Solvent-Free Buchwald-Hartwig (Hetero)arylation of Anilines, Diarylamines, and Dialkylamines Mediated by Expanded-Ring N-Heterocyclic Carbene Palladium Complexes

Article abstract of DOI:10.1002/ejoc.201501616

A highly efficient solvent-free protocol for the Buchwald-Hartwig (hetero)arylation of anilines, diarylamines, and dialkylamines mediated by the expanded-ring N-heterocyclic carbene palladium complex (THP-Dipp)Pd(cinn)Cl [THP-Dipp = 1,3-bis(2,6-diisopropylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene; cinn = cinnamyl, 3-phenylallyl] was developed. The catalytic protocol was efficient for the coupling of amines and (hetero)aryl chlorides and bromides bearing donor, acceptor, and bulky substituents.

Full text of DOI:10.1002/ejoc.201501616

DOI: 10.1002/ejoc.201501616
Full Paper
Solvent-Free C–N Cross-Coupling
Solvent-Free Buchwald–Hartwig (Hetero)arylation of Anilines,
Diarylamines, and Dialkylamines Mediated by Expanded-Ring
N-Heterocyclic Carbene Palladium Complexes
Maxim A. Topchiy,[a,b] Pavel B. Dzhevakov,[b] Margarita S. Rubina,[b,c] Oleg S. Morozov,[b]
Andrey F. Asachenko,[b] and Mikhail S. Nechaev*[b,c]
Abstract: A highly efficient solvent-free protocol for the Buch- idene; cinn = cinnamyl, 3-phenylallyl] was developed. The cata-
wald–Hartwig (hetero)arylation of anilines, diarylamines, and di-
alkylamines mediated by the expanded-ring N-heterocyclic
carbene palladium complex (THP-Dipp)Pd(cinn)Cl [THP-Dipp =
1,3-bis(2,6-diisopropylphenyl)-3,4,5,6-tetrahydropyrimidin-2-yl-
lytic protocol was efficient for the coupling of amines and (het-
ero)aryl chlorides and bromides bearing donor, acceptor, and
bulky substituents.
Introduction
free coupling of aryl chlorides efficiently catalyzed by the
[Pd(cinn)Cl]2/Mor-DalPhos [cinn = cinnamyl, 3-phenylallyl; Mor-
DalPhos = di(1-adamantyl)-2-morpholinophenylphosphine] sys-
tem.[7] The bulky N-heterocyclic carbene palladium complex
[Pd(IPr*)(cinn)Cl] {IPr* = 1,3-bis[2,6-bis(diphenylmethyl)-4-meth-
ylphenyl]imidazol-2-ylidene} showed excellent activity in an ef-
ficient solvent-free protocol for the Buchwald–Hartwig amin-
ation of nonactivated aryl halides, as described by Nolan in
2013.[8] Yet, heteroaryl halides were out of the scope of this
reaction, and only four examples of the coupling of secondary
amines were presented. Recently, our group developed a highly
efficient solvent-free protocol for the Buchwald–Hartwig amin-
ation of (hetero)aryl halides by using secondary amines. The
reaction was mediated by the Pd(OAc)2/RuPhos (RuPhos = 2-
The Buchwald–Hartwig amination reaction is a powerful tool in
modern synthetic organic chemistry. This reaction has found a
number of applications in the pharmaceutical and fine-chemi-
cal industries.[1] Thus, it is highly important to develop efficient,
selective, high-yielding, and “green” environmentally friendly
and safe protocols for this reaction.[2] The measure of “green-
ness” of a process is the E factor, introduced by Sheldon.[3] It is
defined as the ratio of weight of waste to weight of product.
The E factor for most fine chemicals exceeds 100. The largest
contributors to the magnitude of the E factor are organic sol-
vents, many of which are ecologically harmful and require ex-
pensive regeneration. Thus, elimination of solvents from or-
ganic synthesis is of high importance. In the last two decades,
several approaches to eliminate solvents from organic synthesis
were developed.[4] However, solvent-free methods for Buch-
wald–Hartwig amination remain rare.
