reaction of enamines with o-quinone mono-nitrogenous derivatives

Benzo [c] phenanthrene- 5,6-dione 5-oxime reacts with l-[l-cyclopentenyl] piperidine and l-[l-cyclohexene] piperidine to give [Ia, b] in which the [1:1] addition reaction involves the C = N- group only whereas it reacts with 4- [1-cyclopentenyl] morpholine and 4- [1-cyclohexenyl] morpholine to give the cyclic addition products [2a,b]. 5 Iminobenzo [c] phenanthren-6 [5H]-one reacts with 1-[1-cyclopentenyl] piperidine and l-[1-cyclohexenyl] piperidine to give the expected cyclic [1:1] addition product [4a,b] whereas it reacts with 4-[1-cyclopentenyl] morpholine to give the unexpected product [5], in which the [1:1] addition involves the C=N. group only