7-Functionalized 7-deazapurine ribonucleosides related to 2-aminoadenosine, guanosine, and xanthosine: glycosylation of pyrrolo[2,3-d]pyrimidines with 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribofuranose

[reaction: see text] The Silyl-Hilbert-Johnson reaction as well as the nucleobase-anion glycosylation of a series of 7-deazapurines has been investigated, and the 7-functionalized 7-deazapurine ribonucleosides were prepared. Glycosylation of the 7-halogenated 6-chloro-2-pivaloylamino-7-deazapurines 9b-d with 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribofuranose (5) gave the beta-D-nucleosides 11b-d (73-75% yield), which were transformed to a number of novel 7-halogenated 7-deazapurine ribonucleosides (2b-d, 3b-d, and 4b-d) related to guanosine, 2-aminoadenosine, and xanthosine. 7-Alkynyl derivatives (2e-i, 3e-h, or 4g) have been prepared from the corresponding 7-iodonucleosides 2d, 3d, or 4d employing the palladium-catalyzed Sonogashira cross-coupling reaction. The 7-halogenated 2-amino-7-deazapurine ribonucleosides with a reactive 6-chloro substituent (18b-d) were synthesized in an alternative way using nucleobase-anion glycosylation performed on the 7-halogenated 2-amino-6-chloro-7-deazapurines 13b-d with 5-O-[(1,1-dimethylethyl)dimethylsilyl]-2,3-O-(1-methylethylidene)-alpha-D-ribofuranosyl chloride (17). Compounds 18b-d have been converted to the nucleosides 19b-d carrying reactive substituents in the pyrimidine moiety. Conformational analysis of selected nucleosides on the basis of proton coupling constants and using the program PSEUROT showed that these ribonucleosides exist in a preferred S conformation in solution.     

NaOH-catalyzed thiolysis of alpha,beta-epoxyketones in water. A key step in the synthesis of target molecules starting from alpha,beta-unsaturated ketones

NaOH (0.02-0.3 molar equiv) is an efficient catalyst for the thiolysis reactions of alpha,beta-epoxy ketones with alkyl and aryl thiols in water. Thiolysis of 3,4-epoxyheptan-2-one (1) with thiols 2a-d has been accomplished in mild conditions (30 degrees C and pH 6 or 9) with complete C-alpha-regioselectivity and anti-stereoselectivity, and the corresponding anti-beta-carbonyl-beta-hydroxysulfides 3a-d have been prepared in excellent yields (95-98%). Compounds 3a-d, depending on their nature and pH conditions, have undergone dehydration, C-3 epimerization reaction, and retroaldol condensation. Dehydration of anti-3a-d has been chemoselectively carried out by in situ acidic treatment at 70 degrees C, giving stereoselectively the related (Z)-vinyl sulfides 4 in 89-94% overall yields. Under NaOH-catalyzed thiolysis conditions, cyclic alpha,beta-epoxyketones 6-9 have shown C-alpha attack only and spontaneously dehydrated to furnish the corresponding vinyl sulfides in high yields (90-96%). The reactions of calchone oxide (10) with thiols 2b-d have exclusively resulted in the formation of beta-carbonylsulfides 10b-d (82-93% yield), coming from the nucleophilic attack at the alpha-position and retroaldol condensation. To highlight the synthetic utility of this procedure, one-pot multisteps preparation of vinyl sulfides 7b and 7c, vinyl sulfoxides 12 and 13, and 1,5,6,7-tetrahydro-4H-1,2,3-benzotriazol-4-one (14) starting from 2-cyclohexen-1-one (11) have also been reported.     

Diels-alder reactions of 3, 6-diphenyl-1, 2, 4, 5-tetrazine and 3, 6-di(2-pyridyl)-1, 2, 4, 5-tetrazine with some 1-morpholinocycloalkenes

The reactions of 3, 6-diphenyl-1, 2, 4, 5-tetrazine 1 and 3, 6-di(2-pyridyl)-1, 2, 4, 5-tetrazine 2 with the enamines 3a-d derived from morpholine and the 5-,6-,7- and 8-membered cyclic ketones have been investigated. A number of pyridazine derivatives 4–7 most of which are new have been reported. Moreover, a novel procedure for the aromatization of pyridazines 5a-d to the corresponding pyridazine 7b-d via oxidative elimination using hydrogen peroxide is described. The structures of products 4–7 were confirmed by spectral methods and elemental analysis.     

