Anions Containing the Bictclo [3.3.1 ]nonane Skeleton 383 parison of the downfield shifts observed in the bisected geometry A (2, 1.1, and 3, 0.8 ppm) and in the unsymmetrical geometry B (8, 0.1-0.5 ppm) provides direct support for the proposition that ground-state cyclopropyl ketone delocalization is maximized in the bisected conformation.An examination of the relevant data for the unsymmetrical vinylcyclopropane 9 (see Table II) leads to conclusions analogous to those obtained for carbonyl group conjugation. There is no evidence to support selective overlap of the C2-C8bond. Since an accurate estimate of the carbon-carbon double-bond anisotropy and other nonconjugative effects on the proton resonances due to the presence of two sp2hydridized carbons in 9 is more tenuous, these tentative conclusions concerning the geometric parameters for vinylcyclopropane participation require further support. Experimental SectionNmr spectra were obtained on a Varían Associates Model HA-100 spectrometer; infrared spectra were measured on a Perkin-Elmer Model 237 or 257 grating infrared spectrometer. Nortricyclene (2h) was prepared by the method of Schleyer.18The cyclopropyl hydrogen-carbon-13 coupling constant of Vuch =' 175 Hz was measured.20(19) P. von R. Schleyer, J. Amer. Chem. Soc., SO, 1700 (1858).Ttortricyclanone (2c) was prepared by the method of Meinwald.8 The *Jhch for the Ha position was 184 Hz and for the H/s position 185 Hz.20 The chemical shifts of the , H#, and ezo-CHa-(1.65 ppm) protons remained constant (±1 Hz) on going from a neat sample to a 2.5% CC14 solution. The C4 H8 and the endo-CH2~(1.97 ppm) protons were shifted ca. 8 and 4Hz, respectively, upon dilution.3-Methylenetricyclo [2.2.1.02•6]heptane (2m) was prepared from nortricyclanone (2c) using the Corey21 modification of the Wittig reaction. The crude product was purified by chromatography on silica gel using pentane. Distillation furnished pure 2m: bp 113-114°; average yield of three runs ca. 16%; ir (CC14) 1684 cm-1; nmr (CC14), 4.48, 1 H (singlet), 4.60 ppm, 1 H (d, / ~1 Hz) (see Table I).Tricyclo [3.3.0.02 8] octane (8h) was prepared from ketone 8c14 using the Huang-Minlon adaptation of the Wolff-Kishner reduction.22 The crude product was purified by preparative vpc to give hydrocarbon 8h:23 mol wt (mass spectrum) 108; nmr (CC14), 1.17-1.65 (6 H, complex), 1.65-2.05 ppm (5 H, complex) (see Table II).

Saponification of 7 gave 2-ethylidene-3-methylglutaric acid as needles from benzene-hexane, mp 129-130°(lit.16 mp 129°).

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Notes bicyclo [3.2.1 ]oct-3-en-6-one and numerous other bicyclo [3.2.1 ]oct-2-ene derivatives. On the other hand, the pattern found in the vinyl region of related bicyclo-[2.2.2 [octene derivatives was consistently much sharper and more symmetrical.8Experimental Section 3-Cyclohexenylmethyl p-Bromobenzenesulfonate (1).-Sodium borohydride reduction of 3-cyclohexenecarboxaldehyde in absolute ethanol gave 3-cyclohexenylcarbinol, bp 64-65°( 4.8 mm), n21 d 1.4827, in 87% yield. To a solution of 3-cyclohexene-lcarbinol (70 g, 0.625 mol) in 360 ml of anhydrous pyridine at -10°was slowly added 190 g (0.745 mol) of p-bromobenzenesulfonyl chloride over a period of 30 min. The reaction mixture was constantly stirred in a methanol-ice bath during addition. The reaction was stirred for 2 hr at -10°after addition was complete, allowed to stand in a refrigerator for 24 hr, and poured directly into a 1-1. ice solution containing 180 ml of concentrated hydrochloric acid. Vigorous stirring produced a white slushy solid. Filtration of the solid, drying over anhydrous magnesium sulfate in methylene chloride, removal of methylene chloride by vacuum distillation, and recrystallization from absolute ethanol at -40 and -78°g ave 157 g (0.469 mol, 75%) of 3-cyclohexenylmethyl p-bromobenzenesulfonate (1), mp 33-35°( lit.9 34.5-35°).3-Cyclohexenylmethyl Thioacetate (2).-To 400 ml of anhydrous methanol containing 3-cyclohexenylmethyl p-bromobenzenesulfonate (80 g, 0.242 mol) was added, with constant stirring