Heterocyclization of functionalized heterocumulenes with C,N-, C,O-, and C,S-binucleophiles: VIII. Synthesis of pyrano(chromeno)[3,4-e][1,3]oxazines by condensation of 1-chloroalkyl isocyanates with 4-hydroxy-6-methylpyran-2-one and 4-hydroxycoumarin

1-Chlorobenzyl isocyanates react with 4-hydroxy-6-methylpyran-2-one and 4-hydroxycoumarin forming 4-aryl-3,4-dihydro-2H,5H-pyrano(chromeno)[3,4-e][1,3]oxazine-2,5-diones. The reaction of 1-aryl-2,2,2-trifluoro-1-chloroethyl isocyanates with the above substrates gives rise to structurally isomeric 2-aryl-2-trifluoromethyl-2,3-dihydro-2H,5H-pyrano(chromeno)[3,4-e][1,3]-oxazine-4,5-diones.     

Novel heterocycles. Synthesis of 2,3-dihydro-6-methyl-2-phenyl-4H,6H-pyrano[3,2-c][2,1]benzothiazin-4-one 5,5-dioxide and related compounds

The reaction of 2-chloro-4-(methylsulfonyl)benzoyl chloride ( 5 ) with 1-methyl-1H-2,1-benzothiazin-4-(3H)-one 2,2-dioxide ( 4 ) gave the O-benzoyl compound, 1-methyl-2,2-dioxido-1H-2,1-benzothiazin-4-yl 2-chloro-4-(methylsulfonyl)benzoate ( 6 ), which rearranged to give the C-benzoyl isomer, [2-chloro-4-(methylsulfonyl)phenyl] (4-hydroxy-1-mefhyl-2,2-dioxido-1H-2,1-benzothiazin-3-yl)methanone ( 7 ). The O-cinnamoyl compound 13 that resulted from the addition of 2,4-dichlorocinnamoyl chloride ( 11 ) to compound 4 rearranged to give the C-cinnamoyl compound, 3-(2,4-dichlorophenyl)-1-(4-hydroxy-1-methyl-2,2-dioxido-1H-2,1-benzothiazin-3yl)-2-propen-1-one ( 15 ). On the other hand, 1-methyl-2,2-dioxido-1H-2,1-benzothiazin-4-yl 3-phenyl-2-propenoate ( 19 ) (from cinnamoyl chloride ( 17 ) and compound 4 ) rearranged to give 2,3-dihydro-6-methyl-2-phenyl-4H,6H-pyrano[3,2-c][2,1]benzothiazin-4-one 5,5-dioxide ( 21 ), an example of a hitherto unknown ring system. Additional examples of this novel heterocycle were prepared from 1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4(3H)-one 2,2-dioxide ( 23 ) and 1-methyl-1H-thieno[3,2-c][1,2]thiazin-4(3H)-one 2,2-dioxide ( 8 ).     

New heterocyclic structures. [1,2,5]Thiadiazolo[3′,4′:4,5]pyrimido-[2,1-b][1,3]thiazine and thiazolo[3,2a][1,2,5]thiadiazolo[3,4-d]pyrimidine

