J . Org. Chem., Vol. 35,No. 19, 1970 4283
NOTES
TABLE I ISOLATION OF THE ALDOXIMES AND NITROOLEFINS@ NHOH
RCHO
I + ArCHCH2N02 ---t anti-RCH=NOHb + ArCH=CHNOa 5
4 Run
Compd 4 R
Yield, MP, ' C
Lit. mp,
O C
70
Compd 6 Ar
Yield, Mp, OC
Lit. mp, OC
%
45 2-Fury1 74-75 74-75m 35 2-Thienyl 79-80 79-80" 73 Phenyl 56-57 57-580 C 50 3,4-Methylene159-160 158" d dioxyphenyl 58 5-Sitro-2-thienyl 74 156.5-157. 5 h 47 2-Fury1 e 157-158 35 f 74 5-Xitro-2-pyrryl 16@ 55 2-Fury1 179-180 dec 44 4-Xitrophenyl 72 2-Fury1 74-75 176d 176i R 97 h (5-Nitro-2-fury1)vinyl 167-168# 163k 64 2-Fury1 74-75 83 i (2-Nitropheny1)vinyl 148' 138l 83 2-Fury1 73-75 a The products were isolated by column chromatography on silica gel, Materials from runs a-d were eluted with benzene-chloroform (4: 1) while runs e-i were eluted with benzene-acetonitrile (9: 1). Purities were determined by tlc (Eastman chromagram sheet, 6060 silica gel) using the same solvent system as the columns. b Syn is the isomer having the hydroxyl cis to the hydrogen: S. W. Tinsley, J . Org. Chem., 26,4723 (1961). 0 Syn oxime, mp 119-120, (reportedI4mp 121). d Syn oxime, mp 129-131 (reportedI6 mp 129). h Reference 18. Reference 0 See ref 4b. e Syn oxime, mp 160 (reported20mp 156). f Syn oxime, mp 131-133 (reported'6" mp 134). 25. Reference 17. Reference 14. Reference l5b. Reference 3. Reference 11. 0 Reference 12. p Reference 13. a b
5-Nitro-2-fury1 5-Nitro-2-fury1 5-Nitro-2-fury1 5-Nitro-2-fury1
158-160c 155-156' 158-160c 135-158"
159-1610
65 54 46 47
benzaldoxime, syn and anti isomers of 5-nitrof~raldoxime,~ 5nitro-2-thiophene carboxaldehyde oxime,'* and 5-nitro-2-pyrrolecarboxaldehyde oxime1Qwere prepared according t o the literature. Rearrangement to anti-Aldoximes and Nitro Olefins. General Procedure.-A solution of nitroaromatic carboxaldehyde (1, Experimental Section 25 mmol) and N - ( 1-aryl-2-nitroethy1)hydroxylamine (2, 25 hlelting points were taken in open capillary tubes using a mmol) in absolute EtOH was stirred at 0'. The reaction temperThomas-Hoover melting point apparatus and are uncorrected. ature was gradually brought to room temperature and the solution Infrared spectra were obtained with a Beckman IR-5 infrared was stirred overnight. Tlc of the reaction mixture showed two spectrophotometer (KBr). Nmr spectra were obtained with a spots corresponding to nitro olefin and aldoxime. The crude Varian A-60 spectrometer, using MerSi as an internal standard. product was chromatographed on a silica gel columnz0 (100 g, Evaporation of solvents was done under reduced pressure using a 4.3 X 18 cm) with eluents described in Table I. The nitro olefin rotary evaporator. was always eluted first, Recrystallization of the products from Starting Materials.