Synthesis of tetracyclic dibenzo[b,f][1,4]oxazepine-fused ß-lactams via visible-light-induced Staudinger annulation.

An efficient visible-light-induced Staudinger [2 + 2] annulation reaction between α-diazo ketones and dibenzo[b,f][1,4]oxazepine/thiazepine-imines under catalyst-free conditions has been developed. This protocol provides a facile method to synthesize tetracyclic dibenzo[b,f][1,4]oxazepine/thiazepine-fused ß-lactams bearing a quaternary carbon center with a broad substrate scope and high efficiency (37 examples, up to >99% yield).

Metal-free [3 + 2 + 1]/[2 + 2 + 1] biscyclization: stereospecific construction with concomitant functionalization of indolizin-5(1H)-one.

A metal-free [3 + 2 + 1]/[2 + 2 + 1] biscyclization strategy has been developed for the stereospecific construction with concomitant derivation of biologically significant indolizin-5(1H)-ones from simple and commercial starting materials. The transformations are notable because they can yield five new σ bonds and six stereocenters including a quaternary carbon center in a single operation.

Synthesis of ß-Ketonitriles via N-Heterocyclic-Carbene-Catalyzed Radical Coupling of Aldehydes and Azobis(isobutyronitrile).

Herein, an NHC (N-heterocyclic carbene)-catalyzed radical coupling reaction between aldehydes and azobis(isobutyronitrile) (AIBN) has been developed. This method provides an efficient and convenient approach for the synthesis of ß-ketonitriles containing a quaternary carbon center (31 examples, up to >99% yield) utilizing commercially available substrates. This protocol features broad substrate scope, good functional group tolerance, and high efficiency under metal-free and mild reaction conditions.

Stereoselective synthesis of C3-tetrasubstituted oxindoles via copper catalyzed asymmetric propargylation.

Herein, a copper catalyzed asymmetric propargylation of 2-oxindole-3-carboxylate esters with terminal propargylic esters is described. This strategy successfully provides a direct approach to constructing a broad range of chiral C3-tetrasubstituted oxindoles with contiguous tertiary and quaternary carbon stereocenters in high yields and excellent enantioselectivities (16 examples, up to 99% yield and 98% ee). Moreover, the diastereoisomers of the two newly formed stereocenters can be separated by silica gel chromatography, thereby providing a valuable stereoselective access to all four possible stereoisomers of C3-tetrasubstituted oxindoles.

Diaqua-bis-[5-(1-oxidopyridin-1-ium-2-yl)-1,2,3,4-tetrazolido]manganese(II) di-hydrate.

In the title compound, [Mn(C(6)H(4)N(5)O)(2)(H(2)O)(2)]·2H(2)O, the Mn(II) ion is situated on an inversion centre and is coordinated by the O and N atoms of two bis-chelating 5-(2-pyridyl-1-oxide)tetra-zolate ligands and two O atoms of two water mol-ecules in a distorted octa-hedral geometry. All the water H atoms are involved in O-H⋯N and O-H⋯O hydrogen bonds with uncoordinated water O atoms and tetra-zole N atoms, which link the mol-ecules into a three-dimensional network.

One-pot combinatorial synthesis of 4-aryl-1H-thiopyrano[3,4-b]pyridine-5-one derivatives.

A simple and efficient method for the combinatorial synthesis of highly substituted thiopyrano[3,4-b]pyridin-5(4H)-one, thiopyrano[3,4-b]quinoline-4,6(3H,5H)-dione, dithiopyrano[3,4-b:4',3'-e]pyridine-4,6(1H,3H)-dione, and pyrazolo[3,4-b]thiopyrano[4,3-e]pyridin-5(1H)-one derivatives has been developed. The synthesis was achieved via one-pot multicomponent reaction of aromatic aldehyde, 2H-thiopyran-3,5(4H,6H)-dione and enamine (such as the derivatives of amine and 1,3-dicarbonyl compounds and 3-methyl-1-phenyl-1H-pyrazol-5-amine) in glacial acetic acid. This procedure features short reaction time, generally good to excellent yields, easily available starting materials, and operational simplicity. This chemistry provides an efficient and promising synthetic strategy to diversity-oriented construction of the thiopyrano[3,4-b]pyridine skeleton.

Ethyl 7-(2-chloro-phen-yl)-5-trifluoro-meth-yl-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine-6-carboxyl-ate.