Derivatives of two new molecular structures, namely, 7,8-dihydro-6H,10H-[1,2,5]thiadiazolo[3′,4′:4,5]pyrimido[2,1-b][1,3]thiazin-10-one and 6,7-dihydro-9H-thiazolo[3,2-a][1,2,5]thiadiazolo[3,4-d][pyrimidin-9-one, and derivatives of N-substituted sulfamic acid, namely, (8-amino-3,4-dihydro-2H,6H-pyrimido[2,1-b][1,3]thiazin-6-on-7-yl)sulfamic acid and (7-amino-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidin-5-on-6-yl)sulfamic acid, were separated out as by-products in the reduction reaction of 8-amino-3,4-dihydro-7-nitroso-2H,6H-pyrimido[2,1- b][1,3]thiazin-6-one and 7-amino-2,3-dihydro-6-nitroso-5H-thiazolo[3,2-a]pyrimidin-5-one derivatives, respectively, with sodium hydrosulfite. A mechanism of reaction, which hypothesizes the action of sodium hydrosulfite in an asymmetic form, is proposed. The results of single-crystal X-ray investigation on 7,8-dihydro-6H,10H-[1,2,5]thiadiazolo[3′,4′:4,5]pyrimido[2,1-b][1,3]thiazin-10-one (R = 0.032 for 863 reflections) and (8-amino-3,4-dihydro-2H,6H-pyrimido[2,1-b]- [1,3]thiazin-6-on-7-yl)sulfamic acid, sodium salt (R = 0.028 for 3507 reflections) are reported.     

Acylation reaction of γ,β-unsaturated β-keto esters and of ethyl hydrogen malonate. Synthesis of 6-alkenyl-5-ethoxycarbonyl-2,3-dihydro-4H-pyran-4-ones and 4,5-dioxo-2,3,7,8-tetrahydro-4H,5H-pyrano[4,3-b]pyran derivatives

The syntheses of 6-alkenyl-5-ethoxycarbonyl-2,3-dihydro-4H-pyran-4-one derivatives by acylation of γ,β-unsaturated β-keto esters or by diacylation of ethyl hydrogen malonate with α,β-unsaturated acyl chlorides are described. These compounds were converted to 4,5-dioxo-2,3,7,8-tetrahydro-4H,5H-pyrano[4,3-b]pyran derivatives.     

Synthesis of some 5H,12H-[1]benzoxepino[4,3-b]indol-6-ones. A new heterocyclic ring system

The synthesis of the title compounds 5H,12H-[1]benzoxepino[4,3-b]indol-6-ones 10 was effected by the Fischer indole cyclization of some 2,3-dihydro-4-phenylhydrazono[1]benzoxepin-5-ones 9 , obtained from the 3,4-dihydro-4-hydroxymethylene[1]benzoxepin-5(2H)-ones 7 by the Japp-Klingemann reaction. The structure of these new heterocyclic compounds was supported by ir, ¹H nmr and ms spectral data.     

New Synthesis of (±)-5-hydroxymarmesin,biogenetic precursor of the skin photosensitizing agent bergapten (5-MOP)

A convenient synthesis is described of (±)-5-hydroxymarmesin, 4-hydroxy-2-(1-hydroxy-1-methylethyl)-2,3-dihydro-7H-furo[3,2-g][1]benzopyran-7-one, a physiological intermediate in the biogenetic pathway of 5-O-alkylfurocoumarins. The synthesis was achieved by a regiospecific 6-C isoprenylation of 5,7-diacetoxy-coumarin; the 6-C isoprenylated derivative is then submitted to an oxidative cyclization obtaining mainly the title compound together with its angular isomer.     

Reaction of ketenes with N,N-disubstituted à-aminomethyleneketones. IX. Synthesis of 2H,5H-pyrano[3,2-c][1]benzopyran derivatives

Cycloaddition of dichloroketene to N,N-disubstituted 3-aminomethylene-4-chromanones gave in good yield N,N-disubstituted 4-amino-3,3-dichloro-3,4-dihydro-5H-pyrano[3,2-c][1]benzopyran-2-ones only in the case of aromatic N-substitution. Dehydrochlorination with triethylamine of these adducts afforded N,N-disubstituted 4-amino-3-chloro-5H-pyrano[3,2-c][1]benzopyran-2-ones in good to moderate yield. The cycloaddition to 3-dimethylaminomethylene-4-chromanone led directly to 3-chloro-4-dimethylamino-5H-pyrano[3,2-c][1]benzopyran-2-one.     

