A direct iron(III)-catalyzed Prins-Peterson reaction involving -substituted - triphenylsilyl bis-homoallylic alcohols and aldehydes is described. Thus cis- 4 -2,7- disubstituted oxepenes were synthesized in a diastereoselective reaction using sustainable catalytic conditions (3-5 mol%). This highly productive process is the result of a cascade of three chemical events with the concomitant formation of a C-O bond, a C-C bond and a 4 endocyclic double bond, through a Prins cyclization followed by a Peterson-type elimination. This tandem reaction is chemoselective vs the classical Prins cyclization
