Organic Letters
Letter
reaction course; for photoinduced reduction of 4-benzoylpyridine in
alcohol solution, see: (a) Kegelman, M. R.; Brown, E. V. J. Am. Chem.
Soc. 1953, 75, 4649. (b) Bencze, W. L.; Burckhardt, C. A.; Yost, W. L.
J. Org. Chem. 1962, 27, 2865.
ASSOCIATED CONTENT
Supporting Information
■
*
S
General experimental procedure and characterization of
(7) (a) Albini, A.; Bortolus, P.; Fasani, E.; Monti, S.; Negri, F.;
̈
Orlandi, G. J. Chem. Soc., Perkin Trans. 2 1993, 691. (b) Gorner, H. J.
Photochem. Photobiol. A 2009, 208, 141. (c) Du, Y.; Xue, J.; Li, M.-D.;
Guan, X.; McCamant, D. W.; Phillips, D. L. Chem.Eur. J. 2010, 16,
6
961.
AUTHOR INFORMATION
■
*
(
8) The reactions were conducted in 0.04 M acetone solution
because of the low solubility of the starting materials.
9) The photoinduced oxidation of benzylated androstanediol
(
resulted in a complex mixture of products probably due to the
sensitivity of the benzyl ether moiety under the present oxidation
conditions.
Notes
The authors declare no competing financial interest.
(10) The reaction using an LED lamp (365 nm, a KEYENCE UV-
4
00 with UV-50A or UV-50H) gave a higher yield of the product 2k.
ACKNOWLEDGMENTS
■
Under irradiation of a Hg lamp, the derived keto amide 2k seems to be
gradually decomposed.
(
and a significant amount of the alcohol recovery was observed.
Oxidation of 4-(hydroxymethyl)cyclohexanol resulted in a complex
mixture of multiple unidentified products, and thus chemoselective
clean oxidation to 4-(hydroxymethyl)cyclohexanone failed at the
present stage.
This research was supported by a Grant-in-Aid for Scientific
Research on Innovative Areas “Advanced Molecular Trans-
formations by Organocatalysts” (MEXT, Japan) and by the
Program to Disseminate Tenure Tracking System (MEXT,
Japan) to S.K. We thank Prof. Katsuya Ishiguro at Yamaguchi
University for fruitful discussions on the reaction mechanism.
11) Oxidation of the primary alcohol, 1-nonanol, was very sluggish,
(
12) The value of KIE (K /K ) was calculated based on the
REFERENCES
H D
■
consumed starting materials 1v and 1v-d since both of them provided
the same product 2v.
(
1) For reviews on oxidation, see: (a) Comprehensive Organic
Synthesis; Ley, S. V., Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford,
(
13) The C−H bond of alcohol 1 should be preferentially cleaved
over the O−H bond due to the difference of bond dissociation energy
BDE). The BDE of Me CHOH is 94.8 kcal/mol, and that of
1
991; Vol. 7. (b) Handbook of Reagents for Organic Synthesis, Oxidizing
and Reducing Agents; Bruke, S. D., Danheiser, R. L., Eds.; Wiley:
Weinheim, 1999. (c) Modern Oxidation Methods, 2nd ed.; Backvall, J.-
E., Ed.; Wiley-VCH: Weinheim, 2010. (d) Handbook of Reagents for
Organic Synthesis, Catalytic Oxidation Reagents; Fuchs, P. L., Ed.; Wiley:
Weinheim, 2013. (e) Comprehensive Organic Synthesis, 2nd ed.;
Knochel, P., Molander, G. A., Eds.; Elsevier: Oxford, 2014; Vol. 7.
(
2
̈
Me CHOH is 105.7 kcal/mol; see: Luo, Y.-R. Comprehensive
Handbook of Chemical Bond Energies; CPC Press: Boca Raton, FL,
2
2
007; pp 71 and 257.
(14) As a referee pointed out, two hydrogen transfers from the
starting alcohol 1 to the photoexcited ketone A could be taking place
in a nearly concerted fashion based on the low KIE as well as the no
cyclopropane ring opening. Indeed, we observed formation of ca. 20%
deuterated phenyl(pyridyl)methanol (PhPyCDOH) after the oxida-
tion of ca. 76% deuterated cyclododecanol (cyclo-C H OD) with 4-
BzPy. Further investigations are needed to obtain more detailed
information on the reaction mechanism.
