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.