Synthesis of isotopically labelled SGLT inhibitors and their metabolites

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 was developed. This pathway was also applied to obtain stable isotopically labelled analogues of both AVE2268 and AVE8887. Finally, the synthesis of two metabolites, sulfate 12 and glucuronide 13 were achieved by applying interesting protecting group and oxidation strategies.