Photocyclization reactions. Part 4 . Synthesis of naphtho[1,8-bc]-furans and cyclohepta[cd]benzofurans using photocyclization of Ethyl 2-(8-Oxo-5,6,7,8-tetrahydro-1-naphthyloxy)acetates and ethyl 2-(5-Oxo-6,7,8,9-tetrahydro-5H-benzocyclohepten-4-yloxy)acetates

Photocyclization reactions were carried out on ethyl 2-(8-oxo-5,6,7,8-tetrahydro-1-naphthyloxy)acetates 1a-e and ethyl 2-(5-oxo-6,7,8,9-tetrahydro-5H-benzocyclohepten-4-yloxy)acetates 2a-e in acetonitrile. Irradiation of 1a-e gave naphtho[1,8-bc]furanols 3a-e and naphtho[1,8-bc]furans 4a-e in 33–83% yields and ethyl acrylates 5b-d were produced in 3–25% yields during irradiation of 1b-d . On the other hand, 2a-e afforded cyclohepta[ad|benzofuranols 6a-e and cyclohepta[ad]benzofurans 7a-e in 44–87% yields. Ethyl acrylates 8b-d were also produced in 7–43% yields from irradiation of 2b-d . Substituent effects on photocyclization and reaction pathways are discussed.     

Condensed 1,3-benzothiazinones 3. Synthesis of 3-substituted 1,2,4-triazolo[3,4-b][1,3]benzothiazin-5-ones

Refluxing 2-hydrazono-3,4-dihydro-2H-1,3-benzothiazin-4-one 3 with triethyl orthoformate neat or with trimethyl orthoformate 4a , triethyl orthoacetate, orthopropionate, orthobenzoate 4b-d in xylene gave 1,2,4-triazolo[3,4-b][1,3]benzothiazin-5-one 2a and its 3-substituted derivatives 2b-d in 56–95% yields. On the other hand, when 3 was treated with trifluoro-, trichloroacetic anhydride 4e,f , dichloro-, chloroacetyl chloride 4g,h , 2-chloropropionyl and ethoxyoxalyl chloride 4i,j , the corresponding open-chain condensates were produced, together with the title compounds 2g-i , or the Dimroth rearrangement isomers 1e,g,i,j each depending on the reaction conditions. Nevertheless efficient preparation of 2h and 3-hydroxy-derivative 2k to get rid of such rearrangement was developed.     

Studies on quinoline derivatives and related compounds. VI. A novel displacement reaction of 1-ethylquinolinium iodides with nucleophiles

The reaction of 4-amino- ( 3a ) and 4-anilino-3-carbethoxy-1-ethyl-6,7-methylenedioxy-quinolinium iodide ( 3b ) with nucleophilic reagents produced 7-substituted 4-amino-3-carboxy-1-ethyl-6-hydroxyquinolinium betaines ( 5b-d ) and 7-substituted 1-ethyl-1,4-dihydro-6-hydroxy-4-phenylimino-3-quinolinecarboxylic acid ( 6b-d ), respectively, which led to 7-substituted 1-ethyl-1,4-dihydro-6-hydroxy-4-oxo-3-quinolinecarboxylic acids ( 1b-d ) by alkaline hydrolysis. With a variety of 1-ethyl-1,4-dihydroquinoline carboxylates ( 16a-e ) these novel displacement reactions were attempted.     

