Decomposition of [delta]³-dihydropyran -dihydropyran over hot alumina

Abstract

Thesis (M.A.)--Boston University.In previous work it was found that tetrahydrofurfuryl alcohol dehydrates, with a corresponding ring expansion, to delta^2-dihydropyran. If the tetrahydrofurfuryl alcohol is labeled with carbon-14 on the external methylene carbon atom, the resulting delta^2 -dihydropyran is labeled in approximately equal proportions on position 2 and on position 6. In addition delta^2 -dihydropyran labeled with carbon-14 on position 6 rearranges when passed over hot alumina. The resulting delta^2 -dihydropyran was labeled approximately equally on position 2 and 6. One way to account for the above rearrangement is to postulate double bond migration around the carbon ring from one side to the other. If this process is operating, delta^3 -dihydropyran when passed over hot alumina should lead to delta^2-dihydropyran. To preclude the possibility that this process is operating, delta^3 -dihydropyran was synthesized and tested in this manner [TRUNCATED]