Highly Chemoselective Synthesis of 4-Aminocinnolines via Electrophilic Activation Strategy
Jia-Wang Li1,2, Jia-Cheng Li1,2, Rui Zhang1
1Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China.
Abstract:
Chemoselective cyclodehydration of α-arylhydrazonoamides via an electrophilic activation strategy has been described. A series of polysubstituted 4-aminocinnolines are chemoselectively synthesized in 67-90% yields from α-arylhydrazono-β-oxoamides in the presence of hexaphenyloxodiphosphonium triflate (Hendrickson reagent) and triflic anhydride (Tf2O) at room temperature, whereas several substituted quinolino [3,2-c]cinnolines are obtained in 64-77% yields under reflux. The readily available starting materials, mild conditions, good yields and high chemoselectivity make this novel synthetic protocol much attractive and practical.
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