395s
VOL.32
FREEMAN, RAO,GEORGE,AND FENWICK
mmole), glacial acetic acid ( 3 ml), and acetic anhydride (1 ml) was refluxed for 6 hr. The solvent was removed under reduced pressure and the residue taken up in ether ( 5 ml). This ether solution was washed with distilled water, 10% sodium bicarbonate solution, and saturated salt solution, dried over anhydrous magnesium sulfate, and evaporated. The infrared Experimental Section spectrum of the resulting oil exhibited no absorption at 2.83 and 5.79 p (indicative of starting alcohol and its acetate ester) Melting points were determined with a Fisher-Johns melting which had been observed when shorter reaction periods were point apparatus and are corrected. Ultraviolet spectra were employed. Although the oil showed two spots on thin layer recorded with a Cary spectrophotometer, Model 11M. Infrachromatography (Woelm alumina plate developed in petrored spectra were obtained with a Perkin-Elmer grating spectroleum ether (bp 30-60’)), elution column chromatography on a photometer, Model 237. Nmr spectra were recorded with a column of 3 g of alumina (Woelm, neutral, activity grade I) Varian A-60 nmr spectrometer. failed to give a separation. Vapor phase chromatography using Nitration of [3.2]Metacyclophane-2-carboxylicAcid ( I).-A an Apiezon L column likewise gave only a broad unresolved solution of [3.2]metacyclophane-2-carboxylic acid (100 mg, band. 0.375 mmole), glacial acetic acid (30 ml), and 70% nitric acid The nmr spectrum of the product taken in carbon tetrachlo(10 ml) was niamtained at 30-35” for 72 hr. The solution was ride contains a singlet at 5.35 ppm assigned to the 9,17 protons poured on to crushed ice (100 g) and stirred. Water (100 ml) of 2-isopropylidene[3.2]metacyclophane,while a more complex was added and the solution was extracted with five 20-ml pormultiplet at 4.8 ppm is assigned to the terminal olefinic and tions of ether. The combined ether extract was washed with 9,17 protons of 2-isopropenyl[3.2]metacyclophane. Integradistilled water and with saturated salt solution, and then dried tion of these signals indicates a composition of ca. l :3, respecover anhydrous magnesium sulfate. Evaporation of the ether tively. This composition is supported by integration of the gave 104 mg of orange oil to which an ethereal solution of methyl protons signal (1.76 ppm) which indicates 3.8 protons diazomethane (0.4 mmole) was added. The solvent was evap(25% of six protons plus 75% of three protons). Strong absorporated and the resulting oil taken up in carbon tetrachloride tion a t 6.10 and 11.3 p in the infrared taken as a neat liquid is (0.25 ml) and placed on a column of 3 g of alumina (Woelm, indicative of a terminal olefin. neutral, activity grade I). Elution with benzene gave an A solution of the olefinic mixture (169 mg), p-toluenesulfonic early fraction containing 35 mg of colorless oil identified as acid (50 mg), and glacial acetic acid (5 ml) was refluxed for 12 hr. methyl [3.2]metacyclophane-2-carboxylate by comparison of its The solvent was removed under reduced pressure and the resinmr and infrared spectra with those of an authentic sample.? due taken up in ether (5 ml). The ether solution was washed A latter fraction, eluted with benzene, contained 37 mg (31 % yield) of 2-nitro-4,5-(2’-carbomethoxypropano)-9,10-dihydro- with 10 % sodium bicarbonate solution, distilled water, and saturated salt solution and dried over anhydrous magnesium phenanthrene as a pale yellow oil. Repeated recrystallization sulfate. Evaporation of the ether gave 160 mg of semisolid from methanol gave 15 mg of yellow plates, mp 134-136’. The residue which was taken up in petroleum ether and chromacomposition was determined by a high resolution mass spectographed on 2.5 g of alumina (Woelm). Elution with petrotrometric measurement. An exact mass measurement of the leum ether gave 73 mg (43% yield) of 2,3-dimethyl[4.Z]metaCIS-containing molecular ion was found to be m / e 324.1193. cyclophan-1-ene as white crystals, mp 101-102.5°. This agrees well with the molecular ion ClPH1?NOI+containing A n d . Calcd for C~aH22: C, 91.54; H, 8.46. Found: C, one atom of C13 calculated‘s to exhibit m / e 324.1190. 91.63; H, 8.57. A final fraction eluted from the column with ether contained Absorption a t 11.9 p (observable in chloroform solution) can 20 mg of orange oil. Thin layer chromatography (Woelm alube assigned to a vinyl hydrogen out-of-plane deformation. The mina plate developed in methylene chloride) of this material ultraviolet absorption spectrum contains a broad maximum a t gave one red and two yellow spots, demonstrating the presence 208 mp (log e 4.75) with a sharp shoulder at 265.5 mp (log e 2.62). of a t least three colored products. None of the components was isolated in sufficient quantity for identification. 2,3-Dimethyl[4.2]metacyclophan-l-ene.-A solution of diRegistry No.-2, 14698-41-0 ; 2-isopropylidene[3.2]methyl-2-[3.2]metacyclophanylmethanol~(200 mg, 0.714
into the extent to which the interesting properties of the [2.2]metacycl.ophanes are reflected in their larger homologs.
(18) J. H.Beynon and A. E. Williams, “Mass and Abundance Tables for Use in Mass Spectrometry,” American Elsevier Publishing Co., Ino., New York, N. Y., 1963.
metacyclophane, 14633-62-6; 2-isopropenyl[3.2]metacyclophane, 14633-63-7; 2,3-dimethy1[4.2]metacyclophan-1-ene, 14698-42-1.
