1a,11b‐dihydrobenz[5,6]anthr[1,2‐ B ]azirine. A non k‐region polycyclic arene imine

The synthesis of the title compound 9 is described. Benz[a]anthracene 8,9‐oxide (6) was reacted with sodium azide in aqueous acetone and the trans ‐9‐azido‐8,9‐dihydrobenz[a]anthr‐8‐ol (7), so formed, was cyclized by tri‐ n ‐butylphosphine. Attempts to dehydrogenate 10,11‐dihydrobenz[a]anthracene 8,9‐imine (4) with DDQ or by allylic bromination followed by base assisted dehydrobromination was unsuccessful. The N ‐tosyl derivative of 4, prepared from the free imine, N ,O‐bis(trimethylsilyl)acetamide and tosyl chloride underwent rapid aziridine‐ring cleavage by the silylating agent to give trans ‐8,9,10,11‐tetrahydro‐8‐(4‐methyl)benzensulfon‐amido‐9‐ [(trimethyl)oxy]benz[ a ]anthracene (10).