Cobalt-Catalyzed C(sp2)-C(sp3) Cross-Coupling Reactions of Diarylmanganese Reagents with Secondary Alkyl Iodides

Article abstract of DOI:10.1021/acs.orglett.6b03349

A cobalt-catalyzed cross-coupling of diarylmanganese reagents with secondary alkyl iodides using the THF-soluble salt CoCl₂·2LiCl, which leads to the cross-coupling products in up to 92% yield, is reported. High diastereoselectivities can be re

Full text of DOI:10.1021/acs.orglett.6b03349

Letter
pubs.acs.org/OrgLett
Cobalt-Catalyzed C(sp2)−C(sp3) Cross-Coupling Reactions of
Diarylmanganese Reagents with Secondary Alkyl Iodides
Maximilian S. Hofmayer, Jeffrey M. Hammann, Diana Haas, and Paul Knochel*
Department of Chemistry, Ludwig-Maximilians-Universitat, Butenandtstrasse 5-13, 81377 Munchen, Germany
̈
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S
* Supporting Information
ABSTRACT: A cobalt-catalyzed cross-coupling of diarylmanganese
reagents with secondary alkyl iodides using the THF-soluble salt CoCl2·
2LiCl, which leads to the cross-coupling products in up to 92% yield, is
reported. High diastereoselectivities can be reached in these cross-couplings
(dr up to 99:1). Remarkably, rearrangement of secondary alkyl iodides to
unbranched products was not observed in these C−C forming reactions.
alladium-catalyzed cross-couplings have widely been used.1
This encouraging result led us to examine the scope of this
cross-coupling more extensively (Table 1). CoCl2·2LiCl was the
2
3
PHowever, cost and toxicity considerations led to the search
of alternative transition metal catalysts for cross-coupling reactions.
Especially cobalt-catalyzed transformations have shown their
synthetic utility.4 Pioneering work of Oshima,5 Cahiez,6 Gosmini,7
and Cossy8 demonstrated the broad field of applications of cobalt
salt catalysis for forming new carbon−carbon bonds. Ackermann9
and Yoshikai10 also used cobalt complexes for direct C−H
activationof various unsaturated systems. Recently, we have shown
that cobalt halides are excellent catalysts for the cross-couplings
between C(sp3)−C(sp2),11 C(sp3)−C(sp),12 and C(sp2)−C(sp2)13
centers using magnesium or zinc organometallics. However,
these organometallic reagents are not always the best choice
for performing C−C bond formations since homocouplings are
often observed side-reactions.
Table 1. Reaction Condition Optimization of the
Cross-Coupling of Alkyl Iodide 1a with the Manganese
Reagent 3a
Herein, we report a new cobalt-catalyzed cross-coupling
between secondary alkyl iodides and diarylmanganese reagents
catalyzed by CoCl2·2LiCl and performed in the absence of any
additional ligand. Thus, preliminary experiments have shown
that the cross-coupling between the secondary alkyl iodide 1a
and p-anisylmagnesium bromide (2) proceeds in the presence of
20 mol% CoCl2·2LiCl in THF at −20 to 25 °C (8 h) to produce
the substitution product 4a in only 40% yield due to extensive
homocoupling side reactions.
However, we found that by replacing 2 with the corresponding
dianisylmanganese reagent (3a) prepared by the transmetalation
of 2 with MnCl2·2LiCl14 (0.5 equiv), the same cross-coupling
now produces 4a in 75% isolated yield (Scheme 1). Remarkably,
we did not observe rearrangement products (branched to
unbranched) during these couplings.15
a
b
Using 40% of the ligand. Calibrated GC-yield using undecane as
c
d
internal standard. Isolated yield. Using 10% CoCl2·2LiCl.
