59514-64-6Relevant articles and documents
Reactions of Some Cyclic Ethers in Superacids
Baig, Mirza Azam,Banthorpe, Derek V.,Carr, Graham,Whittaker, David
, p. 1981 - 1986 (2007/10/02)
The reactions of some epoxides and tetrahydrofuran derivatives in superacidic media have been studied.The tetrahydrofurans decompose only at 0 deg C or above, yielding, in some cases, unsaturated carbocations which react to give carbocyclic products, though many yield only tar.Cyclohexene oxides decompose more readily; unsubstituted, they slowly form an allylic ion; with one carbon at the epoxide link substituted they yield the ketone, and with both carbons substituted they give the ring-contracted aldehyde.Limonene 1,2-oxide behaves in a similar manner, though yielding small amounts of the ring-contracted protonated aldehyde (10).Reaction of geraniol 2,3-oxide is initially similar but the intermediate is intercepted intramolecularly to yield the hydroxy-iridoid ethers, 3,3,6β-trimethyl-cis-perhydrocyclopentafuran and 3,3,6α-trimethyl-cis-perhydrocyclopentafuran.Protonation of cyclohexene oxide or norbornene oxide yields onium salts, stable at -70 deg C, which show the addition to be either unsymmetrical (i.e. edge protonation) or to take place in two different positions.
