Copper-catalyzed recycling of halogen activating groups via 1,3-halogen migration

Article abstract of DOI:10.1021/ja306446m

A Cu(I)-catalyzed 1,3-halogen migration reaction effectively recycles an activating group by transferring bromine or iodine from a sp² to a benzylic carbon with concomitant borylation of the Ar-X bond. The resulting benzyl halide can be reacted in the same vessel under a variety of conditions to form an additional carbon-heteroatom bond. Cross-over experiments using an isotopically enriched bromide source support intramolecular transfer of Br. The reaction is postulated to proceed via a Markovnikov hydrocupration of the o-halostyrene, oxidative addition of the resulting Cu(I) complex into the Ar-X bond, reductive elimination of the new sp³ C-X bond, and final borylation of an Ar-Cu(I) species to turn over the catalytic cycle.

Full text of DOI:10.1021/ja306446m

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Communication
Cu-catalyzed Recycling of Halogen
Activating Groups via 1,3-Halogen Migration
R. David Grigg, Ryan Van Hoveln, and Jennifer M Schomaker
J. Am. Chem. Soc., Just Accepted Manuscript • Publication Date (Web): 17 Sep 2012
Downloaded from http://pubs.acs.org on September 19, 2012
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Cu-catalyzed Recycling of Halogen Activating Groups via
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R. David Grigg‡, Ryan Van Hoveln‡ and Jennifer M. Schomaker*
Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
Supporting Information Placeholder
Scheme 1. Traditional crossꢀcoupling approach vs. a
new mode of arene functionalization.
ABSTRACT: A Cu(I)ꢀcatalyzed 1,3ꢀhalogen migration
reaction effectively recycles an activating group by transꢀ
ferring bromine or iodine from a sp2 to a benzylic carbon
with concomitant borylation of the ArꢀX bond. The reꢀ
sulting benzyl halide can be reacted in the same vessel
under a variety of conditions to form an additional carꢀ
bonꢀheteroatom bond. Crossꢀover experiments using an
isotopically enriched bromide source support intramoꢀ
lecular transfer of Br. The reaction is postulated to proꢀ
ceed via a Markovnikov hydrocupration of the oꢀ
halostyrene, oxidative addition of the resulting Cu(I)
complex into the ArꢀX bond, reductive elimination of the
new sp3 CꢀX bond, and final borylation of an ArꢀCu(I)
species to turn over the catalytic cycle.
The work described herein arose from our attempts to
The ability to functionalize aromatic rings is an imꢀ
portant tool in the synthetic chemist’s repertoire.1
Typically, aryl halides or pseudohalides are employed to
provide reliable regioselectivity (Scheme 1, top).
However, use of an activating group imbues these transꢀ
formations with lessꢀthanꢀideal atom economy, as only
one new bond is formed at the expense of the waste
product. Direct CꢀH functionalization eliminates the
need for preꢀactivation, yet the additives necessary for
many of these reactions means it is not a foregone conꢀ
clusion that this approach is less wasteful.2 Important
advances have recently been made towards more practiꢀ
cal and general directing groups for CꢀH functionalizaꢀ
tion,3 but the use of halide or pseudohalide activating
groups remains the most convenient and commonly emꢀ
ployed route to aryl functionalization. We felt that the
use of activating groups might be more attractive if a way
to “recycle” the halide could be developed.4 In this comꢀ
munication, we report a Cuꢀcatalyzed 1,3ꢀhalogen migraꢀ
tion/borylation reaction that permits a halogen activatꢀ
ing group to be used for the sequential formation of two
new carbonꢀheteroatom bonds.
prepare 3 from 1 using a reported CuCl/dppbz catalyst
(Table 1, entry 1).5 While none of the desired
hydroboration was noted, due mainly to polymerization
of the styrene, we observed small amounts of an unexꢀ
pected byꢀproduct 2. Curious as to whether 2 might be
obtained exclusively, we undertook an investigation of
several monoꢀ and bidentate ligands for CuCl (Table 1).