-The nitro olefins 2-(2-nitro~inyl)furan,~ appropriate solvents gave pure material. Results are shown in 3:(nitrovinyl)thiophene,l' w-nitrostyrene,la and 3,4-(methyleneTable I. dioxy)-P-nitrostyrene13 were prepared according t o the literature. K-(1-Thienyl-2-nitroethy1)hydroxylamine (2b).-2b was preRegistry No.-2b, 26153-96-8; 2d, 26153-97-9; 5e, pared by a procedure of Hurd and Patterson2 from 2-(2-nitro699-18-3. viny1)thiophene (62.07 g, 0.40 mol). Recrystallization of the crude product from 2-propanol gave a white solid (31.60 g, 42%): mp 61-62'; vmax 3311, 3125 (-"OH), 1550, and (18) E. C. Hermann, U. 8. Patent 2,649,461 (1953); Chem. Abslr., 48, 1370 cm-l (NOS); nmr (CDCls) 8 7.48 (9, 1 H , thienyl Hb), 8264 (1954). (19) P. Fournari and J. Tirouflet, Bull. SOC.Chim. Fr., 484 (1963); Chem. 7.16 (t, 2 H, thienyl Hd and H3), 6.28, 5.83 (2 s, 2 H, exAbstr., 69, 1570 (1963). and 4.49 (m, 3 H, -CHCHZNOZ). changeable with DzO, -"OH), (20) Silica gel was purchased from Gebr. Hermann, D 5000 Koln-EhrenAnal. Calcd for C&NZO~S: C, 38.29; H, 4.28; N, 14.89; feld, Grtiner Weg 8-10, Weat Germany, under the name kieselegel. S, 17.04. Found: C,38.18; H , 4.16; N, 14.95; S, 17.18. K-( 1-Piperonyl-2-nitroethy1)hydroxylamine(2d).-This compound was obtained from 3,4-(methylenedioxy)-~-nitrostyrene (19.32 g, 0.10 mol) in a manner similar t o that described for 2b. Recrystallization of the product from absolute EtOH gave a Formation af Cyclopentadienone Oxime1 white solid (14.34 g, 63y0): mp 95-96'; vmaX 3425, 3226 (-"OH), 1563, 1381 (NOZ), and 1247 cm-1 (-CO-); nmr (CDC13) 6 7.37 (s, 1 H, Hz), 6.92 (s, 2 H, HE and He), 6.07 (s, B. W. PONDER* AND P. L. WALKER 2 H, -CHZ-), 8.45 (b, -"OH), and 4.78 (m, -CHCH,NOz) (total area = 5 H). Department of Chemistry, University of Alabama, Anal. Calcd for CqH10jS205:C, 47.79; H, 4.46; N, 12.39. University, Alabama 56.486 Found: C,47.89; H,4.53; jS,12.31. Nitroaromatic Carboxaldehyde Oxirne~.-Syn~~ and anti isomers of 5-nitrofuranacrolein oxime, o-nitrocinnam-syn-aldoxReceived May 16, 1970 imeIKaand anti-ald~xime,~~b synX6and anti" isomers of p-nitro-
hopelessly mixed with the vinyl protons. As a result, assignments were made by melting points.
(11) W. J. King and F. F. Nord, J . O m . Chem., 14,405 (1949). (12) H. Gilman and .4. H. Blatt, "Organic Syntheses," Call. Vol. I, Wiley, New York, N . Y., 1941,p 413. (13) W. Wiegrebe, Arch. Pharm., 297, 362 (1964); Chem. Abstr., 61,
6988 (1964). (14) M . Ikeda, A n n . R e p . Fac. Pharm. Kanazawa Univ., 8, 25 (1953); Chem. Abstr., 60,10701 (1956). (15) (a) 0. L. Brady and C. D. Thomas, J . Chem. SOC.,121, 2098 (1922); (b) 0 L.Brady and H. J. Grayson, ibid., 126, 1418 (1924). (16) 0. L.Brady and F. P. Dunn, %bid., 108, 1619 (1913). (17) (a) A. Raoult and M . Vilkas, Bull. S O C . Chim. Fr., 3315 (1968); (b) hl. 0. Forster and F. P. Dunn, J . Chem. Soc., 96,425 (1909).
