Copper complexes oxidation-reduction conversion

A catalytic, enantioselective approach towards the synthesis of polyol chains has recently been reported by Carreira et al. and has been applied in a synthesis of the polyol subunit of amphotericin B (Scheme 5) [13]. Aldol addition of the silyl dienolate 26 to furfural (27) catalyzed by the Tol-BlNAP-CuF -complex (2 mol-%) gives rise to the addition product 28 in 95 % yield and >99 % ee after one recrystallization. Spectroscopic evidence indicates that a copper dienolate is formed in situ from the silyl dienolate 26 and is actually the active nucleophile [14], Standard transformations including a j-yw-selective reduction of the ft-hydroxy ketone by the method of Prasad and the oxidative conversion of the furan ring to the car-... 

It has been shown that the use of ionic liquids may be beneficial in aromatic fluorinations in protic solvents." Aryl fluorides may also be obtained using a copper-catalysed halide exchange reaction. The evidence suggests a redox Cu(I)/Cu(III) catalytic cycle involving oxidative addition of aryl halide at the copper(I) centre followed by halide exchange and reductive elimination." A mechanistic investigation of the palladium-catalysed conversion of aryl triflates to fluorides has shown that C-F reductive elimination from the palladium—arene complex does not occur when the aryl group is electron rich and requires in situ modification of the catalyst." ... 

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