Bamford–Stevens reaction of (+)-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-6-one p-tolysulphonylhydrazone

Abstract

The Bamford–Stevens reaction of (+)-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-6-one tosylhydrazone in protic conditions (sodium dissolved in ethylene glycol) at 115–120 or 135–140° gave 1-[3-(2-hydroxyisopropyl)cyclopentyl]ethanone as the major product, together with pinolone and pinol. In aprotic conditions (sodium methoxide in diglyme or DMF) at 135–140°, the major component was the Δ¹-1,2-diazetine (12), followed by the azine of (+)-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-6-one, transoid and cisoid 1,3,3-trimethyl-6-(1,3,3-trimethyl-2-oxabicyclo[2.2.2]oct-6-ylidene)-2-oxabicyclo[2.2.2]octane, 1,3,3-trimethyl-2-oxabicyclo[2.2.2]oct-5-ene, and p-cymene. Besides these products, 1-[3-(2-hydroxyisopropyl)cyclopentyl]ethanone was found with diglyme, and pinol with DMF. The structures of the new compounds reported are consistent with u.v., ir., n.m.r., and mass spectral data.