2910 (51) A detailed procedure for this reaction has been accepted for publication in Organic Syntheses. (52) T. Zincke. Chem. Ber., 23, 241 (1890). (53) The temperature never exceeded 25 OC during any stage of this reaction. (54) F. Bordwell and M. L. Douglass. J. Am. Chem. SOC.,88, 993 (1966): H. C. Brown and P. J. Geoghegan, ibid., 89, 1522 (1967): H. C. Brown and P. J. Geoghegan, J. Org. Chem., 35, 1844 (1970).
(55) K. L. Williamson and Y.-F. L. Hsu, J. Am. Chem. Soc., 92, 7385 (1970); W. Menzel and M. Froehlich. Ber. Dtsch. Chem. Ges.B., 75, 1055 (1942). (56) K. B.Wiberg, “Physical Organic Chemistry”, Wiley, New York, N.Y., 1964, pp 558-565. (57) F. Daniels and R. A. Alberty, “Physical Chemistry”, 2nd ed, Wiley, New York, N.Y., 1963, pp 650-652. (58) Reference 56, pp 376-379.
Chlorocyanation of Barrelenes as a Route to 1-Cyanosemibullvalenes. Convenient Introduction of an Efficient 7r-Electron Acceptor Substituent and Its Influence on the Cope Equilibrium Leo A. Paquette* and William E. Volz Contribution from the Evans Chemical Laboratories, The Ohio State University, Columbus, Ohio 43210. Received July 18, 1975
Abstract: The two-step sequence of chlorosulfonyl isocyanate addition to a barrelene followed by heating in a dimethylformamide at ca. 90’ proceeds with skeletal rearrangement to a [3.2.1]bicyclic frame and introduction of cyano and chloro substituents in a 1,3 relationship. These products undergo ready dehydrohalogenation with potassium tert-butoxide in Me2SO-THF solution at room temperature to give 1-cyanosemibullvalenes.By NMR and x-ray methods, the parent nitrile is shown to exist in that tautomeric form having the CN substituent bonded to the cyclopropane ring at C1. The mono- and dibenzo analogues lack the capability for Cope rearrangement and are consequently locked into this form as well. The initially formed barreleneCSI adducts have been characterized and certain mechanistic conclusions drawn. The structural parameters of 1 (5)-cyanosemibullvalene are discussed in light of known cyclopropane bond lengths and those features peculiar to the semibullvalene derivative are summarized.
As a consequence of their fluxional character, unsymmetrically bridged homotropilidenes (1) can satisfy internal electronic requirements by shifting the position of structural equilibrium. Although Schroder’s investigation’ of monosubstituted bullvalenes (2) has indicated that such weakly 5
@
in the opposite direction, and this trend is maintained in the azabullvalenes 3g6 and @-lactam3h.’ Goldstein’s more recent finding2 that homobullvalenone 4 is characterized by preferred bonding of the carbonyl terminus to C-5 conflicts with those trends found in the lower homologues and is not easily reconciled with available theoretical assessments of electronic effects in Cope e q ~ i l i b r i a . Because ~,~ complications from larger longicyclic frameworkslo can arise from a number of sources, the true electronic perturbational effects in 4 are conceivably not being revealed. This is not so 0
a ->
H,
H,
2
b
- 1
c=c,
/OR
/
C=C,
/
/COOMe
O,\
e -
I
R@GRQ)
C-”H,
/
% -f , / C-N
FH3
N
43 a-= O
5
accepting and donating groups as methyl, chloro, bromo, and iodo discriminate hardly a t all between the various available sites, fluorobullvalene exists chiefly (80-85%) in that form where the electronegative functionality prefers the lone sp3hybridized aliphatic carbon (C-5). With alkoxy and carbomethoxy substituents, the preferred orientation is that illustrated in 3a-c.’** Therefore, a t the bullvalene level of homologation, a general pattern of preferential equilibration in the C-5 direction is seen. When an electron-withdrawing carbonyl group is introduced as in bullvalone (3d)3 or the lactams 3e4 and 3f,5the result is to alter the prevailing competition chiefly Journal of the American Chemical Society
%, R=CH3 , GH5, CHzOCH3 ,CH;PH
2
\
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98:lO
R
7 , R = CH3, CHzOCH3, F
N
in the twofold degenerate barbaralone series (5) where methyl is recognized to prefer C-1 ( K = 3.28) and deuterium C-5 (K = 0.80).” In those l(5)- and 2(4)-substituted semibullvalenes (6and 7, respectively) examined to date,’2b*cthe equilibria are clearly illustrative of preferential attachment to olefinic > cyclopropyl > aliphatic, irrespective of the particular substituent. With the exception of 7-F, good agreement is found with p r e d i c t i ~ nHowever, .~~~ the effect of an efficient a-electron acceptor such as cyano on the very facile13 Cope rearrangement process which operates in semibullvalenes remained to be assessed.
