The first regioselective oxidative coupling of 2-hydroxycarbazoles is described. With a vanadium catalyst and oxygen as the terminal oxidant, dimers with an ortho-ortho' coupling pattern were obtained with high selectivity. Further oxidation led to ortho'-ortho' coupling to generate a tetramer, which provided insight that the atropisomerization barriers of the unsymmetrical biaryl bonds are muc...

A facile synthesis of unsymmetrical N,N'-diarylureas is described. The utilization of the Pd-catalyzed arylation of ureas enables the synthesis of an array of diarylureas in good to excellent yields from benzylurea via a one-pot arylation-deprotection protocol, followed by a second arylation.

The syntheses of unsymmetrical N-heterocyclic carbenes (NHCs) that contain a single N-bound icosahedral carborane anion substituent are reported. Both anionic C-2 and doubly deprotonated dianionic C-2/C-5 NHC lithium complexes are isolated. The latter species is formed selectively, which reveals a surprising directing effect conveyed by icosahedral carborane anion substituents.

In the unsymmetrical title complex, [Ni(C(20)H(23)N(4)O(4))]ClO(4), the coordination geometry for the Ni(II) atom can be described as square planar. The aromatic rings in the two ligands are almost vertical, with a dihedral angle of 85.3°. In the crystal, cations and anions are linked by weak C(N)-H⋯O hydrogen bonding.

We have successfully prepared an unsymmetrical analogue of a Katsuki-type salen ligand having a single hydroxyalkyl group at its 6-position, and also its Mn(III) complex; attachment of the complex to a polymer gives a highly enantioselective and recoverable catalyst for epoxidation of 1,2-dihydronaphthalene.

SPIHT (Set Partitioning In hierachical trees), being an efficient coding method for wavelet coefficients, has acquired more and more widely application, especially in image/video compression fields. But, conventional SPHIT have some obvious limitions. For example, when for the color image compression, polarmetric SAR image compression, or multispectrum image compression and other multi-channel ...

Unsymmetrical bisazides containing chelating and nonchelating azido groups undergo chemoselective three-component copper(I)-catalyzed azide-alkyne conjugation reactions with two different alkyne molecules. In conjunction with the reactivity gap between aromatic and aliphatic alkynes, a bistriazole molecule can be generated with excellent regioselectivity by mixing two alkynes and a bisazide in ...