The Lewis acid-catalyzed reaction of nitro olefins and ketene methyl trimethylsilyl acetals afforded methyl 4-oxo-carboxylates on hydrolysis of the resulting adducts followed by treatment with diazomethane.
The Michael reaction of silyl enol ethers or ketene silyl acetals with conjugated nitro olefins activated by Lewis acids: new synthesis of 1,4-diketones and .gamma.-oxo esters