1: 1.) bis(tri-n-butyltin)oxide, 2.) tetrabutylammonium bromide / 1.) toluene, reflux, 15 h, 2.) toluene, reflux, 65 h 2: 0.1 N NaOMe / methanol / 3 h / Ambient temperature 3: 1.) NaIO4, 2.) KOH / 1.) H2O, RT, 16 h, 2.) reflux, 1 h View Scheme

1: 1.) bis(tri-n-butyltin)oxide, 2.) tetrabutylammonium bromide / 1.) toluene, reflux, 15 h, 2.) toluene, reflux, 65 h 2: 0.1 N NaOMe / methanol / 3 h / Ambient temperature View Scheme