These preliminary studies revealed that neither
monodentate phosphine ligands (entries 2, 3) or
electronꢀpoor bidentate ligands (entries 4ꢀ8) were
capable of promoting the desired reaction. Phenanthroꢀ
Table 1. Initial ligand screen.
Conventional arene functionalization utilizes a range of
transition metal catalysts and coupling partners to
transform arylꢀX bonds into new carbonꢀcarbon or
carbonꢀheteroatom bonds, as represented by CꢀY in
Scheme 1. Conceptually, our approach differs in that the
catalyst does not interact with the CꢀX bond directly, but
rather with a functional group, such as an olefin.
Activation of the CꢀX bond then occurs with subsequent
transfer of X to a new carbon in the molecule, followed
by the formation of CꢀY. The activating group X is
recycled by the construction of a final CꢀZ bond.
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line (entry 9) gave only recovered starting material. examined. While the 1,3ꢀhalogen migration was obꢀ
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Interestingly, the transꢀspanning Xantphos ligand (entry
10) gave exclusively the hydroboration product 3 in 72%
yield, while a similar DPEphos ligand (entry 11) gave no
2 or 3. Finally, we found that the electronꢀrich and bulky
bidentate phosphine ligand, bis(dicyclohexylphosphino)ꢀ
ethane (dCype, entry 12), exclusively promoted the deꢀ
sired 1,3ꢀhalogen migration.6
served, the conversion was low. Less bulky catalysts are
being developed for sterically encumbered substrates.
Table 3. Substituent effects on 1,3ꢀhalogen migration.
Further reaction optimization was undertaken using
the dCype ligand (Table 2). THF (entry 1) proved
superior to toluene, CH2Cl2, Et2O, CH3CN and CHCl3
(entries 3ꢀ7), although dioxane (entry 2) gave similar
results. Lowering the temperature to 40 °C (entry 8) did
not increase the yield compared to entry 1, but improved
the mass balance. Finally, scaling the reaction to 5 mmol
(entry 9) reproducibly increased the yield to 94% of 2.
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Table 2. Reaction optimization.
The benzyl boronic esters that result from the typical
hydroboration of styrenes are often utilized as synthons
for benzylic carbanions.7 In contrast, the 1,3ꢀhalogen
migration observed in our chemistry allows access to
intermediates which are electrophilic at the benzylic carꢀ
bon. Facile recycling of the activating group was demonꢀ
strated by transforming 1 into a variety of benzylꢀ
substituted boronic esters (Scheme 2). For example, proꢀ
pargyl and pꢀmethoxybenzyl alcohols, aniline and sodiꢀ
um azide were all suitable nucleophiles for reacting with
the benzyl bromide to yield 7-9. These reactions
represent formal Cuꢀcatalyzed hydroalkoxylation and
hydroaminations that are typically accomplished using
more expensive precious metal catalysts including Pd,
Rh, or Au.8,9
With optimized conditions in hand, the scope of the
reaction was explored (Table 3). In general, 1,3ꢀbromine
migration was favored with a variety of substrates. Howꢀ
ever, placing electronꢀwithdrawing halogen groups meta
to the olefin (entries 2 and 3) diminished the 1,3ꢀhalogen
migration and resulted in significant hydroboration.
Other groups at this position favored transposition. Cuꢀ
riously, if a bromide group (entry 8) was placed para to
the olefin, the hydrocupration did not occur at all.
