SYNTHESIS OF OXA-BRIDGED 7- AND 8-MEMBERED RINGS VIA INDIUM-MEDIATED ANNULATION OF 1,4- and 1,5-DICARBONYL COMPOUNDS WITH 3-IODO-2-[(TRIMETHYSILYL)METHYL]PROPENE

摘要

A variety of 1,4- and 1,5-dicarbonyl compounds undergo reaction with 3-iodo-2-[(trimethylsilyl)methyl]propene in the presence of indium metal in aqueous media to produce oxa-bridged 7- and 8-membered rings in good yields. The reaction mechanism likely involves intermolecular indium allylation of one carbonyl of the substrate, followed by indium-halide promoted intramolecular allylsilane cyclization. This procedure offers an environmentally friendly alternative to the analogous tin-mediated annulation process.