Synthesis of 1-acyl-5-aryl biurets

Fourteen new 1-acyl-5-aryl biurets were synthesized by the reaction of aryl ureas with acylisocynantes. The latter was obtained from acyl chloride and lead cyanate in dichloromethane, using pyridine as catalyst. The structures of compounds 3a-n were confirmed by IR,1H NMR and MS spectra.     

Tin(IV) and organotin(IV) derivatives of novel β-diketones: Part IV. Triorganotin(IV) complexes of fluorinated 4-acyl-5-pyrazolones. Crystal structure of (1-(4-trifluoromethylphenyl)-3-methyl-4-acetylpyrazolon-5-ato)triphenyltin(IV)

The synthesis of three 1-(4-trifluoromethylphenyl)-3-methyl-4-R¹(C=O)-5-pyrazolone proligands LH (L¹H; R¹=C₆H₅: L²H; R¹=CH₃: L³H; R¹=CF₃) and their interaction with R₃Sn(IV) acceptors (R=Me, Buⁿ, Ph) are reported. When R=Me or Buⁿ, aquo (4-acylpyrazolonate)SnR₃(H₂O) derivatives are obtained and the anionic donors 4-acylpyrazolonate (L⁻) act in the O–monodentate form. These triorganotin complexes are not stable in chlorohydrocarbon solvents and decompose to R₄Sn and bis(4-acyl-5-pyrazolonate)₂SnR₂. When R=Ph, stable (4-acyl-5-pyrazolonate)SnPh₃ derivatives, both in solution and in the solid state, are obtained. The crystal structure of (1-(4-trifluoromethylphenyl)-3-methyl-4-acetylpyrazolon-5-ato)triphenyltin(IV) shows a five-coordinate tin atom in a strongly distorted cis-bipyramidal trigonal environment (axial angle=161.2(2)°) with the acylpyrazolonate donor acting as an asymmetric O₂–bidentate species (Sn–O(1)=2.081(6) Å: Sn–O(2)=2.424(5) Å). Electronic effects are responsible for the different behavior shown by these trialkyl and triphenyl derivatives.     

A one-pot and three-component synthetic approach for the preparation of asymmetric and multi-substituted 1,4-dihydropyrazines

An efficient, one-pot and three-component synthesis of a new series of 2-acyl-3,4,6-triaryl-1,4-dihydropyrazines is described. This two-step strategy involves treatment of phenacyl bromides and anilines to give the nucleophilic substitution intermediate followed by Michael-addition-cyclization to α-azidochalcones to afford the title compounds in high yields.     

Mechanism of catalytic asymmetric hydrogenation of 2-formyl-1-methylene-1,2,3,4-tetrahydroisoquinoline using Ru(CH3COO)2[(S)-binap]

The mechanism of the asymmetric hydrogenation of 2-acyl-1-alkylidene-1,2,3,4-tetrahydroisoquinolines, the first reported reaction with the Noyori-Takaya Ru(CH₃COO)₂(binap) complex, has been investigated by means of deuterium labeling, kinetics, and NMR analysis. A series of experiments has revealed that (1) a monohydride-unsaturated mechanism operates involving the initial formation of RuH followed by reaction with the enamide substrate, (2) the hydride transfer from RuH to the olefinic double bond is endothermic and reversible, and (3) the rate is determined in the hydrogenolysis step. This view is consistent with that of proposed for the BINAP-Ru catalyzed Kagan reaction.     

A new convenient synthesis of N-acyl-2-(dimethoxyphosphoryl)glycinates

Easily accessible N-acyl-2-triphenylphosphonioglycinate tetrafluoroborates react smoothly with trimethylphosphite in the presence of methyltriphenylphosphonium iodide to give N-acyl-2-(dimethoxyphosphoryl)glycinates in good or very good yields. The dimethoxyphosphorylglycinates may be isolated by column chromatography, or used directly for the Wadsworth-Emmons synthesis of α,β-dehydro-α-amino acids in a one-pot procedure without purification.     