The first example of the solvent-free amination of aryl
bromides catalyzed by Pd(OAc)2/DPEPhos [DPEPhos = (oydi-2,1-
phenylene)bis(diphenylphosphine)] was reported in 2003 by
Beletskaya et al.[5] The first example of the solvent-free amin-
ation of aryl chlorides catalyzed by Pd2(dba)3/IAPU (dba = di-
benzylideneacetone; IAPU = 2,8,9-triisobutyl-2,5,8,9-tetraaza-1-
phosphabicyclo[3.3.3]undecane) was reported in 2011 by Bec-
calli et al.[6] However, this protocol was limited to the use of
indolines at high temperature and gave moderate yields of the
products. In 2012, Tardiff and Stradiotto reported the solvent-
dicyclohexylphosphino-2′,6′-diisopropoxybiphenyl).
catalytic
system in air. Various (hetero)aryl halides were coupled with
diaryl, alkyl–aryl, and dialkylamines in good to excellent
yields.[9] Recently Khalafi-Nezhad demonstrated an efficient
magnetically separable catalyst for the Buchwald–Hartwig cou-
pling of secondary aliphatic amines and aryl halides under sol-
vent-free conditions.[10]
In this contribution, we report on the development of a cata-
lytic system for the Buchwald–Hartwig coupling of anilines and
(hetero)aryl halides under solvent-free conditions. This reaction
is mediated by the expanded-ring N-heterocyclic carbene palla-
dium complex (THP-Dipp)Pd(cinn)Cl [THP-Dipp = 1,3-bis(2,6-di-
isopropylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene].
To-
gether with the previously developed Pd(OAc)2/RuPhos sys-
tem,[9] these two catalysts constitute a toolbox for the highly
efficient solvent-free coupling of anilines, diarylamines, and di-
alkylamines with (hetero)aryl halides.
[a] A. N. Nesmeyanov Institute of Organoelement Compounds of RAS,
119991, Vavilov Str., 28, Moscow, Russian Federation
[b] A. V. Topchiev Institute of Petrochemical Synthesis of RAS,
119991, Leninsky pr., 29, Moscow, Russian Federation
[c] M. V. Lomonosov Moscow State University,
119991, Leninskie gory, 1 (3), Moscow, Russian Federation
E-mail: m.s.nechaev@org.chem.msu.ru
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/ejoc.201501616.
Results and Discussion
To find optimal conditions for the full arylation of anilines to
give triarylamines under solvent-free conditions, we tested vari-
Eur. J. Org. Chem. 2016, 1908–1914
1908
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
ous palladium sources as precatalysts (Figure 1): conventional of (THP-Dipp)Pd(cinn)Cl to 1 and 0.5 mol-% led to a significant
Pd(PPh3)4, (PPh3)2PdCl2, [P(o-Tol)3]2PdCl2; the well-defined phos- decrease in the yields of triphenylamine to 59 and 37 %, respec-
phine-based catalytic systems Pd(OAc)2/RuPhos and Pd(OAc)2/ tively (see Table S2).
2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (SPhos);[11]
We examined the performance of bases other than tBuONa
the N-heterocyclic carbene (NHC) complexes SIPrPd(cinn)Cl,
IPrPd(cinn)Cl,[12] and PEPPSI-IPr;[13] a mixture of Pd(OAc)2 and
IPr·HCl;[14] and complexes bearing expanded-ring NHCs (er-
NHCs) such as (THP-Mes)Pd(cinn)Cl, (THP-Dipp)Pd(cinn)Cl,
(THD-Mes)Pd(cinn)Cl, and (THD-Dipp)Pd(cinn)Cl.[15] After heat-
ing a mixture of aniline and bromobenzene (2.2 equiv.) in the
presence of a palladium catalyst (2 mol-%) and tBuONa
(2.4 equiv.) as a base under an atmosphere of argon at 110 °C
for 24 h we were able to obtain triphenylamine in excellent
yield by using the er-NHC complexes (THP-Mes)Pd(cinn)Cl,
(THP-Dipp)Pd(cinn)Cl, and [(THD-Dipp)Pd(cinn)Cl] (see the Sup-
porting Information; Table S1, entries 10–12). Other palladium
sources that were tested were inefficient and either the starting
materials were recovered or trace amounts of diphenylamine
were obtained (Table S1, entries 1–9, 13, and 14). The highest
activity was exhibited by (THP-Dipp)Pd(cinn)Cl, which gave an
almost quantitative yield of the product.
and found that in all cases the yields of triphenylamine de-
creased significantly (Table S3, entries 5–7). The use of tBuOK,
tBuOLi, and K2CO3 as bases gave triphenylamine in yields of 85,
33, and 26 %, respectively. In the presence of KOH and NaOH,
only starting materials were isolated from the mixture. Utiliza-
tion of K3PO4 and Cs2CO3 provided trace amounts of triphenyl-
amine (Table S3, entries 1–4).