In addition to functionalization at the benzylic carbon,
the boronic ester could also be transformed into either a
carbonꢀheteroatom or carbonꢀcarbon bond. For example,
treatment of 1 under Cu catalysis, followed by reaction
with 3ꢀphenylꢀpropanꢀ1ꢀol and an oxidative workꢀup
t
Neutral and electronꢀdonating substituents F, Ph, Bu
and OMe (entries 9ꢀ12) para to the alkene yielded
predominantly the 1,3ꢀhalogen migration products. For
some of these cases, the benzyl bromide products were
sensitive to elimination and were trapped with propargyl
alcohol prior to isolation, illustrating the potential of this
chemistry in cascade reactions to construct more comꢀ
plex compounds. Consistent with prior observations5a,
the 4ꢀmethoxy substrate (entry 12) reacted slowly. Finalꢀ
ly, substitution on the β carbon of the styrene (entry 13)
was tolerated in the 1,3ꢀhalogen migration, as trans-βꢀ
methylstyrene 4l gave 5l in 75% yield. Although 2ꢀ
chlorostyrenes underwent halogen transposition with
poor conversions, it was found that 2ꢀiodostyrene 4m
did produce the transposed product (entry 14), although
only partial conversion was observed. The sensitive benꢀ
zyl iodide had to be trapped with propargyl alcohol to
give 5m in moderate yield. The reactivity of 2ꢀbromoꢀ3ꢀ
methylstyrene and 2ꢀbromoꢀ6ꢀmethylstyrene was also
using H2O2 yielded the phenol 10.10
Recycling the broꢀ
mine activating group also provided a flexible platform
for convergent syntheses of heterocycles. Tandem 1,3ꢀ
halogen migration/functionalization/Suzuki couplings of
1 were accomplished using (Z)ꢀ3ꢀiodopentꢀ2ꢀenꢀ1ꢀol and
2ꢀiodobenzyl alcohol to yield the heterocyclic dihyꢀ
droxepins 11 and 12.11 Finally, halogen migration folꢀ
lowed by reaction with 2ꢀiodoaniline and subsequent Pdꢀ
catalyzed coupling/oxidation gave the biologically active
phenanthridine core of 13.12
We wanted to ensure that we were not observing direct
borylation of the ArꢀBr bond, followed by an unexpected
bromination of the alkene. Examples of aryl bromides
that undergo Cuꢀcatalyzed borylation in the absence of a
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Scheme 2. Recycling of the activating group. We also demonstrated that the 1,3ꢀhalogen migration is
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likely an intramolecular process by performing a crossꢀ
over experiment using isotopically enriched 79Br. The
enriched aryl bromide 4f (Scheme 3) was prepared by
reacting the tributylaryl tin 16 with ca. 85% isotopically
enriched NH479Br (see the Supporting Information for
further details).14 After ensuring that the unlabeled
styrenes 1 and 4f reacted at comparable rates, reaction of
4f in the presence of nonꢀisotopically enriched 1 showed
no additional incorporation of 79Br into 2 or degradation
of the 79/81Br ratio in the conversion of 4f to 5f within
statistical error.
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One proposed mechanism for the 1,3ꢀhalogen migraꢀ
tion is illustrated in Scheme 4. Reaction of the preꢀ
catalyst 17 with HBpin generates the active, phosphineꢀ
supported CuꢀH species 18.15 In the absence of an ortho
CꢀBr bond, reversible Markovnikov hydrocupration of
the styrenic double bond of 1 to 18 would be followed by
reaction with HBpin to give the typical hydroboration
product 3.16,17 However, the presence of an ortho CꢀBr
Scheme 4. A potential mechanism for the Cuꢀcatalyzed
1,3ꢀhalogen migration.
directing group have been reported, but these reactions
are rare.13 In our case, when both 1,4ꢀdibromobenzene
and 14 were subjected to the reaction conditions (eq 1
and 2), no borylation of either CꢀBr bond was observed.
Subjecting the typical hydroboration product 3 to the
reaction conditions also did not lead to 2, indicating
direct borylation of 1 is not a likely reaction pathway.
bond in 19 may promote a subsequent oxidative addition
to yield a formal Cu(III) species 20.18,19 Reductive
elimination of 19 to 20 could then be followed by a ơꢀ
bond metathesis with HBpin to yield 2 and regenerate
the active CuꢀH catalyst 18.20 Other possibilities for the
mechanism of the 1,3ꢀmigration could involve
intermediate πꢀallyl Cu species, singleꢀelectron transfer
processes, halogen atom transfer or π complexation to
the halide.21 Computational and further experimental
studies are in progress to shed more light on whether a
Cu(I)/Cu(III) or a Cu(I)/Cu(II) cycle is more likely and
will used to guide our further exploration of this 1,3ꢀ
halogen migration reaction.
