J.Org. Chem., Vol. 41, No. 25, 1976 4023
Ionic Reactions in Bicyclic Systems
See ref 6 for discussion of plausible intermediates and appropriate refer23445-15-0;26, 23417-00-7; 27, 59938-61-3; 28, 59938-62-4; 29-OH, ences. 59938-63-5; 29-C1, 59938-64-6;30,59938-65-7; anthracene, 120-12-7; S.J. Cristol and M. C. Kochansky, J. Org. Chem., 40, 2171 (1975). trans-1,3-dichloropropene,10061-02-6; cis-1,3-dichloropropene, We have no information regarding the question of equilibrating vs. meso10061-01-5;acetic acid, 64-19-7; cis-1-propenyl acetate, 3102-47-4; meric cations in this system and use classical ions in our discusslon for convenience. trans-1-propenyl acetate, 1528-10-5; p-bromobenzenesulfonyl . - .- - - chloride, 98-58-8; syn-8-methyl-2-dibenzobicyclo[3.2.l]octadienone, (13) (a) P. K. Sheenoy, Ph.D. Thesis, University of Arizona, 1966 (b) S. J. Cristol, G. C. Schloemer, D. R. James, and L. A. Paquette, J. Org. Chem., 37,3852 59938-66-8; anti-8-methyl-2-dibenzobicyclo[3.2.l]octadienone, (1972). 59981-12-3; lithium aluminum hydride, 16853-85-3;3,6-dibenzo-2(14) Details on the undeuterated compounds were developed by G. C. bicyclo[3.2.2]nonadienone, 24330-03-8; ethyl propiolate-3-d, Schloemer, Ph.D. Thesis, University of Colorado, 1972. 59938-67-9. (15) it has previously been notedi6 in acetolysis experiments that 24-OAc ep-
References and Notes
(16)
(1) Pari 83: S. J. Cristol, H. W. Mueller, W. M. Macintyre, and R. C. Haltiwanger, J. Org. Chem., 41, 1919 (1976). (2) See S. J. Cristol, A. A. Roberts, and T. E.McEntee, J. Org. Chem., 39,829 (1974), and references cited therein. (3) R. Gindig and A. D. Cross, J. Am. Chem. SOC., 87,4629 (1965). (4) H. E. Simmons and R. D. Smith, J. Am. Chem. Soc., 80,5323 (1958); 81, 4256 (1959). (5) It has prevlously6 been shown that the normal stereochemistry required for cyclopropane formation from 1,Mihalides with zlnc is not required with heavily coppered zinc. (6) S. J. Cristol, A. R. Dahl, and W. Y. Lim, J. Am. Chem. SOC., 92, 5670 (1970). (7) (a) S. J. Cristol, R. J. Bopp, and A. E. Johnson, J. Org. Chem., 34, 3574 (1969); (b)S. J. Cristol and R. J. Bopp, ibid., 39, 1336 (1974). (8) J. P. Kochansky, Ph.D. Thesis, University of Colorado, 1971. (9) (a) S. J. Crlstol, F. P. Parungo, and D. E. Plorde, J. Am. Chem. SOC.,87, 2870 (1965); (b) S. J. Cristol, F. P. Parungo, D.E. Plorde, and K. Schwarzenbach, /bid., 87, 2879 (1965).
