Visible-Light-Promoted Radical Cascade Cyclization of 2-Vinyl Benzimidazoles: Access to Benzo[4,5]imidazo[1,2-b]isoquinolin- 11(6H)-ones.

A visible-light-enabled photoredox radical cascade cyclization of 2-vinyl benzimidazole derivatives is developed. This chemistry is applicable to a wide range of N-aroyl 2-vinyl benzimidazoles as acceptors, and halo compounds, including alkyl halides, acyl chlorides and sulfonyl chlorides, as radical precursors. The Langlois reagent also serves as an effective partner in this photocatalytic oxidative cascade process. This protocol provides a robust alternative for rendering highly functionalized benzo[4,5]imidazo[1,2-b]isoquinolin-11(6H)-ones.

Photocatalytic synthesis of azaheterocycle-fused piperidines and pyrrolidines via tandem difunctionalization of unactivated alkenes.

A variety of azaheterocycle-fused piperidines and pyrrolidines bearing CF3 and CHF2 functionalities were obtained using CF3SO2Na and CHF2SO2Na by visible light photocatalysis. This protocol involves a radical cascade cyclization via tandem tri- and difluoromethylation-arylation of pendent unactivated alkenes. Benzimidazole, imidazole, theophylline, purine, and indole serve as applicable anchors, thereby enriching the structural diversity of piperidine and pyrrolidine derivatives. This method features mild, additive-free and transition metal-free conditions.

Aerobic oxidative acylation of nitroarenes with arylacetic esters under mild conditions: facile access to diarylketones.

A facile and regioselective base-mediated aerobic oxidative acylation of nitroarenes to access diarylketones under mild conditions has been developed. It features the use of bench-stable and readily available arylacetates as acyl surrogates, and the absence of transition-metals and synthetic oxidants. This protocol involves a cascade CDC/oxidative decarboxylation process.

Diazotization-Enabled Deaminative Late-Stage Functionalization of Primary Sulfonamides.

We, for the first time, disclosed a simple and efficient strategy for the late-stage functionalization of primary sulfonamides by diazotization, leading to sulfonyl chlorides, sulfonates, and complex sulfonamides. This protocol obviates the requirement for the prefunctionalization of sulfonamides. Its applicability is exemplified by the late-stage functionalization of sulfonamide-type drugs.

Visible-Light Photoredox Catalyzed Double C-H Functionalization: Radical Cascade Cyclization of Ethers with Benzimidazole-Based Cyanamides.

A visible-light photoredox catalyzed radical cascade cyclization of simple ethers with cyanamides is developed at room temperature. This strategy involves sequential inert Csp3-H/Csp2-H functionalizations through intermolecular addition reaction of oxyalkyl radicals to N-cyano groups followed by radical cyclization of iminyl radicals in situ generated with C-2 aryl rings. This method allows for efficient synthesis of tetracyclic benzo[4,5]imidazo[1,2-c]quinazolines. Importantly, this is the first example of an intermolecular-intramolecular radical cascade cyclization reaction of cyanamides.

2-[(N-Benzyl-4-methyl-benzene-sul-fon-amido)meth-yl]pyridinium nitrate.

In the title compound, C(20)H(21)N(2)O(2)S(+)·NO(3) (-), the dihedral angle between the pyridinium and phenyl rings is 81.77 (19)°, that between the pyridinium and tolyl rings is 1.36 (18)°, and that between the phenyl and tolyl rings is 82.69 (19)°. In the crystal, the components are linked by strong charge-assisted bifurcated N(+)-H⋯(O,O) hydrogen bonds and the packing is consolidated by numerous weak C-H⋯O bonds and π-π stacking inter-actions [for the latter, centroid-centroid separation = 3.868 (2) Å].

2-(Benzene-sulfonamido)pyridinium nitrate.

In the title compound, C(11)H(11)N(2)O(2)S(+)·NO(3) (-), the dihedral angle between the benzene and pyridinium rings is 87.59 (8)°. An intra-molecular C-H⋯O inter-action occurs in the cation. In the crystal structure, ion pairs occur, being linked by two strong N-H⋯O inter-actions, forming R(2) (2)(8) loops. The packing is further stabilized by weak C-H⋯O inter-actions.

2,2'-Ethyl-enediisoquinolinium dibromide dihydrate.

In the title compound, C(20)H(18)N(2) (2+)·2Br(-)·2H(2)O, the complete dication is generated by a crystallographic centre of symmetry. In the crystal, O-H⋯Br, C-H⋯Br and C-H⋯O hydrogen bonds and π-π stacking [shortest centroid-centroid separation = 3.657 (2) Å] help to establish the packing.

1,3-Dimethyl-1H-indole-2-carbonitrile.

The title compound, C(11)H(10)N(2), crystallizes with two mol-ecules in the asymmetric unit, both of which are essentially planar (r.m.s. deviations = 0.014 and 0.016 Å). In the crystal, aromatic π-π stacking inter-actions occur [shortest centroid-centroid separation = 3.5569 (11) Å].

N-(4-tert-Butyl-benz-yl)phthalimide.

