Rearrangements of the oxides of hopene-I and hopene-II under the action of boron trifluoride

✍ Scribed by G. Berti; P. Bottari; A. Marsili; I. Morelli; A. Mandelbaum

• Book ID: 104249440
• Publisher: Elsevier Science
• Year: 1968
• Tongue: French
• Weight: 318 KB
• Volume: 9
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)98798-2

✦ Synopsis

Hopene-I oxide (I), a minor constituent of Pol.?nodium vulgare, is transformed into hopa-15,17(21)-diene by UC1 in ethanol (1). Wen the same epoxide is treated with BP, etherate in C9C15 solution, the reaction takes e completely different course, another diene, m.p. 167-168',[~~~' + 51": and a ketone, m.p. 277-281O,[a];' + 86.3', being isolated in 85$ and 1556 yields, respectively. Structure II has now been established for the ketone on the basis of its transformation into a benzal derivative (III), m.p. XC-312',[a-&* -1.4', which was de,qrrded by ozone into the anhydride IV, m.p. 265-268',[#]*' D + 33.3O, &, 5.58, 5.71~. Reduction of II with DiAlHI gave an alcohol (V), m.p. 281--285'@$' + 51°, which was transformed into hopene-I (VI) by POCl, in pyridine. An a confisration of the isopropyl group at C 1, i.n II would be expected fron a migration which is concerted aith the rupture of the p-oxirane ring. The positive Cotton effect of moderate intensity of II (CD, cyclohexane,hE 3*3