A Facile and Efficient Synthesis of Arylsulfonamido‐Substituted 1,5‐Benzodiazepines and N‐[2‐(3‐Benzoylthioureido)aryl]‐3‐oxobutanamide Derivatives

A facile and efficient synthesis of 1,5‐benzodiazepines with an arylsulfonamido substituent at C(3) is described. 1,5‐Benzodiazepine, derived from the condensation of benzene‐1,2‐diamine and diketene, reacts with an arylsulfonyl isocyanate via an enamine intermediate to produce the title compounds of potential synthetic and pharmacological interest in good yields (Scheme 1). In addition, reaction of benzene‐1,2‐diamine and diketene in the presence of benzoyl isothiocyanate leads to N‐[2‐(3‐benzoylthioureido)aryl]‐3‐oxobutanamide derivatives (Scheme 2). This reaction proceeds via an imine intermediate and ring opening of diazepine. The structures were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this type of cyclization is proposed (Scheme 3).     

A study of the reaction of 2-thiazolin-4-ones with some electrophiles under microwave irradiation versus conventional condition

Coupling of 5-dimethylaminomethylene-3-methyl-2-(pyridine-2-ylimino)-thiazolidin-4-one (3) with diazotized methyl anthranilate afforded the 3-methyl-5-(2-methoxycarbonylphenylhydrazono)-2-pyridine-2-ylimino)thiazolidin-4-one (5). Reaction of 2-(arylamino)thiazol-4-ones 1a,b with arylidenemalononitriles under microwave irradiation gave 2-substituted amino-5-arylidenethiazolin-4-ones 9a–f. Alternatively, compound 9 could also be obtained by reacting compound 1 with aromatic aldehydes. Treatment of compound 9 with acetic acid yielded the corresponding thiazolin-2,4-diones 10. However, the reaction of 1 with cyanoacetic acid yielded the corresponding 4-cyanoacetyl derivative 12, in good yield. The ¹H, ¹³C NMR spectra of some representative products and X-ray crystal structure determination are discussed.     

Transformations starting from biotechnologically available materials,part 2: First example of a direct conversion of spirooxiranes into enamines

Summary An unpredecent formation of enamines in the reaction of 5-aryl-1-oxa-5-azaspiro[2.4]heptane-4,6-diones with morpholine and piperidine is reported. The transformations proceed via corresponding -aminoalcohols which were detected by¹³C-NMR.

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Transformationen von biotechnisch verfügbarem Material, 2. Mitt.: Erstes Beispiel für die direkte Konversion von Spirooxiranen in Enamine

Zusammenfassung Es wird über die Bildung von Enaminen aus der Reaktion von 5-Aryl-1-oxa-5-azaspiro[2.4]heptan-4,6-dionen mit Morpholin oder Piperidin berichtet. Die Transformation verläuft über die entsprechenden -Aminoalkohole, die mittels¹³C-NMR nachgewiesen werden können.

     

Synthesis of Aryl- and Pyridinyl-substituted 2-Amino-6-thioxopyridine-3-carbonitrile Derivatives by Tandem Michael Addition and Cyclization Reactions

Summary. The tandem Michael addition and cyclization of 2-, 3-, and (4-pyridinylcarbonyl) thioacetanilides with arylidenemalononitriles yielded polysubstituted pyridines and bipyridines. Tetrahydro-6-thioxopyridine-3-carbonitrile was dehydrogenated to its dihydro derivative by means of HgO or DBU. The reaction of enamines of 3-, and (4-pyridinylcarbonyl)thioacetanilides with malononitrile furnished 3,4′- and 4,4′-bipyridines.     

New functionalized, differently fluorinated building-blocks via Michael addition to γ-fluoro-α-nitroalkenes

The Michael addition of ketone-derived enamines, metalated methylene active compounds and N-methyl pyrroles to γ-fluoro-α-nitroalkenes provided in moderate to good isolated yields the corresponding β-fluoroalkyl nitro compounds, which represent new interesting, highly functionalized building blocks in organofluorine chemistry.     

Transalkylation of N-methyl tertiary amines with 3, 4-dibromobutenolides

The selective transalkylation of N-methyl tertiary amines with 3,4-dibromobutenolides is described.The N-methyl group of the parent tertiary amines was replaced by alkenyl units of the butenolides;and a series of butenolide-containing tertiary enamines were obtained in moderate to good yields.Interestingly,the product 2b has shown a promising anticancer activity against HeLa cell lines(IC50=0.19 mmol/L).     

Synthesis of chromeno[3,4-c][1,2]oxazine-N-oxides via formal [4+2] cycloaddition of 3-nitro-2-trihalomethyl-2H-chromenes with cyclohexanone and pinacolone enamines

3-Nitro-2-trichloro(trifluoro)methyl-2H-chromenes undergo a formal [4+2] cycloaddition reaction to cyclohexanone and pinacolone enamines, producing chromeno[3,4-c][1,2]benzoxazin-6-oxides with high diastereoselectivity and in good yields. In addition, some novel 2,3,4-trisubstituted chromanes were obtained. The stereochemistry of the products was established based on a 2D NOESY experiment and an X-ray diffraction study.     

Facile Approach for the Synthesis of 2,3,4,9-Tetrahydro-1H-xanthen-1-ones and 8,9,10,12-Tetrahydro-11H-benzo[a]xanthen-11-ones via Trapping of o-Quinone Methides

An efficient, simple synthesis of 2,3,4,9-tetrahydro-1H-xanthene-1-ones and 8,9,10,12-tetrahydro-11H-benzo[a]xanthen-11-ones is reported by one-pot condensation of 3-dimethylamino-2-cyclohexen-1-ones with hydroxybenzyl alcohols, phenol, and 2-naphthol Mannich bases or their quaternized derivatives. The mechanism of the reaction is believed to involve the formation of the o-quinone methide intermediate.     

Access to chiral tertiary amines via the iridium-catalyzed asymmetric hydrogenation of enamines

The asymmetric hydrogenation of N,N-dialkyl and N-alkyl-N-aryl enamines to chiral tertiary amines was studied. All the N,P-ligated iridium complexes investigated were active catalysts for the reaction, but only those with bicycle-supported oxazoline-phosphine ligands gave reasonable stereoinduction. The best catalyst produced a range of chiral tertiary amines in up to 87% ee.     

Unusual ring-chain tautomerism in bicyclo[4.2.0]octane derivatives

A new type of ring-chain tautomerism, which consists of the reversible conversion of bicyclo[4.2.0]octane derivatives into trisubstituted enamines was found and studied by ¹H NMR spectroscopy. The starting materials were prepared by the stereoselective reaction of (E)-3,3,3-trichloro-1-nitropropene with cyclohexanone enamines.