α-Arylamino Diazoketones: Diazomethane-Loading Controlled Synthesis, Spectroscopic Investigations, and Structural X-ray Analysis. 
Primary and secondary α-halomethyl diazoketones generated via Arndt-Eistert chemistry with minimum loading of diazomethane efficiently alkylate aromatic amines in the presence of calcium oxide to furnish the corresponding α-arylamino diazoketones under full chemocontrol.  Such a simple inorganic acid scavenger fully neutralizes the hydrohalic acid formed during the nucleophilic displacement which otherwise would immediately react to produce the corresponding α-haloketone.  The methodology can be further exploited in analogous acylation-type processes on secondary arylamino diazoketones.  In depth spectroscopic (1H, 13C, and 15N NMR ) and crystallographic analyses document interesting structural features of these previously unknown diazo derivatives.