Halogenated 7-deazapurine nucleosides: stereoselective synthesis and conformation of 2'-deoxy-2'-fluoro-beta-D-arabinonucleosides

The stereoselective syntheses of 5-halogenated 7-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine nucleosides 3b-d, 4a-c as well as 7-deaza-2'-deoxyisoguanosine are described. Nucleobase anion glycosylation of 2-amino-4-chloro-7H-pyrrolo[2,3-d]pyrimidine (5) with 3,5-di-O-benzoyl-2-deoxy-2-fluoro-alpha-D-arabinofuranosyl bromide (6) exclusively gave the beta-D-anomer, which was deblocked (--> 8), aminated at C4 (--> 3a) and selectively deaminated at C2 to yield 2'-deoxy-2'-fluoro-beta-D-arabinofuranosyl 7-deazaisoguanine (2). Condensation of the 5-halogenated 4-chloro-2-pivaloylamino-7H-pyrrolo[2,3-d]pyrimidines 9a-c with 6 furnished the N7-nucleosides 10a-c together with N2,N7-bisglycosylated compounds 11a-c. The former was converted to the corresponding 2,4-diamino-compounds 3b-d, and the latter was deblocked by NaOMe/MeOH to yield the 4-methoxy-nucleosides 4a-c. Conformational analysis of the sugar moiety of the nucleosides 2 and 3a-d was performed on the basis of vicinal [1H,1H] coupling constants. The fluorine atom in the sugar moiety shifts the sugar conformation from S towards N by about 10%, while the halogen substituents in the base moiety increase the hydrophobicity and polarizability of the nucleobases.     

Reactions of 4,6-bis(acetyl)resorcinol with alkoxycarbonylalkylidene(triphenyl)phosphoranes. Preparation of coumarin derivatives

Reaction of compound 1 with ylide 2a affords compounds 3a, 3b and coumarins 4a, 5a, 5b, 6a in 77% total yield. Reaction of 1 with ylide 2b affords coumarin 4b . The acetylderivatives obtained, react further with ylides 2a-c to give pyrano[3,2-g]chromene-2,8-diones 6b-d .     

General and efficient insertion of carbons carrying benzotriazole

Anions formed from the lithiation of 1-(1-benzotriazolylalkyl)benzotriazoles (1, 6) and 1-(1-methylthioalkyl)benzotriazoles (10 and 10a) with n-BuLi underwent additions to cyclic and acyclic ketones giving intermediates 3a-f, 7b-f, and 11b-d, respectively, in excellent yields. Thermal rearrangements of intermediates 3a,b,d-f and 7b-d,f in the presence of zinc bromide provided one-carbon chain-extended or ring-expanded alpha-benzotriazolyl ketones 4a,b,d-f and 8b-d,f in moderate yields with excellent regioselectivity. By contrast, intermediates 11b-d on treatment with zinc bromide loose a molecule of benzotriazole followed by intramolecular cyclization of the resulting intermediates 12b-d to provide the 2,3- and 1,2,3-substituted indenes 13b-d in good yields.     

3-Oxo-1,2-benzoisothiazoline-2-acetic acid 1,1-dioxide derivatives. II. Reaction of amides with alkoxides

Reaction of some 3-oxo-1,2-benzoisothiazoline-2-acetamide 1,1-dioxides ( 1a-f ) with alkaline alkoxides was carried out under various conditions. Under mild conditions, 1a-f with sodium methoxide gave o-(N-carbox-amidomethylsulfamyl)benzoic acid methyl esters ( 2a-f, R = CH3 ). Compounds 1a or 2a reacted with sodium alkoxides under drastic conditions affording only ester 5 . Under the same conditions, 1b-d or 2b-d gave 4-hydroxy-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxides ( 3b-d ), while 1e-f or 2e-f afforded the acid 6 in variable amounts, together with the expected benzothiazines 3e-f . Isolation of ethyl ether as another product in the reaction of 1e-f with sodium ethoxide supports the suggestion that the formation of 6 involves the O-alkyl fission on the alkyl carbon of the esters 2e-f . An explanation of these results may be related to the acidic character of the amide hydrogen in compounds 2e-f .     

