Syntheses of (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)arenes through Pd-catalyzed borylation of arylbromides with the successive use of 2,2′-bis(1,3,2-benzodioxaborole) and pinacol

Article abstract of DOI:10.1016/j.tetlet.2012.10.118

Syntheses of (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)arenes through the Pd-catalyzed borylation of arylbromides with the successive use of 2,2′-bis(1,3,2-benzodioxaborole) and pinacol were investigated. PdCl ₂(dppf) and AcOK in EtOH or DMSO successfully provided (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)arenes. In particular, this method was more effective in the borylation of arylbromides bearing sulfonyl groups than the conventional Pd-catalyzed borylation using pinacolborane or bis(pinacolato)diboron.

Full text of DOI:10.1016/j.tetlet.2012.10.118

Tetrahedron Letters 54 (2013) 166–169
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Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Syntheses of (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)arenes through
Pd-catalyzed borylation of arylbromides with the successive use of
2,20-bis(1,3,2-benzodioxaborole) and pinacol
⇑
Jun Takagi, Tetsu Yamakawa
Sagami Chemical Research Institute, Catalysis Group, Hayakawa 2743-1, Ayase, Kanagawa 252-1193, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Syntheses of (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)arenes through the Pd-catalyzed borylation of
arylbromides with the successive use of 2,20-bis(1,3,2-benzodioxaborole) and pinacol were investigated.
PdCl2(dppf) and AcOK in EtOH or DMSO successfully provided (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-
yl)arenes. In particular, this method was more effective in the borylation of arylbromides bearing sulfonyl
groups than the conventional Pd-catalyzed borylation using pinacolborane or bis(pinacolato)diboron.
Ó 2012 Elsevier Ltd. All rights reserved.
Received 18 September 2012
Revised 24 October 2012
Accepted 29 October 2012
Available online 3 November 2012
Keywords:
(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-
yl)arenes
2,20-Bis(1,3,2-benzodioxaborole)
Pd catalyst
Borylation
and pin2B2 or pinBH6 in the presence of PdCl2(dppf) (3.0 mol %),
dppf (3.0 mol %), and AcONa in 1,4-dioxane at 105 °C for 16 h. This
conventional borylation afforded rather low yields, 37% and 14%,
respectively. Compound b was obtained from 4-bromobenzene-
sulfonamide and pin2B2 in a moderate yield (68%) by the use of
PdCl2(dppf) (2.7 mol %) and AcOK in DMSO at 80 °C.7 Nevertheless,
a somewhat long reaction time, 16 h, was required.
5
Arylboronic acids and their diol-esters are important reagents
in organic synthesis1 and the applications in transition metal-cat-
alyzed C–C, C–N, and C–O bond formations render them as some
of the most useful synthetic reagents in both academic laboratories
and industry.2 Particularly, (4,4,5,5-tetramethyl-1,3,2-dioxaboro-
lan-2-yl)arenes (pinB-Ar) are some of the most available reagents
because of their stability against air and moisture.1 Numerous
number of reports have been published regarding the syntheses
of pinB-Ar through transition-metal catalyzed borylation of are-
nes3 or arylhalides4 with pinacolborane (pinBH) or bis(pinacola-
to)diboron (pin2B2). Although these borylations are widely
applicable to a variety of substrates, they are unsatisfactory for
pinB-Ar syntheses from substrates bearing several specific substit-
uents. Sulfonyl groups are instances of such substituents. On the
other hand, some sulfonated pinB-Ar are important intermediates
