Reactions of Dimethoxycarbene with N ‐Tosylated Imines

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.