Microwave-assisted reaction between 2-aminobenzoic acids, 2-hydroxybenzaldehydes, and arylboronic acids: A one-pot three-component synthesis of bridgehead bicyclo[4.4.0]boron heterocycles

Article abstract of DOI:10.1016/j.tet.2012.02.030

A one-pot three-component synthesis of 6-aryl-8H-dibenzo[d,h][1,3,7,2] dioxazaborecin-8-ones is described. A mixture of 2-aminobenzoic acid, 2-hydroxybenzaldehyde, and arylboronic acid undergo a 1:1:1 addition reaction in CCl₄ under microwave irradiation to produce bridgehead bicyclo[4.4.0]boron heterocycles in excellent yields.

Full text of DOI:10.1016/j.tet.2012.02.030

Tetrahedron 68 (2012) 3377e3383
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Microwave-assisted reaction between 2-aminobenzoic acids,
2-hydroxybenzaldehydes, and arylboronic acids: a one-pot three-component
synthesis of bridgehead bicyclo[4.4.0]boron heterocycles
,
a
b
c
Mehdi Adib a , Ehsan Sheikhi , Hamid Reza Bijanzadeh , Long-Guan Zhu
*
a School of Chemistry, University College of Science, University of Tehran, PO Box 14155-6455, Tehran, Iran
b Department of Chemistry, Tarbiat Modarres University, PO Box 14115-175, Tehran, Iran
c Chemistry Department, Zhejiang University, Hangzhou 310027, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
A one-pot three-component synthesis of 6-aryl-8H-dibenzo[d,h][1,3,7,2]dioxazaborecin-8-ones is de-
scribed. A mixture of 2-aminobenzoic acid, 2-hydroxybenzaldehyde, and arylboronic acid undergo
a 1:1:1 addition reaction in CCl4 under microwave irradiation to produce bridgehead bicyclo[4.4.0]boron
heterocycles in excellent yields.
Received 10 November 2011
Received in revised form 23 January 2012
Accepted 13 February 2012
Available online 3 March 2012
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
2-Aminobenzoic acids
2-Hydroxybenzaldehydes
Arylboronic acids
Bridgehead bicyclo[4.4.0]boron heterocycles
1. Introduction
There are several reports in the literature concerning the syn-
thesis of boronate complexes by the use of tridentate NOO ligands,
Multi-component reactions (MCRs) have emerged as an efficient
and powerful tool in modern synthetic organic chemistry due to
their valued features, such as atom economy, straightforward re-
action design, and the opportunity to construct target compounds
by the introduction of several diversity elements in a single chem-
ical event. Typically, purification of products resulting from MCRs is
also simple since all the organic reagents employed are consumed
and are incorporated into the target compound.1 MCRs, leading to
interesting heterocyclic scaffolds, are particularly useful for the
construction of diverse chemical libraries of ‘drug-like’ molecules.
There is a considerable interest in the synthesis and character-
ization of organoboron compounds due to their interesting appli-
cations as antibacterial agents (e.g., 1, Fig. 1),2 as anticancer agents
or in Boron Neutron Capture Therapy.3 Moreover, they also display
a wide range of applications in organic synthesis,4 as materials with
fluorescence,5 electro-optical and nonlinear optical properties.6
Boronic acids are ideal partners in MCRs as many different
molecular structures are commercially available, which is particu-
larly noteworthy when designing reactions targeting high levels of
molecular diversity.7
which have been prepared from boronic acids with N-alkyldie-
thanolamines,8 N-methyl-N-(1-methyl-2-phenyl-2-hydroxyethyl)
glycines,9 2-substituted pyridines,10 N-(2-hydroxybenzyl)-
a-amino-
acids,11 N-alkyliminodiacetic acids,12 N-(2-hydroxyethyl)-N-alkyl-
glycines,13 2-[(1-((3-(5-hydroxy)aza)pentyl)imine)ethyl]phenol or
2-[(1-((3-(5-hydroxy)oxa)pentyl)imine)ethyl]phenol,14 N-alkyl-2,20-
diphenolamines,15 3,4-dihydroxypyridine,16 2,6-pyridinedimethanol
and 2-salicylideneaminoethanol,17e22 piperidine and piperazine
alcohols,23 -aminoacids,7,24,25 N-alkylaminodiacetic acids,26 amino-
a
bis-phenols,27 ephedrine and pseudoephedrine derivatives,28 tri-
dentate azomethine ligands,29 ethanolamine derivatives,30 1,2,4,5-
tetrahydroxybenzene and 1,2-bis(4-pyridyl)ethylene or 4,40-bipyr-
idine,31 aminodialcohols,32 o-hydroxybenzylamine-glyoxylic acid
O
R'
B
N
R
1
* Corresponding author. Tel./fax: þ98 21 66495291; e-mail address: madib@
khayam.ut.ac.ir (M. Adib).
Fig. 1. An example of organoboron compounds with biological activity.
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2012.02.030

3378
M. Adib et al. / Tetrahedron 68 (2012) 3377e3383
aldimine,33 as well as the self assembly of boronic-salicylidene
Schiff bases.34 All of these ligands have one nitrogen and two
oxygen donor atoms with strategic variations in the main skeleton
that has allowed evaluation of steric and electronic effects in the
resulting chelate molecules. The studies showed that, in all cases,
the boron atom is tetra-coordinated and forms a dative bond with
the nitrogen atom.
arising from the methoxy group along with the characteristic sig-
nals with appropriate chemical shifts and coupling constants for
the 12 aromatic protons. In NMR spectra of compound 5a, the
characteristic signals at
162.00 ppm in the 13C NMR spectrum confirmed the imine moi-
ety. The 13C NMR spectrum of 5a showed the carbonyl signal at
161.17 ppm in the expected range for boronate esters. The ipso-
carbon attached to boron atom was observed as a broad signal at
144.65 ppm. The 11B NMR spectrum of 5m showed a fairly broad
d
9.56 ppm as a sharp singlet in the 1H and
d
d
d
2. Results and discussion
signal at ꢀ14.25 ppm. Partial assignments of these resonances are
given in the Experimental section.
In connection with an ongoing research program in our labora-
tory concerned with the synthesis of new heterocyclic com-
pounds,35 we became interested in the chemistry of boronic acids.
