Isotopically labelled analogues of two structurally very similar SGLT inhibitors AVE2268 (1a) and AVE8887 (1b) have been synthesized by various routes. The radioactive labelled [14C]- AVE2268 was prepared in five steps including a Friedel–Crafts acylation as the key step for the 14C-label introduction. For [14C]-AVE8887 the same synthetic approach was not successful and therefore an alternative thiophene metallation/Weinreb amide sequence ...