Synthesis of α-Amino-α‘-diazomethyl Ketones via Ring Opening of Substituted Cyclopropanones with Alkyl Azides. A Facile Route to N-Substituted 3-Azetidinones

[reaction: see text] The reaction of alkyl azides with triethyl(1-methoxy-2, 2-dimethyl-cyclopropoxy)silane affords a series of alpha-amino-alpha'-diazomethyl ketones in moderate yields (38-54%). The mechanism of this novel process is discussed. The diazomethyl ketones could also be cyclized to the corresponding N-substituted 3-azetidinones in good yield upon treatment with Rh(2)(OAc)(4).