Electron-deficient naphthalene diimides as efficient planar π-acid organocatalysts for selective oxidative C-C coupling of 2,6-di-tert-butylphenol: A temperature effect

Article abstract of DOI:10.1016/j.molcata.2014.01.014

An efficient planar π-acid electron transfer organocatalyst based on electron-deficient substituted naphthalene diimide has been developed for oxidative C-C coupling of 2,6-di-tert-butylphenol to its dimeric derivative or unexpected ring-rearranged trimeric quinone methide by controlling the reaction temperatures.

Full text of DOI:10.1016/j.molcata.2014.01.014

Journal of Molecular Catalysis A: Chemical 385 (2014) 26–30
Contents lists available at ScienceDirect
Journal of Molecular Catalysis A: Chemical
journal homepage: www.elsevier.com/locate/molcata
Electron-deficient naphthalene diimides as efficient planar ␲-acid
organocatalysts for selective oxidative C–C coupling of
2,6-di-tert-butylphenol: A temperature effect
Hua Kea,b, Li Wanga, Yong Chena, Mei-Jin Lina,b,∗, Jian-Zhong Chena
a College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350108, Fujian, PR China
b State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002,
Fujian, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
An efficient planar ␲-acid electron transfer organocatalyst based on electron-deficient substituted naph-
thalene diimide has been developed for oxidative C–C coupling of 2,6-di-tert-butylphenol to its dimeric
derivative or unexpected ring-rearranged trimeric quinone methide by controlling the reaction temper-
atures.
Received 18 November 2013
Received in revised form 7 January 2014
Accepted 14 January 2014
Available online 23 January 2014
© 2014 Elsevier B.V. All rights reserved.
Keywords:
Naphthalene diimides
Organocatalysis
Electron transfer catalyst and C–C coupling
1. Introduction
electrons from reaction substrates, such unique ␲-acid organocat-
alysts based on electron-deficient ␲-conjugated systems could
The formation of carbon–carbon (C–C) bond is arguably one of
the most important reactions in synthetic chemistry [1], because
it allows the transformations of small, readily accessible reactants
into larger, value-added products with useful physical and chemical
properties. Generally, the C–C bond formation reactions, in partic-
ular the C–C coupling reactions of aromatic molecules, are kinetic
unfavourable, but it can be promoted in the presence of suitable cat-
alysts. Transition-metal based catalysts, such as Pd, Rh, Cu and Ni
complexes, have already been demonstrated to be the most impor-
tant class of catalysts for the C–C bond formations [2]. However,
they also suffer from some intrinsic drawbacks, e.g. the high cost,
high toxicity and air-sensitivity, which somewhat limit their scope
for applications.
To overcome the aforementioned disadvantages of transition-
metal based catalysts, an emerging class of catalysts based on
purely organic molecules (called organocatalysts) has been suc-
cessfully developed in the past decade [3]. Among the reported
organocatalysts, organic ␲-acid catalysts are most distinctive [4].
Different from the common Lewis acid organocatalysts that gen-
erally use only single atom containing empty orbits to accept
abstract the additional electrons through a linear or planar ␲
system, which undoubtedly increase their reaction cross sections
towards the substrates. In spite of foreseeable advantages, so far
only three electron-deficient ␲-conjugated molecules, i.e. tetracya-
noethylene (TCNE, Fig. 1) [5], dicyanoketene acetal (DCKA) [6] and
dichlorodicyanobenzoquione (DDQ) [7], have found catalytic activ-
ities for organic synthesis, wherein few examples deal with the C–C
bond formation reactions [8].
Naphthalene diimides (NDIs) [9] are an attractive class of
electron-deficient ␲-conjugated molecules since their parent core
possesses a high quadrupole moment (QZZ) up to +55.5 B, which
is around three times that of the explosive trinitrotoluene [10].