A temperature of 110 °C was used in all experiments to melt
the reaction mixture. In some cases, the mixture solidified at
high levels of conversion.
The scope and limitations of the solvent-free protocol for the
diarylation of anilines mediated by (THP-Dipp)Pd(cinn)Cl was
studied for two model reactions: the diphenylation of various
anilines by using phenyl bromide (Table 1) and the diarylation
of aniline with various substituted (hetero)aromatic chlorides
and bromides (Table 2).
Table 1. Coupling of various anilines with bromobenzene.[a]
Figure 1. Structures of ligands.
[a] Reaction conditions: (THP-Dipp)Pd(cinn)Cl (2 mol-%), PhBr (2.2 equiv.),
tBuONa (2.4 equiv.), neat, 110 °C, 12 h, Ar. [b] Yield of isolated product.
Expanded-ring NHCs offer markedly different steric and elec-
tronic properties than their five-membered-ring counterparts.
Expansion of the ring leads to a significant increase in their
The diphenylation of alkyl-, donor-, and acceptor-substituted
donor properties; simultaneously, the steric demands of such anilines proceeded in near-quantitative yields, except for 2,6-
ligands increase dramatically.[16] We suppose that these factors diethylaniline (Table 1, entry 7). The arylation of anilines sensi-
are the reasons why the er-NHC complexes have higher activi- tive to strong bases was unsuccessful (Table 1, entries 9 and
ties than five-membered-ring NHC and phosphine complexes 10).
in a number of catalytic transformations.[17a–17e,15a,15b,17f,15c,17g]
The diarylation of aniline with (hetero)aryl chlorides and
Different loadings of (THP-Dipp)Pd(cinn)Cl were tested. A bromides gave high yields, except for aryls bearing ortho sub-
2 mol-% loading of the palladium catalyst was found to be stituents. Thus, coupling with 2-bromotoluene and 2-chlorotol-
optimal for efficient cross-coupling. A decrease in the amount uene led to moderate yields of the products (Table 2, entries 4
Eur. J. Org. Chem. 2016, 1908–1914
www.eurjoc.org
1909
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
and 5), whereas for mesityl bromide, 2-chloroanisole, and 2-
bromoanisole no diarylation products were obtained (Table 2,
entries 6, 8, and 9). In these cases, monoarylation took place.
We suppose that steric crowding by the ortho substituents hin-
dered addition of the second aryl group.
Table 3. Coupling of arylamines with bromobenzene.[a]
Table 2. Coupling of aniline with various haloarenes.[a]
[a] Reaction conditions: (THP-Dipp)Pd(cinn)Cl (1 mol-%), PhBr (1 equiv.),
tBuONa (1.2 equiv.), neat, 110 °C, 12 h, Ar. [b] Yield of isolated product.
tive yield was obtained for the activated 1-bromo-4-nitro-
benzene substrate. Most probably, this was due to its instability
in the presence of a strong base (Table 4, entry 10).
Thus, we developed an efficient catalytic system, that is,
(THP-Dipp)Pd(cinn)Cl, for the monoarylation of anilines
(Tables 3 and 4). (Hetero)aryl halides and anilines bearing do-
[a] Reaction conditions: (THP-Dipp)Pd(cinn)Cl (2 mol-%), (Het)ArX (2.2 equiv.),
tBuONa (2.4 equiv.), neat, 110 °C, 12 h, Ar. [b] Yield of isolated product. [c] Mo-
noarylated product in high yield was obtained, see Table 4.
Given that the diarylation reaction was highly efficient only nor, acceptor, and sterically bulky substituents were efficiently
for ortho-unsubstituted substrates, we studied the first and sec- used as coupling partners.
ond arylation steps in more detail. Monoarylation was studied
for two model reactions: the phenylation of various anilines by
using bromobenzene (Table 3) and the monoarylation of aniline
with various substituted (hetero)aromatic chlorides and brom-
ides (Table 4).
