Synthesis and Evaluation of α-Methylidene-γ-butyrolactone bearing flavone and xanthone moieties

In a search for inhibitors of platelet aggregation, a number of α-methylidene-γ-butyrolactones 5 and 6 bearing flavone or xanthone moieties, respectively, were synthesized and evaluated for their antiplatelet activity against thrombin(Thr)-, arachidonic-acid(AA)-, collagen(Col)?, and platelet-activating-factor(PAF)-induced aggregation in washed rabbit platelets. These compounds were synthesized from 7-hydroxyflavone ( 1 ) or 3-hydroxyxanthone ( 2 ) via O-alkylation (→ 3 and 4 , resp.) and Reformatsky-type condensation (Scheme). Most of the flavone-containing α-methylidene-γ-butyrolactones 5a – d showed potent antiplatelet effects on AA- and Col-induced aggregation, while xanthone derivatives 6c – e were found to have the same pharmacological profile than aspirin in which only AA-induced aggregation was inhibited (Table 1). However, 6c – e were approximately three to ten times more potent than aspirin (Table 2). For the vasorelaxing effects, 5a was the only compound which exhibited significant inhibitory activity on the high-K⁺ medium, Ca²⁺-induced vasoconstriction (Table3). Both 5a and 6a , with an aliphatic Me substituent at C(γ) of the lactone, were active against norepinephrine-induced phasic and tonic constrictions while their γ-aryl-substituted counterparts 5b – f and 6b – f were inactive.     

Photochemical reactivity of α,β-unsaturated δ-lactams: Synthesis of seco-steroids. Photochemical reactions. XIII [1]

The UV. irradiation of 17 β-hydroxy-2-aza-4-androsten-3-one (1) , N-methyl-17 β-hydroxy-2-aza-4-androsten-3-one (3) , 17 β-hydroxy-4-aza-5 β-androst-1-en-3-one (2) and N-methyl-17 β-hydroxy-4-aza-5 β-androst-1-en-3-one (4) , gives rise to 1,10-seco (from 1 and 3 ) and 5, 10-seco (from 2 and 4 ) steroids.     

Natural product chemistry. Part 158. Reactions of ethyl 4-hydroxy-1-methyl-3-quinolin-2(1H)-onecarboxylate with 1,4-dibromo-2-methyl-2-butene

Ethyl 4-hydroxy-1-methyl-3-quinolin-2(1H)-onecarboxylate ( 1 ) which is obtained conveniently by the condensation of N-methylisatoic anhydride with diethyl malonate [4], was reacted with 1,4-dibromo-2-methyl-butene ( 2 ) to give the main products 3 and 4 and the dimeric derivatives 5 and 6 .     

Unambiguously confirmed structure of 2-phenacylidene-1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one and 3-phenacylidene-3,4-dihydro-1H-pyrido[2,3-b]pyrazin-2-one

To determine the structures of two isomeric products, 2-phenacylidene-1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one (2) and 3-phenacylidene-3,4-dihydro-1H-pyrido[2,3-b]pyrazin-2-one (3) obtained by condensation of 2,3-diaminopyridine (1) with ethyl benzoylpyruvate [1–3], these compounds were hydrolyzed to give 2-methyl-4H-pyrido[2,3-b]pyrazin-3-one (4) and 3-methyl-1H-pyrido[2,3-b]pyrazin-2-one (5) , respectively [4,5]. Both hydrolysates 4 and 5 were hydrogenated to afford 2-methyl-1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one (6) and 3-methyl-3,4-dihydro-1H-pyrido[2,3-b]pyrazin-2-one (7) . The latter compound was identical with an unequivocally synthesized compound providing proof for the structures of all these compounds.     

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 ).     

9-Hydroxy-2-methyl-4H-pyrido[1,2-α] pyrimidin-4-one and its derivatives

2-Amino-3-(o-bromobenzyloxy)pyridine ( 1 ) and ethyl acetoacetate gave 9-(o-bromobenzyl-oxy)-2-methyl-4H-pyrido[1,2-α]pyrimidin-4-one ( 2 ) in 2% yield. When 1 and methyl β-amino-crotonate ( 3 ) were reacted, benzyl ether cleavage occurred and the products were 9-hydroxy-2-methyl-4H-pyrido[1,2-α]pyrimidin-4-one ( 4 ) and its ammonium salt ( 5 ). These observations led to an alternative synthesis in which 2-amino-3-pyridinol ( 6 ) and either 3 or methyl acetoacetate, ( 8 ) in diethylbenzene at 185° gave 4 in 86 and 87% yields, respectively, and the anion of 4 and o-bromobenzyl bromide gave 2 in 61% yield. Even in diethylbenzene at 185°, 1 and 8 gave only trace amounts of 2 . Thus, o-bromobenzylation of the 3-hydroxyl group in 6 markedly decreased the reactivity of the amino group in 6 toward reactions with acetoacetic esters.     

