Green Chemistry Using Bismuth Compounds: Bismuth(III) Trifl ate Catalyzed Allylation of Cyclic Acetals

x�) R1.-lX n X=O, S n = 1 , 2 Bi(OTfh (2.0 mol %) �SiMe3 ( 1 .7 eq) Cyclic acetals (dioxolanes, dioxanes, and dithianes) are common protecting groups in organic synthesis but they can also be converted to other useful functional groups. A bismuth(III) triflate-catalyzed multi component reaction involving the allylation of cyclic acetals followed by in situ derivatization with acid anhydrides to generate highly functionalized esters and thioesters has been developed under solvent-free conditions. Most reagents used to date for the allylation of cyclic acetals are highly corrosive or toxic and are often required in stoichiometric amounts. In contrast, the use of a relatively non-toxic and non-corrosive bismuth(III) based catalyst makes this methodology benign and attractive.