Diels-alder reaction of (E)-4-(2-nitroethenyl)-1H-imidazoles and methyl (E)-3-(1-imidazol-4-yl)propenoates

Diels-Alder reaction of methyl (E)-3-(1H-imidazol-4-yl)propenoates 2, 3a-c and (E)4-(2-nitroethenyl)-1H-imidazoles 3d,e with 2,3-dimethyl-1,3-butadiene, cyclopentadiene, and cyclohexa-1,3-diene gave the corresponding cycloadducts 6–9 .     

Regioselective cycloaddition of C-carbamoylnitrones to methyl (E)-2-(2-phenylcyclopropylidene)acetate and methyl (E)-2-methylidene-3-phenylcyclopropane-1-carboxylate

N-Aryl-C-(arylcarbamoyl)nitrones regioselectively add to methyl 2-(2-phenylcyclopropylidene)-acetate and methyl 2-methylidene-3-phenylcyclopropanecarboxylate to give in each case two diastereoisomeric 5-oxa-6-azaspiro[2.4]heptane-4-carboxylates.     

Preparation and Structure of (E)-1-(3′-Hydroxy-2-Furanyl)-3-(3″-Hydroxy-4″-Methoxyphenyl)-2-Propen-1-One

Abstract

A facile procedure is presented for the synthesis of (E)-1-(3′-hydroxy-2′-furanyl)-3-(3″-hydroxy-4″-methoxyphenyl)-2- propen-1-one (6). Galactosylisomaltol (1) was condensed with isovanillin (2) under strong alkaline conditions at 25 [ddot]C to form (E)-1-(3′-O-β-D-galactopyranosyloxy-2′-furanyl)-3-(3″- hydroxy-4″-methoxyphenyl)-2-propen-1-one (4). (E)-1-(3′-hydroxy-2′-furanyl)-3-(3″-hydroxy-4″-methoxyphenyl)-2-propen-1-one (6) was obtained by acid hydrolysis of 4 in a 53.9% yield. This hetero-cyclic 2-propen-1-one was characterized on the basis of spectral data (IR and ¹H NMR), physicochemical properties, and conversion to a mono-O-acetyl derivative.     

Investigation on some (E)- and (Z)-3-heterocyclic-substituted-2-phenylacrylic acids

The synthesis of 3-(2-thiazolyl)-, 3-(2-benzothiazolyl)- and 3-(2-benzo[b] thienyl)-2-phenylacrylic acids is reported. Spectroscopic analyses and pK a determinations were found to be a convenient method for distinguishing the E and Z geometrical configurations.     

Synthesis of Ethyl 2-Hydroxy-3-[aryl(2-naphthylamino)methyl]-2-cyclopentenecarboxylates and Ethyl 3-Arylmethylene-2-(2-naphthylamino)-1-cyclopentenecarboxylates

Condensation of N-arylmethylene-2-naphthylamines with ethyl 2-oxocycopentanecarboxylate in the presence of HCl or CH₃COOH yields ethyl 2-hydroxy-3-[aryl(2-naphthylamino)methyl]-2-cyclopentenecarboxylates and ethyl 3-arylmethylene-2-(2-naphthylamino)-1-cyclopentenecarboxylates, respectively.     

Preparation of enantiomerically pure (3E)-alkyl-4-(hetero-2-yl)-2-hydroxybut-3-enoates by Candida parapsilosis ATCC 7330 mediated deracemisation and determination of the absolute configuration of (3E)-ethyl-4-(thiophene-2-yl)-2-hydroxybut-3-enoate

Deracemisation of racemic (3E)-alkyl-4-(hetero-2-yl)-2-hydroxybut-3-enoates using Candida parapsilosis ATCC 7330 resulted in the formation of one enantiomer in high enantiomeric excess [up to >99% ee] and isolated yields [up to 79%]. The absolute configuration of the enantiomerically pure (3E)-ethyl-4-(thiophene-2-yl)-2-hydroxybut-3-enoate as determined by ¹H NMR of the Mosher esters was found to be (S).     

Effective Synthesis of Polysubstituted Pyrroles from (E)-Dimethyl 2-(Bromomethyl)-3-(diethoxyphosphoryl) Fumarate

Methyl 1-alkyl-4-(diethoxyphosphoryl)-5-oxo-2,5-dihydro-1H-pyrroles-3-carboxylate 4 was synthesized from the reaction of dimethyl 2-(bromomethyl)-3-(diethoxyphosphoryl) fumarate 3- E and primary amines in good yields.     