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291 1 The choice of cyano for the present investigation was predicted upon the following considerations. Thermochemical studies have indicated the effects of nitrile groups on strained ring stability to be minor.I4 Such combustion measurements deal, however, with total stabilizing effects and do not consider specific bond weakening and strengthening influences which may be operating within the molecule." That individual cyclopropane ring bonds are affected by such forces is suggested by the appreciable shift in the cycloheptatriene-norcaradiene equilibrium witnessed in the case of the 7-cyano derivative.I5J6 Unlike the semibullvalene valence isomerization process, this last equilibrium is not degenerate, lies too far to one side in the parent system, and consequently is difficult to assess quantitatively. Because the currently available access routes to nonaryl fused s e m i b u l l ~ a l e n e s ' ~are ~ ~not ~ - conducive ~~ to introduction of a cyano substituent, a new route to this class of compounds was developed, the details of which are now presented. We also report herein on the structural features of the simplest derivative.*'
Scheme I
Synthetic Aspects As a consequence of the pioneering work of Graf and his coworkers,22 it is now feasible to convert a simple alkene to an a,@-unsaturated nitrile through solvolysis in dimethylformamide solution of its chlorosulfonyl isocyanate (CSI) adduct. Moriconi and Jalandoni have addressed the mechanism of these N-(chlorosulfonyl) 0-lactam ring-opening reactions and shown the process to be general.23 Where a comparably Nsubstituted y-lactam is concerned, the action of dimethylformamide at elevated temperatures results instead in conversion to a y-chloro nitrile. The transformation of 8 into 9 is
chloro-anti-8-cyanobicyclo[3.2.l]octa-2,6-diene (12) as a colorless solid in 3 1% yield. The definitive spectral data for 12 include an intense infrared band (in CH2C12) at 2245 cm-' and a ' H N M R spectrum which indicates not only that four olefinic protons are present [6 6.64 (q, J 1 , 7 = 3, J 6 , 7 = 5.5 Hz, H7), 6.26 (m, J I ,=~6, J 2 , 3 = 9.5, J 2 , 4 = 2 Hz, H2), 5.93 (q, J 5 , 6 = 3 Hz, H6), and 5.43 (m, J 3 , 4 = 2, J 3 , 5 = 1 Hz, H3)] but also uniquely defines the stereochemical features at H4 and Hg. As with many dibenzo[3.2. l l o c t a d i e n e ~ the , ~ ~low level of spin interaction between H4 (4.41, m, J4,5 = 3 Hz) and H5 (3.32, m), as well as between the pair of bridgehead protons ( H I ,H5)and Hg (CHCO-). (CDC13) 149.0 (2 C), 133.9 (2 C), 127.7 (2 C), 127.3 (2 C), 125.2 (2 Anal. Calcd for C ~ ~ H I I NC, O 79.17; : H, 5.62; N, 7.10. Found: C, C), 121.1 ( 2 C ) , 5 7 . 1 , 4 5 . 2 ( 2 C ) , a n d 4 4 . 4 p p m . 78.86; H, 5.61; N, 7.13. Anal. Calcd for C ~ ~ H IC, ~ 88.67; N : H, 5.25. Found: C, 88.93; H, Eu(fod)3 pseudocontact shifting of the NMR spectrum gave the 4.85. following AEu values: H I , -2.0; H2, -3.6; >NH, -7.6; H5, -9.9; H6, B. Dehydration of 36. A suspension of 150 mg (0.61 mmol) of 36 -6.7; H7, -4.3; Hg, -1.8; H9-11, -1.2; and Hl2, -2.2. With ethyl acetate as eluent, there was obtained a mixture of the in 15 ml of sodium-dried benzene and 180 PI of anhydrous triethylamine was heated with magnetic stirring until dissolution.The heating above &lactam (360 mg) and y-lactam 28 (297 mg, percentage bath was