Cyclic ketones ring expansion with diazomethane

The well-known reaction leading to ring expansion of cyclic ketones has been applied to derivatives of oxo sugars in an attempt to develop a new route to novel deoxy sugars. By treatment with diazomethane both a five-membered (42) and a six-membered (26) sugar ring have been expanded by insertion of a methylene group. 

Treatment of a cyclic ketone with diazomethane is a method for accomplishing a ring-expansion reaction. For example, treatment of cyclohexanone with diazomethane yields cycloheptanone. Propose a mechanism. 

When a cyclic ketone reacts with diazomethane, the next larger cyclic ketone is formed. This is called a ring expansion reaction. Provide a mechanism for this reaction. 

Ring expansion of cyclic ketones with diazomethane... 

Although the diazomethane-induced ring expansion of cyclic ketones is not usually a clean reaction, it apparently works well with a,a-dichlorocyclo-butanones and provides an indirect method for adding a three-carbon unit to an olefin [e.g. (50) (51)]. 

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