Preparation of cyclic boramides from salicylaldehydes, ammonium acetate and sodium borohydride

Borohydride reduction of salicylaldehyde imines yields surprisingly a cyclic boramide. This is a fairly stable compound, and X-ray analysis shows it has a tetrahedral boron atom. Mechanistic studies show a reaction pathway through an oxazaborinane intermediate. The reaction also works with halogen substituted salicylaldehydes and for the preparation of non-symmetrical boramides.

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