The Reactions of exo- and endo-5-Chloromethylnorbornenewith Sodium1 PETERK. FREEMAN, V. N. MALLIXARJUNA RAO, DANIELE. GEORGE,^
AND
GARYL. FENWICK
Department of Physical Sciences, University of Idaho, MOSCOW, Idaho Received November 68,1966 The reaction of either ezo- or endo-5-chloromethylnorbornene with sodium in n-decane generates 3- and 4-allycyclopentene, cis-bicyclo[3.3.0]octene-2, and bicyclo[3.2.l]octene-2. Mechanistic routes for these ringcleavage and ring-cleavage rearrangement reactions are proposed.
While norbornyl and norbornenyl systems are known to undergo a variety of carbonium ion rearrangements, as a result of the intensive study which these rearrangements have provoked over approximately a twenty-year period13very few investigations, (1) Abstracts, ‘Northwest Regional Meeting of the American Chemical Society, Bellingham, Wash., June 1960,p 25. (2) National Defense Education Act Fellow, 1959-1062. (3) J. A. Berson, “Molecular Rearrangements,” P. de Mayo, Ed., Interscience Publishers. Inc., New York, N. Y., 1963, part I., Chapter 2; G. D. Sargent, Quart. Rev. (London), SO, 301 (1966);G.E. Gream, Rcv. Pure A p p l . Chem., 16,25 (1966);H. C. Brown, Chem. Brit., 1, 199 (1966).
by comparison, have focused attention on other intermediates in these ring systems. Recently we have reported4 that the reaction of either nortricyclyl or dehydronorbornyl chloride with sodium in n-decane results in rearrangement and ring cleavage, yielding a nearly identical mixture of hydrocarbon products: nortricyclene, norbornene, and 3- and 4-vinylc yclopentene (eq 1). The possibility that a similar mechanistic pathway might be uncovered for the reactions of endo (4) P. K. Freeman, D. E. George, and V. N. Mallikarjuna Rao, J . Or& Chem., 18.3234 (1963);19, 1682 (1964).
DECEMBER 1967
REACTIONS OF eX0-
3959
AND endO-5-CHLOROMETHYLNORBORNENE WITH SODIUM
TABLEI REACTIONS OF I AND I1 WITH SODIUM IN WDECANE AT 85-90’
II
I
and ezo-5-chloromethylnorbornene (I and 11) with SOdium aroused our curiosity and stimulated the present study. At the outset there appeared to be at least one complication. Since I and I1 are primary halides, the generation of a bivalent carbon intermediate as a consequence of a elimination induced by alkylsodiumK seemed to be a likely alternative to a carbanionic or free-rad ical-rearrangemen t pathway .
Results and Discussion Treatment of either I or I1 with sodium in n-decane at 85-90’ produced a 23-25% yield of CS hydrocarbons, isolated by direct distillation from the reaction mixtureas Vapor phase chromatographic analysis on a silicone oil column indicated the presence of two components in a 60:40 ratio. The 40% component was easily resolved into three peaks, which appeared in a ratio of 97 :2: 1, using a silver nitrateethylene glycol column. There were small variations in this ratio; nevertheless, the results appear to be nearly independent of the exo or endo nature of the reactant halide (Table I>. Upon catalytic hydrogenation, the 97% component absorbed 1 molar equiv of hydrogen and gave a compound which had an infrared spectrum identical with that of cis-bicycl0[3.3.0]0ctane.~ The nmr spectrum of the parent olefin exhibited absorptions centered at 7 4.5 (two olefinic protons), 6.9 (one tertiary proton a to a double bond), 7.4 (two methylene protons a! to a double bond), 7.9 (one proton 6 to a double bond), and 8.5 (six methylene protons); and, thus, the structure of this olefin must be that of cisbicyclo[3.3.0]octene-2 (V). The nmr spectrum of the 2% component seemed to be consistent with that expected of bicyclo[3.2.l.]octene-2 (VI), since it exhibited absorptions for three protons located a to a double bond (7 7.7) and two olefinic protons (T 4.2 and 4.7). Confirmation of this structural assignment was achieved by comparison of the spectral properties of the 2% component with those of bicyclo[3.2.l]octene-2, prepared by the method of Alder, Krieger, and Weiss,s and by hydrogenation to bicyclo[3.2.l.]octane.9 Since it was difficult to obtain sufficient quantities of the la/cl peak, separated on the silver nitrate column, it was not characterized further. The 60% component, separated and collected using the silicone oil column, was partially resolved on the silver nitrate-ethylene glycol column into two peaks in approximately t~ 60 :40 ratio. The infrared spectrum (5) H. G. Richey, Jr., and E. A. A i l , J . 070. Chsm., PO, 421 (1964); W. Kirmae and W. von Doering, Tdrahedron, 11, 266 (1960); L. Friedman and J. G. Berger, J . Am. Chem. Soo., 83, 492 (1961); 88, 500 (1961); P. S. Skell and A. P. Kraprho, ibid., 83, 754 (1961). (6) The Wurtz hydrocarbon products were not investigated. (7) J. D. Roberts and W. F,Gorham, ibid., 74,2281 (1952). ( 8 ) K. Alder, H. Krieger, and H. Webs, Clem. Bcr., 88, 144 (1955). (9) C. Cup-, W. E. Watts and P. von R. Schleyer, Tetrahedron Letters, No. 36, 2503 (1964).
Iv
I11 Allycyclopentene fraction 111 and I V ,
VI
Bicyclo octene fraction v, VI, % %
Run
Sample
%
1
1:II
60
35
3
61 61 56 56
37 38 39 41
Unknown, %
CS yield, %
2
24
1
1
1