Preparation,molecular structures,and characteristic properties of (E)-1-(2-furyl)- and (E)-1-(2-thienyl)-2-(3-guaiazulenyl)ethylenes and (E)-1-(3-furyl)- and (E)-1-(3-thienyl)-2-(3-guaiazulenyl)ethylenes

Wittig reactions of 2-furaldehyde (20) [and thiophene-2-carbaldehyde (21)] with (3-guaiazulenylmethyl)triphenylphosphonium bromide (19) in ethanol containing NaOEt at 25 °C for 24 h under argon give (E)-1-(2-furyl)-2-(3-guaiazulenyl)ethylene (22E) and (E)-1-(2-thienyl)-2-(3-guaiazulenyl)ethylene (23E) in 53 and 36% yields. Similarly, Wittig reactions of 3-furaldehyde (29) [and thiophene-3-carbaldehyde (30)] with 19 under the same reaction conditions as for 20 and 21 afford (E)-1-(3-furyl)-2-(3-guaiazulenyl)ethylene (31E) and (E)-1-(3-thienyl)-2-(3-guaiazulenyl)ethylene (32E) in 32 and 46% yields. Molecular structures and characteristic properties as well as preparation of the title E (i.e., one of the geometrical isomers) forms, with a view to comparative study, are reported. Moreover, reactions of those conjugated π-electron systems with TCNE (=tetracyanoethylene) in benzene [and in DMF (=N,N-dimethylformamide)] at 25 °C for 24 h under argon yield unique products, possessing interesting molecular structures, respectively, whose characteristic properties and crystal structures are documented, also.     

Methyl and Phenylmethyl 2-Acetyl-3-{[2-(dimethylamino)-1-(methoxycarbonyl)ethenyl]amino}prop-2-enoate in the Synthesis of heterocyclic systems: Preparation of 3-amino-4H-pyrido-[1,2-a]pyrimidin-4-ones

Methyl 2-acetyl-3-{[2-(dimethylamino)-1-(methoxycarbonyl)ethenyl]amino}prop-2-enoate ( 4 ) and phenyl-methyl 2-acetyl-3-{[2-(dimethylamino)-1(methoxycarbonyl)ethenyl]amino}prop-2-enoate ( 5 ) were prepared in three steps from the corresponding acetoacetic esters, and used as reagents for the preparation of N³-protected 3-amino-4H-pyrido[1,2-a]pyrimidin-4-ones 10 – 12 , 5H-thiazolo[3,2-a]pyrimidin-5-one 13 , 4H-pyrido[1,2-a]-pyridin-4-one 19 and 2H-1-benzopyran-2-ones 20 – 23 . Free 3-amino-4H-pyrido[1,2-a]pyrimidin-4-ones 24 – 26 were prepared from 10 – 12 by removal of the 2-(methoxycarbonyl)-3-oxobut-1-enyl or 3-oxo-2-[(phenyl-methoxy)carbonyl]but-1-envl as N-protecting group by various methods.     

Reactions of methyl (E,Z)-2-(2-benzoyl-2-ethoxycarbonyl-1-ethenyl)-amino-3-dimethylaminopropenoate with heteroarylhydrazines. 2-(2-Benzoyl-2-ethoxycarbonyl-1-ethenyl)amino-3-heteroarylhydra-zonopropanoates and 1-heteroaryl-4-ethoxycarbonyl-3-phenylpyrazoles

In the reaction of methyl (E,Z)-2-(2-benzoyl-2-ethoxycarbonyl-1-ethenyl)amino-3-dimethylaminopro-penoate ( 1 ) with heteroarylhydrazines 2 in ethanol in the presence of catalytic amounts of hydrochloric acid two types of products were formed: methyl 2-(2-benzoyl-2-ethoxycarbonyl-1-ethenyl)amino-3-heteroaryl-hydrazonopropanoates 4 in 73-86% yield and 1-heteroaryl-4-ethoxycarbony-3-phenylpyrazoles 5 in 5-16% yield.     

Synthesis and characterization of lanthanide complexes prepared with 2-((E)-(1-hydroxy-2-methylpropan-2-ylimino)methyl)-6-methoxyphenol

