A Nucleobase‐Discriminating Pyrrolo‐dC Click Adduct Designed for DNA Fluorescence Mismatch Sensing

New pyrrolo‐dC click adducts ( 4 and 5 ) tethered with a 1,2,3‐triazole skeleton were synthesized and oligonucleotides were prepared. The triazole system was either directly linked to the pyrrolo moiety ( 5 ) or connected via an n‐butyl linker ( 4 ). The quantum yield of nucleoside 5 (Φ=0.32), which is 10 times higher than those of 8‐methylpyrrolo‐dC ( 1 b , Φ=0.026) or the long linker derivative 4 (Φ=0.03), is maintained in oligonucleotides. Compound 5 was used as a nucleobase‐discriminating fluorescence sensor in duplex DNA. Excellent mismatch discrimination was observed when 5 was positioned opposite the four canonical nucleosides. Compound 5 has the potential to be used for SNP detection in long DNA targets when conventional techniques such as high resolution melt analysis fail.     

Studies on the synthesis of heterocyclic compounds. III. Preparation of some pyrazolo[3,4-C] [1,5]benzodiazocin-10(11H)one derivatives

Starting from the readly available N-melhyl-N-(1-phenyl-3-R-pyrazol-5-yl)-2-nitrobenzamides (1a,b), the pyrazoles, 4-aeetyl substituted 2a,b, were prepared in high yield. Reduction of 2a gave the amino derivative 4a, which was eyclized to the desired pyrazolo[3,4-c][1,5]benzodiazo-cin-10(11H)one (5a). Compound 2b afforded 5b directly. Compound 5b was also prepared by the action of phosphorus oxychloride on N-methyl-N-(1,3-diphenylpyrazol-5-yl)-2-acetamido-benzamide (6b).     

Synthesis and biological evaluation of 9‐thia‐5,10‐dideazafolic acid

The folate analogue, 9‐thia‐5,10‐dideazafolic acid ( 3b ), was obtained in an efficient two‐step procedure in an overall yield of 60%. The previously unknown intermediate dimethyl‐thiocarbamic acid S‐(2‐amino‐3,4‐dihydo‐4‐oxo‐pyrido[2,3‐d]pyrimidin‐6‐yl) ester ( 5 ) was prepared via the condensation of 2,6‐diamino‐3H‐pyrimidin‐4‐one and S‐(2‐malonaldehyde)‐1,1,3,3‐tetramethylthiouronium bromide ( 4 ). Compound 5 , in a one pot procedure, was deprotected using sodium hydroxide and then coupled to diethyl N‐[(4‐chloromethyl)benzoyl]‐L‐glutamate, followed by saponification of the ethyl esters to give the 9‐thia‐5,10‐dideazafolic acid ( 3b ). Compound 3b was a potent inhibitor of human 5‐aminoimidazole‐4‐carboxamide ribonucleotide transformylase (K_i of 8 ± 5 μM) and showed no inhibition of human glycinamide ribonu‐cleotide transformylase at concentrations as high as 50 μM. Compound 3b was screened by the National Cancer Institute Developmental Therapeutics Program against 60 human tumors and was found to be active against a leukemia RPMI‐8226 cell line where the LC₅₀ was 1 μM.     

Synthesis of 5-fluoro-2-methyl-3-(2-trifluoromethyl-1,3,4-thiadiazol-5-yl)-4(3H)-quinazolinone and related compounds with potential antiviral and anticancer activity

The synthesis of ten new substituted 1,3,4-thiadiazolyl-4(3H)-quinazolinones 8–11, 13, 17 , and 20–23 is reported. Compounds 8–11 were prepared by condensation of 5-fluoro-2-methyl-3,1-benzoxazin-4-one (3) and 5-substituted 2-amino-1,3,4-thiadiazoles 4–7. Compound 13 was obtained by condensation of 5-fluoro-2-methyl-3,1-benzoxazin-4-one (3) with DL-α-amino-?-caprolactam (12) . Compound 17 was synthesized by condensation of 6-bromo-2-methyl-3,1-benzoxazin-4-one (16) and 2-amino-5-t-butyl-1,3,4-thiadiazole (5) . Compounds 20–23 were obtained by condensation of 5-chloro-6,8-dibromo-2-methyl-3,1-benzoxazin-4-one (19) and 5-substituted 2-amino-1,3,4-thiadiazoles 4–7, respectively. The substituted 3,1-benzoxazin-4-ones 3, 16, and 19 were obtained in good yield by refluxing the appropriate anthranilic acid, 1,15 , and 18 with acetic anhydride (2) .     

