Allyl deprotection of galacturonic acid derivatives: mechanistic aspects of mercuric-catalyzed prop-1-enyl acetal cleavage

Different deallylation methods were assayed for selective deprotection of allyl galactopyranosiduronic acid derivatives. A two-step procedure using DABCO and (Ph3P)3RhCl followed by mercuric-assisted cleavage gave quantitative yields. Reaction in the presence of [18O]water allowed us to obtain evidence about the mechanism of prop-1-enyl cleavage.