Stereoselective radical cyclization of epoxy silyl enol ethers

Vinyl Epoxides in Organic Synthesis

“…Tin hydride catalyzed the cyclization of epoxy enolsilanes 1030 to generate cis-fused Indane products 1031 (Table 14, entries 1−5). 356 Although deoxygenation to give rise to 1032 is a side reaction which was not observed in the disulfide initiated cyclization, use of tin hydride as the radical initiator achieved comparatively higher diastereoselectivities (Table 14, entries 6 and 7). 356 Kim et al also showed that 1,5-transfer of a silyl group can also be induced for epoxy enolsilanes in which the geometry and distance are favorable.…”

Free radical-mediated ring expansion and related annulations

“…Other examples of alkoxy radical /3-scission have been reported by Marples.68 Treatment Nugent and RajanBabu explored transition metalinitiated, homolytic carbon-oxygen bond cleavage of epoxides. 69 The resulting hexenyl radical undergoes intramolecular trapping by the pendant olefin and leads to annulated products (Table 26).…”

Photochemical, Electrochemical and Enzymatic Methods for Ether‐Bond Cleavage

“…A phenylthiyl radical transforms acetoxyalkenyl oxirane 7 into acetoxyalkenyl cyclopentanol 8 (Scheme 3), [8,9] whereas addition of the phenylthiyl radical to an oxiranesilyl ether occurs smoothly and is followed by ether-bond cleavage to afford the ketone under photochemical conditions. [9][10][11] In another method, the atom-transfer cyclization of iodooxirane leads to iodocyclopentanol under photoirradiation.…”