Heinous Lee Friedman
The focus of my research concerns using electron rich rhenium
metal fragments to activate furans to electrophilic attacks.
Recently, complexes of the type TpRe(CO)(L)(h2-furan) (Tp=tris-pyrazolyl borate) have been
developed. The
L ligand can be pyridine, t-butylisonitrile, trimethylphosphine,
1-methylimidazole, or ammonia. The trimethylphosphine and pyridine
complexes add both methanol and methyl vinyl ketone across the
unbound double bond of the furan to generate 2-methoxy-2,3-dihydrofurans.
Under similar conditions, the pentaammineosmium(II) complex
of furan undergoes ring opening to generate the h2-bound
vinyl ether/aldehyde complex. The trimethylphosphine complex
also will react with ketals. The complex TpRe(CO)(t-butylisonitrile)(h2-2-methylfuran) will react with aldehydes in
a similar manner to the corresponding pentaammineosmium complex
in a reaction in which the aldehyde is incorporated into the
dihydrofuran ring. The goal of this project is to explore the
elementary reactions of these rhenium(I) furan complexes and
compare their reactivity to that of the pentaammineosmium(II)
furan systems. Also of great concern is the diastereomeric nature
of the addition products and what factors determine the observed
diastereoselectivities.
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