We report herein an efficient and experimentally convenient route
for the preparation of a new class of boronate complex from a 1:1:1
addition reaction. The in situ generated 2-salicylideneaminobenzoic
acids, from the reaction between 2-aminobenzoic acids 2a,b and 2-
hydroxybenzaldehydes 3aed, undergo a condensationecyclization
reaction with arylboronic acids 4aec in CCl4 under microwave ir-
radiation with the elimination of 2 equiv of H2O to give the corre-
Single-crystal X-ray analysis of 5b confirmed conclusively its
[4.4.0]bicyclo structure, and by analogy, those of the other isolated
products.11 Selected bond lengths and bond angles for boronate 5b
are summarized in Table 2. An ORTEP diagram of 5b is shown in
Fig. 2.36
These bridgehead bicyclo[4.4.0]boronates 5 show transannular
N/B fusion with a tetrahedral geometry for boron atom as well as
six-membered fused rings. The two heterocyclic rings are linked by
a
dative NeB bond. The values of the intramolecular NeB
donoreacceptor bond length, BeO(1) and BeO(2) distances found
sponding
6-aryl-8H-dibenzo[d,h][1,3,7,2]dioxazaborecin-8-ones
ꢀ
for 5b are 1.579(12), 1.482(12), 1.453(11) A, respectively, in agree-
(5aem) in 95e98% yields. All the reactions reached completion
within 3 min. The 1H NMR spectra of the reaction mixtures clearly
indicated formation of the corresponding boronate complexes 5 in
excellent yields. Any product other than 5 was not detected by NMR
spectroscopy. The reactions proceeded very fast and cleanly, and no
undesirable side reactions were observed. Very conveniently, the
isolation of the boronate complexes was simplified because they
completely precipitated from the reaction mixture. The results are
summarized in Scheme 1 and Table 1.
ment with the distances found in similar boronates described in the
literature.37 A distorted tetrahedral geometry of the boron atom is
evident from the bond angles around the boron atom, which are in
the range from 105.1(7)ꢁ for O(2)eB(1)eO(1) and 112.9(8)ꢁ for O(2)e
B(1)eC(1). The values are similar to those reported in literature.2
Although no detailed mechanistic studies have been carried out,
a possible explanation is proposed in Scheme 2. It is conceivable that
the initial event is the formation of 2-salicylideneaminobenzoic acid
6 from condensation reaction between the 2-aminobenzoic acid 2
and the 2-hydroxybenzaldehyde 3. Next, this adduct may react with
the boronic acid 4 by double dehydrations to form the isolated
bridgehead bicyclo[4.4.0]boronates 5.
The structures of the isolated products 5 were deduced on the
basis of IR, 1H, 13C, and 11B NMR spectroscopy, mass spectrometry,
and elemental analysis. The IR spectrum of 5a showed the
stretching bands for the carbonyl and imine functionalities at 1691
and 1611 cmꢀ1, respectively. The mass spectrum of 5a displayed the
molecular ion (Mþ) peak at m/z¼357, which was consistent with
the 1:1:1 adduct of 2-hydroxy-3-methoxybenzaldehyde, 2-
aminobenzoic acid, and phenylboronic acid with the loss of three
H2O molecules. The base peak in the mass spectrum of 5a corre-
sponds to the [MþꢀC6H5] ion. The 1H NMR spectrum of 5a
3. Conclusions
In conclusion, we have devised a three-component synthesis of
6-aryl-8H-dibenzo[d,h][1,3,7,2]dioxazaborecin-8-ones, which are
of potential chemical, synthetic, and pharmacological interest. We
have established a new method for the one-pot assembly of boron
exhibited a single sharp line at
d 3.80 ppm readily recognized as
O
Y
X
O
CO2H
NH2
X
CHO
OH
_
B(OH)2
CCl4
+
N
B
+
O
+
MW, 450 W, 3 min
Y
R
R
2
3
4
5
CO2H
CO2H
Cl
2a:
3a:
4a:
2b:
3b:
NH2
O
NH2
O
O
O
Br
3c:
4c:
3d:
H
H
H
H
OH
OH
OH
OH
OMe
B(OH)2
B(OH)2
B(OH)2
4b:
F
Scheme 1. Synthesis of 6-aryl-8H-dibenzo[d,h][1,3,7,2]dioxazaborecin-8-ones 5.

M. Adib et al. / Tetrahedron 68 (2012) 3377e3383
3379
Table 1
Synthesis of 6-aryl-8H-dibenzo[d,h][1,3,7,2]dioxazaborecin-8-ones 5aem
Product
Structure
% Yielda
Product
Structure
% Yielda
O
O
O
B
O
B
5a
96
5b
95
N
O
N
O
O
O
N
O
N
Cl
O
B
O
B
O
O
5c
95
5d
98
Br
Br
O
O
N
Cl
Cl
O
O
B
B
5e
97
5f
96
N
O
O
O
O
N
O
F
F
Cl
Cl
O
B
O
B
5g
95
5h
97
O
N
O
O
O
N
O
N
F
F
Cl
O
B
O
B
O
O
5i
97
5j
98
Br
Br
O
N
O
O
Cl
O
B
O
B
5k
98
5l
97
N
O
O
Br
O
O
N
O
B
5m
98
a
Isolated yields.

3380
M. Adib et al. / Tetrahedron 68 (2012) 3377e3383
Table 2
(Switzerland) and were used without further purification. Melting
ꢁ
ꢀ
Selected bond distances (A) and angles ( ) for compound 5b
points were measured on an Electrothermal 9100 apparatus. Ele-
mental analyses for C, H, and N were performed using a Heraeus
CHNeO-Rapid analyzer. Mass spectra were recorded on an
FINNIGAN-MATT 8430 mass spectrometer operating at an ioniza-
tion potential of 20 eV. 1H and 13C NMR spectra were measured
(CDCl3 solution) with a Bruker DRX-500 AVANCE spectrometer at
500.1 and 125.8 MHz, respectively. X-ray crystallography was per-
formed on a Bruker SMART diffractometer equipped with a CCD
Bond distances
B(1)eO(2):
1.453(11)
B(1)eO(1):
1.482(12)
B(1)eN(1):
1.579(12)
B(1)eC(1): 1.600(13)
N(1)eC(13): 1.282(10)
N(1)eC(14): 1.436(11)
O(1)eC(16): 1.310(11)
O(2)eC(7): 1.323(11)
O(3)eC(16): 1.212(11)
Bond angles
O(2)eB(1)eO(1):
105.1(7)
O(2)eB(1)eN(1):
109.0(7)
O(1)eB(1)eN(1):
106.8(7)
O(2)eB(1)eC(1):
112.9(8)
area detector with graphite monochromatized Mo Ka radiation. IR
O(1)eB(1)eC(1): 111.8(7)
N(1)eB(1)eC(1): 111.0(7)
C(13)eN(1)eC(14): 123.4(7)
C(13)eN(1)eB(1): 120.0(7)
C(14)eN(1)eB(1): 116.3(7)
C(16)eO(1)eB(1): 122.9(7)
C(7)eO(2)eB(1): 120.0(7)
spectra were recorded on a Shimadzu IR-460 spectrometer. The
experiments were performed using a microwave oven (ETHOS
1600, Milestone) with a power of 450 W specially designed for
organic synthesis.