Synthesis of N-benzothiazol-2-yl-amides by Pd-catalyzed C(sp~2)–H functionalization

A catalytic synthesis of N-benzothiazol-2-yl-amides from 1-acyl-3-(phenyl)thioureas was achieved in the presence of a palladium catalyst through the C(sp2)–H functionalization/C–S bond formation. This synthetic methodology can produce various N-benzothiazol-2-yl-amides in high yields with good functional group tolerance.     

Isolable atropisomers of 2-aryl indoline derivatives: determination of rotational barrier by density functional theory approach

The rotational process of 2-aryl ring in 1-acyl-2-aryl-3,3-dimethylindolines was determined by density functional theory (DFT) at B3LYP/6-31G(d) level. The calculated barrier height for the rotational process of [2-(2-hydroxynaphthalen-1-yl)-3,3-dimethylindolin-1-yl]phenylmethanone (1) was ca. 30 kcal/mol, comparable to the previously reported experimental values of 26–28 kcal/mol for the corresponding derivatives. The Hartree–Fock (HF) calculation overestimated the barrier. The DFT-calculated rotational barrier height provided valuable information for knowing whether the conformers were isolable or not. The transition structure analyses showed that the presence of 2,6-substituents on the aryl ring is essential for the isolation of the conformers at room temperature. Based on the DFT-calculated geometries, the rotational process and the intramolecular weak interactions in the restricted rotation were analyzed.     

Synthesis and reactions of 5-tributylstannyl-4-fluoro-1H-pyrazole

The palladium-catalyzed cross-coupling reactions of 5-tributylstannyl-4-fluoro-1H-pyrazole with aryl iodides provided high yields of the corresponding 5-aryl-4-fluoro-1H-pyrazoles. Furthermore, these cross-coupling reactions proceeded smoothly under an atmosphere of carbon monoxide (CO) to afford the corresponding 5-acyl-4-fluoro-1H-pyrazoles as CO-insertion products.     

Synthese von 4-(sec-Amino)-1,3-oxazin-2-onen und 4-(sec-Amino)-1,3-oxazin-2-thionen über elektrocyclische Ringschlußreaktion

The title compounds3 and4 are easily obtainable by reaction of 2-acyl-1-chloro-enamines2 with trimethylsilyl-isocyanate, trimethylsilyl-isothiocyanate or sodium rhodanide, respectively. Primarily formed acylvinyl-iso(thio)cyanatesD, G spontaneously undergo electrocyclization. A one-pot operation leads directly to 4-amino-1,3-oxazine-2-thiones4 starting from acylketenedichlorides1 via2 by successive addition of secondary amine and sodium rhodanide. Reaction of2 with ammonium dithiocarbamate results in an unexpected formation of4. Treatment of4 with mercuric acetate offers a further access to 4-amino-1,3-oxazine-2-ones3. Finally,3 are obtained from2 on the sequence of ammonolysis to acylketeneaminals5 and phosgenation. Characteristic scopes and limitations as well as mechanistic features of these transformations are discussed.

Herrn Prof. Dr.Klaus Hafner zum 60. Geburtstag gewidmet.     

Oxalylation of the 3-oxo-<Emphasis Type="Italic">N</Emphasis>-phenyl-3-R-propanethioamides

Oxalylation of 3-oxo-N-phenyl-3-R-propanethioamides in aprotic solvents in the temperature range from −40°C to +20°C results in 4-acyl-5-phenylamino-2,3-dihydrothiophene-2,3-diones and 2-(2-oxo-2-R-ethylidene)-3-phenyl-1,3-thiazolidine-4,5-diones, while in the presence of potassium carbonate, potassium 4-acyl-2,3-dioxo-1-phenyl-2,3-dihydro-1H-pyrrole-5-thiolates are formed.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 757-760, March, 2005.     

