COMMUNICATIONS
[3] K. D. Ginzel, E. Steckhan, D. Degner, Tetrahedron 1987, 43, 5797; T.
Shono, Y. Matsumura, O. Onomura, Y. Yamada, Synthesis 1987, 1099.
[4] J. Yoshida, T. Maekawa, T. Murata, S. Matsunaga, S. Isoe, J. Am.
Chem. Soc. 1990, 112, 1962; J. Yoshida, Top. Curr. Chem. 1994, 170, 39.
[5] E. Meggers, E. Steckhan, S. Blechert, Angew. Chem. 1995, 107, 2317;
Angew. Chem. Int. Ed. Engl. 1995, 34, 2137.
[6] M. A. Brumfield, S. L. Quillen, U. C. Yoon, P. S. Mariano, J. Am.
Chem. Soc. 1984, 106, 6855.
Scheme 5. Model for stereochemical control of the protonation step.
[7] Y. M. Tsai, K.-H. Tang, W.-T. Jiaang, Tetrahedron Lett. 1996, 37, 7767;
D. P. Curran, W.-T. Jiaang, M. Palovich, Y.-M. Tsai, Synlett 1993, 403.
[8] J. M. Harris, I. MacInnes, J. C. Walton, B. Maillard, J. Organomet.
Chem. 1991, 403, C25.
[9] Reduction potentials of the most important sensitizers: H. D. Roth,
Top. Curr. Chem. 1992, 163, 131; S. L. Murov, J. Carmichael, G. L.
Hug, Handbook of Photochemistry, 2nd ed., Marcel Dekker, New
York, 1993.
[10] G. Gutenberger, Diploma Thesis, Universität Bonn 1996; see also
ref. [4].
[11] S. Tazuke, N. Kitamura, J. Chem. Soc. Chem. Commun. 1977, 515; T.
Majima, C. Pac, A. Nakasone, H. Sakurai, J. Am.Chem. Soc. 1981, 103,
4499.
In addition to the intermolecular additions to electron-poor
alkenes described here, intramolecular cyclization of a-silyl
ethers having electron-poor double bonds also seems promis-
ing.
Experimental Section
General conditions for PET reactions: A jacketed Schlenk tube was
charged with a solution of the a-silyl ethers 1 ± 5 in acetonitrile/methanol
(2/1) containing ADC (4 mol%) and BP (10 mol%). The electron-poor
alkenes 6 and 7, each dissolved in 3 mL of CH3CN, were added before
irradiation, solutions of 8 ± 10 were added dropwise during irradiation. A
450W xenon-arc lamp with a wavelength filter (l > 345 nm) was used as a
light source. The solutions were degassed with argon prior to and during
irradiation and thermostated by water-cooling.
[12] J. P. Dinnocenzo, S. Farid, J. L. Goodman, I. R. Gould, W. P.Todd, S. L.
Mattes, J. Am. Chem. Soc. 1989, 111, 8973.
11: (analogous for 12 ± 15 and 20): A mixture of 1 (350 mg, 2.9 mmol), 6
(543 mg, 4.3 mmol), BP (45 mg), and ADC (7 mg) was dissolved in 20 mL
of acetonitrile and 10 mL of methanol. During subsequent irradiation for
11 h two 10-mg portions of ADC were added every 3 ± 4 h (27 mg total).
Evaporation of the solvent followed by flash chromatography on silica gel
(first separation: ethyl acetate/n-heptane 1/5; Rf 0.31), (second separa-
tion: petroleum ether/dichloromethane 2/1; Rf 0.1)) provided 228.5 mg
Heck Reactions without Salt Formation:
Aromatic Carboxylic Anhydrides as
Arylating Agents**
(46%) of a light yellow oil. The signal doubling observed in the 1H and 13
C
NMR spectra indicates the formation of diastereomers. The data for the
1
Massoud S. Stephan,* Antonius J. J. M. Teunissen,
Gerard K. M. Verzijl, and Johannes G. de Vries*
diastereomers are separated by slashes. H NMR (400 MHz, CDCl3): d
0.98/1.05 (d, J 6.8 Hz, 3H), 2.45 ± 2.6 (m, 1H), 3.18 ± 3.22 (1H), 3.25/3.3 (s,
3H), 3.31 ± 3.4 (m, 1H), 3.51/3.9 (d, J 4.2 Hz, 1H), 3.73/3.75 (s, 3H); 13C
NMR (100.6 MHz, CDCl3): d 12.9/14.9, 34.6/35.1, 40.2/41.3, 53.1/53.3,
58.9/59.0, 74.0, 114.8/115.4, 166.2/166.6; MS (EI, 70 eV): m/z (%): 171 (1)
The Friedel-Crafts reaction is still the most commonly used
method for the attachment of a carbon fragment to an
aromatic ring. From an industrial point of view the reaction is
less desirable because of the highly corrosive conditions and
the concomitant formation of a large amount of waste.
