Reduction of chromano–piperidine-fused isoxazolidines: Tandem intramolecular rearrangements leading to 2-(methylamino)-4-oxo-N-phenyl-N-propyl-4H-chromene-3-carboxamide.

Reductive ring opening of isoxazolidine moiety of chromano–piperidine-fused isoxazolidines ( 3a – c ) with HCOONH 4 and 10% Pd/C in a mixture of solvents (THF/MeOH) at ambient temperature, affords novel 2-(methylamino)-4-oxo- N -phenyl- N -propyl-4 H -chromene-3-carboxamide ( 4 ), which is apparently derived from reductive N O bond cleavage followed by tandem intramolecular rearrangements. Plausible mechanistic rationale for the formation of compound 4 is proffered. [ABSTRACT FROM AUTHOR]