Alkyl heterocycles in heterocyclic synthesis (II): Novel synthesis of isoquinoline,thiazolopyridine, and thieno[2,3‐b]pyridine derivatives

Treating 5‐(4‐phenylcarboxamido)‐3‐cyano‐4‐methylpyridin‐2(1H)thione ( 3 ) with elemental sulfur yielded thienopyridine 4 . Compound 4 reacts with acrylonitrile to give isoquinoline 7 . Compound 7 was also, prepared from 3 and methylenemalononitrile. Reaction of 3 with dimethylacetylene dicarboxylate (DMAD) gave the pyridothiazole 9 . Also, 3 reacted with N,N‐dimethylchloroacetamide ( 10 ) to afford compound 11 which further reacted with the reagents 12 , 13 and 14 providing the thieno[2,3‐b]pyridine derivatives 15 , 16 and 17 respectively.     

The synthesis of some 4-nitroisothiazoles as potential antifungal agents

5-Chloro-3-methyl-4-nitroisothiazole (III) was prepared by nitration of 5-chloro-3-methyliso-thiazole. Compound III was found to exhibit significant antifungal activity in vitro against a wide spectrum of fungi. The synthesis of 3-methyl-4-nitro-5-nitroamino, 5-carboxamido, 5-N,N-dimethylamino and 5-β-hydroxyethylaminoisothiazole are here reported. The synthesis of 3-methyl-4-nitroso-5-ethylthioisothiazole (IX) is reported via an unusual reaction of 5-bromo-3-methyl-4-nitroisothiazole (I) and sodium ethyl mercaptide. 5-Bromo-4-nitroisothiazole was prepared by nitration of 5-bromoisothiazole. The nitro group was shown to be essential for antifungal activity.     

Mixed Azines of Naloxone with Dihydromorphinone Derivatives

The mixed azines 4 and 5 were prepared by reaction of naloxazone ( 2 ) with either oxymorphone ( 6 ) or 14-O-methyloxymorphone ( 7 ) and tested in vitro using opioid receptor binding assays and in vivo using the AcOH-writhing test in mice. Compound 4 was found to be a partial agonist, while compound 5 was a potent opioid agonist with higher potency than morphine.     

4‐Toluenesulfonamide as a Building Block for Synthesis of Novel Triazepines,Pyrimidines, and Azoles

N‐{(E)‐(dimethylamino)methylidenearbamothioyl}‐4‐toluenesulfonamide ( 2 ) was obtained by reaction of N‐carbamothioyl‐4‐toluenesulfonamide ( 1 ) with dimethylformamide dimethylacetal or alternatively by the reaction of 1‐(dimethylamino)methylidenethiourea with tosyl chloride. Compound 2 was reacted with substituted anilines to yield anilinomethylidine derivatives 3a , 3b , 3c , 3d , 3e , 3f , 3g . Treatment of 3a , 3b , 3c , 3d , 3e , 3f , 3g with phenacyl bromide gave triazepines 4a , 4b , 4c , 4d , 4e , 4f , 4g and imidazoles 5a , 5b , 5c , 5d , 5e , 5f , 5g . Esterification of compound 3e afforded ester derivative 6 , which was subjected to react with hydrazine to yield hydrazide derivative 7 . Oxadiazole 8 was obtained by reaction of 7 with CS₂/KOH. Compound 3e was treated with o‐aminophenol or o‐aminothiophenol to give benzazoles 9a , 9b . N‐(Diaminomethylidene)‐4‐toluenesulfonamide ( 10 ) reacted with enaminones to yield pyrimidines 11 , 12 , 13 , respectively. The structures of the compounds were elucidated by elemental and spectral analyses. Some selected compounds were screened for their in vitro antifungal activity. In general, the newly synthesized compounds showed good antifungal activity.     

Transformation of 4-(1-dimethylaminoethylidene)-2-phenyl-5(4H)-oxazolone into methyl 2-benzoylamino-3-oxobutanoate. The synthesis of 1-substituted 4-benzoylamino-3-methyl-5(2H)-pyrazolones

Methyl 2-benzoylamino-3-oxobutanoate ( 3 ) was prepared from hippuric acid (1) which was converted with N,N-dimethylacetamide and phosphorus oxychloride into 4-(1-dimethylaminoethylidene)-2-phenyl-5(4H)-oxazolone ( 2 ) followed by hydrolysis with hydrochloric acid in methanol. Compound 3 was treated with hydrazines 4 to give 4-benzoylamino-3-methyl-1H-pyrazol-5(2H)-one ( 6a ) and its 1-substituted derivatives 6b-j . The corresponding hydrazones 5f, i, j were isolated as intermediates.     