Considerable interest has been focused in recent years on the highly elusive cyclopentadienone molecule 1. The extreme reactivity of this dienone as predicted by molecular orbital calculations2 has been borne out experimentally by several unsuccessful attempts to isolate
* To whom correspondence should be addressed. (1) Presented in part a t the Southeastern Regional meeting of the American Chemical Society, Richmond, Va., Nov 5, 1969. (2) W. C. Herndon and L. H . Hsll, Theor. Chim. Acta, 1, 4 (1967),and references cited therein.
4284
J. Org. Chem., Vol. 35, No. 12, 1970
ita3 Although the monomeric species has but fleeting existence, it has been successfully trapped and was found to react almost exclusively as a dienophile in the Diels-Alder dimerization reaction. More recently Garbisch and Sprecher4 reported the isolation of monomeric 3-tert-butyl- and 2,4-di-tert-butylcyclopentadienone. I n these cases, dimerization is retarded by the bulky lert-butyl groups. We wish to report the generation and trapping of a simple, unsubstituted carbonyl derivative of 1, namely cyclopentadienone oxime (2). The transient existence of this monomer has been implied p r e v i ~ u s l y . ~ NOH
1
6
NOTES mp 86-88', in 30% yield. The infrared and nmr spectra confirmed the assigned structure. The chloronitroso dimer 3 and cylcopentadiene do not react under the above conditions in the absence of triethylamine and neither is 4 transformed to 5 in the presence of triethylamine and cyclopentadiene; so it is quite obvious that cyclopentadiene is acting as a trap for the highly reactive monomeric oxime 2. It is interesting to note that only one isomer ( 5 ) is observed in the trapped product; the isomer formed results from cyclopentadienone oxime acting as a dienophile. Numerous attempts to force it to react as a diene, by trapping it with reactive dienophiles such as tetracyanoethylene, tetrachloroethylene, maleic anhydride, etc., were unsuccessful, and led only to the dioxime 4. Thus, cyclopentadienone oxime shows remarkable similarity to cyclopentadienone in its reactivity and stability.
2
The addition reaction of nitrosyl chloride and cyclopentadiene in diethyl ether at - 10" led t o the chloronitroso dimer 3, mp 115-134°, in 92% yield.6 When a refluxing ether solution of this chloronitroso dimer was treated with triethylamine, an immediate precipitate of triethylamine hydrochloride was observed and, after stirring overnight, a quantitative yield of the dioxime5 4 was obtained. A number of attempts in our laboratories to generate and isolate the monomeric oxime at low temperatures have thus far been unsuccessful. The transient existence of the monomer 2 has, however, been shown by trapping experiments. When an ether solution of 3, cyclopentadiene, and triethylamine is held at -30" for 24 hr, the slow formation of triethylamine hydrochloride is observed. Warming this reaction mixture to - 10" resulted in a much faster reaction and an almost quantitative yield of triethylamine hydrochloride. Removal of this salt by filtration and evaporation NOH
Experimental Section7 Chloronitroso Dimer of Cyclopentadiene (3).-Dry carbon tetrachloride (500 ml) was deoxygenated by bubbling a slow stream of dry, oxygen-free nitrogen through for 30 min. The solvent was then cooled to -lo", and 23.25 g (0.35 mol) of freshly distilled cyclopentadiene8 was added under an atmosphere of dry nitrogen. With vigorous stirring, 21 g (0.32 mol) of nitrosyl chloride, which had previously been collected as a liquid in a Dry Ice-acetone trap, was allowed to vaporize into the reaction flask at a rate so as t o maintain the temperature below -5'. After addition was complete, the solution was held at - 10" and stirring was continued for 3 hr. The precipitate was filtered with suction and air-dried to give 34.9 g of a white solid,@ mp 115-134'. Concentration of the filtrate led to an additional 3.8 g of product, making the overall yield 38.7 g (92%): uv max (EtOH) 292 m,u; ir (KBr) 1230, 1260 cm-l (trans azodioxy linkage). Anal. Calcd for CloHlzClzNzOI: C, 45.62; H, 4.56; C1, 26.96; N , 10.65. Found: C, 45.39; H, 4.29; C1, 26.48; N, 10.60. endo-3,lO-Dioximinotricyclo[5.2.1.0236]deca-4,s-diene (4).-A solution of 2.25 g (8.55 mmol) of the chloronitroso dimer 3 in 500 ml of anhydrous ether and 100 ml of methylene chloride was held at reflux and with rapid stirring, 1.73 g (17.1 mmol) of triethylamine was added rapidly. A light yellow solution was observed immediately, and a white precipitate of triethylamine hydrochloride started to form. Stirring and heating was continued for 8 hr, the solution was cooled, and the triethylamine hydrochloride precipitate was filtered with suction. Evaporation of the solvent from the filtrate led to a quantitative yield of the dioxime 4: mp 178-180" dec (lit.5 mp 178-180" dec; uv max (EtOH) 237 mp; ir (KBr) 1647 ((2-3, C=N), 1720 cm-' ('2-10,
C=N).