To note, monoarylated products were obtained with high
selectivity. No measurable signals of diarylated products were
detected in the 1H NMR and 13C NMR spectra (see the Support-
ing Information). TLC monitoring of the reactions revealed that
the er-NHC-catalyzed first arylation is fast, whereas the second
In all cases, except for challenging 2-aminopyridine[18] arylation is much slower. Thus, no significant contamination of
(Table 3, entry 10), the addition of the phenyl group to the monoarylated products with triarylamines was observed, even
anilines proceeded in near-quantitative yields. Notably, mono- at high conversion levels.
arylation proceeded efficiently for donor, acceptor, and even
highly sterically encumbered (Table 3, entries 7–9) anilines.
To find optimal conditions for the arylation of diarylamines
under solvent-free conditions, we re-examined the catalytic ac-
The monoarylation of aniline with (hetero)aryl chlorides and tivities of the er-NHC precatalysts (THP-Mes)Pd(cinn)Cl, (THP-
bromides mediated by (THP-Dipp)Pd(cinn)Cl proceeded with Dipp)Pd(cinn)Cl, (THD-Dipp)Pd(cinn)Cl, and (THD-Mes)Pd-
high efficiency. In most cases, high to quantitative yields were (cinn)Cl that showed the best performance in the diarylation of
obtained for acceptor- and donor-substituted substrates in ad- anilines (Table S1, entries 10–13). After heating a mixture of
dition to sterically encumbered substrates. Even 3-halo-substi- diphenylamine and bromobenzene (1.0 equiv.) in the presence
tuted pyridines[18] and 3-bromothiophene,[19] which are chal- of the palladium catalyst (1 mol-%) and tBuONa (1.2 equiv.) as
lenging substrates for the Buchwald–Hartwig amination, were the base under an atmosphere of argon for 24 h we were able
coupled in good yields (Table 4, entries 15–17). A nonquantita- to obtain triphenylamine in excellent yields by using (THP-
Eur. J. Org. Chem. 2016, 1908–1914
www.eurjoc.org
1910
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
Table 4. Coupling of aryl halides with aniline.[a]
Table 5. Coupling of aryl halides with diphenylamine.[a]
[a] Reaction conditions: (THP-Dipp)Pd(cinn)Cl (1 mol-%), (Het)ArX (1 equiv.),
tBuONa (1.2 equiv.), neat, 110 °C, 12 h. [b] Yield of isolated product.
Consequently, the limitations of the solvent-free protocol by
using (THP-Dipp)Pd(cinn)Cl as the precatalyst include the insta-
bility of the substrates in the presence of a strong base and
ortho-substituted substrates for the second arylation step. The
latter problem could be solved for solvent-free conditions by
using the Pd(OAc)2/RuPhos catalytic system.[9] ortho-Substi-
tuted haloarenes were coupled with diarylamines in high to
quantitative yields. To note, Pd(OAc)2/RuPhos was virtually inac-
tive in the arylation of monoarylamines (Table S1, entry 6),
whereas it was highly active in the arylation of diaryl, alkylaryl,
and dialkylamines under solvent-free conditions.
[a] Reaction conditions: (THP-Dipp)Pd(cinn)Cl (1 mol-%), (Het)ArX (1 equiv.),
tBuONa (1.2 equiv.), neat, 110 °C, 12 h, Ar. [b] Yield of isolated product.
To broaden the scope of the substrates, we tested the activ-
ity of (THP-Dipp)Pd(cinn)Cl in the coupling of dialkylamines.
Morpholine was used as a model substrate (Table 6). In all cases,
we were able to obtain near-quantitative yields. Thus, under
our conditions secondary aliphatic amines were efficiently cou-
pled with acceptor-substituted, donor-substituted, and steri-
cally encumbered (hetero)aryl halides.
Mes)Pd(cinn)Cl, (THP-Dipp)Pd(cinn)Cl, and (THD-Dipp)Pd-
(cinn)Cl (Table S4, entries 1–3). (THD-Mes)Pd(cinn)Cl was ineffi-
cient and the starting materials were recovered (Table S4, en-
try 4). The highest catalytic activity was exhibited by (THP-
Dipp)Pd(cinn)Cl, which gave the desired product in near-quanti-
tative yield (Table S4, entry 2).
