Anomalous Beckmann Reaction in a Series of Oximes of 4-Aryl-2,7,7-trimethyl-5-oxo-5,6,7,8-tetrahydroquinolines in Polyphosphoric Acid. 2. Unexpected Synthesis of 3'-Ethoxycarbonyl-4',7',7'-trimethyl-4-oxo-2',6',7',8'-tetrahydrospiro(cyclohexa-2,5-diene-1,2'-pyrrolo[4,3,2-d,e]quinolines)
One-pot synthesis of 2-amino-3-cyanopyridines and hexahydroquinolines using eggshell-based nano-magnetic solid acid catalyst via anomeric-based oxidation