A bis (acetoacetonato) copper (II) assisted reaction between ethyl diazoacetate and ketene dimethyl acetal (loa) now gave ester llb, indicating that the acetal exhibits normal behavior. When, as a consequence, ethyl diazopyruvate (1) was exposed to catalyzed reactions with the latter acetal as well as methylketene diethyl acetal (lOe), there were formed the expected dihydrofuroates 12a, b, respectively.
