Haloacetylated enol ethers: 3. Synthesis of 3,3a,4,5,6,7-hexahydro-3-halomethylbenzoisoxazoles

The investigation of the halomethyl group effect on the regiochemistry of the reaction of 2-acetylcyclo-hexanones 1a-d and β-methoxyvinyl trifluoro methyl ketone derivative 2a with hydroxylamine to afford 3,3a,4,5,6,7-hexahydro-3-halomethyl-3-hydroxy[2,1]benzoisoxazoles 3a-c , and the respective dehydrated compounds 4a-c , is reported. Compounds 1a-c, 2a proved to be versatile building blocks for the regiospecific synthesis of isoxazole derivatives having a 3-halomethyl substituent, in good yields.     

Iodocyclization of O-(3-Cyclohexenyl)thiocarbamidates. An unexpected approach to vicinal cis-aminocyclohexenols

An unprecedented and unexpected iodocyclization of O-(3-cyclohexenyl)thiocarbamidates 2a-c to diiodides 7a-c, followed by alkaline hydrolysis and iodide elimination, has uncovered an alternative approach to vicinal cis-aminocyclohexenols 10a-c and 11a-c. This represents a new approach to these interesting building blocks.     

3-Mercaptopropionic acid-nitrile imine adducts. An unprecedented cyclization into 1,3,4-thiadiazol-2(3H)-ones and -2(3H)-thiones

3-Mercaptopropionic acid-nitrile imine acyclic adducts (6a-c) undergo cyclocondensation with 1,1'-carbonyldiimidazole to afford the respective 1,3,4-thiadiazol-2-(3H)-ones (7a-c). Corresponding 1,3,4-thiadiazol-2(3H)-thiones (8a-c) were likewise produced from 6a-cand 1,1'-thiocarbonyldiimidazole, with consequent elimination of the propionate moiety. The constitution of these heterocyclic products follows from analytical and spectral data and is confirmed by single crystal X-ray structure determination for 7b.     

Organophosphorus Chemistry 34 1 . The Reaction of Alkyl Phosphites and Hexamethylphosphorus Triamide with 1-Phenyl-3-methyl-4-ylidene-5-pyrazolones

1-Phenyl-3-methyl-4-ylidene-5-pyrazolones ( 1a-c ) produce the respective 1:1 phosphonate adducts ( 4a-i ) upon reaction with the appropriate dialkyl phosphites ( 2a-c ). The reaction of 1a-c with trialkyl phosphites ( 3a-c ) proceeds only in presence of water, also to give phosphonates 4a-c almost exclusively. Hexamethylphosphorus triamide ( 3d ) was successfully utilized to introduce the bis(dimethylamino)-phosphoryl function in the f , g -unsaturated carbonyl moiety in 1a-c , producing phosphoramidates 15a-c . Possible reaction mechanisms were discussed. Compatible elemental and spectroscopic results were recorded for the new products.     

Pyridazines. L . Syntheses and reactions of phenyl(3-pyridazinyl)methane derivatives

A convenient approach to phenyl (3-pyridazinyl) ketone ( 6 ) and phenyl(3-pyridazinyl)methanol ( 7 ) is proposed. Reactions of the related diarylmethyl chloride 8 with various N- and S-nucleophiles were found to afford the expected amines 9a-c, 10a-c and thioethers 11a,b in satisfactory yields.     

1,3-Diradical intermediates in 3H-pyrazole photolyses: 1,4 addition to dienes

The photolyses of pyrazolopyridazines (2a-c) lead to alkenes (4a-c). With added methanol, furan or buta-1,3-diene, intermediates (3a-c) are trapped as compounds (6a-c)–(8a-c) respectively.     

Synthesis and reduction of thieno[2′,3′(3′,2′ or 3′,4′):5,6]-azocino[2,1-a]isoindole-7, 13-diones

A synthesis of the thieno[2′,3′(3′,2′ or 3′,4′):5,6]azocino[2,1-a]isoindole-7,13-diones 6a-c was developed from N-thienylethylphthalimides 3a-c using a Wittig reaction followed by a Friedel-Crafts cyclization of acetic acid derivatives 5a-c . Reduction of ketones 6a-c into alcohols 7a-c was stereo specific.     

Cyanothioacetamide in Heterocyclic Chemistry: Synthesis of Piperidine-3-carbonitrile,Pyrazolopyridine, Thiinopyridine-3-carbonitrile Derivatives,and Their Theoretical Calculations

Cyanothioacetamide ( 1 ) reacted with acrylonitrile ( 2 ) to afford the corresponding 6-oxo-2-sulfanylpiperidine-3-carbonitrile ( 6 ), which oxidized to give compounds 7 and 8 under different conditions. Moreover, compound 6 was used as a starting material to synthesize 12a-c , 16a-d , 26a-c , 27a-c , and 30a-c via reactions with aromatic aldehydes 9a-c , diazonium chlorides 13a-d , and 3-arylpropennitrile derivatives 18a-i respectively. Considering the data of IR, 1 H NMR, mass spectra, elemental analyses, and theoretical calculations, all the structures of the newly synthesized heterocyclic compounds were elucidated.     