removed and 180 mg (1.5 mmol) of thionyl chloride was composition derived from ' H NMR integration). The latter compointroduced. After 5 h at the reflux temperature, the solution was nent was isolated in pure form by repeated recrystallization from dicooled, diluted with ether (50 ml) ahd dichloromethane (50 ml), and chloromethane-ether as colorless crystals, mp 191-191.5 O C ; umax poured into ice water. The aqueous phase bas separated and extracted (CHC13) 1707 cm-'; 6h.lessj(CDCI3) 6.93-7.43 (m, 4 H, aryl), 6.70 with ether (50 ml). The combined organic layers were washed with (br s, 1 H, >NH), 5.98-6.33 (m, 1 H, olefinic), 5.50-5.81 (q of m, 1 H, olefinic), 3.92-4.20 (m, 1 H, >CHCO-), 3.66-3.92 (m, 1 H, 50-ml aliquots of 5% hydrochloric acid, saturated sodium bicarbonate, and brine solutions prior to drying and evaporation. The crude product >CH-NCHNCHCO-). 6 ~ (CDCI3) ~ 6.86-7.28 ~ ~ (m, i 4 H, aryl), 6.13 (br s, 2 H, -NH2), 5.39 Anal. Calcd for C I ~ H ~ ~ C I N C, O ~59.03; S : H, 3.50; N, 4.05. Found: (br s, 1 H, OH), 3.56 (m, 1 H, >CHO-), 3.1 1 (m, 1 H, bridgehead), C, 58.98: H, 3.63; N, 4.06. and 1.68-2.45 (m, >CHCO- and cyclopropyl).
Journal of the American Chemical Society
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May 12, 1976
2917 (13)A. K. Cheng, F. A. L. Anet, J. Mloduski, and J. Meinwald, J. Am. Chem. Sm., Several early fractions in the latter series contained small amounts 98, 2887 (1974). of 35a (estimated 2.2% yield) which resisted purification by fractional (14)H. K. Hall. Jr., and J. H. Baldt, J. Am. Chem. Soc.,93, 140 (1971). crystallization or preparative TLC. The derived @lactam could in (15)(a) E. Ciganek, J. Am. Chem. SOC.,89, 1454 (1967);(b) C. H. Bushweller, contrast be purified without difficulty (see below). M. Sharpe, and S.J. Weinlnger, Tetrahedron Lett., 453 (1970). (16)C. J. Frltchie, Jr., Acta Crystallogr., 20, 27 (1966). Dechlorosulfonylation of 34a. A solution of 110 mg (0.31 8 mmol) (17)H. E. Z i m " a n and G. L. Cfunewald, J. Am. Chem. Soc., 88, 183 (1966); of 34a in 5 ml of dichloromethane and 10 ml of ether was stirred H. E. Zimmerman, R. W. Binckley, R. S.Givens, G. L. Grunewald, and M. magnetically while IO ml of 25% sodium sulfite solution and 10 drops A. Sherwin, bid., 91,3316(1969); H. E. Zimmerman and H. Iwamura. ibid., of 10% KOH were added. After 4 h, dichloromethane was added to 90, 4763 (1968). (18)J. Melnwald and D. Schmidt, J. Am. Chem. Soc.,91, 5877 (1969);H. E. dissolve the solid which formed and stirring was continued for an Zimmerman, J. D. Robbins, and J. Schantl, ibid., 91,5878 (1969). additional hour. After addition of ether (50 ml) and 5% HCl(100 ml), (19)L. A. Paauette. J. Am. Chem. Soc.. 92.5766 (1970):R. Askani. Teb.aheckon the organic layer was separated, washed with saturated NaHCO3 and Lett., 3349 (1970); 447 (1971);R: M.'Moria&, C.'L. Yeh, and N. Ishibe, J. NaCl solutions, dried, and evaporated. Lactam 34b was obtained in Am. Chem. Soc.,93,3085 (1971); R. Askani, I. Gurang, and W. Schwertfeger, Tetrahedron Lett., 1315 (1975). quantitative yield: mp 256.5-257.5 OC (from dichloromethane-ether); R. Malherbe, Helv. Chim. Acta, 56,2845 (1974). umax (CHC13) 1710 cm-I; d ~ (CDC13) ~ 6.73-7.32 ~ ~ (m, i 8 H, aryl), A preliminary communication on a portion of this study has appeared: L. 5.93(brs,1 H,>NH),4.33(m,lH,H1),4.18(m,2H,HqandHs), A. Paquette, W. E. Volz, M. A. Beno, and