O-methoxycarbonyl-a!diazoacetophenone

Interaction of a carbonyl group with an electrophilic metal carbene would be expected to lead to a carbonyl ylide. In fact, such compounds have been isolated in recent years 14) the strategy comprises intramolecular generation of a carbonyl ylide whose substituent pattern guarantees efficient stabilization of the dipolar electronic structure. The highly reactive 1,3-dipolar species are usually characterized by [3 + 2] cycloaddition to alkynes and activated alkenes. Furthermore, cycloaddition to ketones and aldehydes has been reported for l-methoxy-2-benzopyrylium-4-olate 286, which was generated by Cu(acac)2-catalyzed decomposition of o-methoxycarbonyl-m-diazoacetophenone 285 2681... 

The reaction was carried out by adding a solution of o-methoxycarbonyl-ct-diazoacetophenone in CH2CI2 over aperiod of 1 h to a suspension of the PyBOX-i-Pr-Sc(OTf)3 complex (10mol%), MS 4A, Rh2(OAc)4 (2mol%), and benzyloxyacetaldehyde derivatives in CH2CI2. 

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