Transformations of 2-(3-Hydroxy-3-methyl-1-butynyl)adamantan-2-ol >Catalyzed by Acids

Reaction of 2-(3-hydroxy-3-methyl-1-butynyl)adamantan-2-ol with acetonitrile under Ritter reaction conditions is accompanied by isomerization and partial hydration where the water addition to the triple bond occurs nonselectively. As a result of reaction carried out in the presence of 8 equiv of sulfuric acid a mixture was obtained of N ²-[4-(1-acetylamino-2-adamantyl)-2-methyl-3-butyn-2-yl]acetamide, N ³-[1-(1-acetylamino-2-adamantyl)-3-methyl-2-oxo-3-butyl]-acetamide, and N ³-[1-(1-acetylamino-2-adamantyl)-3-methyl-1-oxo-3-butyl]acetamide in ~10:3:2 ratio. In the presence of 2 equiv of the acid the mixture obtained consisted of N ²-[4-(1-acetylamino-2-adamantyl)-2-methyl-3-butyn-2-yl]acetamide, N ³-[1-(1-acetylamino-2-adamantyl)-3-methyl-2-oxo-3-butyl]acetamide, and 1-(1-acetylamino-2-adamantyl)-3-methyl-2-buten-1-one in the same ratio. In Rupe reaction conditions we obtained instead of the expected ,-unsaturated ketones a mixture of 1-(1-hydroxy-2-adamantyl)-3-hydroxy-3-methylbutan-1-one and 1-(1-hydroxy-2-adamantyl)-3-hydroxy-3-methylbutan-2-one in a 5:3 ratio.     

Synthesis of 4<Emphasis Type="Italic">H</Emphasis>-imidazole-5-carbaldoxime 3-oxides and 4<Emphasis Type="Italic">H</Emphasis>-imidazole-5-carbonitrile 3-oxides

The condensation of 3-hydroxyamino-3-methylbutan-2-one or 3-ethyl-3-hydroxyamino-pentan-2-one with aldehydes and ammonia afforded a series of new 1-hydroxy-4-methyl-2,5-dihydroimidazoles, whose oxidation gave rise to the corresponding 5-methyl-4H-imidazole 3-oxides. The latter, like 1-hydroxy-4-methyl-2,5-dihydroimidazoles, react with PrⁱONO in the presence of bases to form 4H-imidazole-5-carbaldoxime 3-oxides, which are transformed into 4H-imidazole-5-carbonitrile 3-oxides in the reaction with TsCl in the presence of Et₃N. The by-products produced in different steps of the synthesis were isolated and characterized. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1487–1503, July, 2008.     

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 ).     

Synthesis of 3-(3-Methyl-1-aryl-1H-pyrazol-5-yl)-2H-2-chromen-2-one Derivatives via a One-Pot,Three-Component Reaction

An efficient synthesis of 3-(3-methyl-1-aryl-1H-pyrazol-5-yl)-2H-2-chromen-2-one derivatives by the reaction of salicylaldehydes, 4-hydroxy-6-methyl-2H-pyran-2-one, and arylhydrazine in acetonitrile under reflux condition and in the presence of piperidine is reported. This three-component reaction has some advantages such as ease of handling, good yields, and easy purification. All structures were confirmed by infrared, mass, ¹H NMR, and ¹³C NMR spectroscopy.     

Synthese von 5-Methyl-3-oxa-A-nor-5β-cholestan und 3-Oxa-Δ4-cholesten-2-on

2, 3-seco-Δ⁴-Cholestene-2, 3-dicarboxylic acid ( 5 ) was prepared in 30% yield from 2-hydroxymethylene-Δ⁴-cholestene-3-one ( 1 ) by ozonolysis under special conditions. Pyrolysis of the pure di-acid 5 gave A-nor-Δ³⁽⁵⁾-cholestene-2-one ( 6 ), the anhydride 2 and 5-methyl-3-oxa-A-nor-5β-cholestane-2-one ( 8 ). Pyrolysis of amorphous acidic material obtained by the ozonolysis of 1 yielded the enol-lactones 7 and 9 as additional products. LiA1H₄-reduction of the γ-lactone 8 gave the diol 10 , which was transformed into 5-methyl-3-oxa-A-nor-5β-cholestane ( 13 ) by treatment with tosyl chloride in pyridine.     

The synthesis of 3H-pyrazol-3-one derivatives containing a 9H-xanthene ring

2,4-Dihydro-5-methyl-2-phenyl-4-(9H-xanthen-9-yl)-3H-pyrazol-3-one ( 3 ) was prepared by the condensation of phenylhydrazine and ethyl α-acetyl-9H-xanthene-9-acetate ( 2 ), or 9H-xanthen-9-ol ( 1 ) and 2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-one ( 4 ). 5-Amino-2,4-dihydro-2-phenyl-4-(9H-xanthen-9-yl)-3H-pyrazol-3-one ( 6 ) was obtained by the condensation of 1 and 5-amino-2,4-dihydro-2-phenyl-3H-pyrazol-3-one ( 5 ).     

Substituted γ-lactones. XXX. Reactions of α-Keto-β-Subtituted-γ-butyrolactones with diamines

The condensation reaction between α-keto-β-aroyl (or acyl) -γ-butyrolactones, 4a-4e and o-phenylenediamine or 2, 3-diaminonaphthalene leads under retrograde aldol condensation involving loss of formaldehyde to formation of 3-substituted-3, 4-dihydro-2 (1H) quinoxalinones or benzo [g] quinoxalinones, 7a-7g , respectively as a new convenient synthesis of this type of heterocyclic systems. The reaction of type 4 compound with 4, 5-diaminopyromidine, 8 , was found to proceed differently. 2-[(4-Amino-5-pyrimidinyl)amine]-4-oxo-3-(hydroxymethyl)-4-phenyl-2-butenoic acid 9 was the only product formed when the reaction between 4a and 8 was run in ethanol. The same reaction in glacial acetic acid proceeds with loss of formaldehyde, to afford 7-phenacylidene-7,8-dihydro-6 (1H)-pteridione 10 . The reaction between type 4 compounds and ethylenediamine or 1, 4-phenylenediamine leads to the formation of the bis-condensation products 13–15 , respectively.     

On Triazoles. XXXII. The reaction of 5-amino-1 H-1,2,4-triazolylcarbothiohydrazides with β- and γ-oxo-esters

5-Amino-lH-1,2,4-triazolylcarbothiohydrazides gave β and γ-oxo-esters in boiling ethanol [1,2,4]triazolo- [1,5-d][1,2,4,6]tetrazepine-5-thiones 3 . Analogously ethyl 2-oxocyclohexanecarboxylate provided a mixture of two diastereomeric spiro derivatives 5 and 6 . At 130°, 2-acetonyl-5-methyl-4,5-dihydro-1,3,4-oxadiazole-5-thione ( 8 ) was formed. Ring closure of 3e (R¹ = CH₃, R² = CH₂CH₂COOEt, Q = morpholino) lead to the isomeric pyrrolo[2,1-g][1,2,4]triazolo[1,5-d][1,2,4,6]tetrazepin-8(11H)-one ( 12 ) and pyrrolo[1,2-f][1,2,4]triazolo-[1,5-d][1,2,4,6]tetrazepin-10(7H)-one ( 13 ) derivatives representing two new ring systems.     

Synthesis and microbial screening of 8-(benzyloxy)-5-(2-[1,3-diphenyl-1H-pyrazol-4-yl]thiazol-4-yl)quinolin-2(1H)-one derivatives

The present investigation describe the synthesis of 8-(benzyloxy)-5-(2-[1,3-diphenyl-1H-pyrazol-4-yl]thiazol-4-yl)quinolin-2(1H)-one derivatives. Quinolin-8-ol was transformed by five step synthetic procedures into 8-Benzyloxy-5-(2-bromo-acetyl)-1H-quinolin-2-one. Subsequently, 8-Benzyloxy-5-(2-bromo-acetyl)-1H-quinolin-2-one condensed with 1,3-Diphenyl-1H-pyrazole-4-carbothioic acid amide in the presence of acetonitrile to afford 8-(benzyloxy)-5-(2-[1,3-diphenyl-1H-pyrazol-4-yl]thiazol-4-yl)quinolin-2(1H)-one derivatives. Synthesized compounds were screened for their antimicrobial activity against gram-positive and gram-negative bacteria. Most of the synthesized compounds are found to be active against tested bacterial strains and fungal strain.     

2-Phenyl-4-quinolinone Alkaloids from Casimiroa edulis Llave et Lex (Rutaceae)

 Three new 4-quinolinone alkaloids (5,6-dimethoxy-2-(3-methoxyphenyl)-1H-quinolin-4-one, 5,6-dimethoxy-2-(3,4-dimethoxyphenyl)-1H-quinolin-4-one, 5,6-dimethoxy-2-(2,5,6-trimethoxyphenyl)-1H-quinolin-4-one) were isolated from the leaves of Casimiroa edulis Llave et Lex (Rutaceae) cultivated in Egypt. Their structures were determined by UV/Vis, IR, ¹H and ¹³C NMR, and EI mass spectroscopy. The alkaloids were also detected in the kernels of the seeds.     

New alkaloids from <Emphasis Type="Italic">Casimiroa edulis</Emphasis> fruits and their pharmacological activity

The extract of Casimiroa edulis was investigated for antihypertensive activity. The ethanol and total alkaloids (in chloroform) extracts were found to have antihypertensive properties at doses of 500 and 200 mg/kg, respectively. Four quinolinone alkaloids were isolated and identified as: 2-(2′-hydroxy-4′-methoxyphenyl)-5,8-dimethoxy-3-propyl-1H-quinolin-4-one (1), 5,8-dimethoxy-2-(3′-methoxyphenyl)-3-propyl-1H-quinolin-4-one (2), 5,8-dimethoxy-2-(3′,4′-dimethoxyphenyl)-3-propyl-1H-quinolin-4-one (3), and 5,6-dimethoxy-2-(2′,5′,6′-trimethoxyphenyl)-1H-quinolin-4-one (4). Interestingly, compounds 1, 2, and 3 were found to be new alkaloids. The four isolated alkaloids showed antihypertensive activity at doses of 50, 100, 200, and 300 mg/kg, respectively. Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 473–476, September–October, 2007.     

Geiparvarin Analogues: Synthesis and Anticancer Evaluation of α-Methylidene-γ-butyrolactone-Bearing Coumarins

To determine some of the structural features of geiparvarin that account for its cytostatic activity in vitro, certain geiparvarin analogues modified in the furan-3(2H)-one moiety and the alkenyloxy substituent were synthesized and tested against the growth of 60 human cancer cell lines derived from nine cancer-cell types. These compounds demonstrated a strong growth-inhibitory activity against leukemia cell lines but were relatively inactive against non-small-cell lung cancers and CNS cancers. Comparison of the mean log GI₅₀ values of γ-[(E)-1-methylprop-1-enyl]-α-methylidene-γ-butyrolactones 7 – 9 revealed that 7-[(E)-3-(2,3,4,5-tetrahydro-4-methylidene-5-oxofuran-2-yl)but-2-enyloxy]-2H- 1-benzopyran-2-one ( 8 ; −5.47) was more active than its 6-substituted counterpart 7 (−5.21) and its 3-chloro-4-methyl derivative 9 (−5.31) and had a potency similar to that of geiparvarin (log GI₅₀=−5.41). These results indicated that the furan-3(2H)-one moiety of geiparvarin could be replaced by an α-methylidene-γ-butyrolactone unit without losing the anticancer potency, and that the best substitution site at the coumarin moiety was C(7). The alkenyloxy substituent of 8 was also replaced by a methoxy substituent. Among these α-methylidene-γ-butyrolactones, 7-[(2,3,4,5-tetrahydro-4-methylidene-5-oxo-2-phenylfuran-2-yl)methoxy]-2H-1-benzopyran-2-one ( 11 ) was the most potent with a mean log GI₅₀ value of −5.83 and a range value of 132 (10^2.12).     

New,Convenient, One-Pot Method for the Synthesis of Thiazolyl-pyrazolones from Dehydroacetic Acid Derivative via a Multicomponent Approach

A convenient one-pot method for the synthesis of thiazolyl-pyrazolones was described in excellent yields. Reaction of 3-(2-bromoacetyl)-4-hydroxy-6-methyl-2H-pyran-2-one with thiosemicarbazide and ethyl 2-(2-arylhydrazono)-3-oxobutanoates in anhydrous ethanol under reflux conditions afforded the corresponding 4-(2-arylhydrazono)-1-(4-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)thiazol-2-yl)-3-methyl-1H-pyrazol-5(4H)-one in good yields. The structures of newly synthesized compounds were established on the basis of elemental analysis, infrared, ¹H NMR, and mass spectroscopic studies.     

The synthesis of benzofuroquinolines. III. Two dihydroxybenzofuroquinolinones

Two dihydroxybenzofuroquinolinones, 3,9-dihydroxy-5H-benzofuro[3,2-c]quinolin-6-one (V) and 3,8-dihydroxy-6H-benzofuro[2,3-b]quinolin-11-one (VI), were obtained by the demethyl-cyclization of 3-(2,4-dimethoxyphenyl)-4-hydroxy-7-methoxy-1H-quinolin-2-one (IV). By the methylation with diazomethane, V gave a dimethylated compound (VII), while VI gave a trimethylated compound (VIII).