A series of heterocyclic quinones based on benzofuran, benzothiophene, indazole and benzisoxazole has been synthesized, and evaluated for their ability to function as substrates for recombinant human NAD(P)H:quinone oxidoreductase (NQO1), a two-electron reductase upregulated in tumor cells. Overall, the quinones are excellent substrates for NQO1, approaching the reduction rates observed for men...

N-heterocyclic carbenes are a class of persistent carbenes stabilized by adjacent heteroatoms that are part of a heterocycle. They play a central role in multiple enzymatic biosynthetic reactions that involve thiamine diphosphate. Inspired by this biocatalysis machinery, N-heterocyclic carbenes have emerged as one of the most versatile classes of organocatalysts for organic reactions. However, ...

A novel bridged nucleic acid (BNA) analogue, 2 0-O,4 0-C-methyleneoxymethylene bridged nucleic acid (2 0,4 0-BNA), was synthesized and incorporated into oligonucleotides. The 2 0,4 0-BNA modified oligonucleotides showed high binding affinity with an RNA complement and significant enzymatic stability against snake venom phosphodiesterase. 2005 Elsevier Ltd. All rights reserved. 2',4'-BNA/LNA (Re...

The lithiation of ferrocenylphosphane Fc-PH(2) (Fc = -C(5)H(4)FeC(5)H(5)) has been reinvestigated and both Fc-PHLi and Fc-PLi(2) have been identified by NMR-spectroscopy. The lithiated phosphanides have been converted to the corresponding mono and bis(silylated) species the latter of which gave synthetic access to an oligomer in which three ferrocene units are symmetrically connected by phospha...

In this paper, all graphs are simple and connected, but they are not necessarily finite. As is well known, a (connected) graph G comes equipped with a natural metric on its vertex set V (G), given by defining the distance xy between any pair of vertices x, y ∈ V (G) to be the length of some shortest path or geodesic between x and y. Given a quartet x, y, u, v ∈ V (G), define δ(x, y, u, v) to be...

an efficient and environmentally friendly procedure for one-pot synthesis of 13-acetyl-9-methyl-11-ox-8-oxa-10,12-diazatricyclo [7.3.1. ] trideca-2,4,6-triene from salicylaldehyde, acetylaceton and urea via biginelli condensation and intramolecular michael-addition by using magnesium bromide as an expensive and easily available catalyst under solvent-free condition is desired. the structural el...

Abstract Chemical reactions of ball-mill activated [Nb 6 I 11 ] with alcohol solutions Mg alcoholates result in the formation three new hexanuclear Nb cluster compounds 8 (HOCH 3 ) ][Nb (OCH 18 ]·2CH OH ( 1 ), (PPh 4 2 (OC H 5 12 ]·C and (PPN) ). They contain anions, which have edges octahedra, i.e. inner coordination sites, μ -bridged by O atoms methanolato or ethanolato ligands. Thereby, they...

The reaction of Cp*Sn[OTf] (Cp* = C 5 Me ; OTf O 3 SCF ) with one equivalent IPrNLi (IPrN bis(2,6-diisopropylphenyl)imidazolin-2-iminato) resulted in the binuclear [OTf]-bridged tin complex 1 . Similarly, [BF 4 ]-bridged bimetallic 2 was synthesized by Cp*Sn[BF ] (1 eq.). It also possible to prepare from via an anion exchange reaction. high-yield conversion into iodostannylene [IPrNSnI] accompl...

The bleomycins (BLMs) are natural products that in the presence of iron and oxygen bind to and cause single-strand and double-strand cleavage of DNA. The mode(s) of binding of the FeBLMs that leads to sequence-specific cleavage at pyrimidines 3' to guanines and chemical-specific cleavage at the C-4' H of the deoxyribose of the pyrimidine has remained controversial. 2D NMR studies using the hydr...