FURANOSIDES AND FURANONES BEARING ACRYLATE SIDE-CHAINS VIA PALLADIUM-MEDIATED CYCLIZATIONS OF GAMMA-OXOALLENES

Treatment of 4,5-hexadienal with catalytic palladium(II) chloride and excess copper(II) chloride, methanol and carbon monoxide in the presen ce of an acid and a water scavenger resulted in a net acetalization-cy clization-methoxycarbonylation to form a novel methyl furanoside beari ng a methyl acrylate sidechain. Treatment of 4,5-hexadienoic acid unde r the same conditions yields the corresponding furanone, and 3-(tert-b utylidimethylsilyloxy)-4,5-hexadienal yields a methyl tert-butyldimeth ylsilyloxy)-2'-deoxyribofuranoside bearing the acrylate sidechain, wit h high stereoselectivity. This methodology provides access to sidechai n-branched ribofuranoside compounds.