Heterocycles structurally influenced by a side chain. X. Effect of temperature and side chain on the imine-enamine tautomerism in the quinoxalinone and pyridopyrazinone systems

3-(1-Benzoyl)ethyl-1H-pyrido[2,3-b]pyrazin-2-one ( 7 ), 3-(1-ethoxycarbonyl)ethyl-1H-pyrido[2,3-b]-pyrazin-2-one ( 8 ), and 3-(1-benzoyl)ethyl-1H-quinoxalin-2-one ( 9 ) exist only in the imine form due to the steric effect of the methyl substituent. As regards the imine-enamine tautomerism, 3-(β-carbonylmethylene) derivatives of 1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one such as 12 and 15–18 gradually change from the enamine form to the imine form with elevated temperatures; however, 3-(carbonylmethylene) derivatives of 3,4-dihydro-1H-pyrido[2,3-b]pyrazin-2-one such as 10, 19 and 20 show little temperature effect. 2-Phenacylidene-1,2-dihydro-4H-pyrido[3,4-b]pyrazin-3-one ( 21 ) and 3-phenacylidene-3,4-dihydro-1H-pyrido[3,4-b]pyrazin-2-one ( 22 ), which exist in the enamine form, show no temperature effect.     

5a-Carba-β-D-, 5a-Carba-β-L- and 5-Thio-β-L-xylopyranosides as New Orally Active Venous Antithrombotic Agents

Mitsunobu displacement of (−)-(1S,4R,5S,6S)-4,5,6-tris{[(tert-butyl)dimethylsilyl]oxy}cyclohex-2-en-1-ol ((−)- 12 ; a (−)-conduritol-F derivative) with 4-ethyl-7-hydroxy-2H-1-benzopyran-2-one ( 16 ) provided a 5a-carba-β-D -pyranoside (+)- 17 that was converted into (+)-4-ethyl-7-[(1′R,4′R,5′S,6′R)-4′,5′,6′-trihydroxycyclohex-2′-en-1′-yloxy]-2H-1-benzopyran-2-one ((+)- 5 ) and (+)-4-ethyl-7-[(1′R,2′R,3′S,4′R)-2′,3′,4′-trihydroxycyclohexyloxy]-2H-1-benzopyran-2-one ((+)- 6 ). The 5a-carba-β-D -xyloside (+)- 6 was an orally active antithrombotic agent in the rat (venous Wessler's test), but less active than racemic carba-β-xylosides (±)- 5 and (±)- 6 . The 5a-carba-β-L -xyloside (−)- 6 was derived from the enantiomer (+)- 12 and found to be at least 4 times as active as (+)- 6 . (+)-4-Cyanophenyl 5-thio-β-L -xylopyranoside ((+)- 3 ) was synthesized from L -xylose and found to maintain ca. 50% of the antithrombotic activity of its D -enantiomer. Compounds (±)- 5 , (±)- 6 , and (−)- 6 are in vitro substrates for galactosyltransferase 1.     

Synthesis of new arylbenzofurodiazepin-6-ones

Two new tetracyclic structures, containing the diazepine ring, were synthesized: 5,6-dihydro-12H-benzofuro[3,2-b][1,5]benzodiazepin-6-one and 5,6-dihydro-12H-benzofuro[3,2-b]pyrido[3,2-f][1,5]diazepin-6-one. Thus N-(2-haloaryl)-2-[(2-cyanophenyl)oxy]acetamides were cyclized to the corresponding N-(2-haloaryl)-3-amino-2-benzofurancarboxamides and then, through the formation of the central diazepine ring, to the title compounds. Formation of the diazepine ring took place only when an electron-withdrawing group was present in the molecule to facilitate the nucleophilic attack of an amine in the benzofuran intermediate.     