5
of the solvent led to a solid residue, which, when separated on a silica gel column, yielded two products: the dioxime 4, in 68% yield, and the trapped product 5 , (3) (a) M. A. Ogliaruso, M . G. Romanelli, and E. I. Becker, Chem. Rev., 66, 261 (1965); (b) C. H.DePuy, M. Isaks, and K . L. Eilers, Chem. I n d . (London), 428 (1861); (c) K. Hafner and K. Goliasch, Chem. Ber., 9 4 , 2500 (1961); (d) C. H.DePuy, M . Isaks, K. L. Eilers, and G. F. Morris, J . O w . Chem., 29, 3503 (1964). (4) (a) E. W.Garbisch and R . F. Sprecher, J . Amer. Chem. Soc., 88, 3433 (1966); (b) zbid., 91, 6785 (1969). (5) (a) 3 . Thiele, Be?., 33, 665 (1500); (b) W. Von E. Doering and C. H. DePuy, J . Amer. Chem. Soc., 711, 5995 (1953). (6) The nitroso chloride dimer 3 has been shown b y nmr analysis t o be a 54:46 mixture of products resulting from competing 1,2 and 1,4 addition. Further stereochemical characterization of these isomers is currently in progress, but both isomers undergo elimination t o yield the dioxime 4.
Trapping of Cyclopentadienone Oxime (2).-A solution of 2 g (7.6 mmol) of the chloronitroso dimer 3 and 8 g (0.12 mol) of freshly distilled cyclopentadiene in 100 ml of dry methylene chloride and 500 ml of dry ether was cooled to -30" and maintained at this temperature while 10 ml of triethylamine was added with rapid stirring. The reaction was held at -30' for 24 hr, during which time the slow formation of triethylamine hydrochloride was observed. The temperature was then brought to - l o o , which resulted in a much faster reaction and an almost quantitative yield of triethylamine hydrochloride. After removing this salt by suction filtration, the solvent was removed to yield a slightly yellow solid. Separation of this solid on a silica gel column using ether as eluent yielded the dioxime 4 (0.987 g, 687,) and the trapped product 5 , endo-3-oximinotricycl0[5.2.1.O~~~]deca-4,8-diene (0.714 g, 30%): mp 86-88'; ir (7) Melting points were determined on a Fisher-Johns apparatus and are uncorrected. Infrared spectra mere taken on a Perkin-Elmer Model 337 spectrophotometer. The nuclear magnetic resonance spectra were determined on a Varian HA-100 spectrometer using tetramethysilane as internal reference. Microanalyses were performed by Galbraith Laboratories, Inc., Knoxville, Tenn. (E) M. Korach, D. R . Xielsen, and 17'. H. Rideout, Org. Sun., 42, 50 (1962).
