Stereoselective Synthesis of 2,3,4,6-Tetrasubstituted Tetrahydropyrans

The construction of stereodefined, highly substituted tetrahydropyrans has attracted a lot of interest over the years since they constitute ubiquitous fragments of numerous biologically active natural products.1] During the course of our synthetic studies toward ambruticin, a fascinating antibiotic2] which came back in the front scene with three recent total synthesis, 3] we have been interested in the synthesis of 2,3,4,6-tetrasubstituted tetrahydropyrans 5 (Scheme 1). 4] Moreover, this kind of subunit is found to be embedded in several other natural products such as lasonolide A, polycavernoside A, ratjadone, or concanamycin A.