It was of particular interest for us to exhibit the utility of a
The second arylation step was studied for the model diphen- developed protocol in real-life applications. Triarylamines are
ylamine substrate and various (hetero)aryl halides (Table 5). building blocks in many organic materials exhibiting optoelec-
(Hetero)aryl chlorides and bromides unsubstituted in the ortho tronic properties.[20] The developed solvent-free method was
position give good to near-quantitative yields, whereas ortho- tested in the synthesis of commercially available TTA,[21] MeO-
substituted substrates (Table 5, entries 11–14) did not provide TPD,[22] DDP,[23] and TPD (Figure 2),[24] all of which are used in
any coupling products.
organic light-emitting diodes (OLEDs).
Eur. J. Org. Chem. 2016, 1908–1914
www.eurjoc.org
1911 © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
Table 6. Coupling of aryl halides with morpholine.[a]
to be obtained without the use of organic solvents. Calculated
E factors for the large-scale reactions were very low: 1.66 and
1.94 for TTA and MeO-TPD, respectively. DDP and TPD were
obtained, both in 99 % yield, by reaction of diphenylamine with
1,4-dibromobenzene and 4,4′-dibromobiphenyl, respectively, by
using the Pd(OAc)2/RuPhos catalytic system.[9]
Conclusions
In conclusion, we developed a toolbox for the Buchwald–Hart-
wig arylation of primary and secondary arylamines and second-
ary alkylamines under solvent-free conditions. The results are
summarized in Scheme 1. Anilines were mono(hetero)arylated
with (hetero)aryl chlorides and bromides bearing donor, ac-
ceptor, and bulky substituents by using the er-NHC precatalyst
(THP-Dipp)Pd(cinn)Cl (Scheme 1, a). For cases in which the (het-
ero)aryl halide was unsubstituted in the ortho position, we were
the first to show that anilines could be di(hetero)arylated with
the same catalyst in one step (Scheme 1, b). To note, reac-
tions (a) and (b) were mediated only by expanded-ring NHC
complexes. Conventional palladium sources, five-membered-
ring carbene complexes, and well-defined bulky phosphine cat-
alysts were not active under the solvent-free conditions. The
introduction of ortho-substituted (hetero)aryl groups into the
anilines was performed over two steps: first, (hetero)arylation
mediated by (THP-Dipp)Pd(cinn)Cl; second, (hetero)arylation
mediated by Pd(OAc)2/RuPhos (Scheme 1, c).[9] Dialkylamines
were (hetero)arylated in near-quantitative yields by using both
the (THP-Dipp)Pd(cinn)Cl and Pd(OAc)2/RuPhos catalytic sys-
tems (Scheme 1, d).
[a] Reaction conditions: (THP-Dipp)Pd(cinn)Cl (1 mol-%), (Het)ArX (1 equiv.),
morpholine (1.2 equiv.), tBuONa (1.2 equiv.), neat, 110 °C, 12 h. [b] Yield of
isolated product.
Scheme 1.
The developed protocol has a number of advantages: one,
no solvent is used; two, a low catalyst loading is used; three,
the bases are readily available; four, the reaction is activated by
conventional heating (no milling, sonication, or other means
needed). Thus, we developed a versatile, robust, highly active
catalytic system for Buchwald–Hartwig amination. Furthermore,
the reaction protocol can be scaled with no significant loss in
efficiency.
Figure 2. Structures of the synthesized OLED materials.
By using the (THP-Dipp)Pd(cinn)Cl catalyst, TTA was synthe-
sized from p-toluidine and 4-bromotoluene in 99 % yield, and
MeO-TPD was synthesized from benzidine and 4-bromoanisole
in one step (see the Supporting information) in 95 % yield.
Large-scale reactions followed by distillation of the products
This protocol meets the demands of “green” chemistry; Shel-
from the mixtures allowed pure TTA (95 %) and MeO-TPD (89 %) don's E factors for given examples are presented above. We
Eur. J. Org. Chem. 2016, 1908–1914
www.eurjoc.org
1912
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
(231 mg,2.4 mmol). The vial was transferred to a preheated oil bath
(110 °C). After 12 h, the mixture was cooled, dissolved in CH2Cl2,
and filtered through short pad of silica gel.
believe that our findings will lead to broader and more efficient
use of the Buchwald–Hartwig amination reaction in laboratory
practice and the development of “green” industrial technolo-
gies.