(
(
2) (a) Haines, A. H. Methods for the Oxidation of Organic
Compounds; Academic Press: London, 1988; Chapter 2. (b) Larock,
R. C. Comprehensive Organic Transformations; VCH: New York, 1989;
pp 604−614.
12
23
(
3) For representative examples of photoinduced alcohol oxidation,
see: (a) Binkley, R. W. J. Org. Chem. 1976, 41, 3030. (b) Stenberg, V.
I.; Singh, S. P.; Narain, N. K.; Parmar, S. S. J. Org. Chem. 1977, 42, 171.
c) Hussein, F. H.; Pattenden, G.; Rudham, R.; Russell, J. J.
Tetrahedron Lett. 1984, 25, 3363. (d) Wang, Q.; Zhang, M.; Chen,
C.; Ma, W.; Zhao, J. Angew. Chem., Int. Ed. 2010, 49, 7976.
e) Rueping, M.; Vila, C.; Szadkowska, A.; Koenigs, R. M.; Fronert, J.
15) Formation of the intermediate D is reported by the
(
photochemical reaction between 4-benzoylpyridine and 2-propanol;
see: Du, Y.; Xue, J.; Ma, C.; Kwok, W. M.; Phillips, D. L. J. Raman
Spectrosc. 2008, 39, 503.
(
(16) We monitored the oxidation of cyclododecanol 1a with NMR
ACS Catal. 2012, 2, 2810. (f) Matsusaki, Y.; Yamaguchi, T.; Tada, N.;
Miura, T.; Itoh, A. Synlett 2012, 23, 2059. (g) Shimada, Y.; Hattori, K.;
Tada, N.; Miura, T.; Itoh, A. Synthesis 2013, 45, 2684. (h) Liu, Z.;
Caner, J.; Kudo, A.; Naka, H.; Saito, S. Chem.Eur. J. 2013, 19, 9452.
measurements; however, formation of the intermediate D could not be
detected, probably due to its instability. Only the formation of
cyclododecanone 2a and phenyl(pyridyl)methanol was clearly
observed in the reaction mixture.
(
i) Nguyen, J. D.; Matsuura, B. S.; Stephenson, C. R. J. J. Am. Chem.
(
17) (a) Lund, T.; Lundgren, B.; Lund, H. Acta Chem. Scand. 1995,
9, 755. (b) Lund, T.; Wayner, D. D. M.; Jonsson, M.; Larsen, A.;
Daasbjerg, K. J. Am. Chem. Soc. 2001, 123, 12590.
Soc. 2014, 136, 1218. (j) Mitchell, L. J.; Moody, C. J. J. Org. Chem.
014, 79, 11091. For related photoinduced oxidation of benzyl ethers,
see: (k) Tucker, J. W.; Narayanam, J. M. R.; Shah, P. S.; Stephenson,
4
2
C. R. J. Chem. Commun. 2011, 47, 5040.
(
4) (a) Kamijo, S.; Hoshikawa, T.; Inoue, M. Tetrahedron Lett. 2011,
52, 2885. (b) Kamijo, S.; Hoshikawa, T.; Inoue, M. Org. Lett. 2011, 13,
5928. (c) Hoshikawa, T.; Kamijo, S.; Inoue, M. Org. Biomol. Chem.
2013, 11, 164. (d) Hoshikawa, T.; Yoshioka, S.; Kamijo, S.; Inoue, M.
Synthesis 2013, 45, 874. (e) Amaoka, Y.; Nagatomo, M.; Watanabe, M.;
Tao, K.; Kamijo, S.; Inoue, M. Chem. Sci. 2014, 5, 4339. (f) Kamijo, S.;
Hirota, M.; Tao, K.; Watanabe, M.; Murafuji, T. Tetrahedron Lett.
2
014, 55, 5551. (g) Kamijo, S.; Tao, K.; Takao, G.; Murooka, H.;
Murafuji, T. Tetrahedron Lett. 2015, 56, 1904.
5) (a) Ciamician, G.; Silber, P. Ber. 1900, 33, 2911. (b) Bachmann,
W. E. Org. Synth. Coll. Vol. 1948, 2, 71.
6) We initially expected the replacement of the phenyl ring to the
(
(
pyridyl ring could reduce the amount of the oxidant, aryl ketone, by
avoiding the pinacol coupling of the ketyl radical generated during the
D
Org. Lett. XXXX, XXX, XXX−XXX