Simple and efficient preparation of 3-substituted 6-(4-chlorophenyl)-9-methyl-12H-[1]benzofuro[3,2-e][1,2,4]triazolo[4,3-b][1,2]diazepines via a silylation–amination reaction

Abstract  

A series of new 3-substituted 6-(4-chlorophenyl)-9-methyl-12H-[1]benzofuro[3,2-e][1,2,4]triazolo[4,3-b][1,2]diazepines was synthesized from the corresponding bicyclic 1-(4-chlorophenyl)-3,5-dihydro-8-methyl-4H-[1]benzofuro[2,3-d][1,2]diazepin-4-one. The synthesis strategy makes use of silylation–amination as the key step, allowing a wide range of derivatives to be prepared.     

Simultaneous Formation of 8H-Isoquino[2,1-b][2,7]naphthyridin-8-ones and 13H-Pyrido[4′,3′:3,4]pyrrolo[2,1-b][3]benzazepin-13-ones,a Novel Potential Alkaloidal System

Condensation of 3,4-dihydro-6,7-dimethoxyisoquinoline ( 4 ) with 4-methylnicotinoyl chloride ( 12 ) in refluxing pyridine gives 5,6,13,13a-tetrahydro-2,3-dimethoxy-8H-isoquino[2,1-b][2,7] naphthyridin-8-one ( 11 ), along with some of its 13,13a-didehydro derivative 7 . A similar reaction of 4 with 4-(chloromethyl)nicotinoyl chloride ( 14 ) affords, in addition to 7 , the isomeric product 10,11-dihydro-7,8-dimethoxy-13H-pyrido[4′,3′:3,4]pyrrolo[2,1- b][3]benzazepin-13-one ( 3 ). Analogous pairs of products are obtained from 3,4-dihydro-6,7-(methylenedioxy)- and 3,4-dihydro-6,7,8-trimethoxy-isoquinolines ( 15 and 18 , resp.). The structure of 3 was established by extensive NMR data and confirmed by single-crystal X-ray studies. Structure 7 has the ring system of the Alangium alkaloids like alangimarinc ( 1 ), while the isomeric ring system 3 is predicted to be present in nature on biogenetic reasoning.     

Synthesis of 1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4(3H)-one 2,2-dioxide

The reaction of methyl 2-bromo-6-(trifluoromethyl)-3-pyridinecarboxylate ( 1 ) with methanesulfonamide gave methyl 2-[(methylsulfonyl)amino]-6-(trifluoromethyl)-3-pyridine-carboxylate ( 2 ). Alkylation of compound 2 with methyl iodide followed by cyclization of the resulting methyl 2-[methyl(methylsulfonyl)amino]-6-(trifluoromethyl)-3-pyridinecarboxylate ( 3 ) yielded 1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4(3H)-one 2,2-dioxide ( 4 ). The reaction of compound 4 with α,2,4-trichlorotoluene, methyl bromopropionate, methyl iodide, 3-trifluoromethylphenyl isocyanate, phenyl isocyanate and 2,4-dichloro-5-(2-propynyloxy)phenyl isothiocyanate gave, respectively, 4-[(2,4-dichlorophenyl)methoxy]-1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazine 2,2-dioxide ( 5 ), methyl 2-[[1-methyl-2,2-dioxido-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4-yl]oxy]propanoate ( 6 ), 1,3,3-trimethyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4(3H)-one 2,2-dioxide ( 7 ), 4-hydroxy-1-methyl-7-(trifluoromethyl)-N-[3-(trifluoromethyl)phenyl]-1H-pyrido[2,3-c][1,2]thiazine-3-carboxamide 2,2-dioxide ( 8 ), 4-hydroxy-1-methyl-7-(trifluoromethyl)-N-phenyl-1H-pyrido[2,3-c][1,2]thiazine-3-carboxamide 2,2-dioxide ( 9 ) and N-[2,4-dichloro-5-(2-propynyloxy)phenyl]-4-hydroxy-1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2] thiazine-3-carboxamide 2,2-dioxide ( 10 ).     

