Diazoacetophenone, Wolff rearrangement

Example 4.29. 77te Wolff rearrangement of diazoacetophenone to methyl phenyl-acetate. 

Wolff rearrangement. Finding that the Wolff rearrangement of diazoketones with silver oxide and methanol gave erratic, highly variable results, Newman and Beal developed a procedure for carrying out the reaction in homogeneous solution under mild conditions. A solution of diazoacetophenone in methanol was treated at room temperature with a few drops of a filtered solution of 0.004 mole of silver... 

While ketocarbenes are known to readily undergo Wolff rearrangement, they have also been postulated to react via 1,3-dipolar addition as zwitterions. For example the uncatalyzed reaction of ketene with diazoacetophenone (40) has been interpreted as a 1,3-dipolar addition of a zwitterionic ketocarbene (41). 

Photoelimination of nitrogen from diazoketones is complicated by Wolff rearrangement of the intermediate carbene, as shown below for diazoacetophenone ... 

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