J. Org. Chem., Vol. 36, N o . i2,i970
NOTES (KBr) 3240 (broad, OH), 1650 cm-1 (C-3, C=N); nmr (CD3COCD3) 6 9.52 (s, 1, OH), 6.18 (d, 1, J = 6 Hz, C-5 H), 5.86 (d, 1, J = 6 Hz, C-4 H), 5.73 (m, 2, C-8, C-9 H), 3.33 (m, 1, C-1 H), 3.27 (m, 2, C-2, C-6 H), 2.86 (m, 1, C-7 H), 1.5 (m, 2, (2-10 H). Anal. Calcd for CloHllNO: C, 74.51; H, 6.88; N, 8.68. Found: C, 74.32; H, 6.75; N , 8.55.
Registry No.-Z, 26527-00-4; 3, 26523-38-6; 4, 26527-01-5; 5,26527-02-6.
Stereocbernical Studies in the sec-Butyl Systern. A n Unusual Reduction of a wic-Dibromide during Attempted Dehydrobromination DENNIS D. DAVIS*AND G. GHAUSANSARI Department of Chemistry, New Mmico State University, Las Cruces, New Mexico 88001 Received M a y 16, 1970
The preparation of optically active see-alkyl derivatives not available through resolutions and determinations of their configurations and rotatory powers have been the subject of recent ~ o r k . l - ~I n~ view of the partial success in predicting rotations and configurations by semiempirical mean^,^&-^ we desired several secbutyl compounds containing the phenyl group several carbon atoms removed from the asymmetric center. I n the present paper we report the synthesis of (8)( )-3-met hyl- 1-phenylpent ane and (8)- ( )-3-met hyl1-phenyl-1-pentene, relationships between their optical rotations and optical purities, and the observation of an unusual debromination-reduction reaction which occurs during the treatment of a vie-dibromide with sodamide. 1-(R,S)-3-(S)-(+)-3-h!Iethyl-l-phenyl-l-pentanol(1) was prepared by the addition of (S)-2-methyl-l-butylmagnesium chloride to benzaldehyde. I n our hands this reaction gave appreciably higher yield (65%) than an earlier literature preparation.6 The alcohol had [ a ]4-11.1" ~ (neat) and, based upon the optical purity of 83% for the starting 2-methyl-l-chlorobutane, a lower limit to the rotation of the optically pure alcohol is 13.3" (Table I). The configuration at C-1 is taken to be racemic since asymmetric induction due to the see-butyl group of the Grignard should be small. (X)-(+)-3Methyl-1-phenyl-1-pentene (2) was prepared by treating the alcohol with dry HC1 in ether at 0" and subsequent heating at 100" with pyridines7 The alkene fraction after distillation was shown to be the trans isomer by the C=C stretching mode at 1685 cm-l and the absence of the generally stronger absorption due to
+
+
4285
TABLE I ROTATIONS O F OPTICALLY PURE SeC-BuTYL DERIVATIVES Compda
[UIz0D
[aIz0D
min,b deg
r n & ~deg ,~
RCH&H(OH)Ph (1) f13.3 f13.8 trans-RCH=CHPh (2 ) +48.8 $50.5 RCHzCHzPh (3) $18.5 (+19.2)c erythro-RCHBrCHBrPh ( 5 ) f47.0 f48.6 a R is (8)-see-butyl. b For optically pure materials based upon the rotation of optically pure (8)-(+)-2-methyl-l-chlorobutane as [aI20n +1.64', see D. H. Brauns, J . Res. Nat. Bur. Stand., 18, 315 (1937). Estimated.
