ORGANIC
LETTERS
2009
Vol. 11, No. 9
1879-1881
Aerobic Photooxidation of Phosphite
Esters Using Diorganotelluride Catalysts
Makoto Oba,† Yasunori Okada,† Kozaburo Nishiyama,*,† and Wataru Ando*,‡
Department of Materials Chemistry, Tokai UniVersity, 317 Nishino, Numazu,
Shizuoka 410-0395, Japan, and National Institute of AdVanced Industrial Science and
Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
nishiyam@wing.ncc.u-tokai.ac.jp; wataru.ando@aist.go.jp
Received February 4, 2009
ABSTRACT
Diorganotellurides containing bulky aromatic substituents are found to catalyze the photooxidation of phosphite esters using aerobic oxygen
as a terminal oxidant. A Hammett plot with substituted triaryl phosphites yielding G ) 2.88 agrees with a nucleophilic oxygen transfer from
telluroxide to phosphite.
Oxidation reactions are a significant class of important and
essential chemical processes. In general, such reactions are
conducted using traditional inorganic and organic oxidants,
such as dichromates, permanganates, organic peroxides, etc.,
stoichiometrically.1 Recently, increasingly severe environ-
mental constraints have generated greater interest in the use
of environmentally benign molecular oxygen or hydrogen
peroxide as oxidants.2 Although oxidation of organic mol-
ecules by the ground-state triplet oxygen or hydrogen
peroxide is thermodynamically favored, they are not kineti-
cally competent to serve as an oxidant. Therefore, a large
number of catalytic strategies have been proposed to achieve
rate enhancement in the oxidation processes that have been
developed.3
triplet oxygen as a result of its low activation energy.
Furthermore, photosensitized oxygenations of organosulfur5
and phosphorus6 compounds have been extensively studied
with respect to their synthetic and mechanistic aspects.
However, reports explaining the use of singlet oxygen in
catalytic systems are still scarce. It was demonstrated
independently by Abatjoglou and Krief that diorganose-
lenides promoted the reoxidation of osmium(VI) to osmi-
um(VIII) using singlet oxygen in the olefin dihydroxylation
(3) For recent reviews, see: (a) Matsumoto, T.; Ueno, M.; Wang, N.;
Kobayashi, S. Chem. Asian J. 2008, 3, 196–214. (b) Imada, Y.; Naota, T.
Chem. Rec. 2007, 7, 354–361. (c) Schultz, M. J.; Sigman, M. S. Tetrahedron
2006, 62, 8227–8241. (d) Stahl, S. S. Angew. Chem., Int. Ed. 2004, 43,
3400–3420. (e) Sheldon, R. A.; Arends, I.W. C. E.; ten Brink, G.-J.;
Dijksman, A. Acc. Chem. Res. 2002, 35, 774–779.
Direct oxygenation of an organic substrate through singlet
oxygen via [2 + 2], [4 + 2], and ene additions is one of the
most often used pathways in organic synthesis,4 because the
reaction rate of singlet oxygen is much greater than that of
(4) (a) Clennan, E. L. Tetrahedron 2000, 56, 9151–9179. (b) Stratakis,
M.; Orfanopoulos, M. Tetrahedron 2000, 56, 1595–1615. (c) Wasserman,
H. H.; Ives, J. L. Tetrahedron 1981, 37, 1825–1852. (d) Prein, M.; Adam,
W. Angew. Chem., Int. Ed. 1996, 35, 477–494. (e) Adam, W.; Prein, M.
Acc. Chem. Res. 1996, 29, 275–283. (f) Schenck, G. O.; Eggert, H.; Denk,
W. Liebigs Ann. Chem. 1953, 584, 177–198. (g) Foote, C. S.; Wexler, S.
J. Am. Chem. Soc. 1964, 86, 3979–3981.
† Tokai University.
‡ National Institute of Advanced Industrial Science and Technology
(AIST).
(5) (a) Ando, W.; Takata, T. Photooxidation of Sulfur Compounds
Singlet Oxygen; Frimer, A. A., Ed.; CRC Press: Boca Raton, FL, 1985;
Vol. III, pp 1-117. (b) Clennan, E. L. Acc. Chem. Res. 2001, 34, 875–
884.
(1) (a) Haines, A. H. Methods for the Oxidation of Organic Compounds;
Academic Press: London, 1988. (b) Sheldon, R. A.; Kochi, J. K. Metal
Catalyzed Oxidation of Organic Compounds; Academic Press: New York,
1981.
(6) (a) Ho, D. G.; Gao, R.; Celaje, J.; Chung, H.-Y.; Selke, M. Science
2003, 302, 259–262. (b) Gao, R.; Ho, D. G.; Dong, T.; Khuu, D.; Franco,
N.; Sezer, O.; Selke, M. Org. Lett. 2001, 3, 3719–3722. (c) Tsuji, S.; Kondo,
M.; Ishiguro, K.; Sawaki, Y. J. Org. Chem. 1993, 58, 5055–5059.
(2) (a) Ba¨ckvall, J.-E. Modern Oxidation Methods; Wiley-VCH: Wein-
heim, 2004. (b) Eissen, M.; Metzger, J. O.; Schmidt, E.; Schneidewind, U.
Angew. Chem., Int. Ed. 2002, 41, 414–436.
10.1021/ol900240s CCC: $40.75
Published on Web 04/02/2009
2009 American Chemical Society