Scheme 1. Cobalt-Catalyzed Cross-Coupling Reactions of
Various Metal Reagents with Alkyl Iodide 1a
preferred catalyst since Co(acac)2, Co(acac)3, CoBr2, and CoCl2
gave inferior yields (entries 1−4). The use of 10% CoCl2·2LiCl
instead of 20% reduced the yield of 4a to 64% (compare entries 5
Received: November 9, 2016
© XXXX American Chemical Society
A
DOI: 10.1021/acs.orglett.6b03349
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Letter
and 6). Attempts to improve the reaction by adding ligands such
as TMEDA (L1),16 4-fluorostyrene (L2),17 or neocuproine
(L3)12,18 did not improve the reaction yield (entries 7−9). Using
NHC ligands L4 or L5 did not improve the reaction outcome
(entries 10 and 11). Also alternative transition metal salts such as
PdCl2, CuCl2, CrCl2, NiCl2, or FeCl2 were inefficient (entries
12−16). A solvent screening showed that THF was the best
solvent when compared to NMP, DMPU, DME, 1,4-dioxane,
and tBuOMe.
Furthermore, a range of functionalized diarylmanganese
reagents could also be readily used in this reaction (Table 3).
(p-MOMO-C6H4)2Mn (3b) reacted smoothly with the alkyl
Table 3. Cobalt-Catalyzed Cross-Couplings of Diaryl
Manganese Reagents of Type 3 with Secondary Alkyl Iodides
of Type 1
These cobalt-catalyzed alkylations proved to be general, and
the cross-coupling between the dianisylmanganese reagent (3a)
and various secondary alkyl iodides has been successfully
performed (Table 2).19 Thus, various secondary alkyl iodides
Table 2. Cobalt-Catalyzed Cross-Coupling Reactions between
Various Secondary Alkyl Iodides of Type 1 and the
Diarylmanganese Reagent 3a
a
b
20% CoCl2 was used instead of CoCl2·2LiCl. dr ca. 70:30.
bearing a range of various functional groups (OTBS, CF3, OAc;
1b−d) reacted with the dianisylmanganese reagent (3a)
providing the expected products 4b−d in 73−77% yield (entries
1−3). Also, various cyclohexyl iodides underwent the cross-
coupling with 3a yielding the desired arylated products 4e−g
in 75−84% yield. Additionally, this cross-coupling can also be
performed with cyclopentyl iodides 1h−i, leading to the
expected products 4h and 4i in 59−70% yield (entries 7
and 8). When a TBSO substituent was present in position 2 to
the carbon-iodide bond, excellent diastereoselectivities were
observed (dr up to 99:1, see entries 6 and 8).20
a
20% CoCl2 was used instead of CoCl2·2LiCl.
B
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iodides 1c and 1j, leading to the arylated products 4j−k in
75−76% yield (entries 1 and 2). The coupling of the electron-
poor manganese reagent 3c with 1a or 1k afforded the cross-
coupling products 4l−m in 81−87% yield (entries 3 and 4).
Interestingly, the manganese reagents bearing an OBoc (3d)
or an OTBS group (3e) were well tolerated, and the cross-
coupling with 1h and 1i (dr = 99:1) led to the desired products
4n−p in 74−92% yield (entries 5−7). Moreover, the electron-
rich diarylmanganese reagent 3f was readily coupled with the
cyclic alkyl iodides 1e and 1b to provide the correspond-
ing arylated products 4q−r in 60−80% yield. The cross-
coupling of 1l or 1m with the di(1,3-benzodioxol-5-yl)
manganese reagent (3g) afforded the arylated compounds
4s−t in 66−70% yield (entries 10 and 11). Also, the di(4-
methoxy-3,5-dimethylphenyl)manganese reagent (3h) was
successfully coupled with 1h and 1i (dr = 99:1), leading
to the desired products 4u−v in 63−82% yield (entries 12
and 13). For the diarylmanganese reagents 3e and 3h using
the protected heterocyclic iodohydrine 1i (dr = 99:1), we
also observed excellent diastereoselectivities (dr = 99:1, see
entries 7 and 13).
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: paul.knochel@cup.uni-muenchen.de.
