Chromatography-free entry to substituted salicylonitriles: Mitsunobu-triggered domino reactions of salicylaldoximes.

A mild and efficient one-pot procedure is described to transform salicylaldoximes into salicylonitriles using Mitsunobu chemistry. The reactions proceed through the corresponding 1,2-benzisoxazoles that undergo the Kemp elimination in situ to generate the target salicylonitriles in excellent yields. The chemistry exhibits a broad scope, and the salicylonitriles can be readily isolated by a simple acid-base workup. In addition to functioning as useful synthetic precursors, salicylonitriles may serve as more cell penetrable bioisosteres of carboxylic acids.