In the title compound, C(15)H(12)ClF(3)N(4)O(2), the dihydro-pyrimidine ring exhibits an envelope conformation. The dihedral angle between the mean planes of the dihydro-pyrimidine and phenyl rings is 83.94 (6)°. The OCH(2)CH(3) group is disordered over two sites with occupancies of 0.155 (3) and 0.845 (3). The crystal packing is stabilized by inter-molecular N-H⋯N hydrogen bonds.

5-Amino-7-(4-bromo-phen-yl)-3,7-di-hydro-2H-thieno[3,2-b]pyran-6-carbo-nitrile 1,1-dioxide.

In the title compound, C(14)H(11)BrN(2)O(3)S, the 2,3-dihydro-thio-phene ring is almost planar [maximum deviation = 0.006 (1) Å]. The pyran ring is in an envelope conformation [puckering parameters Q = 0.115 (2) Å, θ = 77.5 (10), ϕ = 172.9 (10)°]. The pyran and phenyl rings are approximately perpendicular, making a dihedral angle of -76.4 (2)°. The crystal packing is stabilized by inter-molecular N-H⋯O hydrogen bonds, with the sulfone O atoms acting as acceptors.

Ethyl 7-(4-bromo-phen-yl)-5-trifluoro-methyl-4,7-dihydro-tetra-zolo[1,5-a]pyrimidine-6-carboxyl-ate.

In the title compound, C(14)H(11)BrF(3)N(5)O(2), the pyrimidine ring adopts a flattened envelope conformation with sp(3)-hybridized carbon as the flap [deviation = 0.177 (3) Å]. The dihedral angle between tetra-zole and bromo-phenyl rings is 84.3 (1)°. In the crystal, mol-ecules are linked into centrosymmetric dimers by pairs of N-H⋯N hydrogen bonds.

5'-Amino-2-oxo-2',3'-dihydro-spiro-[indoline-3,7'-thieno[3,2-b]pyran]-6'-carbonitrile 1',1'-dioxide.

In the title compound, C(15)H(11)N(3)O(4)S, the dihedral angle between the mean planes of the dihydro-indol-2-one (r.m.s. deviation = 0.015 Å) and dihydro-thieno[3,2-b]pyran (r.m.s. deviation = 0.011 Å) ring systems is 89.53 (3)°. The crytal packing is consolidated by inter-molecular N-H⋯O and N-H⋯N hydrogen bonds, which link the mol-ecules into a two-dimensional network into sheets lying parallel to (100).

5-Amino-7-(3-chloro-phen-yl)-3,7-di-hydro-2H-thieno[3,2-b]pyran-6-carbo-nitrile 1,1-dioxide.

The title compound, C(14)H(11)ClN(2)O(3)S, with fused thiophene and pyran rings, was synthesized via the condensation of dihydro-thio-phen-3(2H)-one 1,1-dioxide and 2-(3-chloro-benz-yl-idene)malononitrile catalysed by triethyl-amine in ethanol. The thio-phene ring adopts an envelope conformation and the pyran ring is planar (r.m.s. deviation = 0.0067 Å). The dihedral angle between the pyran and phenyl rings is 80.8 (1)°. The crystal packing is stabilized by inter-molecular N-H⋯N and N-H⋯O hydrogen bonds in which the cyano N and sulphone O atoms, respectively, acting as acceptors.

Ethyl 2-amino-4-(3-chloro-phen-yl)-5,10-dioxo-5,10-dihydro-4H-benzo[g]chromene-3-carboxyl-ate.

The title mol-ecule, C(22)H(16)ClNO(5), was obtained by the reaction of (E)-ethyl 3-(3-chloro-phen-yl)-2-cyano-acrylate and 2-hydroxy-naphthalene-1,4-dione catalysed by triethylamine in ethanol. In the crystal structure, the chlorobenzene ring makes a dihedral angle of 88.63 (4)° with the fused ring system. The six-membered ring formed by an intra-molecular N-H⋯O hydrogen bond is almost planar. The crystal packing is stabilized by N-H⋯O hydrogen bonds.

4-Phenyl-1,2,3,4-tetra-hydro-pyrimido[1,2-a]benzimidazol-2-one.

In the title compound, C(16)H(13)N(3)O, the tetrahydropyrimidin-one ring adopts a sofa conformation. In the crystal structure, mol-ecules are linked by N-H⋯N hydrogen bonds and C-H⋯π inter-actions.

