27362-69-2Relevant articles and documents
Prostaglandin Endoperoxide Model Compounds. Part 2. Stereospecific Synthesis of Isomeric 5-Bromo-2,3-dioxabicycloheptanes and 2-Bromo-6,7-dioxabicyclooctanes
Bloodworth, A. J.,Eggelte Henny J.
, p. 3272 - 3278 (1981)
Cyclopent-3-enyl hydroperoxide (9) has been prepared from cyclopentadiene via hydroboration and autoxidation, and converted by bromination into trans-3,cis-4-dibromocyclopentyl hydroperoxide (10).Reaction of compound (10) with silver oxide has afforded endo-5-bromo-2,3-dioxabicycloheptane (11) (42percent), whereas treatment of compound (10) with silver trifluoroacetate has provided exo-5-bromo-2,3-dioxabicycloheptane (15) (6percent) and exo-5-trifluoroacetoxy-2,3-dioxabicycloheptane (16) (14percent).The exo-bromide (15) (11percent) has also been prepared from cyclopent-3-enyl bromide by trans-hydroperoxybromination and ring closure with silver oxide.The configurations of the peroxides have been confirmed by catalytic hydrogenation.Cyclohex-3-enyl hydroperoxide (26) has been prepared from anisole by a 5-step procedure ending with oxidation of N-cyclohex-3-enyl-N'-tosylhydrzide, and converted by bromination into a mixture of two diastereoisomeric 3,4-dibromocyclohexyl hydroperoxides.Treatment of the trans-3,cis-4-dibromide (27) with silver oxide has afforded endo-2-bromo-6,7-dioxabicyclooctane (29) (40percent), whereas reaction of the cis-3,trans-4-dibromide (28) with silver trifluoroacetate has provided exo-2-bromo-6,7-dioxabicyclooctane (30) (18percent).Treatment of compound (27) with silver trifluoroacetate yielded a 9:1 mixture of peroxides (30) and (29) (19percent), but compound (28) did not react with silver oxide.It is suggested that the silver oxide-induced dioxabicyclizations proceed by an SN2 mechanism whereas the silver trifluoroacetate reactions involve a bromonium ion intermediate.
