Extension of the Willgerodt–Kindler reaction: protected carbonyl compounds as efficient substrates for this reaction

Nitrogen derivatives of carbonyl compounds such as oximes, hydrazones, and semicarbazones were found to be excellent candidates for the Willgerodt–Kindler reaction. They can be used directly in a solvent-free reaction, under both classical and microwave conditions, to give the corresponding thiomorpholides in good yields.