G. G. Christoph, J. Am. Chem. and 3.54 (t of d, 1 H, >CHCO-); m/e (calcd) 247.0997, (found) SOC.,97,2562 (1975). R. Graf. DBP 1 218 448,Farbwerke Hoechst AG (1963); K. Matterstock 247.100 1, and G. Lohaus, DAS 1 253 704,Farbwerke Hoechst AG (1964). Dechlorosulfonylationof 35a. A 273-mg sample of a mixture of 35a E.J. Moriconi and C. C. Jalandoni, J. Org. Chem., 35,3796 (1970). and 34a was treated with sodium sulfite solution as above to give 200 T. J. Katz and K. C. Nicolaou, J. Am. Chem. Soc., 96, 1948 (1974). H. E. ZimmermanandR. M. Paufler, J. Am. Chem. Soc.,82, 1514(1960); mg (80%)of a mixture of 35b (three parts) and 34b (five parts). ReH. E. Zimmerman and G. L. Grunewald, ibid.. 86, 1435 (1964);H.E. Zimpeated recrystallization from dichloromethane-ether removed 35b merman, G. L. Grunewald, R. M. Paufler, and M. A. Sherwin, ibid., 91,2330 and provided ultimately 26 mg of pure p-lactam, mp 246-247 O C dec; (1969). v, (CHC13) 1758 cm-I; 6hle4si(CDC13) 6.83-7.83 (m, 8 H, aryl), S.J. Cristol. J. L. Mohrig, and D. R. Plorde, J. Org. Chem., 30, 1956 (1965); A. R. Katritzky and B. Wallis, Chem. hd. (London), 2025 (1964). 5.58 (br s, 1 H, >NH), 4.33 (m, 2 H, benzylic bridgeheads), 3.75 (m, (27)T. Durst and M. O'Sullivan, J. Org. Chem., 35,2042 (1970). 1 H, >CHNCHCO-); m/e (calcd) (28)Comparable chromatographic destruction of lactams has been encountered 247.0997, (found) 247.1001. during isolation of homobarrelene-CSI adducts: W. E. Volz and L. A. Pa-
Acknowledgment. The authors wish to express their grati-
tude to the Donors of the Petroleum Research Fund, administered by the American Chemical Society, for financial support and to Mr. J. M. Geckle for the I3C NMR spectra. References and Notes (1) G. Schrbder and J. F. M. Oth, Angew. Chem., lnt. Ed. Engl.. 6,414(1967); H.-P. Loffler and G. Schrbder, ibid.. 7,736 (1968); J. F. M. Oth, R. Merenyi, H. Rottele, and G. Schrbder. Tetrahedron Lett., 3941 (1968);J. F. M. Oth, E. Machens. H. Rottele, and G. SchrMer, Justus Liebigs Ann. Chem., 745, 112(1971). (2)M. J. Goldstein. R. C. Krauss, and S.-H. Dai, J. Am. Chem. SOC.,94,680 ( 1972). (3)W. von E. Doering, B. M. Ferrier, E. T. Fossell, J. H. Hartenstein, M. Jones, Jr., G. Klumpp, R. M. Rubin, and M. Saunders, T e W o n , 23,3943(1967). (4)L. A. Paquette and T. J. Barton. J. Am. Chem. SOC.,89,5480(1967). (5) G.R. Krow and K. C. Ramey, Tetrahedron Lett., 3141 (1971). (6)L. A. Paquatte. T. J. Barton, and E. B. Whipple, J. Am. Chem. Soc., 89,5481 (1967);L. A. Paauette, J. R. Malpass, G. R. Krow, and T. J. Barton, ibid., 91,5296 (1969): (7)L. A. Paauette, S. Kirschner, and J. R. Malpass, J. Am. Chem. SOC.,91, 3970 (1969). (8)R. Hoffmann and W.-D. Stohrer. J. Am. Chem. SOC..93, 6941 (1971). (9)M. J. S.Dewar and W. W. Schoeller, J. Am. Chem. Soc.. 93,1481 (1971); M. J. S. Dewar and D. H. Lo, ibid., 93,7201 (1971). (IO)M. J. Goldstein and R. Hoffmann, J. Am. Chem. SOC.,93,6193 (1971). (1 1) J. C. Barborak. S.Chari, and P. v. R. Schleyer, J. Am. Chem. Soc., 93,5275 (1971). (12)(a) L. A. Paquette. R. E. Wingard. Jr., and R. K. Russell, J. Am. Chem. Soc., 94,4739 (1972);(b) L. A. Paquette, D. R. James, and G. H. Birnberg. J. chefn. Soc., the" Commun., 722 (1974); (c) D. R. James, G. H. Birnberg. (d) R. E. Wingard. and L. A. Paquette, J. Am. Chem. Soc., 96,7465 (1974); Jr.. R. K. Russell, and L. A. Paquette. ibid., 96,7474 (1974).
