Attempted oxidative deamination of N-deacetylcolchicinoids with 3,5-di(tert-butyl)-1,2-benzoquinone: Synthesis of 2H-1,4-benzoxazine-type adducts

In an attempt to use 3,5-di(tert-butyl)-1,2-benzoquinone for the oxidative deamination of N-deacetylcolchicine (4) and N-deacetylthiocolchicine (= N-d eacetyl-10-demethoxy-10-(methylthio)colchicine; 5) to give the correspondin g ketones 2 and 3, the 2H-1,4-benzoxazine-type adducts 8/9 and 11/12. respe ctively, were formed instead, showing a new and unexpected behavior of Core y's reagent. The adducts were separated and spectroscopically characterized , and a plausible scheme of formation is reported.