Recently the Heck reaction has come into the spotlight as a
means of arylating double bonds.[1] Though the reaction has a
wide scope, the arylating agent is limited to aryl bromides,
iodides, or triflates, aroyl halides, arylsulfonyl halides, and
aryldiazonium salts. In all cases a stoichiometric amount of
base is required to neutralize the acid that is formed during
the reaction. In addition, an equivalent amount of halide salt
is formed as waste.
The development of a stable palladium catalyst, based upon
a palladacycle, has allowed the conversion of activated aryl
chlorides with high turnover numbers and has brought the
Heck reaction into the industrial realm.[2] But also in this
reaction a stoichiometric amount of chloride salt is formed as
waste product. There clearly is a need for a cheap aryl source
that does not lead to the formation of halide salts in the Heck
reaction.
[M ], 140 (7), 109 (7), 72 (58), 45 (100); HRMS (EI, 70 eV): calcd for
C8H13NO3: 171.0895; found 171.0890; CHN analysis calcd for C8H13NO3: C
56.13, H 7.65, N 8.18; found C 56.40, H 7.83, N 7.64.
18: (analogous for 16, 17, and 19): A mixture of 4 (348 mg, 1.6 mmol), ADC
(21.8 mg, 0.09 mmol), and BP (24.6 mg, 0.16 mmol) were dissolved in
20 mL of acetonitrile and 10 mL of methanol. A solution of 9 (300 mg,
2.4 mmol) in 3 mL of CH3CN was added dropwise to the reaction mixture,
which was irradiated for 18 h. Evaporation of the solvent and subsequent
flash chromatography on silica gel (cyclohexane/ethyl acetate 10/1; Rf
0.05) provided 115 mg (18%) of a light yellow oil. The data refer to the cis
product. The relative configuration was determined by NOE experiments.
1H NMR (500 MHz, C6D6): d 0.11 (s, 3H), 0.09 (s, 3H), 0.70 (s, 9H),
1.26 (d, J 6.9 Hz, 3H), 2.76 ± 2.85 (m, 2H), 2.88 (s, 3H), 3.42 ± 3.45 (dd,
J 10.0 Hz, J 2.0 Hz, 1H), 3.86 ± 3.89 (dd, J 10.0 Hz, J 3.2 Hz, 1H);
13C NMR (100.6 MHz, CDCl3): d 181.1, 179.0, 60.4, 47.1, 37.6, 26.0, 25.1,
18.3, 9.7, 5.2, 5.3; MS (EI, 70 eV): m/z (%): 270 (1) [M
H], 256 (41),
214 (100), 156 (4), 129 (4), 75 (14); HRMS (EI, 70 eV): calcd. for
C13H25NO3Si: 271.1603; found: 256.1371 [M
15]; CHN analysis calcd for
C13H25NO3Si ´ 1/6H2O: C 57.53, H 9.28, N 5.16; found: C 56.99, H 9.26, N
5.27.
Received: September 12, 1997 [Z10916IE]
German version: Angew. Chem. 1998, 110, 679 ± 681
Keywords: electron transfer ´ photochemistry ´ radical ions
´ silicon
[*] Dr. M. Stephan, Dr. J. G. de Vries, A. J. J. M. Teunissen,
G. K. M. Verzijl
DSM Research, Dept. Fine Chemicals
PO Box 18, NL-6160 MD Geleen (The Netherlands)
Fax: (31)46-476-7604
[1] J. E. Saavedra in Umpoled Synthons (Ed.: T. A. Hase), Wiley, New
York, 1987.
[2] P. Sommerfeld, D. Hoppe, Synlett 1992, 764; W. Guarnieri, M. Grehl,
D. Hoppe, Angew. Chem. 1994, 106, 1815; Angew. Chem. Int. Ed. Engl.
1994, 33, 1734.
[**] We thank Dr. Paul L. Alsters for stimulating discussions.
662
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