Synthetically useful base-induced rearrangements of aldonolactones

Aldonolactones can be activated at the alpha and omega positions by selecti ve bromination or tosylation. The activated aldonolactones can be transform ed into epoxyaldonolactones by treatment with base under non-aqueous condit ions. Treatment of epoxy- or bromodeoxyaldonolactones with aqueous base giv es epoxyaldonates in which the epoxide can undergo Payne rearrangement to m ore stable epoxyaldonates. These can subsequently be opened by the carboxyl ate group with inversion of the configuration at the attacked carbon. Using this method a number of less available aldonolactones/acids have been prep ared, in a reaction sequence where the configuration at one, two or three c arbon centers has been stereospecifically interconverted. An attractive syn thesis Of L-gluconic acid from D-gluconolactone is presented.