A simple synthesis of 3-phosphonyl-4-aminoquinolines from β-enaminophosphonates

An easy and efficient synthesis of 4-aminoquinolines substituted with a phosphorylated group or a phosphine oxide group in the 3-position is described. The key step is a regioselective addition of lithiated β-enamino phosphonates to isocyanates to give functionalized amides. Subsequent cyclization of these compounds with triphenylphosphine and hexachloroethane in the presence of triethylamine afforded substituted 4-aminoquinolines. The deprotection of N -PMP substituted 4-amino-quinolines with CAN in acetonitrile gave primary 4-aminoquinolines.