Acknowledgments
This study was partially supported by the Russian Foundation
for Basic Research (RFBR), research project number 13-03-
1224013 ofi_m.
Experimental Section
General Information: Unless otherwise stated, all reactions were
performed under an argon atmosphere. All starting compounds,
catalysts, and tBuONa were weighed in air. Chemicals and solvents
were obtained from commercial sources and were used without
further purification.
Keywords: Green chemistry · Cross-coupling · Amination ·
Palladium · Carbene ligands
General Procedure for the Solvent-Free Preparation of Diaryl-
amines by Diarylation of Primary Arylamines: A one-necked,
round-bottomed, 10 mL flask equipped with a reflux condenser
with an argon inlet and a magnetic stir bar was charged with the
arylamine (1 mmol), the aryl halide (2.2 mmol), (THP-
Dipp)Pd(cinn)Cl (13.2 mg, 0.02 mmol), and finally powdered tBuONa
(230.6 mg,2.4 mmol). The mixture was degassed with freeze–
pump–thaw cycles (3×). The flask was then transferred to a pre-
heated oil bath (110 °C). After 12 h, the mixture was cooled, dis-
solved in CH2Cl2, and filtered through a short pad of silica gel. In
some cases, additional purification by flash chromatography (hex-
anes/dichloromethane) was required.
[1] a) J. S. Carey, D. Laffan, C. Thomson, M. T. Williams, Org. Biomol. Chem.
2006, 4, 2337–2347; b) D. S. Surry, S. L. Buchwald, Angew. Chem. Int. Ed.
2008, 47, 6338–6361; Angew. Chem. 2008, 120, 6438–6461; c) C. Torborg,
M. Beller, Adv. Synth. Catal. 2009, 351, 3027–3043; d) C. Fischer, B. Koenig,
Beilstein J. Org. Chem. 2011, 7, 59–74; e) C. Valente, S. Calimsiz, K. H. Hoi,
D. Mallik, M. Sayah, M. G. Organ, Angew. Chem. Int. Ed. 2012, 51, 3314–
3332; Angew. Chem. 2012, 124, 3370–3388; f) J. Bariwal, E.
Van der Eycken, Chem. Soc. Rev. 2013, 42, 9283–9303.
[2] P. Anastas, N. Eghbali, Chem. Soc. Rev. 2010, 39, 301–312.
[3] R. A. Sheldon, Chem. Ind. 1992, 903–906.
[4] a) G. W. V. Cave, C. L. Raston, J. L. Scott, Chem. Commun. 2001, 2159–
2169; b) P. J. Walsh, H. M. Li, C. A. de Parrodi, Chem. Rev. 2007, 107,
2503–2545; c) A. Bruckmann, A. Krebs, C. Bolm, Green Chem. 2008, 10,
1131–1141; d) M. A. P. Martins, C. P. Frizzo, D. N. Moreira, L. Buriol, P.
Machado, Chem. Rev. 2009, 109, 4140–4182; e) M. S. Singh, S. Chow-
dhury, RSC Adv. 2012, 2, 4547–4592.
[5] G. A. Artamkina, M. V. Ermolina, I. P. Beletskaya, Mendeleev Commun.
2003, 158–160.
[6] a) L. Basolo, A. Bernasconi, E. Borsini, G. Broggini, E. M. Beccalli, ChemSus-
Chem 2011, 4, 1637–1642; b) L. Basolo, A. Bernasconi, G. Broggini, S.
Gazzola, E. M. Beccalli, Synthesis 2013, 45, 3151–3156.
[7] B. J. Tardiff, M. Stradiotto, Eur. J. Org. Chem. 2012, 3972–3977.
[8] A. Chartoire, A. Boreux, A. R. Martin, S. P. Nolan, RSC Adv. 2013, 3, 3840–
3843.
[9] M. A. Topchiy, A. F. Asachenko, M. S. Nechaev, Eur. J. Org. Chem. 2014,
3319–3322.
[10] N. Zarnaghash, F. Panahi, A. Khalafi-Nezhad, J. Iran. Chem. Soc. 2015, 12,
2057–2064.
[11] M. D. Charles, P. Schultz, S. L. Buchwald, Org. Lett. 2005, 7, 3965–3968.