2-Amino-1H-benzoimidazol-3-ium 4,4,4-trifluoro-1,3-dioxo-1-phenyl-butan-2-ide.

In the title compound, C(7)H(8)N(3) (+)·C(10)H(6)F(3)O(2) (-), 1H-benzoimidazol-2-amine system adopts a planar conformation with an r.m.s. deviation of 0.0174 Å. The cation and anion in the asymmetric unit are linked by N-H⋯O hydrogen bonds. There are also additional inter-molecular N-H⋯O hydrogen bonds and π-π stacking inter-actions between the phenyl rings of neighbouring anions with centroid-centroid distances of 4.0976 (13) Å.

Ethyl 4-(4-nitro-phen-yl)-2-(trifluoro-meth-yl)pyrimido[1,2-a]benzimidazole-3-carboxyl-ate.

In the title compound, C(20)H(13)F(3)N(4)O(4), the fused pyrimido[1,2-a]benzimidazole ring system is nearly planar, with a maximum deviation from the mean plane of 0.126 (1) Å. Mol-ecules are linked by C-H⋯N and C-H⋯O hydrogen bonds and by π-π inter-actions with inter-planar distances of 3.2661 (6) and 3.2775 (6) Å.

5-Benzoyl-4-hydr-oxy-6-(4-nitro-phen-yl)-4-trifluoro-meth-yl-3,4,5,6-tetrahydro-pyrimidin-2(1H)-one monohydrate.

The asymmetric unit of the title compound, C(18)H(14)F(3)N(3)O(5)·H(2)O, contains two independent formula units. The two heterocyclic mol-ecules differ in the orientations of the benzoyl-phenyl group with respect to the tetra-hydro-pyrimidine ring [C-C-C-C torsion angles of 64.5 (3) and 67.1 (3)°]. In both mol-ecules the pyrimidine ring adopts a half-chair conformation. The mol-ecules are linked into a two-dimensional network parallel to (001) by N-H⋯O and O-H⋯O hydrogen bonds.

3-Ethyl 5-methyl 2-hydr-oxy-6-methyl-4-(4-nitro-phen-yl)-2-trifluoro-methyl-1,2,3,4-tetra-hydro-pyridine-3,5-dicarboxyl-ate.

In the title compound, C(18)H(19)F(3)N(2)O(7), the tetrahydropyridine ring adopts a half-chair conformation. The nitro group is disordered over two sites with occupancies of 0.780 (15) and 0.220 (15). An intra-molecular N-H⋯F hydrogen bond is observed in the mol-ecular structure. The mol-ecules are linked into a two-dimensional network parallel to (100) by O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds.

The synthesis and herbicidal activity of 1-alkyl-3-(alpha-hydroxy-substituted benzylidene)pyrrolidine-2,4-diones.

In the search for better herbicides a series of 1-alkyl-3-(alpha-hydroxy-(un)substituted benzylidene)pyrrolidine-2,4-diones were prepared and their structure-activity relationships studied. All their structures have been confirmed by (1)H-NMR and elemental analysis. The preliminary bioassay results indicated that some of them have high herbicidal activity against annual dicotyledonous and monocotyledonous plants.

Combinatorial synthesis of pyrazoloquinoline and pyrazoloacridine derivatives with high regioselectivity.

Three-component reaction of aldehyde, 1H-indazol-6-amine and 1,3-dicarbonyl compounds in EtOH under catalyst-free conditions, generates the corresponding pyrazolo[3,4-a]acridine, cyclopenta[b]pyrazolo[3,4-f]quinoline, indeno[1,2-b]pyrazolo[3,4-f]quinoline and benzo[h]pyrazolo[3,4-a]acridine derivatives in high yields and regioselectivity, respectively. The dicarbonyl compounds include 5,5-dimethylcyclohexane-1,3-dione, cyclopentane-1,3-dione, 2H-indene- 1,3-dione and 2-hydroxynaphthalene-1,4-dione.

A one-pot multicomponent strategy for stereospecific construction of tricyclic pyrrolo[1,2-a]quinolines.

A novel multicomponent strategy for the efficient synthesis of tricyclic pyrrolo[1,2-a]quinolines has been described. The bond-forming efficiency, accessibility and generality of this synthesis make it highly attractive to assemble tri-heterocyclic scaffolds.