Thermolysis and photolysis of cyclic diazo compounds

The rhodium-catalyzed decomposition of the diazoketones 4 in tert-butyl alcohol at 130 degrees C furnishes the monoenolethers 5 and, after deprotection, the aci-reductones 6. In absence of intercepting agents the intermediate carbenes preferentially undergo Wolff rearrangement with ring contraction. In this case the beta-thiolactone 10b or the beta-lactone 13 or the beta-lactam 14 are thermolysis products of the corresponding diazoketones. During photolysis of the diazoketones 4d/4g in presence of alcohols the 2-azetidinones 10c/d are formed.