&-Biotin has been converted by the Raney nickel hydrogenolysis reaction into dl- desthiobiotin. dl-Allobiotip and dl-epi-allobiotin have been converbd to a common desthio derivative, dl-desthioallobiotin, which differs from dl-desthiobiotin. These desthio derivatives were obtained also by an alternative series of reactions starting with the 3-acetamido-4- benzamidotetr~ hydro-2-thiophenevaleric acid methyl esters which were treated with ...