Synthesis of a novel pyrrolo-benzoxaborole scaffold and its derivatization via Friedel–Crafts reaction catalyzed by anhydrous stannic chloride

A novel pyrrolo-benzoxaborole, 6-(pyrrol-1-yl)-1,3-dihydro-1-hydroxy-2,1-benzoxaborole, was synthesized with 27% overall yield over six steps from 2-bromo-1-methyl-4-nitrobenzene as starting material. Its derivatization was achieved via Friedel–Crafts reaction catalyzed by anhydrous stannic chloride with various acyl chlorides giving 3-acyl-1-phenylpyrroles as the main products.     

A novel convenient synthesis of 5-acyl-1,2-dihydropyrimidin-2-ones via 4-trichloromethyl-1,2,3,4-tetrahydropyrimidin-2-ones

A novel four-step methodology for the synthesis of 5-acyl-1,2-dihydropyrimidin-2-ones has been developed. The reaction of readily available N-[(1-acetoxy-2,2,2-trichloro)ethyl]ureas with Na-enolates of 1,3-diketones or β-oxoesters followed by heterocyclization-dehydration of the oxoalkylureas formed gave 5-acyl-4-trichloromethyl-1,2,3,4-tetrahydropyrimidin-2-ones. The latter, in the presence of NaH, eliminate CHCl₃ to give the target compounds.     

4-甲基吡咯并[2,1,5-cd]中氮茚的合成

以2-乙基吡啶生成的叶立德为原料,采用1,3-偶极环加成反应,得到了一系列3-乙酰基(或苯甲酰基)-5-乙基中氮茚衍生物,后者与KOH在加热条件下发生分子内缩合,得到了一系列4-甲基吡咯并[2,1,5-cd]中氮茚.     

Ethynylation of pyrroles with 1-acyl-2-bromoacetylenes on alumina: a formal ‘inverse Sonogashira coupling’

Pyrroles are cross-coupled with 1-acyl-2-bromoacetylenes on the surface of Al₂O₃ at room temperature under solvent-free conditions to afford 2-(acylethynyl)pyrroles with 100% regioselectivity and in good yields, thus representing the first example of a palladium-, copper-, base-, and solvent-free (‘green’) ethynylation of pyrroles, which can be considered a formal ‘inverse Sonogashira coupling’. Given the interest in functionalized pyrroles and acetylenes, this new facile and environmentally friendly cross-coupling should be of significant interest for the role of acylhaloacetylenes in pyrrole and acetylene chemistry.     

Synthesis of 5H-thiazolo[3,2-a]pyrimidine derivatives from 6-methyl-2-thiouracil and 1-acyl-2-bromoacetylenes. X-ray structural study of 3-benzoyl-7-methyl-5H-thiazolo[3,2-a]pyrimidin-5-one

3-Acyl-7-methyl-5H-thiazolo[3,2-a]pyrimidin-5-ones were synthesized by the reaction of 1-acyl-2-bromoacetylenes with 6-methyl-2-thiouracil, carried out with heating in DMF, dioxane, or acetonitrile in the presence of triethylamine. The structure of 3-benzoyl-7-methyl-5H-thiazolo[3,2-a]pyrimidin-5-one was established by X-ray structural analysis.Deceased in 1995.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2306–2308, September, 1996.     

Synthesis and decarboxylation of N-acyl-α-triphenylphosphonio-α-amino acids: a new synthesis of α-(N-acylamino)alkyltriphenylphosphonium salts

4-Phosphoranylidene-5(4H)-oxazolones 1 undergo hydrolysis in THF in the presence of HBF₄ at room temperature to give N-acyl-α-triphenylphosphonioglycines 3 (R² = H) in very good yields. 4-Alkyl-4-triphenylphosphonio-5(4H)-oxazolones 2 react with water in CH₂Cl₂/THF solution without any acidic catalyst at 0-5 °C in a few days yielding N-acyl-α-triphenylphosphonio-α-amino acids 3 (R² = Me) or α-(N-acylamino)alkyltriphenylphosphonium salt 4 (R² = CH₂OMe). α-Triphenylphosphonio-α-amino acids 3, on heating up to 105-115 °C under reduced pressure (5 mmHg) or on treatment with diisopropylethylamine in CH₂Cl₂ at 20 °C undergo decarboxylation to give the corresponding α-(N-acylamino)alkyltriphenylphosphonium salts 4, usually in very good yields.     

