Organometallics
NOTE
lengths in both complexes did not change from those in complex
1a itself,10 and neither the oxygen nor nitrogen atom coordinated
to the Cr atom. When complex 2aa was exposed to sunlight in the
air for a day, complete demetalation occurred, and ethyl 2-phe-
nylethyl ether was quantitatively obtained.
In conclusion, we elucidated that the (styrene)Cr(CO)3 com-
plexes underwent regioselective nucleophilic addition of various
heteronucleophiles such as alcohols, amines, and thiols, and the
corresponding products were obtained in moderate to excellent
yields. The structural details and features of the product com-
plexes were also elucidated.
(5) When complex-free styrene was tested under the conditions of
entry 5 in Table 1, no reaction proceeded.
(6) We checked the inverse reaction: when complex 2aa was
submitted to the same reaction conditions of entry 5 in Table 1,
(styrene)Cr(CO)3 complex 1a was obtained in 14% yield along with
the recovery of complex 2aa (78%).
(7) We examined the reaction under nonprotic conditions using
EtONa as a nucleophile and MeI as a trapping agent of the carbanion,
but no addition product was detected.
(8) The reaction of 1a did not proceed at 40 °C.
(9) We also checked the inverse reaction of thiol-adduct 4aa, but
complex 1a was not obtained at all.
(10) Brown, G. M.; Frazier, C. C. Acta Crystallogr. 1989, C45, 1158.
’ EXPERIMENTAL SECTION
Experimental Procedure for a Nucleophilic Addition of
EtOH. (Styrene)Cr(CO)3 (1a) (20.4 mg, 0.085 mmol), KOH (7.2 mg,
0.13 mmol), and EtOH (0.10 mL, 1.7 mmol) were dissolved in THF
(0.20 mL) in a Schlenk tube. The solution was stirred at 60 °C for 45 h.
After the volatiles were evaporated, the obtained crude products were
purified by thin-layer chromatography (hexane/AcOEt, 5/1) to give
analytically pure 2aa (77%) as a yellow solid.
’ ASSOCIATED CONTENT
S
Supporting Information. Complete experimental proce-
b
dures, spectral characterization for arene-Cr(CO)3 as β-addition
products, and X-ray structural details for complexes 2aa and 3aa.
This material is available free of charge via the Internet at http://
pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*Tel and Fax: þ81-3-5286-8098. E-mail: tshibata@waseda.jp.
’ ACKNOWLEDGMENT
M.O. is grateful to the Japan Society for the Promotion of
Science for the fellowship support. This work was also supported
by a Waseda University Grant for Special Research Projects.
’ REFERENCES
(1) (a) K€undig, E. P. Transition Metal Arene π-Complexes in Organic
Synthesis and Catalysis; Springer-Verlag: Heidelberg, Germany, 2004.
(b) Abel, E. W.; Stone, F. G. A.; Wilkinson, G. Comprehensive Organo-
metallic Chemistry II; Pergamon: New York, 1995; Vol. 12, Chapter 9.
(c) Polunin, K. E.; Schmalz, H.-G. Russ. J. Coord. Chem. 2004, 30, 252.
(2) (a) Semmelhack, M. F.; Seufert, W.; Keller, L. J. Am. Chem. Soc.
1980, 102, 6584. (b) Uemura, M.; Minami, T.; Hayashi, Y. J. Chem. Soc.,
Chem. Commun. 1984, 1193. (c) Gibson, S. E.; Jefferson, G. R.; Prechtl,
F. J. Chem. Soc., Chem. Commun. 1995, 1535. (d) Gibson, S. E.; Gil, R.;
Prechtl, F.; White, A. J. P.; Williams, D. J. J. Chem. Soc., Perkin Trans. 1
1996, 1007. (e) Dehmel, F.; Lex, J.; Schmalz, H. -G. Org. Lett. 2002, 4,
3915.
(3) Byers, J. H.; Janson, N. J. Org. Lett. 2006, 8, 3453.
(4) As far as we know, there is no example of the nucleophilic
addition of oxygen and sulfur nucleophiles to (styrene)Cr(CO)3 com-
plexes. There are only a few examples of the addition of nitrogen nucleo-
philes to styrene derivativeꢀCr(CO)3 complexes: (a) Blagg, J.; Davies,
S. G. J. Chem. Soc., Chem. Commun. 1985, 653. (b) Sainsbury, M.; Williams,
C. S.; Naylor, A.; Scopes, D. I. C. Tetrahedron Lett. 1990, 31, 2763.
(c) Sainsbury, M.; Mahon, M. F.; Williams, C. S.; Naylor, A.; Scopes,
D. I. C. Tetrahedron 1991, 47, 4195.
3685
dx.doi.org/10.1021/om200268v |Organometallics 2011, 30, 3683–3685