Rare-earth complexes of the general formula [Ln(H₂L₁)₂(NO₃)₃] [Ln = Gd (1), Ho (2) or Nd (3)] were prepared from an o-vanillin derived Schiff base ligand, 2-((E)-(1-hydroxy-2-methylpropan-2-ylimino)methyl)-6-methoxyphenol (H₂L₁). The single-crystal X-ray diffraction studies and SHAPE analyses of the Gd(III) and Ho(III) complexes show that the complexes are ten-coordinate and exhibit distorted tetradecahedron geometries. The phenolate oxygen-bridged dinuclear complex, [Ce₂(H₂L₁)(ovan)₃(NO₃)₃] (4, ovan = monodeprotonated o-vanillin), was obtained from the reaction of Ce(NO₃)₃?6H₂O with H₂L₁. X-ray analysis revealed that hydrolysis of H₂L₁ occurred to yield o-vanillin, which bridged two cerium atoms with the Ce?Ce distance equal to 3.8232(6) Å. The Ce(III) ions are both ten-coordinate, but have different coordination environments, showing tetradecahedron and staggered dodecahedron geometries, respectively. With proton migration occurring from the phenol group to the imine function, complexation of the lanthanides to the ligand gives the Schiff base a zwitterionic phenoxo-iminium form.     

Synthesis and structural studies of (2E,3E)-3-[(6-{[(1E,2E)-2-(hydroxyimino)-1-methylpropylidene]amino}pyridin-2-yl)imino]butan-2-one oxime, ligand and its mono-, di- and trinuclear copper(II) complexes

A new dioxime ligand, (2E,3E)-3-[(6-{[(1E,2E)-2-(hydroxyimino)-1-methylpropylidene]amino}-pyridin-2-yl)imino]butan-2-one oxime, (H₂Pymdo) (3) has been synthesized in H₂O by reacting 2,3-butenedione monoxime (2) with 2,6-diaminopyridine. Mono-, di- and tri-nuclear copper(II) complexes of the dioxime ligand (H₂Pymdo) and/or 1,10-phenanthroline have been prepared. The dioxime ligand (H₂Pymdo) and its copper(II) complexes were characterized by ¹H-n.m.r., ¹³C-n.m.r. and elemental analyses, magnetic moments, i.r. and mass spectral studies. The mononuclear copper(II) complex of H₂Pymdo was found to have a 1:1 metal:ligand ratio. Elemental analyses, stoichiometric and spectroscopic data of the metal complexes indicated that the metal ions are coordinated to the oxime and imine nitrogen atoms (C=N). In the dinuclear complexes, in which the first Cu(II) ion was complexed with nitrogen atoms of the oxime and imine groups, the second Cu(II) ion is ligated with dianionic oxygen atoms of the oxime groups and are linked to the 1,10-phenanthroline nitrogen atoms. The trinuclear copper(II) complex (6) was formed by coordination of the third Cu(II) ion with dianionic oxygen atoms of each of two molecules of the mononuclear copper(II) complexes. The data support the proposed structure of H₂Pymdo and its Cu(II) complexes.     

Synthesis of Ethyl (2RS,3SR)-1-Tosyl-3-Vinylazetidine-2-carboxylate and ethyl (2RS,E)-3-ethylidene-1-tosylazetidine-2-carboxylate (=rac-ethyl N-tosylpolyximate)

The synthesis of 3-ethylideneazetidine-2-carboxylic acid (=polyoximic acid; 3 ) is a approached in two different ways leading to potential precursors of 3 . The first way involved a ring closure to a vinyl-subsatituted azetidin. Thus, Ireland-Claisen rearrangement of the Boc-glycinates 6 and 10 of (Z)- and (E)-2-butene-1,4-diol afforded, after exchange of the N-protecting groups, the isomeric 2-(tosylamino)-3-vinylbutanolides 13 and 14 with high stereoselectivity. Only the cis-isomer 14 could be further transformed to 3-(bromomethyl)-2-(tosylamino)-4-pentenoate 17 , and in a smoth cyclization with K₂CO₃, to trans-3-vinylazetidtene-2-carboxylaze 18 (Scheme 2). In the second approach, the 3-ethylidene isomer 19 of 18 was obtained more directly by a [2+2] cycloaddition, together with the two isomers 23 and 24 , from methlallene 20 and (tosyliminno)acetate 21 (Scheme 3). The main product of this reaction was, however, 2-(tosylamino)-4-hexinoate 22 , the product of an ene reaction.     

Synthesis of methyl (E)-2-[(3S,4S)-4-hydroxy-3-(pent-3-yloxy)-pyrrolidin-2-ylidene]propanoate and its unusual recyclization

Methyl (2E,4S,5S)-5-hydroxy-6-mesyloxy-2-methyl-4-(pent-3-yloxy)hex-2-enoate was synthesized from l-tartaric acid. Attempted substitution of the mesyloxy group by the reaction with NaN₃ directly led to methyl (E)-2-[(3S,4S)-4-hydroxy-3-(pent-3-yloxy)pyrrolidin-2-ylidene]propanoate. The latter on treatment with CF₃COOH and then NaOH gave methyl (2E)-2-methyl-4-[(S)-oxiran-2-yl]-4-(pent-3-yloxy)but-2-enoate.     