Oligomers with four 3,4-quinolinediyl units and α,ω-bis (4-chloro-3-quinolinylthio)alkanes

Starting from the reaction of thioquinanthrene 1 with sodium methoxide followed by the reaction with α,ω-dihalogenoalkanes, title bis-methoxy oligomers 4a-c with four 3,4-quinolinediyl units were prepared (40–91%). Acid catalysed hydrolysis of methoxy groups in 4a-c gave tetramers 5a-c (46–94%) with two 4(1H)-quinolinone functions. The reactions of bis-quinolinones 5a-c with phosphoryl chloride in DMF run as deoxo-chlorination and afforded tide dichlorotetramers 6a-c (51–66%) with 4-chloroquinolinyl groups. The treatment of bis-methoxy tetramers 4a -c with boiling phosphoryl chloride led to title α,ω-bis(4-chloro-3-quinolinylthio)alkanes 7a-c (52–56%) and thioquinanthrene (65–70%).     

Reactions of 3-isopropenyltropolones with bromine and N-bromosuccinimide: Formation of 8H-cyclohepta[b]furan-8-one derivatives

3-Isopropenyltropolones 1a-c were treated with bromine in carbon tetrachloride to give 3-methyl-8H-cyclohepta[b]furan-8-ones 2a-c and their corresponding 7-bromo-substituted compounds 3a-c , while reactions in acetic acid gave the bromo-substituted compounds 3a-c . On the other hand, bromination of 1a-c with N-bromosuccinimide afforded 7-bromo-3-(2-bromo-1-methylethenyl)tropolones 5a-c . The compound 2a was treated with bromine to give 2-bromo-3-methyl-8H-cyclohepta[b]furan-8-one ( 4 ). The tropolones 5a-c were heated in the presence of potassium carbonate to give the cyclized compounds 3a-c .     

Substituted γ-Lactones. 35 . Reduction of 4-aroyl-3-hydroxy-2(5H)-furanones

The reduction of 4-aroyl-3-hydroxy-2(5H)-furanons 1a-c was investigated using different reducing agents. Sodium borohydride reacts with type 1 compounds by loss of water to yield 4-(arylmethylene)-2,3(4H,5H)-furandiones 2a-c . Platinum or charcoal supported by pallodium chloride transforms 1a to 4-benzyl-3-hydroxy-2(5H)-furanone ( 3). Compounds 2a and 2b react with o-phenylenediamine to give 3-(E-(1′-hydroxymethyl-2′-aryl)ethenyl]-2-quinoxalinones 4a and 4b . The lactone 3 under the same conditions splits out formaldehyde and forms 3-(2′-phenylethyl)-2-quinoxalinone ( 6 ). The structure assignments of the novel compounds are based on elemental analysis and nmr as well as ir spectroscopic data.     

A new method for the synthesis of novel 1-aryl-3-quinoxalinyl-1,2,4-triazol-5-ones

The reactions of 3-methoxycarbonylmethylene-2-oxo-1,2,3,4-tetrahydroquinoxaline 1 with aryl diazonium salts gave 3-(α-aryldiazenylmethoxycarbonylmethylene)-2-oxo-1,2,3,4-tetrahydroquinoxalines 2a-c , whose reactions with hydrazine hydrate afforded 3-(α-aryldiazenylhydrazinocarbonylmethylene)-2-oxo-1,2,3,4-tetrahydroquinoxalines 3a-c . The reactions of 3a-c with nitrous acid resulted in the Curtius rearrangement to provide the 1-aryl-3-quinoxalinyl-1,2,4-triazol-5-ones 4a-c.     

Efficient Conversion of Esters to α-Trimethylsilylketones. Preliminary communication

Secondary and tertiary carboxylic methyl or ethyl esters ( 2a-c ) were converted with trimethylslylmethyllithium ( 3a-c ) in high yields. Under identical reaction conditions the primary esters 2d,e gave 3d, e in lower yields. Since the trimethylsilyl (TMS) group α to a ketone is known to undergo facile elimination under a variety of reaction conditions, the method also constitutes a highly versatile ester to methylketone sequence.     

Synthesis of 2-Arylthiopyrano[2, 3-d]Pyrimidines and Thieno[2, 3-D]Pyrimidines

Diethyl thiopyrano[2,3-d]pyrimidine-6,7-dicarboxylates 2a, b ; thiopyrano[23-d]pyrimidines 3a-c and 4a-c thieno[2,3-d]pyrimidine-6-carbonitriles 5a-c and thieno[2, 3-d]pyrimidine-6-carboxamides 5d-f have been prepared.     