Reactions of 6-Amino-5-Cyano-3-Methyl-1,4-Diphenyl-1H 4H-Pyrano[2,3-C]Pyrazole and its Methanimidate

Reaction of 6-amino-5-cyano-3-methyl-1,4-diphenyl- 1H,4H-pyrano[2,3-c]pyrazole 1 with triethyl orthoformate in acetic anhydride gave its methanimidate 2, which reacts with primary aliphatic and aromatic amines to give 4,6-dihydro-3-methyl-1,4-diphenyl-6- (alkyl)pyrazolo[4′,3′:5,6]pyrano[2,3-d]pyrimidine-5(lH)- imine 3 and the starting compound 1 , respectively. Treatment of 1 with o-aminophenol gave 5-(2-benzoxalyl)- 1,4-dihydro-3-methyl-1,4-diphenylpyrano[2,3-c]pyrazol- 6-amine 9.     

Two New Iridoid Glycosides from Hedyotis tenelliflora Blume

Two new iridoid glycosides, teneoside A (=(2aR,5S)‐5‐[(β‐D ‐glucopyranosyl)oxy]‐2a,4a,5,7b‐tetrahydro‐4‐{[(α‐L ‐rhamnopyranosyl)oxy]methyl}‐1H‐2,6‐dioxacyclopenta[cd]inden‐1‐one; 1 ) and teneoside B (=methyl (1S,5R)‐1‐[(β‐D ‐glucopyranosyl)oxy]‐1,4a,5,7a‐tetrahydro‐5‐hydroxy‐7‐{[(α‐L ‐rhamnopyranosyl)oxy]methyl}cyclopenta[c]pyran‐4‐carboxylate; 2 ), were isolated from the roots of Hedyotis tenelliflora Blume , along with two known compounds, deacetylasperuloside ( 3 ) and scandoside methyl ester ( 4 ). Their structures were elucidated by chemical methods (acid hydrolysis) and spectroscopic analyses.     

Cycloaddition reactions of 2,3-dihydro-1H-1,4-diazepines with nitrile oxides and imines. Synthesis of bis[1,2,4]oxadiazolo-and bis[1,2,4]triazolo[1,4]diazepine derivatives

New heterotricyclic systems, 6,10a,11,11a-tetrahydro-5H-bis[1,2,4]oxadiazolo[4,5-d:5′,4′-g][1,4]diazepines 6,7,9-11 and 5,6,10,10a,11,11a-hexahydro-1H-bis[1,2,4]triazolo[4,3-d:3′,4′-g][1,4]diazepines 8,12 have been obtained by double site- and regie-specific 1,3-dipolar cycloaddition of mesitylnitrile oxide ( 1 ) or diphenylnitrile imine ( 2 ) to 5,7-disubstituted 2,3-dihydro-1H-1,4-diazepines 3-5. The structure of the synthesized bis-adducts 6-12 shows that the hetero double bonds are much more reactive than the olefinic ones in the dipolarophiles under study. No evidence for the formation of mono-adducts was obtained.     

Synthesis of [1]benzothienonaphthyridines

3-Chlorobenzo[b]thiophene-2-carbonyl chloride reacted readily with 2-amino-, 3-amino-, or 4-aminopyridine to give the corresponding amides. Photocyclization of the amides afforded the following lactams: [1]ben-zothieno[2,3-c][1,5]naphthyridin-6(5H)-one ( 14 ), [1]benzothieno[2,3-c][1,6]naphthyridin-6(5H)-one ( 7 ), [1]benzo-thieno[2,3-c][1,7]naphthyridin-6(5H)-one ( 11 ), and [1]benzothieno[2,3-c][1,8]naphthyridin-6(5H)-one ( 3 ). These lactams have been converted to other derivatives including in two instances the unsubstituted ring system.     

