No abstract

The deuterionorborneols 2a, b, c, and e have been prepared and converted to the brosylates l a , b, c, and e. The deuterium isotope effects determined spectrophotometrically for solvolysis in HOAc-KOAc are 1 . OO 0.01, 1.01 + 0.01, 0.99 + 0.01, and 1.1 I f 0.01, respectively. These data establish that: (a) a steric deuterium isotope effect does not operate at C-5 and therefore probably not at C-6; (b) hyperconjugative stabilization of the norbornonium ion to the C-5 hydrogens is confirmed to be not important, and (c) provides the first experimental evidence that the hydrogen (deuterium) shift -internal return pathway contribution to the y-deuterium isotope effects observed for I d and e is minor.

Das ausgehend von Norbornadien über mehrere Stufen dargestellte Ketoacetat (I) wird zu den Hydroxyacetaten (II) reduziert, die mit Brosylchlorid (III) in Pyridin zu den Brosylaten (IV) umgesetzt werden.