Preparation of some substituted imidazo[1,2-a]pyridine derivatives

2-Bromopyridine derivatives 2a-2c were prepared. Compounds 2b and 2c and ammonia yielded aminopyridines 3b and 3c which were converted to imidazo[1,2-a]pyridine derivatives 4b and 4c . Compound 4b was nitrated giving the analogue 5b of metronidazole 1 .     

Synthesis and reactions of 6‐methylsulfanyl‐2,4‐dithioxo‐1,2,3,4‐tetrahydropyrimidin‐5‐carbonitrile

The synthesis of 6‐methylsulfanyl‐2,4‐dithioxo‐1,2,3,4‐tetrahydropyrimidine‐5‐carbonitrile 4 is described. Compound 4 was reacted with various alkylants. The reaction with chloroacetic acid derivatives results in the formation of thieno[2,3‐d]pyrimidines 8 . When methyl iodide was used 2,4,6‐tris(methylsul‐fanyl)pyrimidine‐5‐carbonitrile 5 was obtained. The substitution of the methylsulfanyl groups in compound 5 by several N‐nuclophiles leads to amino substituted pyrimidines.     

Enaminones as building blocks in heterocyclic synthesis: New syntheses of nicotinic acid and thienopyridine derivatives

Reacting 1,3‐diphenyl‐propan‐2‐one with equimolecular amount of dimethylformamide dimethylacetal afforded the enaminone 4. This when reacted with another equimolecular amount of dimethylformamide dimethylacetal afforded the dienaminone 5. Compound 4 condenses with cyanothioacetamide and with cyanoacetamide to yield 2‐thioxo‐ and 2‐oxo‐pyridine‐3‐carbonitrile derivatives 6a,b respectively. Compound 6a reacted with α‐chloroacetone 8 to yield the thieno[2,3‐b]pyridine derivative 10 that cyclized further into 4,7,8‐trisubstituted pyrido[2′,3′:2,3] thieno[4,5‐d]pyrimidine 12. Compound 4 also afforded 2,5,6‐trisubstituted nicotinic acid ethyl ester 13 by reaction with ethyl acetoacetate in acetic acid in the presence of ammonium acetate. The dienaminone 5 reacted with acetic acid, ammonium acetate/acetic acid, phenylhydrazine and 5‐amino‐3‐methylpyrazole yielding 3,5‐diphenyl‐pyran‐4‐one 15a , 3,5‐diphenyl‐1H‐pyridin‐4‐one 15b and 1,3,5‐trisubstituted pyridin‐4‐ones 16a‐b.     

Reactions with heterocyclic diazonium salts: New routes for the synthesis of pyrazolo[1,5-c]-1,2,4-triazoles and pyrazolo[1,5-c]-as-triazines

3-Phenylpyrazole-5-(liazonium chloride ( 1 ) couples with α-chloro derivatives of acetylacetone, ethyl acetoacetate and aceto-o-anisidine to yield the corresponding pyrazole-5-yl hydrazonyl chloride derivatives 2a-c . Compounds 2a,b were cyclised to yield either the pyrazolo[1,5-c]-1,2,4-triazole derivatives 3a,b or the pyrazolo[1,5-c]-as-triazines 4a,b depending on the applied reaction conditions. Compound 2c cyclised only into 3c under different cyclization conditions. The pyrazolo[1,5-c]-as-triazine derivatives 4c-e could be prepared via condensation of 2a with potassium cyanide. Compound 2d reacted with aromatic thioles and with sodium benzene-sulphonate to yield the pyrazolo[1,5-c]-as-triazine derivatives 6a-d . Compound 1 reacted with activated double bond systems to yield pyrazolo[1,5-c]-as-triazines 8a,b and 9 .     

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 .     

The reaction of isothiocyanates with 2-cyanoethanoic acid hydrazide. A novel synthesis of 1,3,4-thiadiazoles

Benzoyl and ethoxycarbonyl isothiocyanates reacted with 2-cyanoethanoic acid hydrazide 2 to afford 1-cyanoacetyl-4-substituted thiosemicarbazide ( 5a,b ). Compound 5a afforded the pyrazolo[1,5-a]-s-triazine derivative 6 on treatment with 5% potassium hydroxide, and cyclised to 2-benzoylamino-5-cyanomethyl-1,3,4-thiadiazole ( 8 ) when boiled under reflux in glacial acetic acid. Compound 8 condensed with aromatic aldehydes to yield the corresponding arylidene derivatives 9a-c . It undergoes coupling with aromatic diazonium salts to afford the hydrazones 11a-c . Similarly, it coupled with diazotised aminopyrazole to afford the cyclic product 12 .     