the cis isomer in the region 1650-1662 cm-l. The ~ (neat) and again, based upon alkene had [ a ]+40.7" the 2-methyl-1-chlorobutane optical purity of 83%, a minimum rotation at optical purity of 48.8" is calculated for 2. Low pressure hydrogenation of the alkene ( [ a ] ~ +40.7') in ethanol with Pt-C catalyst yielded (X)-(+)3-methyl-1-phenylpentane (3)) [ a ] ~ 15.4". Based upon a maximum optical purity of 83% for 2, the minimum rotation of 3 at optical purity is thus 18.5". This is somewhat higher than the value 17.2' observed by Klages and Sautter,s who followed a more drastic reduction scheme using sodium in ethanol. The alkene was oxidized by permanganate-periodate reagentg in 20% aqueous tert-butyl alcohol to yield 2-methylbutanoic acid [ a ]+l5.9" ~ (neat). On the basis of the literature ~ for (X)-2-methylbutanoic acid,1° value of [ a ]+19.8" the optical purity of the acid is 80.5%; thus a maximum value for the rotation of the alkene 2 is 50.5". The upper limit value is in good accord with the value of +50.3' reported by Klages and Sautter.8 The rotation at optical purity for the alkene, then, lies within the range 48.8-50.5". Synthesis of the corresponding alkyne, 3-methyl1-phenyl-1-pentyne (4), was attempted by dehydrohalogenation of 2,3-dibromo-&meth~~l-l-phenylpentane ( 5 ) . The dibromide was prepared by low temperature bromination of 2 in CHC1, in the dark. The product had a rotation of [ a ]+39.1°, ~ considerably higher than the literature8 value of 32". The dehydrohalogenation was carried out under a variety of conditions" to yield mainly the alkene or bromoalkene. No acetylenic products could be detected. However, in liquid ammonia-ether mixtures with sodamide, the resulting product appeared to be recovered alkene with a rotation of +31.8". The starting alkene had [ a ]+40.7" ~ and hence the product appeared to be partially racemized. Vapor phase chromatography, however, showed that the product was a 65335 mixture of alkene and alkane. Hydrogenation of this mixture yielded alkane with essentially the same rotation, +15.2', as obtained from hydrogenation of 2 directly, +15.4".
+
* To whom correspondence should be addressed. (1) D. G. Goodwin and H. R. Hudson, J . Chem. SOC.B , 1333 (1968). ( 2 ) P. Salvadori, L. Lardicci, and M . Stagi, Ric. Sci., 37, 990 (1967). (3) L. Lardicoi, C. Botteghi, and E. Benedetti, J . Org. Chem., 31, 1534 (1966). (4) P. S.Skell, R,. G. Allen, and G. Helmkamp, J. Amer. Chem. Soc., 82, 410 (1960). (5) (a) D. D. Davis and F. K. Jensen, J. Org. Chenz., 35, 3410 (1970). (b) J. H. Brewster J . Amer. Chem. Soc., 81, 5475, 5483 (1959). (0) T. R . Thomson, ibid., 76, 6076 (1953). (d) R . E. Marker, ibid., 68, 976 (1936). (6) W. C. Davies, R. 9. Dixon, and W. J . Jones, J . Chem. SOC.,468 (1930). (7) 9. Reich, R. Van Wyek, and C. Waelle, H e h . Chem. Acta, 4 , 244 (1921).
(8) A . Klages and R. Sautter, Ber., 37, 653 (1904). (9) R . V. Lemieux and E . Yon Rudloff, Can. J . Chem., 63, 1701, 1710 (1955).
(10) K. Freudenberg and W. Lwowski, Justus Liebigs Ann. Chem., 694, 76 (1955). (11) Various conditions were tried t o effeot the dehydrobromination: NaNHz, mineral oil, 160°; KOH, mineral oil, 250'; NaH, benzene, 80'; tert-BuOK, tert-BuOH, 8 5 O ; diethylaniline, benzene, 80'. The previous conditions resulted only in debromination t o form the alkene. KOH in either refluxing ethanol or methanol led to a mixture of alkene and l-bromo3-methyl-1-phenyl-I-pentene. Attempts t o further dehydrobrominate the bromoalkene in liquid ammonia with sodamide resulted in the formation of alkene.