Scheme 3. Crossꢀover experiment using isotopically
enriched 79Br.
In conclusion, Cu(I) promotes a cascade 1,3ꢀhalogen
migration/borylation/functionalization that proceeds
under mild conditions to recycle the bromine activating
group. Future studies will focus on expanding the reacꢀ
tion scope to include other functional groups capable of
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Gauthier, R.; Elford, T.G.; Aggarwal, V.K. J. Am. Chem. Soc.
directing the Cu catalysis and other activating groups
that can be transferred. Initial promising results in enanꢀ
tioselective migration are being optimized. The developꢀ
ment of other efficient cascade reactions and computaꢀ
tional studies to better understand the mechanism of this
unusual transformation are underway.
2011, 133, 16794. d) Crudden, C.M.; Glasspoole, B.W.; Lata,
C.J. Chem. Commun. 2009, 6704. e) Matteson, D.S. Pure
Appl. Chem. 2003, 75, 1249. f) Chen, A.; Ren, L.; Crudden,
C.M. J. Org. Chem. 1999, 64, 9704.
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(8) Selected reports of transition metal catalyzed hydroalkoxyꢀ
lation of alkenes: a) Salah, A.B.; Offenstein, C.; Zargarian, D.
Organometallics, 2011, 30, 5352. b) Hirai, T.; Hamasaki, A.;
Nakamura, A.; Tokunaga, M. Org. Lett. 2009, 11, 5510. c) Liu,
C.; Bender, C.F.; Han, X.; Widenhoefer, R.A.; Chem. Commun.
2007, 3607. d) Yang, C.G.; He, C. J. Am. Chem. Soc. 2005,
127, 6966. e) Matsukawa, Y.; Mizukado, J.; Quan, H.; Tamura,
M.; Sekiya, A. Angew. Chem. Int. Ed. 2005, 44, 1128. f) Qian,
H.; Han, X.; Widenhoefer, R.A. J. Am. Chem. Soc. 2004, 126,
9536.
(9) Recent reviews of transition metal catalyzed hydroaminaꢀ
tion of alkenes: a) Mueller, T.E.; Hultzsch, K.C.; Yus, M. Chem.
Rev. 2008, 108, 3795. b) Hultzsch, K.C. Adv. Synth. Catal.
2005, 347, 367. c) Beller, M.; Seayad, J.; Tillack, A.; Jiao, H.
Angew. Chem. Int. Ed. 2004, 43, 3368. d) Hong, S.; Marks,
T.J. Acc. Chem. Res. 2004, 37, 673.
ASSOCIATED CONTENT
Experimental procedures and characterization for all new
compounds. This material is available free of charge via the
Internet at http://pubs.acs.org.
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Corresponding Author *schomakerj@chem.wisc.edu
‡These authors contributed equally.
Funding Sources Financial support was provided by
startꢀup funds from the University of Wisconsin, Madison.
The NMR facilities at UWꢀMadison are funded by the NSF
(CHEꢀ9208463, CHEꢀ9629688) and NIH (RR08389ꢀ01).
(10) Examples of Pdꢀcatalyzed hydrofunctionalization of oꢀ
vinyl phenols: a) Zhang, Y.; Sigman, M.S. Org. Lett. 2006, 8,
5557. b) Pathak, T.P.; Sigman, M.S. Org. Lett. 2011, 13, 2774.
(11) Selected examples of Suzukiꢀcoupling strategies for
benzoxepines: a) Colombel, V.; Joncour, A.; Thoret, S.; Dubois,
J.; Bignon, J.; WdzieczakꢀBakala, J.; Baudoin, O. Tet. Lett.
2010, 51, 3127. b) Colombel, V.; Baudoin, O. J. Org. Chem.
