Phenacyl halides, reduction

Displacement of bromine on phenacyl halide with imidazole gives Reduction with sodium borohydride followed by displacement with 2,6-dichloro-benzyl alcohol in HMPA then produces antifungal orconazole (37). ... 

An alternative route to sulphones utilizes the reaction of the appropriate activated halide with sodium dithionite or sodium hydroxymethanesulphinite [6], This procedure is limited to the preparation of symmetrical dialkyl sulphones and, although as a one-step reaction from the alkyl halide it is superior to the two-step oxidative route from the dialkyl sulphides, the overall yields tend to be moderately low (the best yield of 62% for dibenzyl sulphoxide using sodium dithionite is obtained after 20 hours at 120°C). The mechanism proposed for the reaction of sodium hydroxymethanesulphinite is shown in Scheme 4.20. The reaction is promoted by the addition of base and the best yield is obtained using Aliquat in the presence of potassium carbonate. It is noteworthy, however, that a comparable yield can be obtained in the absence of the catalyst. The reaction of phenacyl halides with sodium hydroxy-methane sulphinite leads to reductive dehalogenation [7]. 

Displacement of bromine on phenacyl halide with imidazole gives Reduction with sodium borohydride followed by... 

The validity of the hypothesis that quaternization favors ring reduction over ketone function is given support in the work on 1-phenacyl-pyridinium halides. Krohnke and Faslod (117) found that in water... 

Fukuzumi S, Mochizuki S, Tanaka T (1990) Photocatalytic reduction of phenacyl halides by 9,10-dihydro-10-methylacridine control between the reductive and oxidative quenching pathways of tris(bipyridine)ruthenium complex utilizing an acid catalysis. J Phys Chem 94 722-726... 

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