ORCID
Paul Knochel: 0000-0001-8167-272X
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank the DFG (SFB749), the LMU Munich, and the
International Associated Laboratory IrMaCaR between the
research groups of P. Knochel and G. Cahiez for financial
support. We also thank Albemarle (Hoechst, Germany) for the
generous gift of chemicals. M.S.H. thanks the Richard-Winter
Foundation for a fellowship.
REFERENCES
■
(1) (a) Metal-Catalyzed Cross-Coupling Reactions; Meijere, A.,
Diederich, F., Eds.; Wiley-VCH: Weinheim, Germany, 2004. (b)
Organotransition Metal Chemistry; Hartwig, J. F., Ed.; University Science
Books: Sausalito, CA, 2010.
(2) (a) World market prices for Pd: 22300€/kg. World market prices
for Co: 29€/kg. http://www.infomine.com/ (retrieved 15th November
2016).
(3) (a) Handbook on the Toxicology of Metals; Friberg, L., Nordberg, G.
F., Vouk, V. B., Eds.; Elsevier: Amsterdam, 1986. (b) Hughes, M. N.
Compr. Coord. Chem. II 1987, 67, 643.
(4) For recent cobalt-catalyzed examples, see: (a) Lautens, M.;
Crudden, C. M. Organometallics 1989, 8, 2733. (b) Lautens, M.; Tam,
W.; Sood, C. J. Org. Chem. 1993, 58, 4513. (c) Gensch, T.; Klauck, F. J.
R.; Glorius, F. Angew. Chem., Int. Ed. 2016, 55, 11287. (d) Lerchen, A.;
In order to demonstrate the synthetic utility of this method,
we prepared the protected iodopiperidine 1n, which is a key
intermediate for the synthesis of ( )-preclamol (5). Thus, the
commercially available carboxylic acid 6 was converted into the
iodide 1n according to the procedure of Boto and co-workers
(Scheme 2).8d,21 The cobalt-catalyzed cross-coupling with the
Scheme 2. Formal Synthesis of ( )-Preclamol (5)
́ ́
Vasquez-Cespedes, S.; Glorius, F. Angew. Chem., Int. Ed. 2016, 55, 3208.
(5) For recent examples, see: (a) Ikeda, Y.; Nakamura, T.; Yorimitsu,
H.; Oshima, K. J. Am. Chem. Soc. 2002, 124, 6514. (b) Ohmiya, H.;
Yorimitsu, H.; Oshima, K. J. Am. Chem. Soc. 2006, 128, 1886.
(c) Someya, H.; Ohmiya, H.; Yorimitsu, H.; Oshima, K. Org. Lett.
2007, 9, 1565. (d) Kobayashi, T.; Ohmiya, H.; Yorimitsu, H.; Oshima,
K. J. Am. Chem. Soc. 2008, 130, 11276. (e) Murakami, K.; Yorimitsu, H.;
Oshima, K. Chem. - Eur. J. 2010, 16, 7688.
(6) For recent examples, see: (a) Cahiez, G.; Avedissian, H.
Tetrahedron Lett. 1998, 39, 6159. (b) Avedissian, H.; Berillon, L.;
Cahiez, G.; Knochel, P. Tetrahedron Lett. 1998, 39, 6163. (c) Cahiez, G.;
Chaboche, C.; Duplais, C.; Giulliani, A.; Moyeux, A. Adv. Synth. Catal.
2008, 350, 1484. (d) Cahiez, G.; Chaboche, C.; Duplais, C.; Moyeux, A.
Org. Lett. 2009, 11, 277.
(7) For recent examples, see: (a) Kazmierski, I.; Bastienne, M.;
Gosmini, C.; Paris, J.-M.; Perichon, J. J. Org. Chem. 2004, 69, 936.
(b) Amatore, M.; Gosmini, C.; Perichon, J. Eur. J. Org. Chem. 2005,
2005, 989. (c) Begouin, J.-M.; Gosmini, C. J. Org. Chem. 2009, 74, 3221.
(d) Qian, X.; Auffrant, A.; Felouat, A.; Gosmini, C. Angew. Chem., Int. Ed.