2009, 74, 4329. c) Joncour, A.; Dècor, A.; Thoret, S.; Chiaroni,
A.; Baudoin, O. Angew. Chem. Int. Ed. 2006, 45, 4149.
(12) Selected examples of Suzukiꢀcoupling strategies for
phenanthridine synthesis: a) Geen, G.R.; Mann, I.S.; Mullane,
M.V.; McKillop, A. Tetrahedron 1998, 54, 9875. b) Kim, Y.H.;
Lee, H.; Kim, Y.J.; Kim, B.T.; Heo, JꢀN. J. Org. Chem. 2008,
73, 495. c) Genès, C.; Michel, S.; Tillequin, F.; Porèe, F.
Tetrahedron 2009, 65, 10009.
ACKNOWLEDGMENT This paper is dedicated to Proꢀ
fessor Robert G. Bergman of the University of California,
Berkeley on the occasion of his 70th birthday, as well as for
many helpful discussions. Dr. Martha Vestling and Rob Risi
of the University of Wisconsin are thanked for mass spec
data.
REFERENCES
(1) a) Negishi, E.ꢀi.; de Meijere, A. Ed. Handbook of Organo-
palladium Chemistry for Organic Synthesis; Wiley: New York,
2002. b) de Meijere, A.; Diederich, F. Ed. Metal-Catalyzed
Cross-Coupling Reactions, 2nd ed. WileyꢀVCH: Weinheim,
2004.
(2) Selected reviews of CꢀH functionalization: a) Mkhalid, I.A.;
Barnard, J.H.; Marder, T.B.; Murphy, J.M.; Hartwig, J.F.
Chem. Rev. 2010, 110, 890. b) Lyons, T.W.; Sanford, M.S.
Chem. Rev. 2010, 110, 1147. c) Engle, K.M.; Mei, TꢀS.; Wasa,
M.; Yu, JꢀQ. Acc. Chem. Res. 2012, 45, 788. d) Neufeldt, S.R.;
Sanford, M.S. Acc. Chem. Res. 2012, 45, 936. e) Song, G.;
Wang, F.; Li, X. Chem. Soc. Rev. 2012, 41, 3651. f) Ackermann,
L. Chem. Rev. 2011, 111, 1315. g) Davies, H.M.L.; Morton, D.
Chem. Soc. Rev. 2011, 40, 1857. h) Wendlandt, A.E.; Suess,
A.M.; Stahl, S.S. Angew. Chem. Int. Ed. 2011, 50, 11062.
(3) a) Bedford, R.B.; Coles, S.J.; Hursthouse, M.B.; Limmert,
M.E. Angew. Chem. Int. Ed. 2003, 42, 112. b) Ihara, H.;
Suginome, M. J. Am. Chem. Soc. 2009, 131, 7502. c) Robbins,
D.W.; Boebel, T.A.; Hartwig, J.F. J. Am. Chem. Soc. 2010, 132,
4068. (d) Dai, H.ꢀX.; Stepan, A.F.; Plummer, M.F.; Zhang, Y.ꢀ
H.; Yu, J.ꢀQ. J. Am. Chem. Soc. 2011, 133, 7222. (e) Huang, C.;
Chattopadhyay, B.; Grevorgyan, V. J. Am. Chem. Soc. 2011,
133, 12406. (f) Gulevich, A.V.; Melkonyan, F.S.; Sarkar, D.;
Gevorgyan, V. J. Am. Chem. Soc. 2012, 134, 5528.
(4) Recent examples of activating group recycling: a) Newman,
S.G.; Lautens, M. J. Am. Chem. Soc. 2011, 133, 1778. b) Hoopꢀ
er, J.F.; Chaplin, A.B.; GonzálezꢀRodríguez, C.; Thompson,
A.L.; Weller, A.S.; Willis, M.C. J. Am. Chem. Soc. 2012, 134,
2906.
(5) a) Noh, D.; Chea, H.; Ju, J.; Yun, J. Angew. Chem. Int. Ed.
