Metal–metal multiple bonded intermediates in catalysis

Reactive intermediates in cytochrome p450 catalysis.

Recently, we reported the spectroscopic and kinetic characterizations of cytochrome P450 compound I in CYP119A1, effectively closing the catalytic cycle of cytochrome P450-mediated hydroxylations. In this minireview, we focus on the developments that made this breakthrough possible. We examine the importance of enzyme purification in the quest for reactive intermediates and report the preparati...

Detection and accumulation of tetrahedral intermediates in elastase catalysis.

Tetrahedral intermediates in the reaction of elastase with specific di- and tripeptide p-nitroanilide substrates have been detected, accumulated, and stabilized at high pH by using subzero temperatures and fluid aqueous/organic cryosolvents. The tetrahedral adducts are characterized by spectra with lambda max of 359 +/- 2 nm, compared with thata of 380 nm for p-nitroaniline and 315-320 nm for t...

Enamine carboxylates as stereodetermining intermediates in prolinate catalysis.

Experimental and computational studies probing the nature of intermediates in the α-amination of aldehydes catalyzed by prolinate salts support an enamine carboxylate intermediate in the stereodetermining step.

Barrierless tautomerization of Criegee intermediates via acid catalysis.

The tautomerization of Criegee intermediates via a 1,4 β-hydrogen atom transfer to yield a vinyl hydroperoxide has been examined in the absence and presence of carboxylic acids. Electronic structure calculations indicate that the organic acids catalyze the tautomerization reaction to such an extent that it becomes a barrierless process. In contrast, water produces only a nominal catalytic effec...

Multiple Hydrogen-Bonded Supramolecular Polymers