Amidoximes. Tiemann rearrangement

The rearrangement of amidoximes to derivatives of urea is called the Tiemann Rearrangement. 

The Tiemann rearrangement of amidoximes affords carbodiimides through a nidene intermediate. For example, reaction of the shown amidoxime 98 with benzenesulfonyl chloride in pyridine affords N-phenyl-N -cyclohexylcarbodiimide 99 in 64 % yield. ... 

DiaryIcarbodiimides are similarly obtained from amidoximes andPOCls in pyridine.The yields range from 51-74 %. Cyclic carbodiimides are also synthesized using the Tiemann rearrangement (see Section 11.2.3). 

The modified Tiemann rearrangement of cyclic amidoxime derivatives 21 (where R = Me, Tos) using aqueous potassium hydroxide is also used to synthesize the listed homocyclic carbodiimides 22. 

CCC2767>. Modified Tiemann rearrangement of cyclic amidoxime 0-methanesulfonate afforded the carbodiimide on treatment with NaOH and Aliquat 336 in CHjClj <83JOCi694>. 

The Tiemann Reaction. Amidoximes undergo rearrangement to s-ureas when treated first with benzenesulfonyl chloride and then with water. This is the Tiemann reaction, which has so far been pri-... 

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