2011, 50, 10402. (e) Moncomble, A.; Floch, P. L.; Lledos, A.; Gosmini,
C. J. Org. Chem. 2012, 77, 5056. (f) Corpet, M.; Bai, X.-Z.; Gosmini, C.
Adv. Synth. Catal. 2014, 356, 2937. (g) Cai, Y.; Qian, X.; Gosmini, C.
Adv. Synth. Catal. 2016, 358, 2427. (h) Pal, S.; Chowdhury, S.;
Rozwadowski, E.; Auffrant, A.; Gosmini, C. Adv. Synth. Catal. 2016, 358,
2431.
diarylmanganese reagent 3e furnished the desired product 4w in
60% yield.
In summary, we have reported a new cobalt-catalyzed cross-
coupling of polyfunctional diarylmanganese reagents with
secondary alkyl iodides using the highly soluble cobalt salt
CoCl2·2LiCl in the absence of any additional ligand. Remarkably,
no rearrangement of the secondary alkyl group is observed.
Also, this cross-coupling was applied to the preparation of a key
intermediate for the synthesis of ( )-preclamol. Further
extension of this method as well as mechanistic studies are
currently underway.
(8) For recent examples, see: (a) Nicolas, L.; Angibaud, P.; Stansfield,
I.; Bonnet, P.; Meerpoel, L.; Reymond, S.; Cossy, J. Angew. Chem., Int.
Ed. 2012, 51, 11101. (b) Nicolas, L.; Izquierdo, E.; Angibaud, P.;
Stansfield, I.; Meerpoel, L.; Reymond, S.; Cossy, J. J. Org. Chem. 2013,
78, 11807. (c) Barre, B.; Gonnard, L.; Campagne, R.; Reymond, S.;
Marin, J.; Ciapetti, P.; Brellier, M.; Guerinot, A.; Cossy, J. Org. Lett.
2014, 16, 6160. (d) Gonnard, L.; Guerinot, A.; Cossy, J. Chem. - Eur. J.
2015, 21, 12797.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.orglett.6b03349.
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Full experimental details; H and 13C NMR spectra
(PDF)
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(9) For recent examples, see: (a) Li, J.; Ackermann, L. Angew. Chem.,
Int. Ed. 2015, 54, 3635. (b) Li, J.; Ackermann, L. Angew. Chem., Int. Ed.
2015, 54, 8551. (c) Moselage, M.; Sauermann, N.; Richter, S. C.;
Ackermann, L. Angew. Chem., Int. Ed. 2015, 54, 6352. (d) Li, J.; Tang,
M.; Zang, L.; Zhang, X.; Zhang, Z.; Ackermann, L. Org. Lett. 2016, 18,
2742. (e) Mei, R.; Loup, J.; Ackermann, L. ACS Catal. 2016, 6, 793.
(f) Wang, H.; Lorion, M. M.; Ackermann, L. Angew. Chem., Int. Ed. 2016,
55, 10386. (g) Wang, H.; Moselage, M.; Gonzalez, M. J.; Ackermann, L.
ACS Catal. 2016, 6, 2705. (h) Zell, D.; Bu, Q.; Feldt, M.; Ackermann, L.
Angew. Chem., Int. Ed. 2016, 55, 7408.
(10) For recent cobalt-catalyzed examples, see: (a) Gao, K.; Yoshikai,
N. J. Am. Chem. Soc. 2011, 133, 400. (b) Jin, M.-Y.; Yoshikai, N. J. Org.
Chem. 2011, 76, 1972. (c) Ding, Z.; Yoshikai, N. Angew. Chem., Int. Ed.
2012, 51, 4698. (d) Tan, B.-H.; Dong, J.; Yoshikai, N. Angew. Chem., Int.
Ed. 2012, 51, 9610. (e) Gao, K.; Yoshikai, N. J. Am. Chem. Soc. 2013, 135,
9279. (f) Tan, B.-H.; Yoshikai, N. Org. Lett. 2014, 16, 3392. (g) Yang, J.;
Seto, Y. W.; Yoshikai, N. ACS Catal. 2015, 5, 3054. (h) Xu, W.; Yoshikai,
N. Angew. Chem., Int. Ed. 2016, 55, 12731. (i) Yan, J.; Yoshikai, N. ACS
Catal. 2016, 6, 3738.
