The reactions of dimethoxycarbene (DMC; 2), which was generated in situ by thermal decomposition of 2,5-dihydro-2,2-dimethoxy-5,5-dimethyl-1,3,4-oxadiazole (1), with N-tosylated imines of xanthone and 2,3 : 6,7 dibenzosuberenone, 3a and 3d, respectively, led to different adducts with rearranged skeletons. In the case of 3a, the 1 :1 adduct 5 as well as the 2 : 1 adduct 6 were obtained (Scheme 2). The formation of both products can be explained by a migration of a MeO group of the DMC fragment in a zwitterionic intermediate. On the other hand, migration of a Me group of DMC is necessary for the formation of the two 1 :1 adducts 13 and 14 of 2 and 3d (Scheme 5). The structures of all products have been established by X-ray crystallography.