C. Galli et al.
FULL PAPER
tion of the nature and yield of the hydrodehalogenated product(s).
From 2a, only 3 was obtained; from 2b, only 5 was obtained. No
difference was observed at a shorter or longer sampling time.
Ϫ
1H NMR (CDCl3): δ ϭ 7.1Ϫ6.9 (bs, 3 H, ArH), 3.9 (s, 2 H,
ArCH2CO), 2.2 (s, 6 H, ArCH3), 1.18 (s, 9 H, CMe3). Ϫ MS; m/z:
204 (Mϩ), 147 (Mϩ Ϫ CMe3), 119 (Mϩ Ϫ COCMe3), 85
(COCMe3ϩ), 57 (CMe3ϩ). Preliminary GC-MS and GC analyses
of the crude mixture of this reaction had revealed the formation of
a sizeable quantity (13%) of m-xylene 11.
Synthesis of the Products of the SRN1 Reaction: meta-Xylene 11 is
commercially available. An apparently sound synthetic strategy to
obtain reaction products 7 and 9 was through the SRN1 reaction of
13 with the enolate ion of pinacolone, to give the pinacolyl-substi-
tuted aniline 14. Diazotisation of this, followed by iododediazotis-
ation, would give 7 (Scheme 14), while hydrodediazotisation would
give 9.
Acknowledgments
Financial support from the Italian Ministry of Universities and
Scientific and Technological Research (MURST) is gratefully
acknowledged.
[1]
C. Galli, T. Pau, Tetrahedron 1998, 54, 2893Ϫ2904.
[2]
M. G. Evans, M. Polanyi, Trans. Faraday Soc., 1938, 34,
11Ϫ24.
[3]
H. C. Brown, C. W. McGary, J. Am. Chem. Soc. 1955, 77,
2310Ϫ2312.
[4]
[4a] D. Crich, F. Recupero, J. Chem. Soc., Chem. Commun. 1998,
Scheme 14
[4b]
189Ϫ190. Ϫ
D. Crich, J.-T. Hwang, S. Gastaldi, F. Recup-
ero, D. J. Wink, J. Org. Chem. 1999, 64, 2877Ϫ2882.
[5]
[6]
See also: X. Chen, H. Yamataka, C. Galli, Z. Rappoport, J.
Chem. Soc., Perkin Trans. 2 1999, 1369Ϫ1373.
Unfortunately, the photostimulated SRN1 reaction[10d] of 13 with
[6a] J. F. Bunnett, Acc. Chem. Res. 1978, 11, 413Ϫ420. Ϫ
J.-
[6b]
Ϫ
Me3CCOCH2 gave only a trace amount of 14, thus supporting a
[6c]
´
M. Saveant, Acc. Chem. Res. 1980, 13, 323Ϫ329. Ϫ
R. A.
previous report on adverse effects of an NH2 substituent on the
viability of an aryl halide SRN1 process.[9] In order to circumvent
this problem, we carried out an SRN1 reaction of 2a (0.041 ) with
Rossi, R. H. de Rossi in Aromatic Substitution by the SRN
1
Mechanism, ACS Monograph 178, American Chemical Soci-
ety; Washington, DC, 1983.
[7]
[7a] S. G. Lias, H. M. Rosenstock, K. Draxl, B. W. Steiner, J. T.
Herron, J. L. Holmes, R. D. Levin, J. F. Liebman, S. A. Kafafi
in Ionization Energetics Data, NIST Standard Reference Data-
base Number 69 (Eds.: W. G. Mallard and P. J. Linstrom), Na-
Ϫ
Me3CCOCH2 (0.062 ) in DMSO (55 mL, distilled from CaH2)
under photostimulation with 16 ‘350’ nm lamps for 20 min.[10d]
Conventional workup with brine and diethyl ether, followed by re-
moval of the organic solvent, gave a crude mixture of products,
which was chromatographed on silica gel with petroleum ether
(40Ϫ70 °C) to separate a mixture of 3 ϩ 4, followed by a small
amount of unchanged 2a, along with a small amount of 9; the
latter was characterized by its GC and GC-MS retention times and
MS spectrum (m/z 204). The residue of this chromatography was
chromatographed once more on silica gel with a toluene/hexane 1:3
eluent and, as a first pure fraction, afforded 15 mg of 7 as an oil.
tional Institute of Standard and Technology, Gaithersburg,
[7b]
MD, 1997 (http://webbook.nist.gov). Ϫ
J. E. Bartmess in
NIST Negative Ion Energetics Database, Version 3.0, Standard
Reference Database 19B, National Institute of Standard and
[7c]
Technology, Gaithersburg, MD, 1993. Ϫ
K. D. Jordan, P.
[7d]
D. Burrow, Acc. Chem. Res. 1978, 11, 341Ϫ348. Ϫ
Chem.
