title: Metal-free, one-pot, sequential protocol for transforming α,β-epoxy ketones to β-hydroxy ketones and α-methylene ketones.
abstract: A new sequential, one-pot protocol for transforming 1,3-disubstituted 2,3-epoxy ketones to β-hydroxy ketones and α-methylene ketones has been developed. Reaction of epoxy ketones with boron trifluoride etherate (BF3·OEt2) generates the cationic intermediates by regioselective epoxide ring opening and an acyl shift. Then, a treatment of these cations with 2-aryl-1,3-dimethylbenzimidazolines (DMBIH) results in formation of 1,2-disubstituted 3-hydroxy ketones. DMBIH serves as a hydride donor in the second step of this process. Finally, the β-hydroxy ketones can be converted to 1,2-disubstituted 2-methylene ketones by treatment with methanesulfonic acid or a combination of methanesulfonyl chloride and triethylamine. Importantly, the sequential steps involved in formation of the α-methylene ketone products can be carried out in one pot.
authors.affiliation: Department of Chemistry, Faculty of Science, Niigata University , Ikarashi-2 8050, Niigata 950-2181, Japan.
authors.forename: Eietsu
authors.initials: E
authors.lastname: Hasegawa
authors.forename: Saki
authors.initials: S
authors.lastname: Arai
authors.forename: Eiji
authors.initials: E
authors.lastname: Tayama
authors.forename: Hajime
authors.initials: H
authors.lastname: Iwamoto