and is highly effective in intermolecular oxidopyrylium cycloadditions. For the reductive ring-opening, we drew inspiration from a previously reported side-product observed during work on a samarium iodide-mediated conversion of bicycle 7 to 8 (9, Scheme 2A). It seemed rational that a methoxy group would have less propensity to eliminate than a bromide, thereby facilitating higher yields of the analogous methoxytropone. Thus, cycloadduct 21 was generated from reaction between alkyne 17 and oxidopyrylium ylide dimer 15, and treated with samarium iodide followed by an acidic aqueous workup (pH 3 phosphate buffer). Excitingly, the only product observed was the AC ring analog iso-6 (Scheme 2B). This was surprising given that the expectations were that -based upon prior mechanistic proposals -there would be a fairly even mixture of tropones due to competitive elimination of both methoxy and hydroxy groups. One potential explanation for this phenomenon could be that the elimination takes place prior to hydrolysis -potentially through a Sm(III) complex that may form following the reductive ring-opening (see Scheme 2B for details). Alternatively, there could be electronic preference for the elimination of water (25 ® 26) as compared to methanol (25 ® 24) on account of carbocation character stabilization (Scheme 2C). Substrate scope and mechanistic studies are currently underway.