[12] N. Marion, O. Navarro, J. G. Mei, E. D. Stevens, N. M. Scott, S. P. Nolan, J.
Am. Chem. Soc. 2006, 128, 4101–4111.
General Procedure for the Solvent-Free Preparation of Diaryl-
amines by Arylation of Primary Arylamines: A one-necked,
round-bottomed, 10 mL flask equipped with a reflux condenser
with an argon inlet and a magnetic stir bar was charged with the
arylamine (1 mmol), the aryl halide (1 mmol), (THP-Dipp)Pd(cinn)Cl
(6.6 mg, 0.01 mmol), and finally powdered tBuONa
(115.3 mg,1.2 mmol). The mixture was degassed with freeze–
pump–thaw cycles (3×). The flask was transferred to a preheated
oil bath (110 °C). After 12 h, the mixture was cooled, dissolved in
CH2Cl2, and filtered through short pad of silica gel. Flash chroma-
tography (hexanes/dichloromethane) yielded the pure product.
General Procedure for the Solvent-Free Preparation of Diaryl-
amines by Arylation of Diarylamines: Under an ambient atmos-
phere, a screw-cap vial equipped with a magnetic stir bar was
charged with diphenylamine (169 mg, 1 mmol), the aryl halide
(1 mmol), (THP-Dipp)Pd(cinn)Cl (6.6 mg, 0.01 mmol), and finally
powdered tBuONa (115.3 mg, 1.2 mmol). The vial was transferred
to a preheated oil bath (110 °C). After 12 h, the mixture was cooled,
dissolved in CH2Cl2, and filtered through short pad of silica gel. In
some cases, additional purification by flash chromatography (hex-
anes/dichloromethane) was required.
[13] K. H. Hoi, S. Calimsiz, R. D. J. Froese, A. C. Hopkinson, M. G. Organ, Chem.
Eur. J. 2012, 18, 145–151.
[14] G. A. Grasa, M. S. Viciu, J. K. Huang, S. P. Nolan, J. Org. Chem. 2001, 66,
7729–7737.
[15] a) E. L. Kolychev, A. F. Asachenko, P. B. Dzhevakov, A. A. Bush, V. V. Shunt-
ikov, V. N. Khrustalev, M. S. Nechaev, Dalton Trans. 2013, 42, 6859–6866;
b) V. P. Ananikov, L. L. Khemchyan, Y. V. Ivanova, V. I. Bukhtiyarov, A. M.
Sorokin, I. P. Prosvirin, S. Z. Vatsadze, A. V. Medved'ko, V. N. Nuriev, A. D.
Dilman, V. V. Levin, I. V. Koptyug, K. V. Kovtunov, V. V. Zhivonitko, V. A.
Likholobov, A. V. Romanenko, P. A. Simonov, V. G. Nenajdenko, I. Shmat-
ova, V. M. Muzalevskiy, M. S. Nechaev, A. F. Asachenko, S. Morozov, P. B.
Dzhevakov, S. N. Osipov, D. V. Vorobyeva, M. A. Topchiy, M. A. Zotova,
S. A. Ponomarenko, V. Borshchev, Y. N. Luponosov, A. A. Rempel, A. A.
Vaeeva, A. Y. Stakhee, V. Turov, I. S. Mashkovsky, S. V. Sysolyatin, V. V.
Malykhin, G. A. Bukhtiyarova, A. O. Terent'ev, I. B. Krylov, Russ. Chem. Rev.
2014, 83, 885–985; c) P. B. Dzhevakov, A. F. Asachenko, A. N. Kashin, I. P.
Beletskaya, M. S. Nechaev, Russ. Chem. Bull. 2014, 63, 890–894; d) O. S.
Morozov, A. F. Asachenko, D. V. Antonov, V. S. Kochurov, D. Y. Paraschuk,
M. S. Nechaev, Adv. Synth. Catal. 2014, 356, 2671–2678.
General Procedure for the Solvent-Free Synthesis of N-Aryl-
morpholines by Arylation of Morpholine: Under an ambient at-
mosphere, a screw-cap vial equipped with a magnetic stir bar was
charged with morpholine (95.8 mg, 1.2 mmol), the aryl halide
(1 mmol), (THP-Dipp)Pd(cinn)Cl (6.6 mg, 0.01 mmol), and finally
powdered tBuONa (115.3 mg, 1.2 mmol). CAUTION: In some cases a
strong exothermic reaction was observed. The vial was transferred to
a preheated oil bath (110 °C). After 12 h, the mixture was cooled,
dissolved in CH2Cl2, and filtered through short pad of silica gel.
