of the aliene 13 in 10 mL of CH2C12, and the resulting solution was allowed to warm to room temperature. The reaction solution was concentrated under reduced pressure, mixed with 48.6 mg of (+)-borneol, and analyzed (HPLC). The products were the furan adducts 3 (5%), the dimer 4a (5%), the dimer 4b (20%), and the dimer 4c (12%), accompanied by 6% of the bromo ketone lb and minor unidentified peaks at 7.7 and 26.4 min. In addition, three minor peaks were observed that corresponded in retention times to the dimers 14 of the aliene 13.In a second experiment designed to test the possibility that the enone 2a might react with the aliene at 25 °C, a solution of 321 mg (1.40 mmol) bromo ketone lb in 2.56 g (21 mmol) of the aliene 13 was mixed with 10 mL (13.7 g, 138 mmol) of EtaN and heated to 35 °C with stirring. A white precipitate separated from the initially clear solution as the reaction proceeded. After the mixture had been heated with stirring for 36 h, it was poured into aqueous 1 M HC1 and extracted with CH2C12. The organic extract was washed with aqueous NaCl, dried, and concentrated under reduced pressure. The residual yellow solid was mixed with 40.2 mg of (+)-borneol (an HPLC standard). The reaction mixture was subjected to preparative HPLC to separate 21 mg (7%) of the bromo ketone lb, 39.6 mg of bomeol, 23.8 mg (12.5%) of dimer 4a, and 154 mg (80.1%) of a mixture of dimers 4b and 4c. All products were identified with authentic samples by comparison of spectral data and/or by a mixture melting point determination.Treatment of the Enone 2a with Molecular Oxygen. The cold (-78 °C) pyrolysate from 500 mg (2.45 mmol) of adduct 3 was dissolved in 25 mL of cold (-78 °C), anhydrous hexane and a stream of air (dried in a column packed with Drierite) was passed through the cold solution for 45 min. The resulting solution was allowed to warm to room temperature and then concentrated under reduced pressure and mixed with 45.5 mg of (+)-borneol for HPLC analysis. The crude product contained 2% of the furan adducts 3, 2% of the dimer 4a, 11% of the dimer 4b, and 5% of the dimer 4c. Additional small unidentified peaks were present at 7.8, 26.7, and 30.5 min.

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Several a-(trifluoromethyl)-and a-(pentafluoroethyl)carbinols were synthesized by the addition of perfluoroalkylating agents (TMSCF3, TMSC2F5, and/or C2F5L1) to polycyclic ketones. An improved procedure for the preparation of a-(perfluoroalkyl)trimethylsilyl ethers from (perfluoroalkyl)trimethylsilanes and ketones was developed to facilitate the synthesis of the compounds of interest. All of the alcohols featured the bicyclo[2.2.1]heptyl skeleton or some analog of this structure containing double bonds or cyclopropyl groups. Sulfonate esters of the carbinols were prepared, and these sulfonates were solvolyzed in different solvents to examine the competition between destabilization of the carbocationic intermediates by perfluoroalkyl groups and stabilization by neighboring-group participation. The extent of the destabilization of the cations was gauged by the difference in rates of solvolysis of the -hydrogen and a-(perfluoroalkyl) derivatives. The ^ -/^ -ratios ranged from 8 to ~104, and the extent of anchimeric assistance that occurred in each system influenced the difference in rates. The pentafluoroethyl group exerted a slightly smaller rate-retarding effect when compared to the trifluoromethyl group (£

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