Synthesis of nonaphenylenes and dodecaphenylenes using electron-transfer oxidation of Lipshutz cuprates and formation of nanostructural materials from hexadodecyloxynonaphenylene

Nonaphenylenes and dodecaphenylenes have been synthesized by using electron-transfer oxidation of Lipshutz cuprates with duroquinone. Oxidation of the Lipshutz cuprate derived from 4,4'-dibromo-o-terphenyl 3a in THF produced nonaphenylene 1a in 46% yield, whereas the similar oxidation of the Lipshutz cuprates derived from 4,4'-diiodo-4',5'-dialkyl-o-terphenyls 3b-d in ether afforded the corresponding nonaphenylenes 1b-d and dodecaphenylenes 2b-d in moderate total yields. In the case of 4,4'-diiodo-4',5'-didodecyloxy-o-terphenyl 3e as the starting material, oxidation of the corresponding Lipshutz cuprate in ether or THF only led to the formation of nonaphenylene 1e. Both nonaphenylenes 1a-e and dodecaphenylenes 2b-d are unreactive to light, atmospheric oxygen, and prolonged heating. These oligophenylenes showed strong UV absorption and fluorescent emission and exhibited some redox properties on CV analysis. Moreover, hexadodecyloxynonaphenylene 1e exhibits different nanostructures on the surface and in solution to form a film by casting a solution of 1e in cyclohexane, benzene, chloroform, THF, or diisopropyl ether (IPE) and nanofibers from IPE-MeOH (1:1), indicating different absorption and emission spectra and XRD patterns. The absorption maxima of THF solution, fiber, and film are in the order of 1e film (315 nm) > fiber (302 nm) > solution (295 nm), whereas the emission maxima are in the order of 1e fiber (425 m) > solution (418 nm) > film (401 nm). XRD analysis revealed that 1e aligns laterally on a glass or silicon surface to form a thin film with a lamella structure; however, it forms a nanofiber with a Lego-like stacking structure without pi-pi stacking interaction of the aromatic rings. Reflecting the different nanostructures of the 1e film and fiber, a spin-coated 1e film is found to be effective in detecting the vapor of explosives due to the intercalation of nitroaromatics to the cracked surface of the loosely stacked 1e. In contrast, the 1e fiber is not effective in detection of nitroaromatics but exhibits fluorescence anisotropy. The maximum fluorescence intensity is obtained in a direction perpendicular to the longitudinal axis of the fiber, indicating the stacking direction to be parallel to the longitudinal axis of the fiber.     

1,3-Dipolar cycloaddition reactions of 1-(4-phenylphenacyl)-1,10-phenanthrolinium N-ylide with activated alkynes and alkenes

The 3+2 cycloaddition reaction of 1-(4-phenylphenacyl)-1,10-phenanthrolinium ylide 4 with activated alkynes gave pyrrolo[1,2- 4a][1,10]phenanthrolines 6a-d. The "one pot" synthesis of 6a,b,d from 4, activated alkenes, Et(3)N and tetrakis-pyridine cobalt (II) dichromate (TPCD) is described. The helical chirality of pyrrolophenanthrolines 6b-d was put in evidence by NMR spectroscopy.     

Dihydropyrimidines and related structures. I. N2-substituted 2-pyrimidinamines and dihydro-2-pyrimidinamines by reaction of phenylbutenones and monosubstituted guanidines

The reactions of monosubstituted guanidines 2 with phenylbutenones 7 and 10 exclusively yield N²-substituted 2-pyrimidinamines 8 and 9 . The structure of the reaction products is proved and their differing stability is discussed. Action of methyl- and benzylguanidine respectively ( 2b, c ) on 4-phenyl-3-buten-2-one ( 7 ) and of 2c on l-phenyl-2-buten-1-one ( 10 ) under atmospheric oxygen affords aromatic N²-substituted 2-pyrimidinamines 9b and c . The dihydropyrimidines 8b and c, probable intermediates of the reactions, could not be isolated. In contrast, heating of arylguanidines 2d , e with 7 leads to stable dihydropyrimidinarnines 8d and e, which can be isolated as bases. Addition of methanol to 8d yields 6-methoxy-2-pyrimidinamine 11d , boiling of 8d in DMF affords 9d . Under nitrogen, guanidine adds to 7 to yield aminopyrimidinol 13a , which is transformed by heating in benzene into pyrimidine 9a . The low stability of 8a-c is attributed to their strong basicity, the greater stability of 8d and e to their lower basicity. The structural formulae of 8d , e and 9b-d and their salts respectively were established partly ( 8e ) by nmr and partly ( 9b-d ) by comparison of the corresponding picrates with authentic samples [17].     