A convenient synthesis of 3-aryl-4H- Benzopyrano[3,4-d]isoxazol-4-ones

Regioselective 1,3-dipolar cycloaddition of nitrile oxides 5a-c to ethyl o-hydroxycinnamate (3) gave the corresponding ethyl trans-3-aryl-4,5-dihydro-5-(2-hydroxyphenyl)-4-isoxazolecarboxylates 6a-c . Their structure was confirmed by reductive cleavage to 1 and compounds 9a-c . Compounds 6a-c afforded upon heating in the presence of pyridine the 3-aryl-4H-[1]benzopyrano[3,4-d]isoxazol-4-ones 11a-c . Compound 10c was also isolated from 6c and transformed thermally into 11c .     

Polycondensed nitrogen heterocycles. XXII. A new synthesis of 5,6-dihydro-7H-pyrazolo[1,5-d][1,4]benzodiazepin-6-ones

A new synthesis of 2-methyl-9-R'-10-R-5,6-dihydro-7H-pyrazolo[1,5-d][1,4]benzodiazepin-6-ones ( 4a-c ) is deserved. Reaction of ethyl hydrazinoacetate hydrochloride with 1,3-diketones 1a-c gave both 3-methyl-5-(4R'-5-R-2-nitrophenyl)pyrazol-1-yl-acetate acids ( 2a-c ) and the corresponding ethyl esters 3a-c . Reduction with the appropiate reducing agent of compounds 2a-c and 3a-c directly gave the title compounds. Compound 4a showed insecticidal properties against the house fly.     

Synthesis of 5-alkoxymethyl derivatives of 3'-amino-2',3'-dideoxyuridine and evaluation of their activity against HIV and cancer.

5-Alkoxymethyluracils 2a-c have been prepared by acid-catalyzed etherification of 5-hydroxymethyluracil (1). Compounds 1, 2a-c, 5-methoxymethyl- and 5-benzyloxymethyl-uracil were silylated and coupled with 1,5-di-O-acetyl-3-phthalimido-2,3-dideoxy-beta- D-erythro-pentofuranose (3), in the presence of trimethylsilyl triflate as a catalyst, to give the corresponding 3'-phthalimido-2',3'-dideoxynucleosides 5a-f and 6 which on treatment with 33% methylamine-ethanol afforded the corresponding 3'-amino-2',3'-dideoxynucleosides 7a-f and 8 in high yields. Compound 7d showed colony inhibition when tested against human epidermoid cervical cancer cells. Nucleosides 5a-e, 7a-f and 8 did not show any significant activity against HIV-1.     

Synthetic approaches to 2-substituted 1-oxo- and 3-oxotetrahydroisoquinolines

2-Substituted homophthalimides 2a-c were reduced regioselectively with sodium borobydride to carbinol-lactam intermediates 3a-c , which were dehydrated, followed by hydrogenation, to give 1-oxo-tetrabydroisoquinolines or 3,4-dihydroisoquinolin-1(2H)ones 5a-c . The isomeric 3-oxo-tetrahydro-isoquinolines or 1,4-dihydroisoquinolin-3(2H)-ones 8a-i were obtained in satisfactory yields via heating 3-isochromanone ( 6 ) with the corresponding amines 7a-i in the presence of aluminum chloride.     

Studies on 5-arylidene-3-phenyl-2-methylmercaptohydantoins

The action of ammonium acetate on 5-arylidene-3-phenyl-2-methylmercaptohydantoins 1g,h in acetic acid led to the formation of the 5-arylidene-3-phenylhydantoin derivatives 4a,b . In absence of a solvent, ring opening and rearrangement took place with the formation of the 5-arylidene-N²-phenylglycocyamidine derivatives 7a-c . Compounds 7a-c reacted with methyl iodide to afford the corresponding 3-methyl derivatives 9a-c . The structures of the synthesised products were established and the mechanism proposed for the rearrangement reaction was discussed.     

Hypbrvalent Iodine Oxidation of 3-(2-Furyl)-1-(2-hydroxyaryl)prop-2-enones : Synthesis of Novel 2-(2-Furyl)-cis-3-hydroxvchromanones and Derived 3-Hydroxychromones

The synthesis of novel 2-(2-furyl)-cis-3-hydroxychro-manones(3a-c) has been achieved from 3-(2-furyl)-1-(2-hydroxy-aryl)-2-enones (1a-c) via acid catalyzed hydrolysis of dimethylacetals (2a-c), formed by hypervalent iodine oxidation using iodobenzene diacetate in methanolic potassium hydroxide. Action of dil. alkali on 3a and 3b provides a new synthesis of 2-(2-furyl)-3-hydroxychromones (6a, 6b).