in the synthesis of medicines. For example, pentafluorophenyl 4-
(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzenesulfonate (a)
is an intermediate in the synthesis of protein kinase inhibitors5
and IKK2 inhibitors,6 and 4-(4,4,5,5-tetramethyl-1,3,2-dioxaboro-
lan-2-yl)benzenesulfonamide (b) is an intermediate in the synthe-
sis of phosphodiesterase inhibitors.7 The reported synthetic
methods of compounds a and b employed conventional Pd-
catalyzed borylations using pinBH or pin2B2. Compound a was
synthesized from pentafluorophenyl 4-bromobenzenesulfonate
In the search for an efficient process for the borylation of
these sulfonated arylbromides, we found that the successive
use of 2,20-bis(1,3,2-benzodioxaborole) (cat2B2) and pinacol with
PdCl2(dppf) catalyst successfully provided moderate yields. Thus,
after heating a mixture of cat2B2, PdCl2(dppf), pentafluorophenyl
4-bromobenzenesulfonate, and AcOK in EtOH at 80 °C for 2 h,
followed by the addition of pinacol and stirring at room temper-
ature for 30 min, a was obtained in 90% 1H NMR yield. The prod-
uct was isolated as a white solid in 78% yield (Scheme 1).8,9 In
addition, the borylation of 4-bromobenzenesulfonamide under
the same conditions provided b in 85% 1H NMR yield and 60%
isolated yield. The yield of a was obviously superior to the liter-
ature data.5,6 While the yield of b was slightly lower than the
reported yield,7 the reaction time was considerably shorter than
that for the reported borylation using pin2B2. Although cat2B2 is
an expensive reagent, we can present the advantage of the
present borylation in the syntheses of sulfonated pinB-Ar. Inter-
estingly, both reactions afforded low yields in DMSO solvent,
which is generally used in conventional borylation: 0% and 45%
1H NMR yields, respectively.
⇑
Corresponding author. Tel.: +81 467769268; fax: +81 467774113.
E-mail address: t_yamakawa@sagami.or.jp (T. Yamakawa).
0040-4039/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2012.10.118

J. Takagi, T. Yamakawa / Tetrahedron Letters 54 (2013) 166–169
167
PdCl2(pddf) (3.0 mol%)
AcOK (3.0 equiv)
O
O
B
B
(1.1 equiv)
O
C6F5 O S
O
O
C6F5 O S
O
O
pinacol (2.2 equiv)
rt, 30 min
O
O
Br
Br
B
EtOH, 80 °C, 2 h
O
a
90% NMR yield
78% isolated yield
PdCl2(pddf) (3.0 mol%)
AcOK (3.0 equiv)
O
O
B
B
(1.1 equiv)
O
H2N S
O
O
H2N S
O
O
B
pinacol (2.2 equiv)
rt, 30 min
O
O
EtOH, 80 °C, 2 h
O
b
85% NMR yield
60% isolated yield
Scheme 1. Pd-catalyzed borylation of pentafluorophenyl 4-bromobenzenesulfonate and 4-bromobenzenesulfonamide with the successive use of cat2B2 and pinacol.
Then, we examined the application of this borylation to the
other substrates. At first, the reaction conditions were surveyed
using methyl 4-bromobenzoate as the substrate. Representative
results for the synthesis of methyl 4-(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)benzoate (c) are listed in Table 1.8,9
Next, the scope and limitations of the substrates were investi-
gated. Based on the results in Table 1, we performed the borylation
under two conditions: 3.0 mmol of AcOK in EtOH (conditions A)
and 7.2 mmol of AcOK in DMSO (conditions B). We chose the high-
er yield from the results obtained under these two conditions for
each substrate and summarized them in Table 2.8,9 A variety of
functional groups did not retard the reaction except in the case
of entries 3, 5, 8, 12, and 14. In the first three of these substrates,
the functional groups which exist at the ortho-position to bromine
presumably result in a sterically unfavorable environment.
To date, two similar pinB-Ar syntheses by the use of catecholbo-
rane derivatives were reported.10 One is the Pd-catalyzed syn-
thesis of 2-(1-naphthyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane
through the reaction of 1-iodonaphthalene and catecholborane
(catBH) followed by the addition on pinacol.10a Another is 2-aryl-
4,4,5,5-tetramethyl-1,3,2-dioxaborolanes syntheses from arylbro-
mides and 2-chloro- or 2-bromo-1,3,2-benzodioxaborole (catB-Cl
or catB-Br) in the presence of CoBr2 and Zn followed by the addi-
tion of pinacol.10b In both cases, a catB-Ar is considered to be an
PdCl2(dppf) quantitatively provided c (entry 1). The combined
use of PdCl2(MeCN)2 or Pd(OAc)2 and PPh3 afforded moderate
yields (entries 2 and 3). The use of AcONa also produced an excel-
lent yield (entry 4). Alcohols other than EtOH were suitable as a
solvent for this reaction except tBuOH (entries 5–9). As in the case
of the reactions in Scheme 1, the yield was drastically reduced by
the use of DMSO (entry 10). This low yield was improved to excel-
lent yields by increasing the amount of AcOK to 7.2 mmol (entry
11). Borylation using 7.2 mmol of AcOK also gave an excellent yield
t
even with BuOH as a solvent (entry 12). Various Pd catalysts or
substituted cat2B2 provided excellent yields with 7.2 mmol of
AcOK in DMSO (entries 13–17). In contrast to the borylation in en-
try 4, the yield was declined with 7.2 mmol of AcONa instead of
AcOK (entry 18).
Table 1
Pd-catalyzed borylation of 4-bromobenzoate with the successive use of cat2B2 and pinacol under various conditionsa
Pd catalyst (3.0 mol%)
base
O
O
B
B
(1.1 equiv)
O
pinacol (2.2 equiv)
rt, 30 min
O
O
MeOOC
Br
MeOOC
B
solvent, 80 °C, 2 h
O
c
Entry
Pd catalyst
Base
Solvent
Yieldb (%)
1
2
3
4
5
6
7
8
PdCl2(dppf)
AcOK (3.0 mmol)
AcOK (3.0 mmol)
AcOK (3.0 mmol)
AcONa (3.0 mmol)
AcOK (3.0 mmol)
AcOK (3.0 mmol)
AcOK (3.0 mmol)
AcOK (3.0 mmol)
AcOK (3.0 mmol)
AcOK (3.0 mmol)
AcOK (7.2 mmol)
AcOK (7.2 mmol)
AcOK (7.2 mmol)
AcOK (7.2 mmol)
AcOK (7.2 mmol)
AcOK (7.2 mmol)
AcOK (7.2 mmol)
AcONa (7.2 mmol)
EtOH
EtOH
EtOH
EtOH
PrOH
iPrOH
tBuOH
n-Hexanol
Cyclohexanol
DMSO
99 (96)
83
71
98
99
99
46
99
86
56
99 (96)
94
99
97
99
96
90
52
PdCl2(MeCN)2 + (PPh3)
Pd(AcO)2 + PPh3
PdCl2(dppf)
PdCl2(dppf)
PdCl2(dppf)
PdCl2(dppf)
PdCl2(dppf)
PdCl2(dppf)
PdCl2(dppf)
9
10
11
12
13
14
15
16
17c
18
PdCl2(dppf)
PdCl2(dppf)
DMSO
tBuOH
PdCl2(PPh3)2
Pd(PPh3)4
PdCl2 + 2PPh3
PdCl2(MeCN)2 + (PPh3)
PdCl2(dppf)
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
PdCl2(dppf)
a
b
c
Methyl 4-bromobenzoate 1.0 mmol, solvent 6.0 mL.
1H NMR yield. Isolated yields are shown in parentheses.
5,50-Di-tert-butyl-2,20-bis(1,3,2-benzodioxaborole) was used instead of cat2B2.

168
J. Takagi, T. Yamakawa / Tetrahedron Letters 54 (2013) 166–169
Table 2
Scope and limitations of substrates in Pd-catalyzed borylation with the successive use of cat2B2 and pinacola
Entry
1
Ar
Conditions
A
Isolated yield (%)
Entry
11
Ar
Conditions
A
Isolated yield (%)
60 (d)
84 (n)
HOOC
Me
NC
2
3
B
B
72 (e)
48 (f)
12
13
A
A
44 (o)
95 (p)
HO
Me
Me
MeO
Me
t Bu
PhO
4
5
B
B
88 (g)
44 (h)
14
15
B
B
49 (q)
78 (r)
CF3
F3CO
F3C
F3C
O
O
6
A
92 (i)
16
B
97 (s)
7
8
A
B
82 (j)
17
18
B
A
99 (t)
85 (u)
Cl
Cl
MeS
56 (k)
F3CS
F
F
F
O
Me
9
A
A
63 (l)
19
20
21
A
B
A
77 (v)
72 (w)
65 (x)
O
H2N
F
10
99 (m)
F
O
Me
HN
a
All the products are known compounds and were isolated as a white solid see Ref. 9.
intermediate, though it was not isolated. It seems likely that a
catB-Ar is highly sensitive to moisture and chromatogram and fa-
vors transesterification with pinacol. We also could not isolate a
catB-Ar from the reaction mixture in the present borylation. Nev-
ertheless, a catB-Ar that can be formed through the Pd-catalyzed
borylation of arylbromides with cat2B2 is probably an intermediate
(Scheme 2).
method characteristically exhibited a high yield with sulfonated
arylbromides which previously afforded rather low yields via con-
ventional borylation using pinBH or pin2B2. Mechanistic consider-
ations and the application to a one-pot Suzuki–Miyaura coupling
are now under investigation.
References and notes
As described above, the present borylation is advantageous in
the synthesis of sulfonated pinB-Ar. On the other hand, recent
interests in borylation are focused in the large-scale synthesis of
pinB-Ar using convenient reagents. For example, Molandar and
co-workers reported the borylation of arylchlorides with B2(OH)4
in the presence of Pd/X-Phos catalyst.11 ArB(OH)2 thus generated
in the reaction mixture was readily esterificated with pinacol to
pinB-Ar in a one-pot reaction. Schmidt-Leithoff and co-worker re-
ported Pd-catalyzed borylation of arylhalides or triflates with
pin2B2 that was generated in situ through the esterification of
(Me2N)2B–B(NMe2)2 with pinacol.12 Since both B2(OH)4 and
(Me2N)2B–B(NMe2)2 are stable and easy to handle, these processes
should be suitable for the large-scale synthesis of pinB-Ar. Cat2B2 is
also a stable reagent which is solid at room temperature. From that
point of view, our method seems advantageous for large-scale syn-
thesis of pinB-Ar.
1. Boronic Acids; Hall, D. G., Ed.; Wiley-VCH: Weinheim, 2005.
2. Recent reviews: (a) Liu, C.; Zhang, H.; Shi, W.; Lei, A. Chem. Rev. 2011, 111,
1780–1824; (b) Partyka, D. V. Chem. Rev. 2011, 111, 1529–1595; (c) Rosen, B.
M.; Quasdorf, K. W.; Wilson, D. A.; Zhang, N.; Resmerita, A. M.; Garg, N. K.;
Percec, V. Chem. Rev. 2011, 111, 1346–1416.
3. Recent papers and reviews: (a) Xiao, B.; Li, Y.-M.; Liu, Z.-J.; Yang, H.-Y.; Fu, Y.
Chem. Commun. 2012, 48, 4854–4856; (b) Roering, A. J.; Hale, L. V. A.; Squier, P.
A.; Ringgold, M. A.; Wiederspan, E. R.; Clark, T. B. Org. Lett. 2012, 14, 3558–
3561; (c) Hartwig, J. F. Chem. Soc. Rev. 2011, 40, 1992–2002; (d) Yamazaki, K.;
Kawamorita, S.; Ohmiya, H.; Sawamura, M. Org. Lett. 2010, 12, 3978–3981; (e)
Mkhalid, I. A. I.; Barnard, J. H.; Marder, T. B.; Murphy, J. M.; Hartwig, J. F. Chem.
Rev. 2010, 110, 890–931; (f) Robbins, D. W.; Boebel, T. A.; Hartwig, J. F. J. Am.
Chem. Soc. 2010, 132, 4068–4069; (g) Kawamorita, S.; Ohmiya, H.; Sawamura,
M. J. Org. Chem. 2010, 75, 3855–3858; (h) Ishiyama, T.; Isou, H.; Kikuchi, T.;
Miyaura, N. Chem. Commun. 2010, 46, 159–161; (i) Boebel, T. A.; Hartwig, J. F. J.
Am. Chem. Soc. 2008, 130, 7534–7535; (j) Miyaura, N. Bull. Chem. Soc. Jpn. 2008,
81, 1535–1553; (k) Ishiyama, T.; Murata, M.; Miyaura, N. J. Org. Chem. 1995, 60,
7508–7510.
4. Recent papers: (a) Yamamoto, T.; Morita, T.; Takagi, J.; Yamakawa, T. Org. Lett.
2011, 13, 5766–5769; (b) Tang, M.; Keshipeddy, S.; Zhang, Y.; Wei, X.; Savoie, J.;
Patel, N. D.; Yee, N. K.; Senanayake, C. H. Org. Lett. 2011, 13, 1366–1369; (c)
Kawamorita, S.; Ohmiya, H.; Iwai, T.; Sawamura, M. Angew. Chem., Int. Ed. 2011,
50, 8363–8366; (d) Murata, M.; Sambommatsu, T.; Oda, T.; Watanabe, S.;
Masuda, Y. Heterocycles 2010, 80, 213–218; (e) Kleeberg, C.; Dang, L.; Lin, Z. Y.;
Marder, T. B. Angew. Chem., Int. Ed. 2009, 48, 5350–5354; (f) Billingsley, K. L.;
Buchwald, S. L. J. Org. Chem. 2008, 73, 5589–5591; (g) Bilingsley, K. L.; Barder, T.
E.; Buchwald, S. L. Angew. Chem., Int. Ed. 2007, 46, 5359–5363.
In conclusion, we presented a new route for the synthesis of
pinB-Ar from arylbromides in the presence of a Pd catalyst. This
O
O
O
O
B
B
O
O
pinacol
B
Ar
B
Ar Br
Ar
O
5. Hamajima, T.; Nakamura, H.; Tang, J. WO2007-076320.
O
6. Bamborough, P.; Marker, M. D.; Camps, S. A.; Cousins, R. P. C.; Faulhobbs, H.;
Holmes, D. S.; Johnston, M. J.; Liddle, J.; Payne, J. J.; Pritchard, J. M.; Whitworth,
C. WO2008-034860.
Scheme 2. Speculated reaction scheme of Pd-catalyzed borylation with the
successive use of cat2B2 and pinacol.

J. Takagi, T. Yamakawa / Tetrahedron Letters 54 (2013) 166–169
169
7. Bollbuck, B.; Denholm, A.; Eder, J.; Hersperger, R.; Janser, P.; Révész, L.;
Schlapbach, A. Wälchli, R. WO2004-089913.
(2H, d, J = 8.4 Hz), 7.73 (2H, d, J = 8.4 Hz). 2-(2-Chlorophenyl)-4,4,5,5-
tetramethyl-1,3,2-dioxaborolane (k, 870195-94-1): 1.37 (12H, s), 7.20–7.24
(1H, m), 7.33–7.34 (2H, m), 7.68 (1H, d, J = 7.4 Hz). 2-(3,4-Difluorophenyl)-
4,4,5,5-tetramethyl-1,3,2-dioxaborolane (l, 754226-39-6): 1.33 (12H, s), 7.14
(1H, d, J = 10.7 Hz), 7.50–7.54 (1H, m), 7.56–7.60 (1H, m). 2-(3,4,5-
Trifluorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (m, 827614-70-0):
1.33 (12H, s), 7.36–7.40 (2H, m). 4-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-
2-yl)benzonitrile (n, 171364-82-2): 1.35 (12H, s), 7.64 (2H, d, J = 8.4 Hz), 7.88
(2H, d, J = 8.4 Hz). 4-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)phenol (o,
269409-70-3): 1.33 (12H, s), 4.79 (1H, s), 6.82 (2H, d, J = 8.6 Hz), 7.71 (2H, d,
J = 8.6 Hz). 2-(4-Methoxyphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (p,
171364-79-7): 1.33 (12H, s), 3.83 (3H, s), 6.89 (2H, d, J = 8.7 Hz), 7.75 (2H, d,
8. General procedure: The synthetic procedure for pentafluorophenyl 4-(4,4,5,5-
tetramethyl-1,3,2-dioxaborolane-2-yl)benzenesulfonate (a) is presented as an
example (Scheme 1). 2,20-Bis(1,3,2-benzodioxaborole) (cat2B2, 262 mg,
1.10 mmol), PdCl2(dppf) (25 mg, 0.030 mmol), AcOK (294 mg, 3.0 mmol),
pentafluorophenyl 4-bromobenzenesulfonate (403 mg, 1.0 mmol), and EtOH
(6.0 mL) were charged in a reaction vessel under an Ar atmosphere. The
resulting mixture was stirred for 2 h at 80 °C. After cooling to room
temperature, pinacol (260 mg, 2.20 mmol) was added to the mixture. The
mixture was further stirred for 30 min at room temperature. H2O and n-hexane
were added to the mixture and the product was extracted into the organic
layer. After drying the organic layer with anhydrous MgSO4, solids were
removed by filtration. The filtrate was concentrated. The product was obtained
as a white solid by Kugelrohr distillation.
J = 8.7 Hz).
Phenyl[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)]phenyl
ether (q, 269410-26-6): 1.34 (12H, s), 6.98 (2H, d, J = 8.6 Hz), 7.01–7.03 (2H,
m), 7.13 (1H, tt, J = 1.0, 7.4 Hz), 7.32–7.37 (2H, m), 7.78 (2H, d, J = 8.6 Hz). 2-[4-
9. Characterization of products: All the products were given CAS numbers. We
characterized each compound by 1H NMR. The chemical shifts (d, ppm to
SiMe4) in CDCl3 were listed below. Pentafluorophenyl 4-(4,4,5,5-tetramethyl-
1,3,2-dioxaborolan-2-yl)benzenesulfonate (a, 928656-94-4): 1.32 (12H, s), 7.95
(2H, d, J = 8.6 Hz), 8.02 (2H, d, J = 8.6 Hz). 4-(4,4,5,5-Tetramethyl-1,3,2-
dioxaborolan-2-yl)benzenesulfonamide (b, 214360-51-7): 1.36 (12H, s), 4.75
(2H, s), 7.91 (2H, d, J = 8.4 Hz), 7.95 (2H, d, J = 8.4 Hz). Methyl 4-(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate (c, 171364-80-0): 1.36 (12H, s),
3.92 (3H, s), 7.87 (2H, d, J = 8.4 Hz), 8.02 (2H, d, J = 8.4 Hz). 4-(4,4,5,5-
Tetramethyl-1,3,2-dioxaborolan-2-yl)benzoic acid (d, 180516-87-4): 1.36
(12H, s), 7.90 (2H, d, J = 8.3 Hz), 8.08 (2H, d, J = 8.3 Hz). 2-(3,5-
Dimethylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (e, 325142-93-6):
1.34 (12H, s), 2.32 (6H, s), 7.10 (1H, s), 7.44 (2H, s). 2-(2,6-Dimethylphenyl)-
4,4,5,5-tetramethyl-1,3,2-dioxaborolane (f, 325141-72-8): 1.38 (12H, s), 2.39
(6H, s), 6.94 (1H, s, J = 7.3 Hz), 7.12 (1H, s, J = 7.3 Hz). 2-(4-tert-Butylphenyl)-
4,4,5,5-tetramethyl-1,3,2-dioxaborolane (g, 214360-66-4): 1.32 (9H, s), 1.33
(12H, s), 7.40 (2H, d, J = 8.3 Hz), 7.75 (2H, d, J = 8.3 Hz). 2-(4,4,5,5-Tetramethyl-
1,3,2-dioxaborolan-2-yl)benzotrifluoride (h, 1073339-21-5): 1.37 (12H, s),
7.49–7.51 (2H, m), 7.65–7.67 (1H, m), 7.71–7.73 (1H, m). 2-[3,5-
(Trifluoromethoxy)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane
(r,
474409-28-9): 1.34 (12H, s), 7.20 (2H, d, J = 8.8 Hz), 7.84 (2H, d, J = 8.8 Hz).
5-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-1,3-benzodioxole (s, 94838-
82-1): 1.32 (12H, s), 5.95 (2H, s), 6.83 (1H, d, J = 7.9 Hz), 7.24 (1H, s), 7.36
(1H, dd, J = 1.1, 7.9 Hz). 2-(4-Methylthiophenyl)-4,4,5,5-tetramethyl-1,3,2-
dioxaborolane (t, 190788-58-0): 1.33 (12H, s), 2.49 (3H, s), 7.22 (2H, d,
J = 8.3 Hz), 7.70 (2H, d, J = 8.3 Hz). 2-[4-(Trifluoromethylthio)phenyl]-4,4,5,5-
tetramethyl-1,3,2-dioxaborolane (u, 1005206-25-6): 1.35 (12H, s), 7.64 (2H, d,
J = 8.3 Hz), 7.84 (2H, d, J = 8.3 Hz). 1-[4-(4,4,5,5-Tetramethyl-1,3,2-
dioxaborolane-2-yl)phenyl]ethanone (v, 171364-81-1): 1.36 (12H, s), 2.62
(3H, s), 7.89 (2H, d, J = 8.4 Hz), 7.93 (2H, d, J = 8.4 Hz). 4-(4,4,5,5-Tetramethyl-
1,3,2-dioxaborolan-2-yl)benzamide (w, 179117-44-3): 1.35 (12H, s), 7.80 (2H,
d, J = 7.3 Hz), 7.88 (2H, d, J = 7.3 Hz). 4-(4,4,5,5-Tetramethyl-1,3,2-
dioxaborolan-2-yl)acetanilide (x, 214360-60-8): 1.34 (12H, s), 2.18 (3H, s),
7.51 (2H, d, J = 8.3 Hz), 7.76 (2H, d, J = 8.3 Hz).
10. (a) Murata, M.; Oyama, T.; Watanabe, S.; Masuda, Y. J. Org. Chem. 2000, 65,
164–168; (b) Claudel, S.; Gosmini, C.; Paris, J. M.; Périchon, J. Chem. Commun.
2007, 3667–3669.
11. Molander, G. A.; Trice, S. L. J.; Dreher, S. D. J. Am. Chem. Soc. 2010, 132, 17701–
17703.
Bis(trifluoromethyl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane
(i,
69807-91-6): 1.37 (12H, s), 7.94 (1H, s), 8.23 (2H, s). 2-(4-Chlorophenyl)-
12. Bello, C. S.; Scgmidt-Leithoff, J. Tetrahedron Lett. 2012, 53, 6230–6235.
4,4,5,5-tetramethyl-1,3,2-dioxaborolane (j, 195062-61-4): 1.34 (12H, s), 7.34