1-[Bicyclo[4.2.0]octa-1(6),2,4-trien-3-yl]-3-[bicyclo[4.2.0]octa-1(6),2,4-trien-3-yl-methyl]imidazolium hexa-fluoro-phos-phate.

In the title compound, C(20)H(19)N(2) (+)·PF(6) (-), the two benzocyclo-butene units are essentially planar and they form dihedral angles of 38.0 (2) and 72.7 (2)°, with the central imidazolium ring. In the crystal structure, weak C-H⋯π and π--π stacking inter-actions [centroid-centroid distance = 3.742 (2) Å] contribute to the stability of the crystal structure. The PF(6) (-) ion is disordered over two positions with site occupancies of 0.869 (9) and 0.131 (9).

1-[Bicyclo-[4.2.0]octa-1(6),2,4-trien-3-yl]-3-(but-3-en-yl)imidazolium bromide.

In the title compound, C(15)H(17)N(2) (+)·Br(-), the cyclo-butene and benzene rings are coplanar. The dihedral angle between the benzene and imidazolium rings is 21.2 (3)°. In the crystal structure, the C(15)H(17)N(2) (+) and Br(-) ions are linked into a zigzag chain along the b axis by C-H⋯Br hydrogen bonds, and weak C-H⋯π inter-actions involving the benzene ring of a screw-related cation.

Clockwise-counterclockwise differentiation on the upper rim of a monofunctional gamma-cyclodextrin: efficient topological control in the syntheses of capped cyclodextrins.

Intramolecular condensation of 6(A)-(N-dansyl-l-cysteine)-gamma-cyclodextrin occurred only at 6(B)-OH of the many OH groups to afford the corresponding lactone with an exo-topology.

Dinuclear macrocyclic polyamine zinc(II) complexes: syntheses, characterization and their interaction with plasmid DNA.

The syntheses, characteristics of dinuclear macrocyclic polyamine zinc complexes and their interaction with plasmid DNA are reported. The two cyclen (1,4,7,10-tetraazacyclododecane) moieties are bridged by rigid and flexible linkages. The crystal structures of Zn2C27H43N8O15Cl4 [5c.(ClO4)3.2H2O] and Zn2C30H43N10O13Cl3 [5e.(ClO4)3.H2O] have been determined. The complexes crystallize in the monoclinic space group C2/c and P2(1)/c with the following unit cell parameters: 5c.(ClO4)3.2H2O: a=32.568(4)A, b=14.8593(17)A, c=19.443(2)A, alpha=90.00 degrees , beta=119.435(4) degrees , gamma=90.00 degrees , Dc=1.551 mg/m3, FW=956.71, F(000)=3932; 5e.(ClO4)3.H2O: a=15.807(2)A, b=16.756(2)A, c=16.161(2)A, alpha=90.00 degrees , beta=97.062(4) degrees , gamma=90.00 degrees , Dc=1.546 mg/m3, FW=988.83, F(000)=2032. The distance between the two Zn(II) ions is about 4.0 A. The structures show that two zinc ions can synergistically interact with the substrate DNA. With this novel structural characteristics, the dinuclear macrocyclic polyamine Zn(II) complexes via the synergetic effect between the two zinc ions can catalyze the cleavage of plasmid DNA (pUC18) with unprecedented speed at physiological conditions.

Highly enantioselective alkyne additions to aldehydes in the presence of 1,1'-bi-2-naphthol and hexamethylphosphoramide.

It is found that the addition of hexamethylphosphoramide to the solution of an alkyne, Et(2)Zn, and (S)-1,1'-bi-2-naphthol in methylene chloride allows the generation of an alkynylzinc at room temperature and shows highly enantioselective additions to aldehydes. The mild condition for the formation of the alkynylzinc reagent enables the use of functional alkynes in this asymmetric reaction with excellent enantioselectivity. It avoids the reflux of the toluene solutions of the alkynes and Et(2)Zn as previously reported.

A simple copper salt catalysed the coupling of imidazole with arylboronic acids in protic solvent.

In the presence of a catalytic amount of a simple copper salt, the coupling of imidazole with arylboronic acids was performed in methanol to give corresponding N-arylimidazoles in almost quantitative yields; this coupling reaction could also be performed in aqueous solutions to give N-arylimidazoles in excellent yields.

Highly enantioselective phenylacetylene additions to both aliphatic and aromatic aldehydes.

The readily available and inexpensive BINOL in combination with Ti(O(i)Pr)(4) is found to catalyze the reaction of an alkynylzinc reagent with various types of aldehydes including aliphatic aldehydes, aromatic aldehydes, and other alpha,beta-unsaturated aldehydes to generate chiral propargyl alcohols with 91-99% ee at room temperature. No previous chiral catalysts have exhibited such a broad scope of enantioselectivity with respect to the type of aldehydes for this reaction. [reaction: see text]