4934 time identical with that for the material described above. At least eight additional minor products were also detected. B. With Aqueous Acid. A mixture of 1.22 g of epoxide 17 and 25 ml of 4 % sulfuric acid was stirred at 0" for 90 min under an atmosphere of nitrogen and then saturated with sodium chloride and extracted with ether. Drying of the resulting ether extracts over saturated sodium chloride solution followed by anhydrous sodium sulfate and subsequent removal of the solvent by distillation gave 1.40 g of colorless wet crystals which was chromatographed on 45 g of silica gel. Elution with 1:3 ether-benzene gave 665 mg (53 % yield) of (+)-3a,4/3-carandiol (19)as a colorless oil which was further purified by short-path distillation at 103-104" (0.2 mm), [ a ] 2 3 j 4 6 ~ +87" (c 1.25); nmr spectrum: 7 6.50 (m, 1, CH-4), 8.82 (s, 3, CHz-lO), 8.94 and 8.98 (2s, 6, CH3-8 and -9), and 9.34 (m, 2, CH-1 and -6); lit.7* mp 30", [ C U ] ~ O D +84.15" (c 6, chloroform). Further elution with 1 :1 ether-benzene gave 318 mg (26% yield) of (+)-3@,4P-carandiol (18); colorless needles from ethyl acetate, mp 138.5-139.5"; [CY]?~D$64" (c 1.49): mp 137", [CY]% +61.25"(c4). C. With Methanolic Acid. A solution containing 341 mg of epoxide 17 in 15 ml of 4 methanolic sulfuric acid was stirred at 0" for 90 min under an atmosphere of nitrogen. The resulting mixture was diluted with saturated sodium chloride solution and extracted with ether. The combined ether extracts were washed with saturated sodium bicarbonate solution and dried over saturated sodium chloride solution followed by anhydrous sodium sulfate. Removal of the solvent by distillation gave 450 mg of a colorless liquid which was chromatographed on 20 g of silica gel. Elution with 1:19 ether-benzene gave 283 mg (70%. yield) of (-)-3amethoxy-4/3-caranol (27), mp 57.5-63 Sublimation gave long
'.
colorless needles, mp 63.5-64.5'; [ c ~ ] 2 6-69" ~ ~ ~ ~ (c 1.25); A",:"' 2.75 p ; nmr spectrum: T 6.20 (t, 1, CH-4), 6.60 (s, 3, -OCHa), 8.72 and 8.80 (2s, 9, CH3-8, -9, and -lo), and 9.2 (m, 2, CH-1 and -6); i n j e 184, 152, 137, 134, 125, 123, and 119. Anal. Calcd for CllH2002: C, 71.69; H , 10.94. Found: C, 71.4; H, 11.0. Elution with 1 :3 ether-benzene gave 41 mg (10 % yield) of (+)-4@methoxy-3/3-caranol (28) as a colorless liquid which was further 2.90 p ; purified by short-path distillation at 82" (0.5 mm); A, [ a I z 7 +53" ~ (c 1.74); nmr spectrum: T 5.96 (t, 1, CH-4), 6.90 (s, 3, -OCH8), and 8.86, 8.92, and 8.98 (3s, CHa-8, -9, and -10); m / e 166, 152, 151, 150, 137, 135, 134, 132, and 123. Anal. Calcd for CllHz002: C, 71.69; H, 10.94. Found: C, 71.8; H, 10.9. (+)-3a-Methoxy-4-caranone (29). Titration of a solution of 75 mg of alcohol 27 in 5 ml of acetone with 1 molar equiv of 2.67 M chromic acid solutionz0gave, on isolation, 75 mg of ketone 29 as a pale yellow liquid. Further purification by gas chromatography followed by short-path distillation at 88-89' (3.5 mm) gave a colorless liquid, A, 5.80 p ; [ C X ] ~ ~ ! J 4-21' (c 2.08); nmr spectrum: 7 6.70 (s, 3, CH30-), 8.74 (s, 3, CH3-3), and 8.83 and 9.04 (2s, 6, CH,-9 and -8); m/e 182, 153, 150, 148, 139, 135, 122. This material exhibited spectral and gas chromatographic behavior quite distinct from that of a specimen of (+)-3/3-metho~y-4-caranone.~~~ Atial. Calcd for CllHl8OZ: C, 72.49; H, 9.96 Found: C, 72.6; H , 10.1.
Acknowledgment. The able technical assistance of Messrs. T. R. Walker and H. J. Krauss is gratefully acknowledged.
The Rates of Methoxyl Exchange of Camphor and Norcamphor Dimethyl Ketals in Methanol-d, T. G . Traylor and Charles L. Perrin Contribution f r o m the Department of Chemistry, Revelle College, University of California, San Diego, L a Jolla, California 92038. Received February 14, 1966
Abstract: I n methanol-d4, methoxyl exchange in c a m p h o r a n d norcamphor dimethyl ketals (111) proceeds through the classical 2-methoxybicyclo[2.2.l]heptyl-2cations (IV). T h e exolendo rate ratios for ionization t o IV a n d for reaction of IV with solvent t o give labeled 111 a r e identical. T h e observed exolendo ratios a r e 0.10 for camphor dimethyl ketal (IIIb) a n d 16 for norcamphor dimethyl ketal (IIIa). Reaction of the cations (IV) with hydrides gives exolendo rate ratios very close t o those for the exchange reaction (0.13 a n d 20). These results define the behavior of classical bicycloheptyl systems a n d provide a basis for estimating the importance of steric effects a n d anchimeric assistance in other bicycloheptyl systems. I n particular we conclude that bicyclo[2.2.l]heptyl-2 cations having no 2-substituent are n o t classical.
and c o n t r o v e r s y have arisen of 2-bicyclo[2.2. llheptyl cations.'r2 The large exolendo rate ratios in solvolysis and the high stereospecificity for formation of exo p r o d u c t s h a v e b e e n i n t e r p r e t e d ' s ? as e v i d e n c e for
C
onsiderable interest over the s t r u c t u r e
neighboring group participation, leading to b r i d g e d ions IB.
(1) (a) S. Winstein, E. Clippinger, R. Howe, and E. Vogelfanger, J . A m . Chem. SOC.,87, 376 (1965); (b) A. Colter, E. C. Friedrich, N. J. Holness, and S. Winstein, ibid., 87, 378 (19653; (c) R . Howe, E. C. Friedrich, and S. Winstein, ibid., 87, 379 (1965); (d) S . Winstein, ibid., 87, 381 (1965); (e) S. Winstein, A. H. Le\\in, and I
