Pivoltal synthesis of tetrasubstituted epoxides from ketones and a-halo B/Si ylides with understanding of the activation modes

The epoxidation of ketones with alpha-monohalo borylsilylmethane reagents rendered tetrasubstituted epoxides, opening a new reactive pathway by supression of Boron-Wittig or Peterson olefination pathways. This method enabled the preparation of novel 1,1,2,2-tetrasubstituted borosilylepoxides with intrinsic control of the diastereoselectivity. A mechanism, based on density functional theory calculations, has been postulated analyzing the role of the alpha-iodo B,Si-ylide in the cyclization pathway. Complementarily, enolates generated from ketones can also interact with the -monohalo diborylsilylmethane reagents to acceed the 1,1,2,2-tetrasubstituted borosilylepoxides. The versatility of these entities has been demonstrated through post-functionalization reactions.