Factors relevant for the ruthenium-benzylidene-catalyzed cyclopolymerization of 1,6-heptadyines

Fourteen metathesis initiators that had been designed for use in the living polymerization of diethyl dipropargylmalonate (DEDPM), including the Hoveyda catalyst [RuCl(2)(IMesH(2))([double bond]CH-2-(2-PrO)[bond]C(6)H(4))] (1 a), as well as [Ru(CF(3)COO)(2)(IMesH(2))([double bond]CH-2-(2-PrO)[bond]C(6)H(4))] (1 b), [Ru(CF(3)CF(2)COO)(2)(IMesH(2))([double bond]CH-2-(2-PrO)[bond]C(6)H(4))] (1 c), [Ru(CF(3)CF(2)CF(2)COO)(2)(IMesH(2))([double bond]CH-2-(2-PrO)[bond]C(6)H(4))] (1 d), [RuCl(2)(IMesH(2))([double bond]CH-2,4,5-(MeO)(3)[bond]C(6)H(2))] (2 a), [Ru(CF(3)COO)(2)(IMesH(2))([double bond]CH-2,4,5-(MeO)(3)[bond]C(6)H(2))] (2 b), [Ru(CF(3)CF(2)COO)(2)(IMesH(2))([double bond]CH-2,4,5-(MeO)(3)[bond]C(6)H(2))] (2 c), [Ru(CF(3)CF(2)CF(2)COO)(2)(IMesH(2))([double bond]CH-2,4,5-(MeO)(3)[bond]C(6)H(2))] (2 d), [RuCl(2)(IMes)([double bond]CH-2-(2-PrO)[bond]C(6)H(4))] (3 a), [Ru(CF(3)COO)(2)(IMes)([double bond]CH-2-(2-PrO)[bond]C(6)H(4))] (3 b), [RuCl(2)(IMesH(2))([double bond]CH-2-(2-PrO)-5-NO(2)[bond]C(6)H(3))] (4 a), [Ru(CF(3)COO)(2)(IMesH(2))([double bond]CH-2-(2-PrO)-5-NO(2)[bond]C(6)H(3))] (4 b), [Ru(CF(3)CF(2)COO)(2)(IMesH(2))([double bond]CH-2-(2-PrO)-5-NO(2)[bond]C(6)H(3))] (4 c), and [Ru(CF(3)CF(2)CF(2)COO)(2)(IMesH(2))([double bond]CH-2-(2-PrO)-5-NO(2)[bond]C(6)H(3))] (4 d) (IMes=1,3-dimesitylimidazol-2-ylidene; IMesH(2)=1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) were prepared. Living polymerization systems could be generated with DEDPM by careful tuning of the electronic nature and steric placement of the ligands. Although 1 a, 2 a, 3 a, 3 b, and 4 a were inactive in the cyclopolymerization of DEDPM, and initiators 1 b-d did not allow any control over molecular weight, initiators 2 b-d and 4 b-d offered access to class VI living polymerization systems. In particular, compounds 2 b and 4 d were superior. The livingness of the systems was demonstrated by linear plots of M(n) versus the number of equivalents of monomer added (N). For initiators 2 b-d and 4 b-d, values for k(p)/k(i) were in the range of 3-7, while 1 b, 1 c, and 1 d showed a k(p)/k(i) ratio of >1000, 80, and 40, respectively. The use of non-degassed solvents did not affect these measurements and underlined the high stability of these initiators. The effective conjugation length (N(eff)) was calculated from the UV/Vis absorption maximum (lambda(max)). The final ruthenium content in the polymers was determined to be 3 ppm.     

Reaction of diazoindenothiophenes with mono- and dibenzoylacetylenes

Reaction of diazoindenothiophenes ( 1 and 2 ) with benzoyl acetylene ( 4 ) afforded the rearrangement products ( 6a and b ) of the initial adducts. The major product of the reaction of diazo indenothiophene ( 3 ) with 4 was butadiene derivative 8a . Reaction of 1 with dibenzoylacetylene ( 5a ) gave the rearranged pyrazole ( 12 ), while the reaction of 2 and 3 , afforded the butadiene derivatives ( 8b-d ).     