General Procedure for the Solvent-Free Arylation of Diphenyl-
amine with Dibromoarenes: Under an ambient atmosphere, a
screw-cap vial equipped with a magnetic stir bar was charged with
diphenylamine (341 mg, 2.02 mmol), the dibromoarene (1 mmol),
[16] T. Dröge, F. Glorius, Angew. Chem. Int. Ed. 2010, 49, 6940–6952; Angew.
Chem. 2010, 122, 7094–7107 .
[17] a) A. Binobaid, M. Iglesias, D. J. Beetstra, B. Kariuki, A. Dervisi, I. A. Fallis,
K. J. Cavell, Dalton Trans. 2009, 7099–7112; b) A. Binobaid, M. Iglesias, D.
Pd(OAc)2 (4.5 mg, 0.02 mmol,
2 mol-%), RuPhos (18.7 mg,
0.04 mmol, mol-%), and finally powdered tBuONa
4
Eur. J. Org. Chem. 2016, 1908–1914
www.eurjoc.org
1913
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
Beetstra, A. Dervisi, I. Fallis, K. J. Cavell, Eur. J. Inorg. Chem. 2010, 5426–
5431; c) J. J. Dunsford, K. J. Cavell, Dalton Trans. 2011, 40, 9131–9135; d)
J. J. Dunsford, K. J. Cavell, B. Kariuki, J. Organomet. Chem. 2011, 696, 188–
194; e) P. Hauwert, J. J. Dunsford, D. S. Tromp, J. J. Weigand, M. Lutz, K. J.
Cavell, C. J. Elsevier, Organometallics 2013, 32, 131–140; f) L. R. Collins,
T. M. Rookes, M. F. Mahon, I. M. Riddlestone, M. K. Whittlesey, Organome-
tallics 2014, 33, 5882–5887; g) O. S. Morozov, A. V. Lunchev, A. A. Bush,
A. A. Tukov, A. F. Asachenko, V. N. Khrustalev, S. S. Zalesskiy, V. P. Anani-
kov, M. S. Nechaev, Chem. Eur. J. 2014, 20, 6162–6170.
[20] a) J. Louie, J. F. Hartwig, A. J. Fry, J. Am. Chem. Soc. 1997, 119, 11695–
11696; b) Y. Shirota, J. Mater. Chem. 2000, 10, 1–25; c) P. Strohriegl, J. V.
Grazulevicius, Adv. Mater. 2002, 14, 1439–1452; d) M. Y. Chou, M. K.
Leung, Y. L. O. Su, C. L. Chiang, C. C. Lin, J. H. Liu, C. K. Kuo, C. Y. Mou,
Chem. Mater. 2004, 16, 654–661; e) Y. Shirota, H. Kageyama, Chem. Rev.
2007, 107, 953–1010.
[21] F. Khan, A. M. Hor, P. R. Sundararajan, Synth. Met. 2005, 150, 199–211.
[22] M. Matis, P. Rapta, V. Lukes, H. Hartmann, L. Dunsch, J. Phys. Chem. B
2010, 114, 4451–4460.
[23] J. Y. Kim, D. Yokoyama, C. Adachi, J. Phys. Chem. C 2012, 116, 8699–8706.
[24] J. A. Bardecker, H. Ma, T. Kim, F. Huang, M. S. Liu, Y. J. Cheng, G. Ting,
A. K. Y. Jen, Adv. Funct. Mater. 2008, 18, 3964–3971.
[18]
K. W. Anderson, R. E. Tundel, T. Ikawa, R. A. Altman, S. L. Buchwald,
Angew. Chem. Int. Ed. 2006, 45, 6523–6527; Angew. Chem. 2006, 118,
6673–6677.
[19] M. W. Hooper, M. Utsunomiya, J. F. Hartwig, J. Org. Chem. 2003, 68, 2861–
Received: December 28, 2015
Published Online: March 15, 2016
2873.
Eur. J. Org. Chem. 2016, 1908–1914
www.eurjoc.org
1914
© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim