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as inexpensive hydrogen acceptor. The conveniently in situ
generated manganese catalyst is stabilized by a stable phosphorus-
free NNN-pincer ligand allowing oxidation of aromatic and aliphatic
alcohols.
Conflicts of interest
Fig. 4 Manganese-catalyzed dehydrogenation of aliphatic alcohols. General
There are no conflicts to declare.
5
reaction conditions: substrate (1 mmol), MnBr(CO) (5 mol%), L5 (5 mol%),
NaOtBu (5 mol%), toluene (6 mL), acetone (2 mL), 90 1C, 24 h. Conversion
was determined by GC using hexadecane as an internal standard. Isolated Notes and references
a
yields are given in parentheses. GC yield.
1
I. W. C. E. Arends and R. A. Sheldon, in Modern Oxidation Methods,
ed. J.-E. B ¨a ckvall, Wiley-VCH, Weinheim, 2010, vol. 2, pp. 147–180.
(a) J.-E. B ¨a ckvall, R. L. Choudhury and U. Karlsson, J. Chem. Soc.,
Chem. Commun., 1991, 473; (b) N. A. Owston, A. J. Parker and
J. M. J. Williams, Chem. Commun., 2008, 624; (c) A. V. Polukeev
and O. F. Wendt, Organometallics, 2017, 36, 639; (d) T. W. Funk,
A. R. Mahoney, R. A. Sponenburg, K. P. Zimmerman, D. K. Kim and
E. E. Harrison, Organometallics, 2018, 37, 1133.
R. V. Oppenauer, Recl. Trav. Chim. Pays-Bas, 1937, 56, 137.
(a) M. L. S. Almeida, M. Beller, G.-Z. Wang and J.-E. B ¨a ckvall, Chem. –
Eur. J., 1996, 2, 1533; (b) M. C. Warner, C. P. Casey and J.-E. B ¨a ckvall,
in Bifunctional Molecular Catalysis, ed. T. Ikariya and M. Shibasaki,
Springer, Heidelberg, 2011, pp. 85–125.
2
3
4
Fig. 5 Manganese-catalyzed dehydrogenation of aliphatic alcohols. Gen-
eral reaction conditions: substrate (1 mmol), MnBr(CO) (5 mol%), L5
5 mol%), NaOtBu (5 mol%), toluene (6 mL), acetone (2 mL), 90 1C, 24 h.
5 S. Gauthier, R. Scopelliti and K. Severin, Organometallics, 2004, 23, 3769.
6 J. F. Hartwig and C. K. Hill, Nat. Chem., 2017, 9, 1213.
7 R. Labes, C. Battilocchio, C. Mateos, G. R. Cumming, O. de Frutos,
J. A. Rinc ´o n, K. Binder and S. V. Ley, Org. Process Res. Dev., 2017, 21, 1419.
8 K.-i. Fujita, F. Hanasaka and R. Yamaguchi, Organometallics, 2005,
5
(
Conversion was determined by GC using hexadecane as an internal
a
standard. Isolated yields are given in parentheses. 48 h reaction time.
24, 3422.
9
(a) D. Wang and D. Astruc, Chem. Rev., 2015, 115, 6621; (b) S. Werkmeister,
J. Neumann, K. Junge and M. Beller, Chem. – Eur. J., 2015, 21, 12226;
double bond. Furthermore, the allylic substrate 1z, which is fre-
quently used in the fragrance industry, was effectively transformed to
b-ionone (2z). Similarly, conversion of quinuclidine-3-ol was accom-
plished, yielding 88% of the corresponding ketone (2aa).
Finally, we tested the dehydrogenation of natural steroids
bearing secondary alcohol moieties to showcase the utility of the
catalytic system for modification of bio-active compounds (Fig. 5).
Thus, 3b-hydroxypregn-5-en-20-one and cholest-5-en-3b-ol were
converted entirely to the corresponding ketones using 5 mol%
(
c) G. A. Filonenko, R. van Putten, E. J. M. Hensen and E. A. Pidko, Chem.
Soc. Rev., 2018, 47, 1459; (d) N. Gorgas and K. Kirchner, Acc. Chem. Res.,
018, 51, 1558; (e) K. Junge, V. Papa and M. Beller, Chem. – Eur. J., 2019,
5, 122; ( f ) L. Alig, M. Fritz and S. Schneider, Chem. Rev., 2019, 119, 2681.
2
2
1
1
1
0 M. G. Coleman, A. N. Brown, B. A. Bolton and H. Guan, Adv. Synth.
Catal., 2010, 352, 967.
1 S. Budweg, Z. Wei, H. Jiao, K. Junge and M. Beller, ChemSusChem,
2
019, 12, 2988.