Pyrimidine derivatives and related compounds. A novel synthesis of pyrimidines,pyrazolo[4,3-d]pyrimidines and isoxazolo[4,3-d] pyrimidine

Benzoylacetonitrile (II) reacted with trichloroacetonitrile (III) to yield the β-amino-β-trichloromethylacrylonitrile IV. Compound IV reacted with hydrazine hydrate to yield 5-amino-4-cyano-3-phenylpyrazole (V) and with 2-aminopyridine to yield the aminopyridine derivative VIII (cf., Chart I). Compound IV reacted with III to yield 2,4-bis(trichloromethyl)-5-cyano-6-phenylpyrimidine (I) which could be converted into a variety of pyrazolo[4,3-d]pyrimidine derivatives by treatment with hydrazine hydrate under a variety of different experimental conditions (cf., Chart II).     

Mechanism of Alkaline Hydrolysis of Diazepam

Diazepam (1) is a frequently prescribed hypnotic/anxiolytic drug in worldwide use. Compound 1 is hydrolyzed in alkaline medium to form 2-methylamino-5-chlorobenzophenone imine (2) and 2-methylamino-5-chlorobenzophenone (3) ; the ratio of 2:3 increases with increasing NaOH concentration (J. Pharm. Sci. 85, 745–748, 1996). The mechanism in the conversion of 1 to 2 and 3 via various intermediates is the subject of this report. Results of hydrolysis kinetics and structural identification of some intermediate products indicated an initial hydroxide attack at the C2-carbonyl carbon of 1 , resulting in the formation of a dioxide ( 7 , 7-chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2,2-dioxide). Compound 7 was characterized by proton NMR spectroscopy and via its monomethyl ether ( 8 , 7-chloro-1,3-dihydro-2-hydroxy-2-methoxy-l-methyl-5-pheny]-2H-1,4-benzodiazepine). The seven-member diazepine ring of 7 opened at the N1-C2 bond to form a glycinate [ 5 , 2-methylamino-5-chloro-α-(phenylhenzylidene)glycinate]. Compound 7 (and/or 5 ) underwent an additional hydroxide attack at the C5-N4 imine bond to form a tetrahedral intermediate, which decomposed to form 2 and 3 .     

Synthesis and Biological Evaluation of 14-Alkoxymorphinans. Part 10. 14-O-Methyl derivatives of 5-methylnaltrexone and 5-methylnaloxone

In several steps, 5, 14-O-dimethylnaltrexone ( 3 ) and 5, 14-O-dimethylnaloxone ( 4 ) were prepared starting from 5, 14-O-dimethyloxycodone ( 5 ). Compound 3 exhibited opioid agonism in vitro (guinea-pig ileum and mouse vas deferens preparations) and antagonism in vivo (AcOH-writhing test in mice), while compound 4 was found to be an agonist in vitro and in vivo.     

1,2endo-Trimethylenenorbornane. A novel isomer of adamantane

An easy approach to the novel adamantane isomer 1,2endo-trimethylenenorbornane (2) is described. Starting from a mixture of pent-4-ynylcyclopentadienes 3 the tricyclic monosaturated key intermediate 5 was prepared by intramolecular cycloaddition (→ 4 ) and subsequent regioselective reduction of the C(5), C(6) double bond. The title hydrocarbon 2 was obtained from 5 upon stereoselective hydrogenation by diimide. In addition specifically deuteriated analogues of 2 were prepared applying dideuteriodiimide. Compound 2 rearranged to 2endo, 6endo-trimethylenenorbornane (4-homobrendane, 10 ) in sulfuric acid as well as with aluminium bromide in carbon disulfide.     

A facile and novel synthesis of 5-phenylimidazo[4,5-c][1,8]naphthyridin-4(5H)-ones

A convenient and regioselective synthesis of a new heterocycle, 5-phenyl-1H or 3H-imidazo[4,5-c][1,8]-naphthyridin-4(5H)-one 1-a or 1-b , is described. Methyl 2-anilinonicotinate 15 was transformed into the valuable intermediate, N-phenyl-3-azaisatoic anhydride 4 using trichloromethyl chloroformate (TCF). Treatment of 4 with the anion of ethyl nitroacetate gave 4-hydroxy-3-nitro-1-phenyl-1,8-naphthyridin-4(5H)-one 3 . Compound 3 was chlorinated, aminated, reduced, and cyclized to afford 5-phenylimidazo[4,5-c][1,8]naphthyridin-4(5H)-one 1 . Regioselective substitution at the 1 or 3-position in the imidazole moiety of 1 was achieved by minor changes of the above scheme.