This makes them a strong tendency to compactly interact with
and therefore possibly abstract electrons from the surrounding
electron-rich atoms, groups or molecules. For example, due to a
remarkable anion–␲ interaction with electron-rich anions, such
unique class of ␲-acids has already been applied in the fields
of anion sensors [11] and anion transports [12]. More recently,
Matile and co-workers have indeed demonstrated the applications
of the anion–␲ interactions could be extended to the catalysis field
[13]. Herein, we reported a new oxidative C–C coupling of 2,6-di-
tert-butylphenol (2, Scheme 1) by molecular oxygen in present of
electron-deficient NDI 1 (Fig. 1), which serves as an organocatalyst
through totally electron transfer but not pure anion–␲ interac-
tions. The reason why NDI 1 was chosen is mainly in view of
∗
Corresponding author at: Fuzhou University, College of Chemistry and Chemical
Engineering, Fuzhou 350002, Fujian, PR China. Tel.: +86 591 2286 6143.
E-mail address: meijin lin@fzu.edu.cn (M.-J. Lin).
1381-1169/$ – see front matter © 2014 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molcata.2014.01.014

H. Ke et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 26–30
27
tetracarboxylic anhydrides (3 g, 11.2 mmol), imidazole (15 g,
220.1 mmol), 2,6-diisopropylaniline (10 g, 56 mmol) were added to
a three-necked flask and then heated in 160 ◦C for 12 h. After being
cooled to room temperature, the solid was poured into 1 mol L−1
aqueous HCl (500 mL) and extracted using dichloromethane (DCM)
(100 mL) twice. The obtained organic solution was washed with
aqueous NaHCO3 and water twice, and further dried by anhydrous
Na2SO4 for 2 h. Filtration and removal the organic solvents afford
a gray solid, which was purified by column chromatography (SiO2,
DCM:PE = 1:1) resulting in NDI 1 as a white solid (2.2 g, 40%). 1H
NMR (CDCl3, 400 MHz, 298 K): ı = 8.92 (s, 1H), 7.55 (t, J = 7.2 Hz, 2H),
7.40 (d, J = 6.9 Hz, 4H), 2.84–2.61 (m, 4H), 1.20 (d, J = 5.9 Hz, 24H);
13C NMR (CDCl3, 100 MHz, 298 K): 162.94, 145.54, 131.60, 130.01,
130.00, 127.68, 126.92, 124.25, 29.33, 23.97. MS (ESI): calculated
for [M + H]+ of 3, 587.72, found, 587.19; HRMS (ESI): calculated for
[M + H]+, 587.2832, found, 587.2889.
Fig. 1. Molecular structures of the available ␲-acid organocatalysts TCNE, DCKA,
DDQ and the title compound NDI 1, as well as its electrostatic potential surface (EPS,
blue positive, red negative, 0.01 Hartree, B3LYP/6-311G**). (For interpretation of
the references to color in this figure legend, the reader is referred to the web version
of this article.)
2.2.2. Catalytic experiments of organocatalyst NDI 1 towards
oxidative C–C coupling of 2
its simple structure but high solubility in most organic solvents.
With regards to the reaction substrate, the phenol 2 was chosen as
a proof-of-concept example since the exceptional electron dona-
tion of its anion, which is expected to offer an electron to the
electron-deficient NDI 1. Although the oxidative transformation
of phenol 2 to coupling product 3 by the inorganic catalysts is
very common [14], its organocatalytic reaction and particularly fur-
ther ring-rearranged product quinone methide derivative 4 is first
observed.
To a three-necked flask, a MeOH solution of NDI 1 (for entry
2, 2 is absent), starting material 2 and KOH (for entry 3, KOH is
absent) was added and then reacted at 20 ◦C (entry 5), 40 ◦C (entry
1) or 90 ◦C (entry 6) for 24 h or 200 h (the reaction progress is
monitored by thin layer chromatography). After being cooled to
room temperature, the cooled mixture was poured into 1 mol L−1
aqueous HCl (100 mL) and extracted with DCM (50 mL) twice. The
obtained organic solution was washed with a saturated solution
of NaHCO3 (50 mL) and water for two times, and further dried
by anhydrous Na2SO4. Filtration and removal the organic solvents
afford a brown solid, which was purified by column chromatogra-
phy (SiO2, DCM:PE = 1:1) affording compound 3 as a yellow solid
(815 mg, 80%) and Compound 4 is a light yellow solid (70 mg, 5%)
for entry 1, but 3 of 60 mg (ca. 5%) and 4 of 817 mg (85%) for entry
6. For other trials (entry 2–5), almost no oxidative products was
obtained.