4.2. General procedure for the preparation of compounds
5aem, exemplified with 5a
A mixture of 2-aminobenzoic acid (0.137 g, 1 mmol), 2-hydroxy-
3-methoxybenzaldehyde (0.152 g, 1 mmol), and phenylboronic acid
(0.122 g, 1 mmol) in CCl4 (4 mL) was irradiated for 3 min at 450 W.
TLC showed completion of the reaction. After cooling to room
temperature, the solid precipitate was filtered, washed with CCl4
(2ꢂ3 mL). The product was obtained by recrystallization from
DMSO.
4.2.1. (NeB)-4-Methoxy-6-phenyl-8H-dibenzo[d,h][1,3,7,2]dioxaza-
borecin-8-one (5a). Yellow crystals, mp 292 ꢁC, yield: 0.34 g, 96%. IR
(KBr) (nmax/cmꢀ1): 1691 (C]O),1611 (C]N), 1559, 1453, 1385, 1329,
1296, 1258, 1177, 1144, 1114, 1077, 1026, 991, 923, 849, 823, 774, 730,
694, 647. EI-MS, m/z (%): 357 (Mþ, 10), 326 (1), 280 (100), 265 (6),
237 (22), 77 (5), 51 (4). Anal. Calcd for C21H16BNO4 (357.17): C,
70.62; H, 4.52; N, 3.92. Found: C, 70.5; H, 4.7; N, 3.8%. 1H NMR
(500.1 MHz, CDCl3):
d
9.56 (1H, s, N]CH), 8.12 (1H, d, J¼8.2 Hz, CH),
8.02 (1H, d, J¼7.8 Hz, CH), 7.81 (1H, t, J¼7.8 Hz, CH), 7.56 (1H, t,
J¼7.9 Hz, CH), 7.36 (1H, d, J¼7.9 Hz, CH), 7.33 (1H, d, J¼7.9 Hz, CH),
7.17e7.11 (2H, m, 2CH), 7.10e7.06 (3H, m, 3CH), 7.00 (1H, t, J¼7.9 Hz,
Fig. 2. ORTEP diagram of the molecular structure of 5b.
heterocycles based on 2-aminobenzoic acids, 2-hydroxybenz
aldehydes, and arylboronic acids. The boron complexes derived
from tridentate ligands are readily formed leading in all cases to
bridgehead bicyclo[4.4.0]boron heterocycles containing a dative
NeB bond as evidenced by X-ray analysis. The use of simple starting
materials, high atom economy, very short reaction times, and ex-
cellent yields of the products are the main advantages of our syn-
thesis. Furthermore, the isolation protocol was considerably
facilitated due to complex precipitation from the reaction mixtures.
CH), 3.80 (3H, s, OCH3). 13C NMR (125.8 MHz, CDCl3):
d 162.0 (CH),
161.2 (C]O), 148.9 (C), 144.7 (br, CeB), 139.8 (C), 134.6 and 130.6
(2CH), 130.1 (C), 130.1, 129.5, 127.5, 127.4 and 124.8 (5CH), 123.7 (C),
120.7, 119.8 and 119.6 (3CH), 116.4 (C), 55.9 (OCH3).
4.2.2. (NeB)-6-Phenyl-8H-dibenzo[d,h][1,3,7,2]dioxazaborecin-8-
one (5b). Yellow crystals, mp 286 ꢁC, yield: 0.31 g, 95%. IR (KBr)
(
nmax/cmꢀ1): 1691 (C]O), 1613 (C]N), 1546, 1451, 1387, 1331, 1297,
1204, 1014, 948, 884, 831, 761, 742, 690. EI-MS, m/z (%): 327 (Mþ,
10), 250 (100), 222 (6), 151 (3), 77 (10), 51 (6). Anal. Calcd for
C20H14BNO3 (327.15): C, 73.43; H, 4.31; N, 4.28. Found: C, 73.4; H,
4. Experimental
4.1. General
4.3; N, 4.2%. 1H NMR (500.1 MHz, CDCl3):
d 9.58 (s, 1H, N]CH), 8.13
(d, J¼8.2 Hz, 1H, CH), 8.04 (d, J¼7.2 Hz, 1H, CH), 7.84e7.77 (m, 2H,
2CH), 7.68 (dt, J¼7.2, 1.2 Hz, 1H, CH), 7.55 (t, J¼7.6 Hz, 1H, CH),
7.19e7.13 (m, 2H, 2CH), 7.10e7.04 (m, 3H, 3CH), 7.03 (d, J¼8.5 Hz,
2-Aminobenzoic acids, 2-hydroxybenzaldehydes, arylboronic
acids, and solvents were obtained from Merck (Germany) and Fluka
1H, CH). 13C NMR (125.8 MHz, CDCl3):
d
161.9 (CH), 161.2 (C]O),
O
O
B(OH)2
Y
X
X
O
OH
_
CHO
OH
CO2H
X
(4)
Y
_
+
N
B
H2O
O
+
N
OH
_
2 H2O
NH2
Y
R
R
2
6
5
3
Scheme 2. Possible mechanism for the formation of 6-aryl-8H-dibenzo[d,h][1,3,7,2]dioxazaborecin-8-ones 5.

M. Adib et al. / Tetrahedron 68 (2012) 3377e3383
3381
158.6 (C), 144.0 (br, CeB), 139.9 (CH), 139.8 (C), 134.5, 134.1, 130.5,
130.0, 129.5, 127.5 and 127.4 (7CH), 123.7 (C), 120.1, 119.5 and 118.6
(3CH), 116.3 (C).
and 129.5 (5CH), 127.5 (C), 127.4 (CH), 123.7 (C), 120.2, 119.5 and
118.6 (3CH), 116.4 (C).
4.2.7. (NeB)-10-Chloro-6-(4-fluorophenyl)-8H-dibenzo[d,h][1,3,7,2]
dioxazaborecin-8-one (5g). Yellow crystals, mp 242e244 ꢁC, yield:
0.36 g, 95%. IR (KBr) (nmax/cmꢀ1): 1682 (C]O), 1616 (C]N), 1646,
1504, 1465, 1424, 1385, 1304, 1174, 1085, 1017, 947, 847, 822, 752,
699, 633. EI-MS, m/z (%): 382 (Mþþ1 37Cl, 2), 380 (Mþþ1 35Cl, 6),
327 (3), 286 (34), 284 (100), 250 (83), 196 (12), 152 (13), 119 (22), 91
(17), 69 (16), 57 (21). Anal. Calcd for C20H12BClFNO3 (379.58): C,
63.29; H, 3.19; N, 3.69. Found: C, 63.5; H, 3.3; N, 3.8%. 1H NMR
4.2.3. (NeB)-2-Bromo-6-phenyl-8H-dibenzo[d,h][1,3,7,2]dioxaza-
borecin-8-one (5c). Yellow crystals, mp 286 ꢁC, yield: 0.39 g, 95%. IR
(KBr) (nmax/cmꢀ1): 1680 (C]O),1611 (C]N),1533, 1462, 1430,1380,
1332, 1302, 1234, 1178, 1073, 990, 944, 895, 856, 828, 745, 695, 662.
