Hydrazones 3-Hydride elimination

With benzylic halides, the elimination requires sodium hydride in hot DMF, whereas aliphatic substrates do not undergo elimination at all. This drawback was surmounted by the use of N-4-acetoxyphe-iiyltrifiamide. 3 Elimination now occurs via the quinoneimines under mild conditions, even with aliphatic substrates (Scheme 17). Despite the ingenious chemistry, there appear to be few advantages over other methods. A procedure exists for the synthesis of hydrazones from halides (Scheme 18). ... 

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