2. Experimental
2.1. Materials and measurements
2.1.1. Materials and methods
1,4,5,8-Naphthalenetetracarboxylic (95%), 2,6-diisopropylben-
zenamine (95%), 2,6-di-tert-butylphenol (97%), potassium hydrox-
ide (≥99%), methanol (99.5%), dichloromethane (DCM, 99.5%) and
petroleum ether (PE, 60–90 ◦C) were obtained from commer-
cial suppliers. All chemicals and reagents were used as received
unless otherwise stated. Column chromatography was performed
using silica gel (Si60, mesh size 150 ␮m from Sinopharm Chemical
Reagent Co., Ltd.). NMR spectra were recorded with a Bruker Avance
400 MHz NMR spectrometer. Chemical shifts are given in parts per
million (ppm) and referred to TMS as internal standard. 1H coupling
constants J are given in Hertz (Hz). ESI mass spectra were recorded
on a LCQ Fleet from Thermo Fisher Scientific. High-resolution mass
spectra (HRMS) were acquired on the Thermo Scientific Exactive
Plus Mass spectrometer equipped with an electrospray ionization
(ESI) source.
Compound 3: 1H NMR (CDCl3, 400 MHz, 298 K) ı = 7.73 (s, 4H),
1.38 (s, 36H). 13C NMR (CDCl3, 100 MHz, 298 K): 186.44, 150.43,
136.13, 126.00, 36.03, 29.60. MS (ESI): calculated for [M + H]+
of 3, 409.62, found, 409.20; HRMS (ESI): calculated for [M + H]+,
409.3028, found, 409.3089.
Compound 4: 1H NMR (CDCl3, 400 MHz, 298 K): ı = 8.20 (s, 1H),
7.43 (d, J = 2.5 Hz, 1H), 7.02 (d, J = 2.5 Hz, 1H), 6.88 (d, J = 2.4 Hz,
1H), 6.75 (s, 1H), 6.27 (d, J = 2.3 Hz, 1H), 1.35 (s, 9H), 1.31 (s, 9H),
1.24 (s, 9H), 1.12 (s, 9H), 1.08 (s, 9H), 0.97(s, 9H). 13C NMR (CDCl3,
100 MHz, 298 K): 204.51, 185.58, 185.51, 156.56, 154.19, 149.08,
148.83, 148.06, 147.51, 146.48, 143.30, 134.56, 131.88, 126.39,
126.13, 125.97, 65.01, 38.96, 35.58, 35.55, 35.52, 29.58, 29.41, 29.32,
29.26, 28.49, 27.72. MS (ESI): calculated for [M − H]− of 4, 611.92,
found, 612.25; HRMS (ESI): calculated for [M + H]+, 613.4542, found,
613.4593.
2.2. Synthesis and catalytic experiments
2.2.1. Synthesis of organocatalyst NDI 1
The synthesis of NDI 1 is similar to the procedure reported
in the literature [15]. Under the argon, a mixture of naphthalene
3. Results and discussions
The organocatalyst NDI 1 was prepared according to the pro-
cedure reported in the literature [15], and its molecular structure
was assigned by NMR spectroscopy as well as by single-crystal X-
ray analysis (for details, see Supporting information). Electrostatic
potential surfaces (EPS) of NDI 1 was calculated at the B3LYP/6-
311G** level, which provided a visual indication of the potential
reaction cross section of organocatalyst NDI 1 towards the electron-
rich substrates (Fig. 1). Due to the introduction of two di-iso-propyl
phenyl substituents at two imide positions perpendicularly, the
positive electrostatic surface (blue) of the NDI plane was extended
in a continuous way to the equatorial region of the phenyl plane,
which remarkably expanded the potential reaction cross section of
Scheme 1. Selective oxidative C–C coupling of 2 to its dimer 3 or ring-rearranged
trimeric 4 in the presence of organocatalyst NDI 1.

28
H. Ke et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 26–30
Table 1
Reaction condition optimizations for the selective C–C coupling of 2 to dimeric 3 or rearranged trimeric 4.
Entry
Molar ratioa
Under argonb
Temp. (◦C)
Time (h)
Yield of 3 (%)c
Yield of 4 (%)c
1
2
3
4
5
6
1:1:0.05
1:1:0
1:0:0.05
1:1:0.05
1:1:0.05
1:1:0.05
Not
Not
Not
Yes
Not
Not
40
40
40
40
20
90
24
24
24
24
200
24
80
0
0
Trace
0
5.0
5.0
0
0
Trace
0
85
a
Molar ratio meant 2:KOH:NDI 1.
Not under argon meant the reaction was exposed to the air.
The yield is referred to the starting material 2.
b
c
NDI 1. Accordingly, NDI 1 should be a high performance electron
acceptor for the additional electrons.
described in the following), corroborates such a radical mechanism
(Scheme 2).
The catalytic activities of NDI 1 towards the selective C–C cou-
pling of 2 to its dimer 3 or trimeric 4 (Scheme 1) were attempted
by dissolving a mixture of 2, NDI 1 and KOH in methanol (MeOH)
and then monitoring the reactions under varying conditions (molar
ratio of the reactant, catalyst and base, reaction atmosphere, tem-
perature and time) via thin layer chromatography (TLC) (for the
detailed experiments and characterizations of the oxidative prod-
ucts, see Supporting information). The results for several trials are
shown in Table 1.
As expected, under a base condition and an exposed atmo-
sphere, the oxidative C–C coupling reaction of 2 could indeed be
promoted in the presence of a trace amount of electron-deficient
NDI 1. In more specific terms, the highest conversion to 3 was
obtained in a yield of 80% when the molar ratio of 2, KOH and NDI
1 is 1:1:0.05 and reaction temperature is at 40 ◦C (entry 1). The
absence of NDI 1 and KOH resulted in almost no dimeric products 3
(entry 2 and 3), which confirmed the indispensability of organocat-
alyst NDI 1 and deprotonated 2 in this C–C coupling reaction. Last
but not less important, the oxidant is supposed to be molecular oxy-
gen because only trace product could be detected if the reaction was
performed under argon (entry 4).
Taking all the above observations into consideration, a rad-
ical reaction sequence was the most plausible scenario for the
oxidative C–C coupling reaction of 2 to its dimeric 3. As shown
in Scheme 1, the electron-deficient NDI 1 is supposed to serve as
a single electron transfer catalyst, which can accept an electron
from the deprotonated phenolate ion 2a, making the latter to a 2,6-
di-tert-butyl-phenoxide radical 2b. This intermediate immediately
transforms into a carbon radical 2c and subsequently generates a
new diphenol derivative 2e by a homocoupling reaction. The latter
species may undergo another deprotonation and electron transfer
steps to afford the final product 3. Owing to the reaction exposed to
the air, the organocatalyst NDI 1 could be reactivated from the gen-
erated radical anion NDI 1˙ by transferring the additional electron
to the molecular oxygen in the air [16]. Evidence for the formation
of NDI radical anions is given by a colour change of the solution
from light yellow to orange during the reaction, which is in accor-
dance with the spectral characteristics of spectroelectrochemically
generated NDI radical anions [17]. This proposed radical reaction
mechanism is strongly supported by the high yield of 3 obtained
under the base condition. Analysis of Hammett coefficients sug-
gests that a more pronounced intermolecular electron transfer from
the substrates to NDI 1 could >be achieved upon deprotonation of
hydrogen group (ꢀp+ = −0.92 for –OH) of phenol 2 to its oxide anion
(ꢀp+ = −2.30 for –O−) [18]. Indeed, a similar phenomenon about the
intramolecular electron transfer enhancement has already been
observed in perylene diimides covalently functionalized by one
or two 4-hydroxyphenyl substituents upon addition of base [19].
Moreover, almost no dimeric product 3 generated at low tempera-
ture (20 ◦C, entry 5) but further chain propagation to form a trimeric
4 in a yield of ca. 85% under reflux (90 ◦C, entry 6, the details will be
Interestingly, as mentioned above, an increased temperature of
the reaction resulted in the further chain propagation of the formed
dimeric 3, affording a ring-rearranged trimeric 4 in a high yield
(85%, entry 6). The molecular structure of 4 was firstly assigned
by single-crystal X-ray analysis (for details and crystal data, see
Supporting information), which unequivocally confirm its ring-
rearranged structure with two p-quinone methide moieties (bond
˚
˚
˚
lengths of 1.34–1.37 A for C=C, 1.45–1.49 A for C–C, and ca. 1.23 A
for C=O bonds, Fig. 2c) interconnected by a cyclopentenone unit
˚
˚
(bond lengths of ca. 1.35 A for C=C, 1.45–1.48 A for C–C, and ca.
˚
1.21 A for C=O bonds) through a shared C atom and a C–C bond
˚
(ca. 1.50 A), respectively (Fig. 2). Each quinone and cyclopentenone
moiety was functionalized by two tert-butyl substituents leading
to a high soluble 4. This structural feature was also supported by
1H and HH-COSY NMR spectra of 4 (see Figs. S8–S10 in Supporting
information), which showed six sets of single signals with same
integrated ratios between 6.0 and 8.5 ppm, corresponding to the six
protons in the core of 4. Owing to one p-quinone methide moiety
bonded to cyclopentenone on a sp3 C atom, 4 may be a mixture
of two equimolar enantiomers, which is indeed observed in its
single-crystal structure (Fig. 2a). Although the dimerization of 2
to 3 has already been reported to be promoted by several oxida-
tive catalysts, such as Cu, Mn, Fe and Co complexes [20], no one
exhibited such temperature-dependent selective oxidative cataly-
sis, particularly for synthesis of complex molecules beyond dimeric
3. Considering the possible applications of the quinone methide
H2O
O
O
OH-
OH
R
R
R
R
O
R
R
2b
2a
R
R
2c
2
NDI 1
NDI 1
NDI 1
NDI 1
R
R
R
H
O2
O2
O2
O
O
H
R
2d
O2
R
R
R
R
R
R
OH
HO
O
O
R
R
3
2e
R
R
O
R
R
O
R
OH-
O
O
R
R
H2O
R
2g
2f
Scheme 2. Possible mechanistic pathways for the oxidative C–C coupling reaction
of 2 to its dimer 3 from under an organocatalysis of NDI 1 (R = tert-butyl).

H. Ke et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 26–30
29
Scheme 3. Plausible mechanistic pathways for the oxidative C–C coupling reaction of 2 to its ring-rearranged trimeric 4 from under an organocatalysis of NDI 1 (R = tert-butyl).
Mechanistically, a radical ring-rearranged sequence (Scheme 3)
may account for the formation of 4. Due to the high activity of rad-
ical 2c at high temperature, it could attack the C=C bond of the
generated 3 at the position with a low steric hindrance leading to
a trimeric radical 3a, which could be further chain propagated and
resonated to its phenol 3b. The obtained species may also undergo
a similar deprotonation and electron transfer steps to those in the
formation of dimeric 3 affording an unstable diradical 3d, which is
easy to be transformed to the final product 4 after a key electron
rearrangement and ring-open reaction caused by a steric hindrance.
4. Conclusions
In conclusion, we have demonstrated an efficient planar ␲-
acid electron transfer organocatalyst for the selective oxidative
C–C coupling of 2, 6-di-tert-butylphenol. To the best of our knowl-
edge, although the electron-deficient naphthalene diimides have
been extendedly studied, this is first-time observation of the
C–C coupling catalytic function for such versatile compounds.
More importantly, the reaction products of 2,6-di-tert-butylphenol
(dimeric 3 or ring-rearranged trimeric 4) could be controlled by the
reaction temperatures in the presence of single electron transfer
catalyst NDI 1. Owing to the ring-rearranged trimeric 4 belonging to
the important intermediates quinone methide derivatives, the syn-
thetic method developed in this work will open up a facial approach
for the synthesis of the relative bioactive natural products.
Fig. 2. The molecular structures of two enantiomers of 4 in the crystal ((a), black
C, red O) and a proposed chemical structure of 4 (b) according to its bond length
of its backbone (c). For clarity, the tert-butyl groups were represented by blue balls
and all hydrogen atoms were omitted in (a), however, all the tert-butyl groups and
hydrogen atoms were omitted in (c)1. (For interpretation of the references to color
in this figure legend, the reader is referred to the web version of this article.)
Acknowledgements
derivatives in the pharmaceuticals [21], the organocatalysts NDI
1 is anticipated to open up a facial synthetic approach for such
reactive intermediates.
This work is supported by National Natural Science Foundation
of China (21202020 and J1103303), Doctoral Fund of Ministry of
Education of China (20123514120002), and Science & Technical
Development Foundation of Fuzhou University (2012-XQ-10 and
2013-XQ-14).
1
Crystallographic
data
for
4:
C42H60O3,
M = 612.90,
monoclinic,
◦
◦
◦
˚
˚
˚
a = 12.349(3) A, b = 17.039(3) A, c = 18.483(4) A, ˛ = 90.00 , ˇ = 96.09(3) , ꢁ = 90.00 ,
V = 3867.0(13) A , T = 293(2) K, space group Pc, Z = 4, 37,069 reflections measured,
Appendix A. Supplementary data
3
˚
16,242 independent reflections. The final R1 values were 0.0487 (I > 2ꢀ(I)). The final
wR(F2) values were 0.1169 (I > 2ꢀ(I)). The final R1 values were 0.0787 (all data). The
final wR(F2) values were 0.1304 (all data). The goodness of fit on F2 was 1.024. Flack
parameter = 0.0.(3).
Supplementary data associated with this article can be
found, in the online version, at http://dx.doi.org/10.1016/j.molcata.
2014.01.014.

30
H. Ke et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 26–30
(b) S. Guha, F.S. Goodson, S. Roy, L.J. Corson, C.A. Gravenmier, S. Saha, J. Am.
References
Chem. Soc. 133 (2011) 15256–15259;
(c) M.R. Ajayakumar, D. Asthana, P. Mukhopadhyay, Org. Lett. 14 (2012)
4822–4825;
(d) S. Guha, F.S. Goodson, L.J. Corson, S. Saha, J. Am. Chem. Soc. 134 (2012)
13679–13691.
[1] For selected reviews on the C–C bond formations, see:
(a) A. Suzuki, Angew. Chem. Int. Ed. 123 (2011) 6854–6869;
A. Suzuki, Angew. Chem. Int. Ed. 50 (2011) 6722–6737;
(b) C.S. Yeung, V.M. Dong, Chem. Rev. 111 (2011) 1215–1292;
(c) A. Bhunia, S.R. Yetra, A.T. Biju, Chem. Soc. Rev. 41 (2012) 3140–3152;
(d) L. Wang, W. He, Z. Yu, Chem. Soc. Rev. 42 (2013) 599–621.
[2] For selected reviews on the transition-metal based catalysis, see:
(a) C. Parmeggiani, F. Cardona, Green Chem. 14 (2012) 547–564;
(b) J. Mahatthananchai, A.M. Dumas, J.W. Bode, Angew. Chem. Int. Ed. 124
(2012) 11114–11152;
[12] (a) V. Gorteau, G. Bollot, J. Mareda, A. Perez-Velasco, S. Matile, J. Am. Chem. Soc.
128 (2006) 14788–14789;
(b) V. Gorteau, G. Bollot, J. Mareda, S. Matile, Org. Biomol. Chem. 5 (2007)
3000–3012;
(c) R.E. Dawson, A. Hennig, D.P. Weimann, D. Emery, S. Gabutti, J. Montenegro,
V. Ravikumar, M. Mayor, J. Mareda, C.A. Schalley, S. Matile, Nat. Chem. 2 (2010)
533–538;
J. Mahatthananchai, A.M. Dumas, J.W. Bode, Angew. Chem. Int. Ed. 51 (2012)
10954–10990;
(d) J. Mísˇek, A. Vargas Jentzsch, S.-I. Sakurai, D. Emery, J. Mareda, S. Matile,
Angew. Chem. Int. Ed. 122 (2010) 7846–7849;
J. Mísˇek, A. Vargas Jentzsch, S.-I. Sakurai, D. Emery, J. Mareda, S. Matile, Angew.
Chem. Int. Ed. 49 (2010) 7680–7683.
(c) B. Sundararaju, M. Achard, C. Bruneau, Chem. Soc. Rev. 41 (2012) 4467–4483;
(d) P.B. Arockiam, C. Bruneau, P.H. Dixneuf, Chem. Rev. 112 (2012) 5879–5918.
[3] For selected reviews on the organocatalysis, see:
(a) A. Berkessel, H. Groeger, Asymmetric Organocatalysis, Wiley VCH, Wein-
heim, 2005;
[13] Y. Zhao, Y. Domoto, E. Orentas, C. Beuchat, D. Emery, J. Mareda, N. Sakai, S.
Matile, Angew. Chem. Int. Ed. 52 (2013) 9940–9943.
[14] (a) M. Matsushita, K. Kamata, K. Yamaguchi, N. Mizuno, J. Am. Chem. Soc. 127
(2005) 6632–6640;
(b) B. List, Chem. Rev. 107 (2007) 5413–5415;
(c) W.C. David, MacMillan, Nature 455 (2008) 304–308;
(d) F. Giacalone, M. Gruttadauria, P. Agrigento, R. Noto, Chem. Soc. Rev. 41
(2012) 2406–2447.
(b) J.N.J. Segoviano-Garfias, R. Moreno-Esparza, G. Mendoza-Diaz, Inorg. Chim.
Acta 363 (2010) 3461–3468;
(c) B.-S. Liao, Y.-H. Liu, S.M. Peng, S.-T. Liu, Dalton Trans. 41 (2012) 1158–1164;
(d) J.E.W. Cull, A. Richarda, J. Scott, Green Chem. 15 (2013) 362–364.
[15] (a) W. Yue, Y. Zhen, Y. Li, W. Jiang, A. Lv, Z. Wang, Org. Lett. 12 (2010) 3460–3463;
(b) L.H. Tong, P. Pengo, W. Clegg, J.P. Lowe, P.R. Raithby, J.K.M. Sanders, S.I. Pascu,
Dalton Trans. 40 (2011) 10833–10842.
[16] (a) K.L. Mulfort, J.T. Hupp, J. Am. Chem. Soc. 129 (2007) 9604–9605;
(b) O.K. Farha, Y.-S. Bae, B.G. Hauser, A.M. Spokoyny, R.Q. Snurr, C.A. Mirkin, J.T.
Hupp, Chem. Commun. 46 (2010) 1056–1058.
[17] (a) R.S. Lokey, B.L. Iverson, Nature 375 (1995) 303–305;
(b) S. Guha, S. Saha, J. Am. Chem. Soc. 132 (2010) 17674–17677.
[18] C. Hansch, A. Leo, R.W. Taft, Chem. Rev. 91 (1991) 165–195.
[19] M.J. Lin, B. Fimmel, K. Radacki, F. Würthner, Angew. Chem. Int. Ed. 123 (2011)
11039–11042;
[4] (a) Y. Masaki, Yakugaku Zasshi 126 (2006) 1–26;
(b) O. Sereda, S. Tabassum, R. Wilhelm, Top. Curr. Chem. 291 (2010) 349–393.
[5] (a) Y. Masaki, T. Miura, M. Ochiai, Chem. Lett. (1993) 17–20;
(b) T. Miura, Y. Masaki, J. Chem. Soc., Perkin Trans. 1 (1994) 1659–1660.
