Study of the Rearrangements of Oxonium Ylides Generated from Ketals
Intramolecular exposure of cyclic ketals to metal carbenoids generates a proposed oxonium ylide intermediate that subsequently rearranges to one of three general products. The product resulting from a 1,2-shift to the ketal carbon is favored by larger ketals that lack radical stabilizing groups. A bridged bicyclic structure is formed by competitive 1,2-shift to the exocyclic carbon of the ketal and is favored by smaller ketal ring sizes that possess radical-stabilizing groups. An alternative β-elimination pathway can also operate when neither of the 1,2-shift pathways are favored. The enol ether that is formed in this latter pathway rearranges easily to an isomeric dioxene.
Journal of Organic Chemistry
American Chemical Society
Digital Object Identifier (DOI)
Study of the Rearrangements of Oxonium Ylides Generated from Ketals, Brogan, J. B., Bauer, C., Rogers, R. D., Zercher, C. K. J. Org. Chem. 1997, 62, 3902-3909.
Copyright © 1997 American Chemical Society