[7e]
Rev. 1987, 87, 557Ϫ588. Ϫ
K. L. Stricklett, S. C. Chu, P.
D. Burrow, Chem. Phys. Lett. 1986, 131, 279Ϫ284.
C. Galli, P. Gentili, Acta Chem. Scand. 1998, 52, 67Ϫ76.
J. F. Bunnett, J. E. Sundberg, Chem. Pharm. Bull. 1975, 23,
2620Ϫ2628.
[8]
[9]
Ϫ
1H NMR (CDCl3): δ ϭ 6.8 (bt, 2 H, ArH), 3.7 (s, 2 H,
ArCH2CO), 2.4 (s, 6 H, ArCH3), 1.2 (s, 9 H, CMe3); 13C NMR
[10] [10a]
J. F. Bunnett, R. P. Traber, J. Org. Chem. 1978, 43,
[10b]
1867Ϫ1872. Ϫ
J. F. Bunnett, S. J. Shafer, J. Org. Chem.
Ar
Ar
(CDCl3) 213 (CϭO), 147 (C -Me), 130 (C -pinac.), 128, 98 (C
ipso
ipso
[10c]
1978, 43, 1873Ϫ1877 and 1877Ϫ1879. Ϫ
R. R. Bard, J. F.
Ar
ipsoϪI), 45 (CMe3), 43 (ArCH2CO), 30 (ArCH3), 27.5 (Me3). Ϫ
MS; m/z: 330 (Mϩ), 273 (Mϩ Ϫ CMe3), 245 (Mϩ Ϫ COCMe3),
203 (Mϩ Ϫ I), 127 (Iϩ), 85 (COCMe3ϩ), 57 (CMe3ϩ).
Bunnett, R. P. Traber, J. Org. Chem. 1979, 44, 4918Ϫ4924. Ϫ
[10d]
C. Galli, P. Gentili, J. Chem. Soc., Perkin Trans. 2 1993,
1135Ϫ1140.
[11] [11a]
[11b]
R. A. Rossi, J. Chem. Educ. 1982, 59, 310Ϫ312. Ϫ
C.
´
P. Andrieux, J.-M. Saveant, D. Zann, Nouv. J. Chim. 1984, 8,
A sample of 6 (25 mg), slightly contaminated with 7, was eluted
107Ϫ116. Ϫ [11c] C. P. Andrieux, A. Le Gorande, J.-M. Saveant,
1
´
´
from the column next: H NMR (CDCl3): δ ϭ 7.4 (s, 2 H, ArH),
J. Am. Chem. Soc. 1992, 114, 6892Ϫ6904. Ϫ [11d] J.-M. Saveant,
3.8 (s, 2 H, ArCH2CO), 2.1 (s, 6 H, ArCH3), 1.27 (s, 9 H, CMe3).
Tetrahedron 1994, 50, 10117Ϫ10165.
Ar
13C NMR (CDCl3) δ ϭ 212 (CϭO), 140 (C -Me), 136, 131 (C
[12] [12a]
Ϫ
Ar
ipso
F. A. Beland, S. O. Farwell, P. R. Callis, R. D. Geer, J.
Electroanal. Chem. 1977, 78, 145Ϫ159. Ϫ [12b] E. F. Hilinski, P.
M. Rentzepis, Acc. Chem. Res. 1983, 16, 224Ϫ232.
ipso-pinac.), 96 (CiAprsoϪI), 45.5 (CMe3), 38 (ArCH2CO), 27 (Me3),
20 (ArCH3). Ϫ MS; m/z: 330 (Mϩ), 273 (Mϩ Ϫ CMe3), 245 (Mϩ
Ϫ COCMe3), 203 (Mϩ Ϫ I), 127 (Iϩ), 85 (COCMe3ϩ), 57 (CMe3ϩ).
[13] [13a]
W. J. Pietro, M. M. Francl, W. J. Hehre, D. J. DeFrees, J.
A. Pople, J. S. Binkley, J. Am. Chem. Soc. 1982, 104,
[13b]
Finally, 10 mg of 10 was separated: MS; m/z: 302 (Mϩ), 245 (Mϩ
Ϫ CMe3), 217 (Mϩ Ϫ COCMe3), 132 (Mϩ Ϫ 2 ϫ COCMe3), 85
(COCMe3ϩ), 57 (CMe3ϩ). Its 1H NMR spectrum compared very
well to the one reported in the literature.[16]
5039Ϫ5048. Ϫ
K. D. Dobbs, W. J. Hehre, J. Comput.
Chem. 1986, 7, 359Ϫ378.
[14]
Spartan 5.01, Wavefunction, Inc., 18401 Von Karman Ave.,
Ste. 370 Irvine, CA 92612 U.S.A.
[15]
[16]
C. Galli, J. Org. Chem. 1991, 56, 3238Ϫ3245.
R. A. Alonso, R. A. Rossi, J. Org. Chem. 1980, 45, 4760Ϫ4763.
Received February 17, 2000
Another SRN1 reaction was carried out as above with 4 (see Scheme
10), and gave 8 as an oil (45% yield) after column chromatography.
[O00078]
2668
Eur. J. Org. Chem. 2000, 2663Ϫ2668