amino-3-methoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidine ( 9 ) and 3-methoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-4-(5H)-one ( 12a ), respectively. The structural assignment of 12a was made on the basis of single-crystal X-ray analysis. Application of this general glycosylation procedure to 15 gave the corresponding N-1 glycosyl derivative 16 as the sole product, which on debenzoylation afforded 3-ethoxy-6-(methylthio)-1-(3-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-4(5H)-one ( 17 ). Oxidation of 16 and subsequent ammonolysis furnished the guanosine analog 6-arnino-3-ethoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]-pyrimidin-4(5H)-one ( 19 ). Similarly, starting from 3-methoxy-4,6-bis(methylthio)pyrazolo[3,4-d]pyrimidine ( 20 ), 6-amino-3-methoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-4(5H)-one ( 23 ) was prepared.     

Synthesis,cytotoxic, and carbonic anhydrase inhibitory effects of new 2-(3-(4-methoxyphenyl)-5-(aryl)-4,5-dihydro-1H-pyrazol-1-yl)benzo[d]thiazole derivatives

2-(3-[4-Methoxyphenyl]-5-aryl-4,5-dihydro-1H-pyrazol-1-yl)benzo[d]thiazoles ( 1b-7b ) were synthesized for the first time except 1b , and spectral methods such as ¹H NMR, ¹³C NMR and HRMS were utilized to illuminate the chemical structures of the synthesized compounds. Phenyl ( 1b ), 2-methoxyphenyl ( 2b ), 4-methoxyphenyl ( 3b ), 4-methoxy-3-hydroxyphenyl ( 4b ), 2,5-dimethoxyphenyl ( 5b ), 3,4,5-trimethoxyphenyl ( 6b ), or thiophene-2-yl ( 7b ) was used as a aryl part. The inhibitory effects of the compounds were evaluated toward human carbonic anhydrase I and II enzymes (hCA I and hCA II). In vitro cytotoxic effects of the compounds against human oral squamous carcinomas and human normal oral cells were carried out via MTT. The compounds ( 1b-7b ) had Ki values of 36.87 ± 11.62-66.24 ± 2.99 μM (hCA I) and 22.66 ± 1.41-89.95 ± 6.25 μM (hCA II). Compounds 1b (Ki = 36.87 ± 11.62 μM) toward hCA I, 6b (Ki = 22.66 ± 1.41 μM) toward hCA II had significant enzyme inhibitory potency. Compound 6b had the highest tumor selectivity (TS = 29.3) and potency selectivity expression (PSE = 272.3) values. Therefore, compounds 1b and 6b with CAs inhibition effect and compound 6b with the cytotoxicity may be forwarded to further studies as potent compounds.     

Synthesis of 2,3-dihydro-3-hydroxy-2-(pyrrol-1-ylmethyl)-1H-isoindol-1-one. An intermediate for the synthesis of tetracyclic systems

N-Chloromethylphthalimide 1 and the potassium salt of pyrrole gave N-(pyrrol-1-ylmethyl)pbthalimide 2 . Reduction of 2 led to the hydroxyisoindolone 3 . This hydroxylactam cyclized under acidic conditions to lead to a pyrroloimidazoloisoindolone 4 via an acyliminium ion. Transformation of 3 with acetic acid derivatives provided 5, 7 and 9 which gave by intramolecular cyclization, tetracyclic compounds 6, 10 and 11 .     

Studies on ketene and its derivatives. CXI . Photoreaction of diketene with 2(1H)-quinolone derivatives

Photoreaction of diketene with 4-methyl-2(1H)-quinolone and 1,4-dimethyl-2(1H)-quinolone gave 2R*,2aR*,SbR*- and 2R*,2aS*8bS*-8b-methyl-3-oxo-1,2,2a,3,4,8b-hexahydrocyclobuta[c]quinoline-2-spiro-2′-(oxetan)-4′-one ( 6a and 6b ), and their 4-methyl derivatives 7a and 7b , respectively. Thermolysis of compounds 6 and 7 afforded 2aR*,8bS*-8b-methyl-2-methylene-3-oxo-1,2,2a,3,4,8b-hexahydrocyclobuta[c]quinoline ( 8 ) and its 4-methyl derivatives 9 , respectively. Similarly, photolysis of diketene and 4-acetoxy-2(1H)-quinolone gave 1R*,2aS*,8bS*- and 1R*,2aR*,8bR*-8b-acetoxy-3-oxo-1,2,2a,3,4,8b-hexahydrocyclobuta[c]-quinoline ( 11a and 11b ). Alcoholysis of compounds 11a and 11b with hydrogen chloride in methanol gave 1-hydroxy-1-(methoxycarbonyl)methylcyclobuta[c]quinoline derivative 12 and 13 which were transformed to 4-acetyl-3-methyl-2(1H)-quinolone ( 15 ) by further alcoholysis. Photoreaction of diketene with 2(1H)-quinolone derivatives gave the corresponding cyclobuta[c]quinoline spirooxetanone derivatives 18 and 23 , which, by thermolysis, were transformed to 2-methylenecyclobuta[c]quinoline 23 and 25 , respectively.