EI-MS, m/z (%): 407 (Mþ 81Br, 10), 405 (Mþ 79Br, 10), 330 (100), 328
(84), 280 (12), 249 (20), 221 (7), 77 (11), 53 (6). Anal. Calcd for
C20H13BBrNO3 (406.04): C, 59.16; H, 3.23; N, 3.45. Found: C, 59.2; H,
3.3; N, 3.4%. 1H NMR (500.1 MHz, CDCl3):
d
9.56 (1H, s, N]CH), 8.04
(500.1 MHz, CDCl3):
d
9.57 (1H, s, N]CH), 8.16 (1H, d, J¼8.7 Hz, CH),
(1H, d, J¼7.6 Hz, CH), 8.02 (1H, d, J¼7.6 Hz, CH), 7.97 (1H, d,
J¼2.5 Hz, CH), 7.84 (1H, t, J¼7.6 Hz, CH), 7.80 (1H, dd, J¼8.9, 2.5 Hz,
CH), 7.59 (1H, t, J¼7.6 Hz, CH), 7.17e7.12 (2H, m, 2CH), 7.11e7.06 (3H,
m, 3CH), 7.01 (1H, d, J¼8.9 Hz, CH). 13C NMR (125.8 MHz, CDCl3):
7.96 (1H, s, CH), 7.93 (1H, d, J¼8.7 Hz, CH), 7.80 (1H, d, J¼7.7 Hz, CH),
7.70 (1H, t, J¼7.7 Hz, CH), 7.18 (2H, dd, 4JFH¼5.5, 3JHH¼8.8 Hz, 2CH),
7.08 (1H, t, J¼7.4 Hz, CH), 7.03 (1H, d, J¼8.4 Hz, CH), 6.92 (2H, dd,
3
3JFH¼8.8, JHH¼8.8 Hz, 2CH). 13C NMR (125.8 MHz, CDCl3):
d 162.7
1
d
161.2 (CH),161.0 (C]O),157.6 (C),144.3 (br, CeB),141.8 (CH),139.5
(CH), 162.0 (d, JFC¼243.6 Hz, CeF), 160.0 (C]O), 158.5 (C), 140.3
(CH), 140.2 (br, CeB), 138.6 (C), 134.5 and 134.3 (2CH), 134.0 (C),
(C), 135.4, 134.7, 130.6, 130.0, 129.9, 127.6 and 127.4 (7CH), 123.8 (C),
121.1 and 119.6 (2CH), 117.9 and 110.4 (2C).
3
132.1 (d, JFC¼7.3 Hz, CH), 129.8 (CH), 125.2 (C), 121.9, 120.4 and
118.7 (3CH), 116.2 (C), 114.3 (d, 2JFC¼19.4 Hz, CH).
4.2.4. (NeB)-2-Bromo-10-chloro-6-phenyl-8H-dibenzo[d,h][1,3,7,2]
dioxazaborecin-8-one (5d). Yellow crystals, mp 279e281 ꢁC, yield:
0.43 g, 98%. IR (KBr) (nmax/cmꢀ1): 1697 (C]O), 1615 (C]N), 1536,
1463, 1421, 1361, 1304, 1271, 1231, 1183, 1118, 1079, 1015, 944, 900,
842, 823, 785, 748, 698, 639. EI-MS, m/z (%): 443 (Mþ 81Br37Cl, 3),
441 (Mþ 81Br35Cl and 79Br37Cl, 11), 439 (Mþ 79Br35Cl, 9), 366 (35),
364 (100), 362 (68), 283 (17), 255 (6), 77 (9), 51 (9). Anal. Calcd for
C20H12BBrClNO3 (440.49): C, 54.53; H, 2.75; N, 3.18. Found: C, 54.3;
4.2.8. (NeB)-10-Chloro-6-(4-fluorophenyl)-4-methoxy-8H-dibenzo
[d,h][1,3,7,2]dioxazaborecin-8-one
(5h). Yellow
crystals,
mp
265e266 ꢁC, yield: 0.40 g, 97%. IR (KBr) (nmax/cmꢀ1): 1694 (C]O),1607
(C]N),1558,1446,1380,1260,1169,1115,1076, 999, 918, 839, 788, 746.
EI-MS, m/z (%): 411 (Mþ 37Cl, 1), 409 (Mþ 35Cl, 3), 316 (50), 314 (100),
299 (6), 273 (8), 271 (24), 95 (5), 75 (6). Anal. Calcd for C21H14BClFNO4
(409.61): C, 61.58; H, 3.45; N, 3.42. Found: C, 61.4; H, 3.5; N, 3.3%. 1H
H, 2.6; N, 2.9%. 1H NMR (500.1 MHz, CDCl3):
d
8.68 (1H, s, N]CH),
NMR (500.1 MHz, CDCl3):
d
9.57 (1H, s, N]CH), 8.17 (1H, d, J¼8.6 Hz,
8.23 (1H, d, J¼2.2 Hz, CH), 7.69 (1H, dd, J¼8.9, 2.2 Hz, CH), 7.65 (1H,
d, J¼2.2 Hz, CH), 7.63 (1H, dd, J¼8.6, 2.2 Hz, CH), 7.58 (1H, d,
J¼8.6 Hz, CH), 7.22 (2H, d, J¼7.3 Hz, 2CH), 7.19e7.13 (3H, m, 3CH),
CH), 7.96 (1H, d, J¼2.2 Hz, CH), 7.92 (1H, dd, J¼8.6, 2.2 Hz, CH), 7.37 (1H,
4
d, J¼7.9 Hz, CH), 7.34 (1H, d, J¼7.9 Hz, CH), 7.18 (2H, dd, JFH¼5.5,
3JHH¼8.8 Hz, 2CH), 7.01 (1H, t, J¼7.9 Hz, 1CH), 6.92 (2H, dd, 3JFH¼8.8,
6.99 (1H, d, J¼8.9 Hz, CH). 13C NMR (125.8 MHz, CDCl3):
d
160.1 and
3JHH¼8.8 Hz, 2CH), 3.80 (3H, s, OCH3). 13C NMR (125.8 MHz, CDCl3):
1
159.4 (CeO and C]O), 156.9 (CH), 143.4 (CH), 139.1 (br, CeB), 137.7
and 136.7 (2C), 134.4, 134.1, 132.2, 130.4, 128.4 and 127.8 (6CH),
126.4 (C), 122.3 and 119.0 (2CH), 117.2 and 111.9 (2C).
d
162.7 (CH), 162.1 (d, JFC¼243.7 Hz, CeF), 160.0 (C]O), 148.9 and
148.8 (2C), 140.0 (br, CeB), 138.5 and 134.5 (2CH), 134.0 (C), 132.1 (d,
3JFC¼7.5 Hz, CH),129.8 (CH),125.1 (C),124.9 and 121.9 (2CH),120.9 (C),
120.0 (CH), 116.2 (C), 114.3 (d, 2JFC¼19.4 Hz, CH), 55.9 (OCH3).
4.2.5. (NeB)-10-Chloro-4-methoxy-6-phenyl-8H-dibenzo[d,h]
[1,3,7,2]dioxazaborecin-8-one (5e). Yellow crystals, mp 262 ꢁC,
yield: 0.38 g, 97%. IR (KBr) (nmax/cmꢀ1): 1683 (C]O), 1611 (C]N),
1558, 1451, 1388, 1304, 1262, 1174, 1116, 1077, 993, 921, 849, 787,
733, 698, 650. EI-MS, m/z (%): 393 (Mþ 37Cl, 4), 391 (Mþ 35Cl, 12),
316 (47), 314 (100), 299 (6), 279 (1), 271 (22), 77 (6), 51 (5). Anal.
Calcd for C21H15BClNO4 (391.62): C, 64.41; H, 3.86; N, 3.58. Found:
4.2.9. (NeB)-2-Bromo-10-chloro-6-(4-fluorophenyl)-8H-dibenzo
[d,h][1,3,7,2]dioxazaborecin-8-one
(5i). Yellow
crystals,
mp
266e268 ꢁC, yield: 0.44 g, 97%. IR (KBr) (nmax/cmꢀ1): 1681 (C]O),
1622 (C]N), 1592, 1536, 1505, 1467, 1417, 1376, 1322, 1268, 1230,
1176, 1123, 1081, 1001, 947, 899, 817, 753, 727, 698, 657, 629. EI-MS,
m/z (%): 461 (Mþ 81Br37Cl, 2), 459 (Mþ 81Br35Cl and 79Br37Cl, 7), 457
(Mþ 79Br35Cl, 5), 366 (33), 364 (100), 362 (69), 314 (4), 283 (17), 255
(6), 95 (7), 75 (13). Anal. Calcd for C20H11BBrClFNO3 (458.48): C,
52.40; H, 2.42; N, 3.06. Found: C, 52.1; H, 2.3; N, 2.9%. 1H NMR
C, 64.5; H, 3.7; N, 3.4%. 1H NMR (500.1 MHz, CDCl3):
d 9.56 (1H, s,
N]CH), 8.17 (1H, d, J¼8.6 Hz, CH), 7.96 (1H, d, J¼2.3 Hz, CH), 7.92
(1H, dd, J¼8.6, 2.3 Hz, CH), 7.35 (2H, d, J¼7.7 Hz, 2CH), 7.15e7.07
(5H, m, 5CH), 7.01 (1H, t, J¼7.9 Hz, CH), 3.80 (3H, s, OCH3). 13C NMR
(500.1 MHz, CDCl3):
d
9.55 (s, 1H, N]CH), 8.09 (1H, d, J¼8.7 Hz, CH),
(125.8 MHz, CDCl3):
d
162.6 (CH), 160.0 (C]O), 148.9 (C), 144.9 (br,
7.98 (1H, d, J¼2.5 Hz, CH), 7.97 (1H, d, J¼2.5 Hz, CH), 7.94 (1H, dd,
CeB), 138.6 (C), 134.4 (CH), 133.9 and 130.1 (2C), 130.1, 129.8, 127.6
and 127.5 (4CH), 125.2 (C), 124.9, 121.9, 120.9 and 119.9 (4CH), 116.3
(C), 55.9 (OCH3).
J¼8.7, 2.5 Hz, CH), 7.80 (1H, dd, J¼8.9, 2.5 Hz, CH), 7.18 (2H, dd,
3
4JFH¼5.5, JHH¼8.8 Hz, 2CH), 7.02 (1H, d, J¼8.9 Hz, 1CH), 6.92 (2H,
3
3
dd, JFH¼8.8, JHH¼8.8 Hz, 2CH). 13C NMR (125.8 MHz, CDCl3):
d
162.1 (d, 1JFC¼243.9 Hz, CeF), 162.0 (CH), 159.9 (C]O), 157.5 (C),
4.2.6. (NeB)-10-Chloro-6-phenyl-8H-dibenzo[d,h][1,3,7,2]dioxaza-
borecin-8-one (5f). Yellow crystals, mp 236e238 ꢁC, yield: 0.35 g,
96%. IR (KBr) (nmax/cmꢀ1): 1690 (C]O), 1612 (C]N), 1547, 1453,
1390, 1331, 1298, 1248, 1177, 1010, 948, 884, 833, 760, 692, 647. EI-
MS, m/z (%): 363 (Mþ 37Cl, <1), 361 (Mþ 35Cl, 2), 327 (5), 318 (18),
299 (4), 250 (100), 236 (8), 211 (10), 152 (12), 105 (58), 97 (18), 83
(20), 69 (23), 57 (28). Anal. Calcd for C20H13BClNO3 (361.59): C,
66.43; H, 3.62; N, 3.87. Found: C, 66.3; H, 3.7; N, 3.7%. 1H NMR
142.1 (CH), 139.6 (br, CeB), 138.3 (C), 135.5 and 134.6 (2CH), 134.4
(C), 132.1 (d, 3JFC¼7.3 Hz, CH), 129.9 (CH), 125.2 (C), 121.9 and 121.2
2
(2CH), 117.8 (C), 114.3 (d, JFC¼19.5 Hz, CH), 110.7 (C).
4.2.10. (NeB)-2-Bromo-6-(4-fluorophenyl)-8H-dibenzo[d,h][1,3,7,2]
dioxazaborecin-8-one (5j). Yellow crystals, mp 250e252 ꢁC, yield:
0.42 g, 98%. IR (KBr) (nmax/cmꢀ1): 1681 (C]O), 1617 (C]N), 1536,
1464, 1381, 1332, 1801, 1228, 1170, 591, 944, 863, 824, 764, 729, 692.
EI-MS, m/z (%): 425 (Mþ 81Br, 4), 423 (Mþ 79Br, 4), 330 (100), 328
(93), 249 (24), 221 (9), 200 (6), 177 (5), 95 (8), 75 (11), 63 (6), 50 (5).
Anal. Calcd for C20H12BBrFNO3 (424.03): C, 56.65; H, 2.85; N, 3.30.
(500.1 MHz, CDCl3):
d
9.57 (1H, s, N]CH), 8.13 (1H, d, J¼7.8 Hz, CH),
8.04 (1H, d, J¼7.5 Hz, CH), 7.80 (2H, d, J¼7.3 Hz, 2CH), 7.67 (1H, dd,
J¼7.5, 7.3 Hz, CH), 7.54 (1H, dd, J¼7.5, 7.3 Hz, CH), 7.22e7.00 (6H, m,
6CH). 13C NMR (125.8 MHz, CDCl3):
d
161.9 (CH), 161.3 (C]O), 158.6
Found: C, 56.5; H, 2.9; N, 3.2%. 1H NMR (500.1 MHz, CDCl3):
(1H, s, N]CH), 8.07 (1H, d, J¼7.9 Hz, CH), 8.05 (1H, d, J¼7.8 Hz, CH),
d 9.55
(C), 144.4 (br, CeB), 140.0 (CH), 139.8 (C), 134.5, 134.1, 130.6, 130.1

3382
M. Adib et al. / Tetrahedron 68 (2012) 3377e3383
7.99 (1H, d, J¼1.6 Hz, CH), 7.83 (1H, t, J¼7.6 Hz, CH), 7.78 (1H, dd,
References and notes
4
J¼8.8, 1.6 Hz, CH), 7.58 (1H, t, J¼7.6 Hz, CH), 7.19 (2H, dd, JFH¼5.5,
ꢁ
3JHH¼8.8 Hz, 2CH), 7.01 (1H, d, J¼8.9 Hz, CH), 6.91 (2H, dd, 3JFH¼8.8,
1. (a) Multicomponent Reactions; Zhu, J., Bienayme, H., Eds.; Wiley-VCH: Wein-
heim, 2005; (b) Basso, A.; Banfi, L.; Riva, R.; Guanti, G. J. Org. Chem. 2005, 70,
3JHH¼8.8 Hz, 2CH). 13C NMR (125.8 MHz, CDCl3):
d 161.0 (d,
ꢁ
575e579; (c) Ramon, D. J.; Yus, M. Angew. Chem., Int. Ed. 2005, 44, 1602e1634;
1JFC¼234.7 Hz, CeF), 161.4 (CH), 157.4 (C]O), 141.8 (CH), 139.9 (br,
(d) Nair, V.; Rajesh, C.; Vinod, A. U.; Bindu, S.; Sreekanth, A. R.; Mathen, J. S.;
Balagopal, L. Acc. Chem. Res. 2003, 36, 899e907; (e) Ma, C.; Yang, Y. Org. Lett.
2005, 7, 1343e1345; (f) Cheng, Y.; Meth-Cohn, O. Chem. Rev. 2004, 104,
2507e2530; (g) Lee, C. F.; Yang, L. M.; Hwu, T. Y.; Feng, A. S.; Tseng, J. C.; Luh, T.
Y. J. Am. Chem. Soc. 2000, 122, 4992e4993; (h) Nair, V.; Vinod, A. U. Chem.
Commun. 2000, 1019e1020; (i) Brown, R. C. D. Angew. Chem., Int. Ed. 2005, 44,
850e852.
3
CeB), 139.4 (C), 135.4 and 134.7 (2CH), 132.1 (d, JFC¼7.3 Hz, CH),
130.6 and 129.9 (2CH), 123.7 (C), 121.1 and 119.6 (2CH), 117.9 (C),
2
114.3 (d, JFC¼19.6 Hz, CH), 110.6 (C).
4.2.11. (NeB)-2-Bromo-6-(4-ethylphenyl)-8H-dibenzo[d,h][1,3,7,2]
dioxazaborecin-8-one (5k). Yellow crystals, mp 260e263 ꢁC, yield:
0.43 g, 98%. IR (KBr) (nmax/cmꢀ1): 1690 (C]O), 1620 (C]N), 1541,
1472,1382,1334,1305,1276,1200,1174, 993, 947, 902, 864, 827, 762,
713, 690, 667, 621. EI-MS, m/z (%): 435 (Mþ 81Br, 6), 433 (Mþ 79Br, 6),
330 (100), 328 (86), 249 (20), 221 (7), 91 (7), 77 (7). Anal. Calcd for
C22H17BBrNO3 (434.10): C, 60.87; H, 3.95; N, 3.23. Found: C, 60.8; H,
2. Baker, S. J.; Zhang, Y.-K.; Akama, T.; Lau, A.; Zhou, H.; Hernandez, V.; Mao, W.;
Aller, M. R. K.; Sander, V.; Plattner, J. J. Med. Chem. 2006, 49, 4447e4450.
3. Hawthorne, M. F.; Lee, M. W. J. Neuro-Oncol. 2003, 62, 33e45.
4. (a) Suginome, M.; Uehlin, L.; Yamamoto, A.; Murakami, M. Org. Lett. 2004, 6,
1167e1169; (b) Kennedy, J. W. J.; Hall, D. G. Angew. Chem., Int. Ed. 2003, 42,
4732e4739.
5. Liu, Z.; Fang, Q.; Cao, D.; Wang, D.; Xu, G. Org. Lett. 2004, 6, 2933e2936.
6. (a) Entwistle, C. D.; Marder, T. B. Angew. Chem., Int. Ed. 2002, 41, 2927e2931; (b)
~
ꢁ
Reyes, H.; Munoz, B. M.; Farfan, N.; Santillan, R.; Rojas-Lima, S.; Lacroix, P. G.;
4.0; N, 3.4%. 1H NMR (500.1 MHz, CDCl3):
d 9.53 (1H, s, N]CH), 8.04
Nakatani, K. J. J. Mater. Chem. 2002, 12, 2898e2903.
ꢁ
7. Candeias, N. R.; Cal, P. M. S. D.; Andre, V.; Duarte, M. T.; Veiros, L. F.; Gois, P. M. P.
(1H, d, J¼7.6 Hz, CH), 8.03 (1H, d, J¼7.6 Hz, CH), 7.99 (1H, d, J¼2.4 Hz,
CH), 7.83 (1H, t, J¼7.6 Hz, CH), 7.78 (1H, dd, J¼8.9, 2.4 Hz, CH), 7.57
(1H, t, J¼7.6 Hz, CH), 7.05 (2H, d, J¼7.7 Hz, 2CH), 7.00 (1H, d,
J¼8.9 Hz, 1CH), 6.92 (2H, d, J¼7.7 Hz, 2CH), 2.40 (2H, q, J¼7.6 Hz,
Tetrahedron 2010, 66, 2736e2745.