2009, 48, 6062. b) Noh, D.; Yoon, S.K.; Won, J.; Lee, J.Y.;
Yun, J. Chem. Asian J. 2011, 6, 1967. c) Won, J.; Noh, D.; Yun,
J.; Lee, J.Y. J. Phys. Chem. A 2010, 114, 12112.
(13) a) Kleeberg, C.; Dang, L.; Lin, Z.; Marder, T.B. Angew.
Chem. Int. Ed. 2009, 48, 5350. b) Zhu, W.; Ma, D. Org. Lett.
2006, 8, 261.
(14) Zhou, D.; Zhou, H.; Jenks, C.C.; Lewis, J.S.; Katzenellenꢀ
bogen, J.A.; Welch, M.J. Bioconjugate Chem. 2009, 20, 808.
(15) Selected examples of in-situ generated CuꢀH species: a)
Zhao, D.; Oisaki, K.; Kanai, M.; Shibasaki, M.; J. Am. Chem.
Soc. 2006, 128, 14440. b) Du, Y.; Xu, L.W.; Shimizu, Y.; Oisaꢀ
ki, K.; Kanai, M.; Shibasaki, M. J. Am. Chem. Soc. 2008, 130,
16146. c) Ding, J.; Hall, D.G. Tetrahedron 2012, 68, 3428. d)
Kazuhiko, S.; Tetsuaki, F.; Jun, T. Chem. Eur. J. 2012, 18,
4179.
(16) Dang, L.; Zhao, H.; Lin, Z.; Marder, T.B. Organometallics
2007, 26, 2824.
(17) Examples of isolated benzylic organocopper complexes: a)
Yam, V.W.ꢀW.; Lee, W.ꢀK.; Cheung, K.K.; Lee, H.ꢀK.; Leung,
W.ꢀP. J. Chem. Soc. Dalton Trans. 1996, 2889. b) Laitar, D.S.;
Tsui, E.Y.; Sadighi, J.P. Organometallics 2006, 25, 2405.
(18) For relevant reviews, see: a) Hickman, A.J.; Sanford, M.S.
Nature 2012, 484, 177. b) Ribas, X.; Casitas, A. Ideas in Chem-
istry and Molecular Sciences: Where Chemistry Meets Life (ed.
Pignataro, B.) WileyꢀVCH: Weinheim, 2010, 31ꢀ57.
(19) Selected examples aryl of Cu(III) species from CꢀX oxidaꢀ
tive insertion: a) Maiti, D.; Sarjeant, A.A.N.; Itoh, S.; Karlin,
K.D. J. Am. Chem. Soc. 2008, 130, 5644. b) Casitas, A.; King,
A.E.; Parella, T.; Costas, M.; Stahl, S.S.; Ribas, X. Chem. Sci.
2010, 1, 326.
(20) a) Casitas, A.; Poater, A.; Sola, M.; Stahl, S.S.; Costas, M.;
Ribas, X. Dalton Trans. 2010, 39, 10458. b) Casitas, A.; Canta,
M.; Sola, M.; Costas, M.; Ribas, X. J. Am. Chem. Soc. 2011, 133,
19386.
(21) Sperotto, E.; van Klink, G.P.M.; van Koten, G.; de Vries,
J.G. Dalton Trans. 2010, 39, 10338.
(6) Shiroodi, R.K.; Dudnik, A.S.; Gevorgyan, V. J. Am. Chem.
Soc. 2012, 134, 6928 and references therein.
(7) Selected recent examples of CꢀC and CꢀX bond formation
from boronic esters and related substrates: a) Grigg, R.D.;
Rigoli, J.W.; Van Hoveln, R.; Neale, S.; Schomaker, J.M. Chem.
Eur. J. 2012, 18, 9391. b) Vagutski, V.; Elford, T.G.; Aggarwal,
V.K. Angew. Chem. Int. Ed. 2011, 50, 1080. c) Rarocheꢀ
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