Isomérisation d'époxypinanes fonctionnels en milieu basique
摘要:
Functional pinocarveols and bifunctional spiropinanes could be prepared by basic isomerisation of 2,3-epoxypinanes bearing a function or a functional chain on the carbone 10. Preliminary results are presented, which illustrate a general synthesis of these new compounds. (C) 2000 Elsevier Science Ltd. All rights reserved.
The functionalized 2,3-epoxypinanes 1b-i were submitted to isomerization in the presence of ZnBr2 at 110 degrees (Table 1) or of BF3. Et2O at different temperatures (Table 2), and their behavior was compared with that of the non-functionalized parent 1a and with similar known transpositions. The produced campholenals 2, pinocamphones 3, and in some cases, fencholenals 4 were isolated and characterized. A mechanism involving a concerted oxirane ring opening is proposed (Scheme 4).