The mol-ecule of the title compound [systematic name: 2-(4-tert-butyl-benz-yl)isoindoline-1,3-dione], C(19)H(19)NO(2), is V-shaped with a dihedral angle of 74.15 (7)° between the mean planes of the phthalimide unit and the benzene ring. The methyl groups of the tert-butyl substituent are disordered over two sets of positions, with an occupancy ratio of 0.700 (4):0.300 (4). In the crystal, inter-molecular C-H⋯O hydrogen bonds link adjacent mol-ecules into centrosymmetric dimers. An additional weak C-H⋯O contact, together with weak C-H⋯π and π-π inter-actions [centroid-centroid distance = 3.961 (2) Å] generate a three-dimensional network.

2,2-Dimethyl-2,3-dihydro-1-benzofuran-7-yl N-ethyl-carbamate.

The title compound, C(13)H(17)NO(3), crystallizes with two independent mol-ecules in the asymmetric unit. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules, forming chains propagaiting in [100]. A weak C-H⋯O inter-action also occurs.

2-(2,4-Dichloro-phen-yl)acetic acid.

In the title compound, C(8)H(6)Cl(2)O(2), the dihedral angle between the C-C(=O)-OH carboxyl unit and the benzene ring is 70.70 (4)°. In the crystal, mol-ecules are linked into inversion dimers by pairs of O-H⋯O hydrogen bonds. The dimers are linked into chains extending along [001] by weak C-H⋯Cl inter-actions.

2-Methyl-3-p-tolyl-3H-benzo[e]indole-1-carbonitrile.

In the title compound, C(21)H(16)N(2), the dihedral angle between the benzoindole and tosyl ring systems is 71.99 (7)°. In the crystal, mol-ecules are linked into centrosymmetric dimers by pairs of C-H⋯N hydrogen bonds, generating R(2) (2)(16) loops.

2-mesitylacetic Acid.

In the title compound, C(11)H(14)O(2), the dihedral angle between the CCOO carboxyl unit and the benzene ring is 85.37 (7)°. In the crystal, the mol-ecules are linked into inversion dimers by pairs of O-H⋯O hydrogen bonds.

1-Meth-oxy-2-methyl-1H-benzo[f]indole-3-carbonitrile.

Apart from the methyl group of the meth-oxy fragment, the title compound, C(15)H(12)N(2)O, is almost planar (r.m.s. deviation = 0.045 Å); the C atom deviates from the mean plane by 1.216 (1) Å. In the crystal, π-π stacking [shortest centroid-centroid separation = 3.4652 (10) Å] and C-H⋯π inter-actions occur.

N-tert-Butyl-3-hydr-oxy-5-androstene-17-carboxamide monohydrate.

In the title compound, C(24)H(39)NO(2)·H(2)O, the A and C rings of the pregnolene derivative sterol adopt chair conformations, with the B ring in a flattened chair conformation and the five-membered ring in an envelope conformation twisted about the C/D ring junction. The N-tert-butyl-carboxamide substituent is equatorial. The 3ß-hydr-oxy H atom and one H atom of the water mol-ecule are disordered over two positions with equal occupancies. In the crystal structure, O-H⋯O hydrogen bonds between the 3ß-hydr-oxy groups of neighbouring mol-ecules form dimers in the bc plane and these dimers are stacked along the a axis by additional O-H⋯O hydrogen bonds involving the water mol-ecules. The steric effect of the bulky tert-butyl substituent in the carboxamide chain precludes hydrogen-bond formation by the N-H group.

4-(2-Nitro-benzene-sulfonamido)pyri-dinium trifluoro-acetate.

In the title compound, C(11)H(10)N(3)O(4)S(+)·C(2)F(3)O(2) (-), the dihedral angle between the benzene ring and the pyridinium ring is 88.7 (4)°. In the crystal structure, a network of N-H⋯O, C-H⋯O and C-H⋯F hydrogen bonds links the constituent ions. One O atom of the nitro group is disordered over two positions, with site-occupancy factors of 0.57 (2) and 0.43 (2).

4-(4-Nitro-benzene-sulfonamido)pyridinium trifluoro-acetate.

In the title compound, C(11)H(10)N(3)O(4)S(+)·C(2)F(3)O(2) (-), the benzene ring makes an angle of 87.3 (2)° with the pyridinium ring. The nitro group is essentially coplanar with the benzene ring. The F atoms of the CF(3) group are disordered over two positions with almost equal occupancy [0.531 (12)/0.469 (12)]. The crystal structure is stabilized by N-H⋯O and C-H⋯O hydrogen bonds.

2-Nitro-N-(4-pyridinio)benzene-sulfonamidate.

The title compound, C(11)H(9)N(3)O(4)S, crystallizes with two mol-ecules in the asymmetric unit; each mol-ecule exists as a zwitterion in the solid state. Inter-molecular N-H⋯N hydrogen bonds link the mol-ecules into chains. Weak C-H⋯O inter-actions further stabilize the crystal structure.

1-Isopropyl-4-tosyl-piperazin-1-ium trifluoro-acetate.

In the title compound, C(14)H(23)N(2)O(2)S(+)·C(2)F(3)O(2) (-), the piperazine ring adopts a chair conformation. The crystal packing is stabilized by C-H⋯O and N-H⋯O hydrogen bonds between the cation and anion. The F atoms are disordered over two positions; the site occupancy factors are 0.55 (2) and 0.45 (2).