8. Contreras, R.; García, C.; Mancilla, T.; Wrackmeyer, B. J. Organomet. Chem. 1983,
246, 213e217.
ꢁ
9. Farfan, N.; Mancilla, T.; Castillo, D.; Uribe, G.; Carrillo, L.; Joseph-Nathan, P.;
CH2),1.02 (3H, t, J¼7.6 Hz, CH3). 13C NMR (125.8 MHz, CDCl3):
d 161.0
Contreras, R. J. Organomet. Chem. 1990, 381, 1e13.
ꢁ
10. Farfan, N.; Contreras, R. J. Chem. Soc., Perkin Trans. 2 1988, 1787e1791.
(C]O), 160.9 (CH), 157.6 and 143.0 (2C), 141.7 (CH), 140.8 (br, CeB),
139.5 (C), 135.3, 134.6, 130.6, 130.1, 129.8 and 126.9 (6CH), 123.8 (C),
121.1 and 119.5 (2CH), 117.9 and 110.4 (2C), 27.9 (CH2), 15.4 (CH3).
ꢁ
ꢁ
ꢁ
11. Beltran, H. I.; Zamudio-Rivera, L. S.; Mancilla, T.; Santillan, R.; Farfan, N. J. Or-
ganomet. Chem. 2002, 657, 194e204.
12. Mancilla, T.; Contreras, R.; Wrackmeyer, B. J. Organomet. Chem. 1986, 307, 1e6.
13. Mancilla, T.; Contreras, R. J. Organomet. Chem. 1987, 321, 191e198.
ꢁ
14. Barba, V.; Rodríguez, A.; Ochoa, M. E.; Santillan, R.; Farfan, N. Inorg. Chim. Acta
4.2.12. (NeB)-10-Chloro-6-(4-ethylphenyl)-4-methoxy-8H-dibenzo
2004, 357, 2593e2601.
ꢁ
15. Farfan, N.; Joseph-Nathan, P.; Chiquete, L. M.; Contreras, R. J. Organomet. Chem.
[d,h][1,3,7,2]dioxazaborecin-8-one
(5l). Yellow
crystals,
mp
1988, 348, 149e156.
16. Christinat, N.; Scopelliti, R.; Severin, K. J. Org. Chem. 2007, 72, 2192e2200.
273e275 ꢁC, yield: 0.41 g, 97%. IR (KBr) (nmax/cmꢀ1): 1684 (C]O),
1611 (C]N), 1559, 1452, 1388, 1261, 1171, 1118, 1077, 992, 922, 845,
788, 738. EI-MS, m/z (%): 421 (Mþ 37Cl, 4), 419 (Mþ 35Cl,10), 316 (44),
314 (100), 300 (9), 271 (32), 103 (4), 90 (4), 77 (8). Anal. Calcd for
C23H19BClNO4 (419.67): C, 65.83; H, 4.56; N, 3.34. Found: C, 65.6; H,
€
ꢁ
17. Hopfl, H.; Farfan, N. J. Organomet. Chem. 1997, 547, 71e77.
ꢁ
€
ꢁ
ꢁ
18. Farfan, N.; Hopfl, H.; Barba, V.; Ochoa, M. E.; Santillan, R.; Gomez, E.; Gutierrez,
A. J. Organomet. Chem. 1999, 581, 70e81.
19. Barba, V.; Luna, R.; Castillo, D.; Santillan, R.; Farfan, N. J. Organomet. Chem. 2000,
604, 273e282.
ꢁ
ꢁ
4.5; N, 3.2%. 1H NMR (500.1 MHz, CDCl3):
d 9.55 (1H, s, N]CH), 8.17
ꢁ
ꢁ
20. Barba, V.; Cuahutle, D.; Ochoa, M. E.; Santillan, R.; Farfan, N. Inorg. Chim. Acta
2000, 303, 7e11.
(1H, d, J¼8.6 Hz, CH), 7.95 (1H, d, J¼2.2 Hz, CH), 7.91 (1H, dd, J¼8.6,
2.2 Hz, CH), 7.35 (1H, d, J¼8.3 Hz, CH), 7.33 (1H, d, J¼8.6 Hz, CH), 7.04
(2H, d, J¼7.6 Hz, 2CH), 7.00 (1H, t, J¼7.9 Hz, CH), 6.93 (2H, d, J¼7.6 Hz,
2CH), 3.79 (3H, s, OCH3), 2.40 (2H, q, J¼7.6 Hz, CH2), 1.03 (3H, t,
ꢁ
ꢁ
21. Barba, V.; Cuahutle, D.; Santillan, R.; Farfan, N. Can. J. Chem. 2001, 79,
1229e1237.
22. Braun, M.; Schlecht, S. M.; Engelmann, M.; Frank, W. Eur. J. Org. Chem. 2008,
5221e5225.
€
ꢁ
ꢁ
ꢁ
ꢁ
23. Hopfl, H.; Farfan, N.; Castillo, D.; Santillan, R.; Gutierrez, A.; Daran, J. C. J. Or-
ganomet. Chem. 1998, 553, 221e239.
J¼7.6 Hz, CH3). 13C NMR (125.8 MHz, CDCl3):
d 162.3 (CH), 160.1 (C]
O), 149.0, 148.9 and 143.0 (3C), 140.9 (br, CeB), 138.6 (C), 134.4 (CH),
133.8 (C), 130.1, 129.7 and 126.9 (3CH), 125.2 (C), 124.8, 121.8, 120.8
and 119.9 (4CH), 116.3 (C), 55.8 (OCH3), 27.9 (CH2), 15.4 (CH3).
ꢁ
ꢁ
24. Farfan, N.; Silva, D.; Santillan, R. Heteroat. Chem. 1993, 4, 533e536.
25. Trujillo, J.; Hopfl, H.; Castillo, D.; Santillan, R.; Farfan, N. J. Organomet. Chem.
€
ꢁ
ꢁ
1998, 571, 21e29.
26. Mancilla, T.; Carrillo, L.; de la Paz Reducindo, M. Polyhedron 1996, 15,
3777e3785.
ꢁ
ꢁ
27. Abreu, A.; Alas, S. J.; Beltran, H. I.; Santillan, R.; Farfan, N. J. Organomet. Chem.
2006, 691, 337e348.
