Oxidative cleavage of a 9-c/s xanthophyll probably represents the key regulatory step in abscisic acid (ABA) biosynthesis. A transposon tagged maize (Zea mays) mutant vp14, provided the original DNA sequence data needed to design a VP14 fusion protein capable of catalysing this reaction in vitro. A cDNA encoding a similar protein has now been isolated from a wilt-related tomato (Lycopersicon es...

Key words ozonolysis - photoexcitation alkenes selectivity nitroarenes

Selective carbon-carbon and carbon-heteroatom bond cleavage was achieved in a one reaction system. With this strategy a novel Pd/Cu-catalyzed aerobic oxidative oxosulfonation of olefins with DMSO has been developed. Preliminary mechanistic investigations indicated that CO/O2 assisted the bond cleavage and the leaving groups from the starting materials were trapped by O2 and underwent a hydroxyl...

The oxidative cleavage of alkenes is classically performed by chemical methods, although they display several drawbacks. Ozonolysis requires harsh conditions (-78°C, for a safe process) and reducing reagents in a molar amount, whereas the use of poisonous heavy metals such as Cr, Os, or Ru as catalysts is additionally plagued by low yield and selectivity. Conversely, heme and nonheme enzymes ca...

Excitotoxicity, oxidative stress, and apoptosis have been recognized as routes to neuronal death in various neurological diseases. We examined the possibility that PHF-1 tau, a substrate for various proteases, would be selectively cleaved depending upon routes of neuronal death. Cleavage form of PHF-1 tau was not observed in cortical cell cultures exposed to excitotoxins or oxidative stress tha...

A series of novel bis-1,3,4-oxadizaoles were synthesized by oxidative cyclisation of respective Schiff bases derived from dicarbohydrazide using ceric ammonium nitrate (CAN) as catalyst. The synthesized compounds were screened for in vitro antibacterial activity against Staphylococcus aureus (MTCC 87), Escherichia coli (MTCC 46) and antifungal activity against Candida albicans (NCIM 3471) by tw...

We describe the first electrochemical activation of D–A cyclopropanes and cyclobutanes leading after C(sp3)?C(sp3) cleavage to formation highly reactive radical cations. This concept is utilized formally insert molecular oxygen direct or DDQ-assisted anodic oxidation strained carbocycles, delivering ?- ?-hydroxy ketones 1,2-dioxanes electrocatalytically. Furthermore, insights into mechanism oxi...

The DNA-cleavage properties of the two copper(II) complexes, [Cu(mbpzbpy)Br(2)](H(2)O)(2.5) (1) and [Cu(mpzbpya)Cl](CH(3)OH) (2), obtained from the ligands 6,6'-bis(3,5-dimethyl-N-pyrazolmethyl)-2,2'-bipyridine) (mbpzbpy) and 6'-(3,5-dimethyl-N-pyrazolmethyl)-2,2'-bipyridine-6-carboxylic acid) (Hmpzbpya), respectively, are reported. Upon coordination to Cu(II) chloride in methanol, one arm of t...

The monoanionic N(4)O ligand N-methyl-N,N'-bis(2-pyridylmethyl)ethylenediamine-N'-acetate (mebpena(-)) undergoes oxidative C-N bond cleavage in the presence of Co(II) and O(2). The two resultant fragments are coordinated to the metal ion in the product [Co(III)(2-pyridylformate)(mepena)]ClO(4) (mepena(-) = N-methyl-N'-(2-pyridylmethyl)ethylenediamine-N'-acetato). Bond cleavage does not occur in...

Covalent organic frameworks (COFs) are highly promising photocatalysts with tunable photophysical properties. So far, they have served both as a photosensitizer and solid support. Introducing second catalytic site in the photoactive COF scaffold to form dual photocatalyst is logical next step towards green photocatalytic chemistry by expanding boundaries of visible-light-driven photoredox catal...