Synthesis of (E)-5-oxo-2-(3-α and 3β-hydroxy-1-octenyl)-1-(4-N-pyrrolidine-2-butynyl)pyrrolidine

The synthesis of an oxotremorine analog, (E-5-oxo-2-(3α and 3β-hydroxy-1-octenyl)-1-(4-N-pyrrolidino-2-butynyl)pyrrolidine, is reported.     

Synthesis of Novel New 2-(2-(4-((3,4-Dihydro-4-oxo-3-aryl quinazolin-2-yl)methyl)piperazin-1-yl)acetoyloxy)-2-phenyl Acetic Acid Esters

Stereoselective diazotization of (S)-2-amino-2-phenyl acetic acid (L-phenyl glycine) (4) with NaNO₂ in 6% H₂SO₄ in a mixture of acetone and water gave optically pure (S)-2-hydroxy-2-phenyl acetic acid (L-mandelic acid) (5). Esterification, gave (S)-2-hydroxy-2-phenyl acetic acid esters (6). The latter was treated with chloroacetyl chloride in the presence of triethylamine (TEA) in dichloromethane (DCM) to yield (S)-2-chloroacetyloxy phenyl acetic acid ester (2). In another sequence, the reaction of 2-(chloromethyl)-3-arylquinazolin-4(3H)-one (9) treated with N-Boc piperazine, followed by deprotection of the Boc group, to obtain 3-aryl-2-((piperazin-1-yl)methyl) quinazolin-4(3H)-one (3). Reaction of 2 with 3 in the presence of K₂CO₃ and KI gave the title compound, 2-(2-(4-((3,4-dihydro-4-oxo-3-arylquinazolin-2-yl)methyl)piperazin-1-yl) acetoyloxy)-2-phenyl acetic acid esters (1). The structures of all the new compounds obtained in the present work are supported by spectral and analytical data.     

L-Proline-Catalyzed Knoevenagel Condensation: A Facile,Green Synthesis of (E)-Ethyl 2-Cyano-3-(1H-indol-3-yl)acrylates and (E)-3-(1H-Indol-3-yl)acrylonitriles

L-Proline has been utilized as a novel and ecofriendly catalyst in ethanol medium for the Knoevenagel condensation of indole-3-carboxyaldehydes and their N-methyl derivatives 1(a–e) and 4(a–e) with the active methylene compound, ethyl cyanoacetate (2) to afford substituted (E)-ethyl 2-cyano-3-(1H-indol-3-yl)acrylates 3(a–e) and 5(a–e) respectively. These products were reacted with dimethyl sulfate in the presence of PEG-600 as an efficient and green solvent to afford the corresponding N-mthylated derivatives 5(a–e). These Knoevenagel products react with 5% NaOH, yielding (E)-3-(1H-indol-3-yl)acrylonitriles 6(a–e) and 7(a–e).     

Antimicrobial activity of 3-(substituted methyl)-2-phenyl-4H-l-benzothiopyran-4-ones

A series of 3-(substituted Methyl)-2-phenyl-4H-l-benzothiopyran-4-ones (thioflavones) and thioflavone 1,1-dioxides was prepared to test for antimicrobial activity and for antitumor activity. It was shown that an introduction of a substituted methyl group in the 3-position of thioflavone resulted in significant antimicrobial activity against Trichophytons. 3-(Acetoxymethyl)thioflavone shows the most antimicrobial potency in vitro against Trichophyton mentagrophytes. Most of the thioflavone 1,1-dioxides showed antimicrobial activity against fungi. Five of the 40 related compounds demonstrated weak antitumor activity against P-388 lymphocytic leukemia.     

Umsetzung von 3-(Dimethylamino)-2H-azirinen mit 1,3-Oxazolidin-2-thion zu 3-(2-Hydroxyethyl)-2-thiohydantoinen

Reaction of 3-(Dimethylamino)-2H-azirines with 1,3-Oxazolidine-2-thione to 3-(2-Hydroxyethyl)-2- thiohydantoins The reaction of 3-(dimethylamino)-2H-azirines 1 and 1,3-oxazolidine-2-thione ( 6 ), in MeCN at room temperature, yields, after hydrolytic workup, 3-(2-hydroxyethyl)-2-thiohydantoins 7 (Scheme 2). In the case of the spirocyclic 1c , crystallization of the crude reaction mixture leads to spiro [cyclopentane-1, 7′(7′aH)-imidazo [4, 3-b] oxazole] -5′-thione 8c . The mechanism is discussed.