Azines and Azoles: CXXI. Alkylation of 5,7-Dihydro-4H-pyrano[2,3-d:6,5-d']- dipyrimidine-4,6(3H)-dione and Its 5-Phenyl Derivative

Methylation of 5,7-dihydro-4H-pyrano[2,3-d:6,5-d']dipyrimidine-4,6(3H)-dione and its 5-phenyl analog with dimethyl sulfate in the presence of LiOH in aqueous solution gives rise to the corresponding 3,7-dimethyl derivatives. The same isomers are formed by methylation of 5-phenyl-5,7-dihydro-4H-pyrano[2,3-d:6,5-d']dipyrimidine-4,6(3H)-dione with methyl iodide in the presence of K2CO3 in N,N-dimethylacetamide. However, with ethyl bromide, propyl iodide, or butyl bromide instead of methyl iodide, mixtures of 3,7- and 1,7-dialkyl-5-phenyl-5,7-dihydro-4H-pyrano[2,3-d:6,5-d']dipyrimidine-4,6-diones were obtained.     

Nucleophilic trifluoromethylation of RF-containing 4-quinolones, 8-aza- and 1-thiochromones with (trifluoromethyl)trimethylsilane

Reactions of N-substituted 2-polyfluoroalkyl-4-quinolones and 8-aza-5,7-dimethyl-2-polyfluoroalkylchromones with (trifluoromethyl)trimethylsilane proceed mainly as a 1,4-nucleophilic trifluoromethylation to give N-substituted 2,2-bis(polyfluoroalkyl)-2,3-dihydroquinolin-4(1H)-ones and 5,7-dimethyl-2,2-bis(polyfluoroalkyl)-2,3-dihydro-4H-pyrano[2,3-b]pyridin-4-ones after acid hydrolysis. Similar reaction with 2-trifluoromethyl-4H-thiochromen-4-one proceeds as a 1,2-addition to give 2,4-bis(trifluoromethyl)-4H-thiochromen-4-yl trimethylsilyl ether.     

Studies on quinazolinones. 2. Synthesis of 2-(4-benzylpiperazin-1-ylmethyl)-2,3-dihydro-5H-oxazolo[2,3–6]quinazolin-5-one and -2,3-dihydro-5H-thiazolo[2,3-b]quinazolin-5-one

To search for novel antihypertensive heterocycles in the condensed quinazoline series, two representative compounds were synthesized via a suitable reaction sequences. Treating anthranilonitrile with allyl isocyanate gave 2-(allylureido)benzonitrile ( 10 ) in a quantitative yield. Compound 10 was cyclized to 3-allylquinazoline-2(1H, 4(3H)-dione ( 11 ). Bromination of 11 in carbon tetrachloride converted it into the corresponding 3-(2,3-dibromopropyl) derivative ( 12 ) in 92% yield. Ring closure of 12 was effected by the action of alkali to afford 2-bromomethyl-2,3-dihydro-5H-oxazolo[2,3-b]quinazolin-5-one ( 13 ). The title compound, 2-(4-benzylpiperazin-1-ylmethyl)-2,3-dihydro-5H-oxazolo[2,3-b]quinazolin-5-one ( 7 ) could be obtained by a reaction of either 12 or 13 with 1-benzylpiperazine respectively. Starting from the readily available 3-allyl-2H-thioxoquinazolin-4(3H)-one ( 16 ) via the analogous reactions gave the 2-bromomethyl-2,3-dihydro-5H-thiazolo[2,3-b]-quinazolin-5-one ( 19 ) in good yield. However, the reaction of 19 with 1-benzylpiperazine provided another target compound, 2-(4-benzylpiperazin-1-ylmethyl)-2,3-dihydro-5H-thiazolo[2,3-b]quinazolin-5-one ( 8 ) only in poor yield (8%). As major product, the dehydrobrominated compound, 2-methylene-2,3-dihydro-5H-thiazolo[2,3-b]quinazolin-5-one ( 22 ) was isolated. A preliminary pharmacological evaluation revealed that both compounds 7 and 8 are devoid of the antihypertensive activity.