Boron trichloride has been found to be an efficient reagent for the selective cleavage of sterically hindered methoxy groups in methoxyarenes. The scope and utility of this reaction are explored with examples drawn from derivatives of benzene, naphthalene, 9,lO-dihydrophenanthrene and dibenzofuran. The method is applied to the synthesis of the phytoalexins a-(56) and 8-pyrufuran (58) (1,3,4-trimethoxydibenzofuran-2-01 and 1,2,4-trimethoxydibenzofuran-3-01). A synthesis of tri-0-methylleprolomin (61), a derivative of the unusual lichen metabolite leprolomin (60), is described and its demethylation with boron trichloride is studied. * A preliminary publication has appeared (ref.l).

Die Entfernung der Methylgruppe bei den Polymethoxyarenen (Ia)‐(IVa) erfolgt mit relativ geringer Selektivität unter Bildung der Derivate (Ib)‐(IVb) und.(Ic)‐(IVc).