(11) For recent examples, see: (a) Hammann, J. M.; Steib, A. K.;
Knochel, P. Org. Lett. 2014, 16, 6500. (b) Hammann, J. M.; Haas, D.;
Knochel, P. Angew. Chem., Int. Ed. 2015, 54, 4478. (c) Hammann, J. M.;
Haas, D.; Steib, A. K.; Knochel, P. Synthesis 2015, 47, 1461.
(d) Benischke, A. D.; Knoll, I.; Rerat, A.; Gosmini, C.; Knochel, P.
Chem. Commun. 2016, 52, 3171.
(12) Hammann, J. M.; Haas, D.; Tuellmann, C.-P.; Karaghiosoff, K.;
Knochel, P. Org. Lett. 2016, 18, 4778.
(13) (a) Korn, T. J.; Cahiez, G.; Knochel, P. Synlett 2003, 1892.
(b) Korn, T. J.; Schade, M. A.; Cheemala, M. N.; Wirth, S.; Guevara, S.
A.; Cahiez, G.; Knochel, P. Synthesis 2006, 2006, 3547. (c) Korn, T. J.;
Schade, M. A.; Wirth, S.; Knochel, P. Org. Lett. 2006, 8, 725. (d) Steib, A.
K.; Kuzmina, O. M.; Fernandez, S.; Flubacher, D.; Knochel, P. J. Am.
Chem. Soc. 2013, 135, 15346. (e) Kuzmina, O. M.; Steib, A. K.;
Fernandez, S.; Boudot, W.; Markiewicz, J. T.; Knochel, P. Chem. - Eur. J.
2015, 21, 8242. (f) Haas, D.; Hammann, J. M.; Lutter, F. H.; Knochel, P.
Angew. Chem., Int. Ed. 2016, 55, 3809.
(14) Cahiez, G. Butyl Manganese Chloride and Related Reagents in
Encyclopedia of Reagents for Organic Synthesis; Paquette, L. Ed.; Wiley:
Chichester, 1995; p 925.
(15) (a) Tamao, K.; Kiso, Y.; Sumitani, K.; Kumada, M. J. Am. Chem.
Soc. 1972, 94, 9268. (b) Hayashi, T.; Konishi, M.; Kobori, Y.; Kumada,
M.; Higuchi, T.; Hirotsu, K. J. Am. Chem. Soc. 1984, 106, 158. (c) Joshi-
Pangu, A.; Ganesh, M.; Biscoe, M. R. Org. Lett. 2011, 13, 1218.
(d) Binder, J. T.; Cordier, C. J.; Fu, G. C. J. Am. Chem. Soc. 2012, 134,
17003.
(16) Hammann, J. M.; Steib, A. K.; Knochel, P. Org. Lett. 2014, 16,
6500.
(17) (a) Steib, A. K.; Thaler, T.; Komeyama, K.; Mayer, P.; Knochel, P.
Angew. Chem., Int. Ed. 2011, 50, 3303. (b) Jefferies, L. R.; Cook, S. P. Org.
Lett. 2014, 16, 2026. (c) Jefferies, L. R.; Weber, S. R.; Cook, S. P. Synlett
2015, 26, 331.
(18) (a) Thaler, T.; Guo, L.-N.; Mayer, P.; Knochel, P. Angew. Chem.,
Int. Ed. 2011, 50, 2174.
(19) Using primary or tertiary alkyl halides did not lead to a good
conversion.
(20) The use of TIPS-protected 2-iodocyclohexanol led to a similar
diastereoselectivity (dr 95:5), whereas protection with the bulky
TBDPS-group resulted in a decreased diastereoselectivity (dr 90:10).
(21) Boto, A.; Hernan
Afonso, A. Eur. J. Org. Chem. 2005, 673.
́ ́
dez, R.; de Leon, Y.; Murguía, J. R.; Rodriguez-
D
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