Acyl-tetrahydroindolyl-capped 1,3-diynes in oxidative [4 + 2]-cycloaddition with benzylamine: a one-pot access to 2-acyl-6-phenyl-5-tetrahydroindolylpyridines

1-Acyl-4-tetrahydroindolyldiynes (available from cross-coupling of 4,5,6,7-tetrahydroindole with 1-acyl-4-bromo-1,3-diynes) undergo oxidative [4+2]-cycloaddition with benzylamine in KOH/DMSO or K3PO4/DMSO systems (80°C, 4 h) to afford 2-acyl-6-phenyl-5-tetrahydroindolyl-pyridines in ～40% yields. Non-catalyzed reaction of the same reactants in boiling MeOH (4 h) or in DABCO/MeCN system (reflux, 1 h) gives 3-benzylaminoalk-2-en-4-ynones in ～40% yields.     

Arylmethylene derivatives of 5-R-3H-furan-2-ones and N-aryl-5-R-3H-pyrrol-2-ones in reaction with acetylacetone

Reaction with acetylacetone in the series of 3-arylmethylene-substituted furan-2-ones and pyrrol-2-ones was studied. 8-R-4-Acyl-5-aryl-3-oxo-9-oxabicyclo[4.3.0]nona-1,7-dienes and N-tolyl-8-R-4-acyl-5-aryl-3-oxo-9-azabicyclo[4.3.0]nona-1,7-dienes were synthesized. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, 1457–1462, October, 2007.     

1-苯基-3-甲基-4-甲酰基-5-吡唑啉酮Cu(Ⅱ)配合物的合成及晶体结构

A novel Cu(Ⅱ) complex of 1-phenyl-3-methyl-4-acyl-5-pyrazolone was synthesized and crystallogra-phically characterized. The single-crystal structure of the complex reveals that the crystal belongs triclinic, space group P1 with cell parameters a=0.938 7(4) nm, b=1.124 4(5) nm, c=1.222 3(5) nm, α=99.538(7)°, β=104.049(8)°, γ=113.806(6)°, and Z=2, V=1.093 3(8) nm³. Cu(Ⅱ) ion is coordinated by two 1-phenyl-3-methyl-4-acyl-5-pyrazolone ligands, and one methanol molecule giving a coordination number of five, the coordination polyhedron around Cu(Ⅱ) ion can be described as a square pyramid. Two complex units link to each other through the hydrogen-bonding interactions to form a dimer. Meanwhile, a staircase-like layer structure was built up by offset face-to-face π…π stacking interactions and weak interactions between the dimers. CCDC: 625422.     

Condensed isoquinolines 30. Acylation and alkylation of 5,13-dihydro-11H-isoquino-[3,2-<Emphasis Type="Italic">b</Emphasis>]quinazolin-11-one

It was shown that 6-acyl-5,13-dihydro-11H-isoquino[3,2-b]quinazolin-11-ones are formed when 5,13-dihydro-11H-isoquino[3,2-b]quinazolin-11-one is heated with the chlorides and anhydrides of carboxylic acids in the presence of bases (pyridine, NaOAc) while 5-acyl-5,13-dihydro-11H-isoquino[3,2-b]quinazolin-11-ones are formed in the presence of NaH. In the presence of NaH 6-acyl-5,13-dihydro-11H-isoquino[3,2-b]quinazolin-11-ones form the products from acylation and alkylation at position 5. The action of heat on 5,13-dihydro-11H-isoquino[3,2-b]quinazolin-11-one in oxalyl chloride leads to 7H,8H-2a,7a-diazacyclopenta[fg]naphthacene-1,2,8-trione. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 741–750, May, 2008.