auette. J. Ora. Chem.. 41. 57 11976). i. E. 2imme;man. R. S.Givens, and'R. M. Pagni, J. Am. Chem. Soc., 90,
6096 (1968). M. Karplus, J. Chem. Phys., 30, 1 1 (1959);J. Am. Chem. SOC.,85,2870
(1 963).
S.J. Cristol and B. B. Jarvis. J. Am. Chem. SOC.,89, 401 (1967). See, for example, G. Stork and W. N. White, J. Am. Chem. Soc.. 78,4609 (1956):C. W. Jeffwd, S. N. Mahajan, and J. Gunsher, Tetrahedron, 24,2921 (1968). C. 0.Bender and S.S.Shugarman. J. Chem. SOC.,Chem. Commun., 934 (1974).
S.J. Cristol. G. C. Schloemer, D. R. James, and L. A. Paquette. J. Org. Chem., 37,3852 (1972). See, for example, H. Vorbruggen, Tetrahedron Lett., 1631 (1968). Oxymercuration is an important exception: F. R. Jensen, J. J. Miller, S.J. Cristoi, and R. S. Beckley. J. Org. Chem., 37,4341 (1972). S.J. Cristol. R. P. Arganbright, and D. D. Tanner, J. Org. Chem., 28,1374 (1963);D. D. Tanner and B. G. Brownlee, J. Am. Chem. SOC.,88, 771
(1966). W. R. Vaughan and A. C. Schoenthaler, J. Am. Chem. SOC.,79, 5777 (1957);W. R. Vaughan and A. C. Schoenthaler, ibid., 80,1956 (1958);S. J. Cristol, F. P. Parungo. D. E. Plorde, ibid., 87,2870(1965); S. Masson and A. Thuiller, Bull. SOC.Chim. Fr., 4368 (1969);A. Hassner, R. P. Hoblitt, C. Heathcock. J. E. Kropp, and M. Lwber, J. Am. Chem. Soc., 92,1326(1970); E. Zbiral and A. Stutz, Tetrahedron. 27,4953 (1971). (39)L. A. Paquette, R. K. Russell. and R. L. Burson. ./.'Am. Chem. Soc..97,6124 (1975). (40)E. Wenkert, E. W. Hagaman, L. A. Paquette, R. E. Wingard, Jr.. and R. K. Russell, J. Chem. SOC.,Chem. Commun., 135 (1973). (41)M.A. Beno and G. G. Christoph, manuscript in preparation. (42)Y. C. Wang and S. H. Bauer, J. Am. Chem. SOC.,94,5651 (1972). (43)The coupling constants have been assigned by analogy: C. W. Jefford and K. C. Ramey, Tetrahedron, 24,2927 (1968). (44)S.J. Cristol and N. L. Hause, J. Am. Chem. SOC.,74,2193 (1952); S.J. Cristol, R. P. Arganbright, G. D. Brindell. and R . M. Heitz, ibid.. 79, 6035 (1957).
Paquette, Volz
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Chlorocyanation of Barrelenes
