Still–Gennari–HWE and HWE macrocyclization approach. TBAF, tetrabutylammonium fluoride; TsCl, toluenesulfonyl chloride; KHMDS, potassium hexamethyldisilazane; DMP, Dess–Martin periodinane = 1,1,1-triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one; NMO, N-methylmorpholine-N-oxide; AIBN, azobisisobutyronitrile.