(17) (16) (19) (20) (21) (22) (23) (24) (25) (26)
imers (endo-exo mixturelare principal products of kinetic control, and that these rearrange more or less completely to 7 (along with some elimination products) under acid conditions. (a) E. Cioranescu, M. Banciu. R. Jelescu, M. Rentzea, M. Elian. and C. D. Nenitzescu, Tetrahedron Len., 1871 (1969); (b) Rev. Roum. Chim., 14,911 (1969). Footnote 15 in ref 9b. J. A. Berson, R. T. Luibrand, N. G. Kunder, and D. G. Morrls, J. Am. Chem. SOC., 93, 3075 (1971). E. Cioranescu. A. Bucur, F. Badea, M. Rentzea, and C. D. Nenitzescu, Tetrahedron Lett., 1867 (1969). This compound has been previously prepared in the laboratory by Dr. G. 0. Mayo by another route. D. Y. Curtin and M. Hurwitz, J. Am. Chem. SOC.,74, 5381 (1952). The 'H NMR spectrum of this acetate indicated a 40:60 cis-trans ratio. (a) R. J. Bopp, private communication; (b) J. P. Kochansky, Ph.D. Thesis, university of Colorado, 1971. For details, see A. L. Noreen, Ph.D. Thesis, University of Colorado, 1970. H. G. Kuivila and 0. F. Boemel, J. Am. Chem. SOC., 83, 1246 (1961). An alternative that only two isomers are formed also fits the data, but has no mechanistic support.
Ionic Reactions in Bicyclic Systems. 9. Preparation of Optically Active 1,2-Dimethyl-exo-2-norbornyl, 1,2-Dimethyl-exo-2-benzonorbornenyl,and 6,7-Dimethoxy-l,2-dimethylem-2-benzonorbornenyl Chloride Harlan L. Goering,* Chiu-Shan Chang, and John V. Clevenger Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 Received July 6,1976 Hydrochlorination of optically active 1-methyl-2-methylenenorbornane (1) in pentane at -78 "C gives active 1,2-dimethyl-exo-2-norbornyl chloride (2) with -27% retention of optical configuration. Under similar conditions active 1-methyl-2-methylenebenzonorbornene(3) gives active 1,2-dimethyl-exo- 2-benzonorbornenyl chloride (4) (-80% retention) and active 6,7-dimethoxy-l-methyl-2-methylenebenzonorbornene ( 5 ) gives 6,7-dimethoxy-1,2dimethyl-exo-2-benzonorbornenyl chloride (6) with about 13%retention of optical configuration.
Recently we reported results of solvolytic studies of optilenenorbornane (1),6 1-methyl-2-methylenebenzonorbornene cally active 1,2-dimethyl-exo-2-norbornyl chloride (2)l and (3),7 and 6,7-dimethoxy-l-methyl-2-methylenebenzonor1,2-dimethyl-exo-2-benzonorbornenyl chloride (4).* We have bornene (5)s have been reported el~ewhere.~ Attempts to also investigated the 6,7-dimethoxy-1,2-dimethyl-exo-2- prepare optically active 2 from active 1 under conditions rebenzonorbornenyl system3 including the optically active ported4 to give minimum scrambling of the methyl groups tertiary chloride (6). We now present details of the preparation (hydrochlorinationof neat 1,O "C, 1-2 min) were unsuccessful. of these optically active tertiary chlorides. Hydrogen chloride uptake ceased at about 60% reaction-the A possible route to the optically active tertiary chlorides was remaining liquid 1 was encapsulated by the solid adduct suggested by the work of Brown and L ~ uwho , ~ observed that (%)-and active chloride could not be separated from the under carefully controlled conditions, hydrochlorination of mixture. Evidently, in the earlier work4b unreacted 1 in the deuterium labeled 1-methyl-2-methylenenorbornane (1) gives product did not interfere with NMR analysis of the tertiary 2 with only partial scrambling of the methyl groups. Exposure chloride. In the present work the additional handling required of the product to hydrogen chloride at 0 or -78 "C results in for separation of pure 2 resulted in racemization. randomization of the methyl groups (hydrogen chloride catHydrochlorination of (-)-1 in pentane a t -78 OC is comalyzed isomeric Wagner-Meerwein rearrangement5). A corplete in a few minutes-the reaction is somewhat slower a t 0 ollary of that work is that optically active 1 should lead to "C. Removal of the pentane and excess hydrogen chloride active 2; however, 2 racemizes under the conditions of the under high vacuum a t
