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L. Czollner, J. Fröhlich, U. Jordis, B. Küenburg:
"Reduction of aromatic halides";
Patent: PCT, No. WO 9852885; submitted: 04-30-1998, granted: 11-26-1998.

Redn. of (hetero)arom. halides ArXn (X = halogen; n = 1-10) to ArHn uses a hydride such as LiAlH4 in the presence of O, esp. in the form of an O-inert gas mixt. Redn. in the presence of O gives a good yield in short reaction times, even when working on a semi-industrial or industrial scale. Redn. using LiAlH4 in the presence of O can also be used to reduce complex heteroarom. halides, e.g., for reducing bromonarwedine ketone acetal to narwedine ketone acetal on an industrial scale. Thus, treatment of 2-bromothiophene with LiAlH4 in a stream of O2 gave 99% conversion to thiophene in 2-3 h, vs. 90 h in the absence of O2.
AN 1998:789106