Room Temperature Processable Silicon‐Containing Molecular Resist

A novel silicon‐containing molecular resist material based on polyhedral oligomeric silsesquioxane, possessing trimethoxysilyl groups, was designed in order to reduce post‐exposure delay problems and to improve resolution. Since the acid‐catalyzed cross‐linking reaction of trimethoxysilyl groups occurs at room temperature, there is no necessity of post‐exposure bake. The molecular resist showed 0.7 µm line‐and‐space patterns using a mercury–xenon lamp in a contact printing mode and 100 nm line‐and‐space patterns using electron beam lithography.

     

Benzofuran systems. Synthesis and biological examination of 1-(3-benzofuranyl)-2-phenylethanones

Novel 1-(3-benzofuranyl)-2-phcnylethanones 4a-d have been prepared by acetylation of 2-alkylbenzo-furans 2a-c with phenylacetyl chlorides 3a-b . The methoxy derivatives 4b-d have been demethylated to the corresponding phenols 5b-d with pyridinium hydrochloride. An attempt to obtain the derivatives of 4d and 5a iodinated in the phenyl ring has been undertaken. The novel compounds have been characterized by ir and nmr spectra and their biological activity examined.     

Synthesis of halosulfuron-methyl via selective chlorination at 3- and/or 5-position of pyrazole-4-carboxylates

Reactions of methyl pyrazole-4-carboxylates 4b-d with N-chlorosuccinimide under heating conditions without a solvent gave methyl 3,5-dichloro-1-methylpyrazole-4-carboxylate 4a in good yields. The reaction of 4a with sodium hydrosulfide led to a nucleophilic substitution on the 5-position regioselectively to afford methyl 3-chloro-1-methyl-5-mercaptopyrazole-4-carboxylate 6a, which was followed by oxidative chlorination and amination to obtain 3-chloro-1-methyl-5-sulfamoylpyrazole-4-carboxylate 2a. Finally, the reaction of 2a with phenyl 4,6-dimethoxypyrimidin-2-yl carbamate 7 provided methyl 3-chloro-5-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-1-methylpyrazole-4-carboxylate (halosulfuron-methyl) 1a promising herbicide in com.     

Synthesis of representative 10-aryl-, 10-aralkyl- and 10-heteraryl-9H-naphtho[1′,2′:4,5]thiazolo[3,2-b]- [1,2,4]triazin-9-ones as potential anti-HIV agents

To prepare the title compounds, cyclocondensation of 1-amino-2-iminonaphtho[1,2-d]thiazole ( 2 ) with some representative glyoxylic acid derivatives was investigated. Heating 2 with methyl phenylglyoxylate ( 3a ) in methanol afforded only the open chain intermediates 4a,b . However, when this reaction was performed in re-fluxing glacial acetic acid, the expected compound, 10-phenyl-9H-naphtho[1′,2′:4,5]thiazolo[3,2-b][1,2,4]- triazin-9-one ( 5a ) was produced in 27% yield. Similar treatment of 2 with benzyl-, 2-furyl- and 2-thienylgly-oxylic acids 3b-d gave the corresponding 10-benzyl-, 10-(2-furyl)- and 10-(2-thienyl)-9H-naphtho[1′,2′:4,5]thi-azolo[3,2-b][1,2,4]triazin-9-ones 5b-d in 48–67% yields. As by-products, 9-benzoyl- and 9-(2-thenoyl)naphtho-[1′,2′:4,5]thiazolo[3,2-b][1,2,4]triazoles 6a,d were also isolated. Compound 5a was selected for in vitro anti-HIV evaluation but found to be inactive.     

A New and simple synthesis of 2-aryl-4,9-dihydrocyclohepta[b]pyran-4,9-diones

3-Acetyltropolone ( 1 ) reacted with 2-methoxybenzaldehyde ( 2a ) in the presence of ethyl orthoformate and perchloric acid to afford 2-(2-methoxyphenyl)-4,9-dihydrocyclohepta[b]pyran-4,9-dione ( 3a ). The reactions with 3,4-dimethoxybenzaldehyde ( 2b ), vanillin ( 2c ), and piperonal ( 2d ) gave respectively the corresponding products 3b-d . The reaction with benzaldehyde ( 2e ) gave uncyclized 3-cinnamoyltropolone ( 4 ).