has specified product has specified reactant carboxylic ester alpha-haloketone rearrangement step Aston-Greenburg rearrangement 2021-12-14T08:15:45Z RXNO RXNO:0000678 The rearrangement of an alpha-haloketone into an ester with a tertiary alpha-carbon atom by intramolecular migration of an alkyl or aryl group.