G.P.F. van Strijdonck

Development of supramolecular metalloprotein mimics

Supramolecular mimics of metalloproteins, viz. cytochrome P-450 and iron- sulfur proteins are described. The cytochrome P-450 mimic consists of a Mn porphyrin and a Rh complex which are incorporated within a vesicle membrane in water. This system catalyses the reductive activation of molecular oxygen in the epoxidation of alkenes at Mn, with reducing equivalents derived from the simultaneous Rh catalysed oxidation of formate to carbon dioxide. In the mimics for iron-sulfur proteins, iron-sulfur clusters are encapsulated in diphenylglycoluril and cyclotriveratrylene cavitands. The encapsulation by the cavitands modifies the electrochemical parameters, e.g. the redox potential, of the iron-sulfur clusters, in a way that has certain analogies to the effects of encapsulation by the protein in ferredoxins and high-potential iron-sulfur proteins.

Unexpectedly high diastereomeric induction in the diels-alder reaction of quinones with chiral aryl containing 1-alkoxy-3-trimethylsilyloxybuta-1,3-dienes.

Abstract Chiral 1-alkoxy-3-trimethylsilyloxybuta-1,3-dienes induce a high diastereomeric excess in the cycioaddition with quinones when the chiral alkoxy group is of the type OCH(CH 3 )R with R = aryl. Also forR =vinyl. CH 2 OCH 3 the found induction is higher than that observed for R = ten. butyl. The highest diastereomeric excess (>95%) was achieved in the cycloaddifion of 1-[1-(p-methoxyphenyl)-ethoxy]-3-trimethylsilyloxybuta-1,3-diene with benzoquinone. An explanation is given based on the assumption that the R substituent is suongly enlarged in size by complexation with the used quinones.