2 (a) R. J. Trovitch, Acc. Chem. Res., 2017, 50, 2842; (b) M. Garbe, K. Junge
and M. Beller, Eur. J. Org. Chem., 2017, 4344; (c) F. Kallmeier and
R. Kempe, Angew. Chem., Int. Ed., 2018, 57, 46; (d) T. Zell and R. Langer,
ChemCatChem, 2018, 10, 1930; (e) A. Mukherjee and D. Milstein, ACS
Catal., 2018, 8, 11435.
5
MnBr(CO) , 5 mol% L5 and 5 mol% NaOtBu at 90 1C, furnishing
progesterone (2ab) in 93% yield and cholest-4-en-3-one (2ac) in 13 (a) H. Vald ´e s, M. A. Garc ´ı a-Eleno, D. Canseco-Gonzalez and D. Morales-
Morales, ChemCatChem, 2018, 10, 3136; (b) D. Morales-Morales, Pincer
Compounds: Chemistry and Applications, Elsevier, 2018.
9
8% yield after 24 h. Noticeably, a selective isomerization of the
double bond occurred (499%) to produce the more stable enone
products. Moreover, testosterone was fully oxidized to androstene-
dione (2ad) and isolated in excellent yield of 94%.
1
4 Selected references: (a) F. Kallmeier, T. Irrgang, T. Dietel and R. Kempe,
Angew. Chem., Int. Ed., 2016, 55, 11806; (b) N. Deibl and R. Kempe, Angew.
Chem., Int. Ed., 2017, 56, 1663; (c) S. Fu, Z. Shao, Y. Wang and Q. Liu,
J. Am. Chem. Soc., 2017, 139, 11941; (d) M. B. Widegren, G. J. Harkness,
A. M. Z. Slawin, D. B. Cordes and M. L. Clarke, Angew. Chem., Int. Ed.,
2017, 56, 5825; (e) A. Bruneau-Voisine, D. Wang, V. Dorcet, T. Roisnel,
C. Darcel and J.-B. Sortais, Org. Lett., 2017, 19, 3656; ( f ) G. Zhang,
T. Irrgang, T. Dietel, F. Kallmeier and R. Kempe, Angew. Chem., Int. Ed.,
Importantly, the use of the isolated complex [Mn(Me-dpa)-
3
(CO) ]Br in the dehydrogenation of 1-phenylethanol showed similar
activity compared to the in situ formed catalyst.
Performing in situ IR spectroscopic investigations under cataly-
2018, 57, 9131; (g) Y. Wang, Z. Shao, K. Zhang and Q. Liu, Angew. Chem.,
tic conditions revealed characteristic CO bands at 2030, 1935 and
Int. Ed., 2018, 57, 15143; (h) R. Fertig, T. Irrgang, F. Freitag, J. Zander and
R. Kempe, ACS Catal., 2018, 8, 8525; (i) Z. Shao, Y. Wang, Y. Liu, Q. Wang,
X. Fub and Q. Liu, Org. Chem. Front., 2018, 5, 1248; ( j) H. Li, D. Wei,
A. Bruneau-Voisine, M. Ducamp, M. Henrion, T. Roisnel, V. Dorcet,
C. Darcel, J.-F. Carpentier, J.-F. Soule and J.-B. Sortais, Organometallics,
À1
1920 cm for the in situ generated species dissolved in heptane, as
well as for the isolated complex (for details see ESI,† Fig. S1).
The intensities of the carbonyl bands increased with higher
temperature, due to better solubility. After activation by base
2018, 37, 1271; (k) B. G. Reed-Berendt, K. Polidano and L. C. Morrill, Org.
Biomol. Chem., 2019, 17, 1595; (l) O. El-Sepelgy, E. Matador, A. Brzozowska
and M. Rueping, ChemSusChem, 2019, 12, 3099.
(
NaOtBu), a slight decrease of the original CO bands is observed
À1
and a new band at 1808 cm appeared indicating that in both 15 M. Perez, S. Elangovan, A. Spannenberg, K. Junge and M. Beller,
ChemSusChem, 2017, 10, 83.
cases the same catalytic active species is formed.
In conclusion, we present a convenient protocol for the
transfer-dehydrogenation of secondary alcohols using acetone
1
6 (a) A. Friedrich and S. Schneider, ChemCatChem, 2009, 1, 72;
b) C. Gunanathan and D. Milstein, Science, 2013, 341, 1229712;
(c) R. H. Crabtree, Chem. Rev., 2017, 117, 9228.
(
1
4146 | Chem. Commun., 2019, 55, 14143--14146
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