[6] (a) T. Miura, Y. Masaki, Tetrahedron 51 (1995) 10477–10486;
(b) Y. Masaki, N. Tanaka, T. Miura, Tetrahedron Lett. 39 (1998) 5799–5802;
(c) N. Tanaka, Y. Masaki, Synlett (1999) 1960–1962;
(d) Y. Masaki, T. Yamada, N. Tanaka, Synlett (2001) 1311–1313.
[7] (a) K. Tanemura, T. Suzukia, T. Horaguchi, J. Chem. Soc., Chem. Commun. (1992)
979–980;
(b) K. Tanemura, T. Suzuki, T. Horaguchi, J. Chem. Soc., Perkin Trans. 1 (1992)
2997–2998;
(c) K. Tanemura, T. Horaguchi, T. Suzuki, Bull. Chem. Soc. Jpn. 65 (1992)
304–305.
M.J. Lin, B. Fimmel, K. Radacki, F. Würthner, Angew. Chem. Int. Ed. 50 (2011)
10847–10850.
[20] (a) K. Omura, J. Org. Chem. 63 (1998) 10031–10034;
(b) H. Nishino, H. Satoh, M. Yamashita, K. Kurosawa, J. Chem. Soc., Perkin Trans.
2 (1999) 1919–1924;
[8] (a) N. Tanaka, Y. Masaki, Synlett (2000) 406–408;
(b) N. Tanaka, T. Miura, Y. Masaki, Chem. Pharm. Bull. 48 (2000) 1010–1016;
(c) Y. Masaki, K. Yamazaki, H. Kawai, T. Yamada, A. Itho, Y. Arai, H. Furukawa,
Chem. Pharm. Bull. 54 (2006) 591–593;
(c) V. Mahadevan, J.L. DuBois, B. Hedman, K.O. Hodgson, T.D.P. Stack, J. Am.
Chem. Soc. 121 (1999) 5583–5584;
(d) Y. Masaki, T. Yamada, H. Kawai, A. Itoh, Y. Arai, H. Furukawa, Synlett (2006)
288–290.
(d) Y. C¸ imen, H. Türk, J. Mol. Catal. A: Chem. 265 (2007) 237–243;
(e) A.P. Singhand, R. Gupta, Eur. J. Inorg. Chem. (2010) 4546–4554;
(f) B.S. Liao, Y.H. Liu, S.M. Peng, S.T. Liu, Dalton Trans. 41 (2012) 1158–1164;
(g) J.E.W. Cull, A. Richard, J. Scott, Green Chem. 15 (2013) 362–364.
[21] For selected reviews on the quinone methides, see:
(a) P. Wan, D.W. Brousmiche, C.Z. Chen, J. Cole, M. Lukeman, M. Xu, Pure Appl.
Chem. 73 (2001) 529–534;
[9] For selected reviews on the electron-deficient NDIs, see:
(a) S.V. Bhosale, C.H. Jani, S.J. Langford, Chem. Soc. Rev. 37 (2008) 331–342;
(b) N. Sakai, J. Mareda, E. Vauthey, S. Matile, Chem. Commun. 46 (2010)
4225–4237;
(c) F. Würthner, M. Stolte, Chem. Commun. 47 (2011) 5109–5115;
(d) X. Zhan, A. Facchetti, S. Barlow, T.J. Marks, M.A. Ratner, M.R. Wasielewski,
S.R. Marder, Adv. Mater. 23 (2011) 268–284.
(b) R.W. Van De Walter, T.R.R. Pettus, Tetrahedron 58 (2002) 5367–5405;
(c) P. Wang, Y. Song, L. Zhang, H. He, X. Zhou, Curr. Med. Chem. 12 (2005)
2893–2913;
[10] (a) B.L. Schottel, H.T. Chifotides, K.R. Dunbar, Chem. Soc. Rev. 37 (2008) 68–83;
(b) J. Mareda, S. Matile, Chem. Eur. J. 15 (2009) 28–37.
[11] (a) M.R. Ajayakumar, P. Mukhopadhyay, S. Yadav, S. Ghosh, Org. Lett. 12 (2010)
2646–2649;
(d) S.E. Rokita, Quinone Methides, John Wiley & Sons, Hoboken, NJ, 2009.