4.2.13. (NeB)-14-(4-Ethylphenyl)-16H-naphtho[2,1-c][5,7,1,6]benzo-
dioxazaborecin-16-one (5m). Yellow crystals, mp 212e214 ꢁC, yield:
0.40 g, 98%. IR (KBr) (nmax/cmꢀ1): 1689 (C]O), 1599 (C]N), 1542,
1461, 1392, 1359, 1309, 1201, 1170, 1099, 1015, 950, 822, 751, 692. EI-
MS, m/z (%): 405 (Mþ, 14), 300 (100), 272 (4), 227 (2), 77 (3). Anal.
Calcd for C26H20BNO3 (405.26): C, 77.06; H, 4.97; N, 3.46. Found: C,
€
ꢁ
ꢁ
28. Hopfl, H.; Farfan, N.; Castillo, D.; Santillan, R.; Contreras, R.; Martínez-Martínez,
ꢁ
ꢁ
ꢁ
ꢁ
F. J.; Galvan, M.; Alvarez, R.; Fernandez, L.; Halut, S.; Daran, J. C. J. Organomet.
Chem. 1997, 544, 175e188.
29. Hopfl, H.; Sanchez, M.; Farfan, N.; Barba, V. Can. J. Chem. 1998, 76, 1352e1360.
30. Hopfl, H.; Sanchez, M.; Barba, V.; Farfan, N. Inorg. Chem. 1998, 37, 1679e1692.
31. Christinat, N.; Croisier, E.; Scopelliti, R.; Cascella, M.; Rothlisberger, U.; Severin,
€
ꢁ
€
ꢁ
€
77.1; H, 4.9; N, 3.4%. 1H NMR (500.1 MHz, CDCl3):
d 9.95 (1H, s, N]
K. Eur. J. Inorg. Chem. 2007, 5177e5181.
€
ꢁ
ꢁ
ꢁ
32. Hopfl, H.; Galvan, M.; Farfan, N.; Santillan, R. J. Mol. Struct.: Theochem 1998, 427,
CH), 8.66 (1H, d, J¼8.1 Hz, CH), 8.50 (1H, d, J¼7.9 Hz, CH), 8.25 (1H,
d, J¼8.8 Hz, CH), 8.05 (1H, d, J¼7.4 Hz, CH), 7.91 (1H, d, J¼7.9 Hz,
CH), 7.83 (1H, t, J¼7.3 Hz, CH), 7.71 (1H, t, J¼7.3 Hz, CH), 7.54 (1H, t,
J¼7.3 Hz, CH), 7.49 (1H, t, J¼7.3 Hz, CH), 7.22 (1H, d, J¼8.8 Hz, CH),
7.12 (2H, d, J¼7.3 Hz, 2CH), 6.91 (2H, d, J¼7.3 Hz, 2CH), 2.40 (2H, q,
J¼7.6 Hz, CH2), 1.01 (3H, t, J¼7.6 Hz, CH3). 13C NMR (125.8 MHz,
1e13.
33. Kaiser, P. F.; White, J. M.; Hutton, C. A. J. Am. Chem. Soc. 2008, 130,
16450e16451.
ꢁ
ꢁ
34. (a) Barba, V.; Gallegos, E.; Santillan, R.; Farfan, N. J. Organomet. Chem. 2001, 622,
€
ꢁ
ꢁ
ꢁ
259e264; (b) Barba, V.; Hopfl, H.; Farfan, N.; Santillan, R.; Beltran, H. I.; Za-
mudio-Rivera, L. S. Chem. Commun. 2004, 2834e2835.
35. Adib, M.; Sheikhi, E.; Kavoosi, A.; Bijanzadeh, H. R. Tetrahedron 2010, 66,
9263e9269; Adib, M.; Ansari, S.; Fatemi, S.; Bijanzadeh, H. R.; Zhu, L. G. Tet-
rahedron 2010, 66, 2723e2727; Adib, M.; Ansari, S.; Mohammadi, A.; Bijanza-
deh, H. R. Tetrahedron Lett. 2010, 51, 30e32; Adib, M.; Mohamadi, A.; Sheikhi, E.;
Ansari, S.; Bijanzadeh, H. R. Synlett 2010, 1606e1608; Adib, M.; Mahdavi, M.;
Ansari, S.; Malihi, F.; Zhu, L. G.; Bijanzadeh, H. R. Tetrahedron Lett. 2009, 50,
7246e7248; Adib, M.; Sheibani, E.; Zhu, L. G.; Bijanzadeh, H. R. Tetrahedron Lett.
2009, 50, 4420e4422; Adib, M.; Sheibani, E.; Bijanzadeh, H. R.; Zhu, L. G. Tet-
rahedron 2008, 64, 10681e10686; Adib, M.; Sayahi, M. H.; Ziyadi, H.; Zhu, L. G.;
Bijanzadeh, H. R. Synthesis 2008, 3289e3294; Adib, M.; Mohammadi, B.; Bi-
janzadeh, H. R. Synlett 2008, 3180e3182; Adib, M.; Mohammadi, B.; Bijanzadeh,
H. R. Synlett 2008, 177e180; Adib, M.; Sheibani, E.; Zhu, L. G.; Mirzaei, P. Tet-
rahedron Lett. 2008, 49, 5108e5110; Adib, M.; Sayahi, M. H.; Ziyadi, H.; Bi-
janzadeh, H. R.; Zhu, L. G. Tetrahedron 2007, 63, 11135e11140.
CDCl3):
d 161.2 and 161.1 (CeO and C]O), 156.2 (CH), 143.0 (C),
141.9 (CH), 141.3 (br, CeB), 140.2 (C), 134.4 (CH), 131.8 (C), 130.4,
130.2,129.3,129.2 and 128.8 (5CH),127.6 (C),126.9 and 125.0 (2CH),
123.3 (C), 121.5, 120.3 and 120.0 (3CH), 109.0 (C), 27.9 (CH2), 15.4
(CH3). 11B NMR (160.5 MHz, CDCl3):
d
ꢀ14.25.
Acknowledgements
This research was supported by the Research Council of the
University of Tehran as research project (6102036/1/03).

M. Adib et al. / Tetrahedron 68 (2012) 3377e3383
3383
36. Selected X-ray crystallographic data for compound 5b: C20H14NBO3, mono-
220, wR2¼0.592. CCDC 852557 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
ꢀ
ꢀ
ꢀ
b
clinic, space group¼I2/a, a¼17.776(3) A, b¼7.6010(7) A, c¼24.345(7) A, ¼96.
3
79(2) , V¼3266.3(11) A , T¼295(2) K, Z¼8, Dcalcd¼1.331 g cmꢀ3
,
m
¼0.089 mmꢀ1
,
ꢁ
ꢀ
€
2092 observed reflections, final R1¼0.204, wR2¼0.589 and for all data R1¼0.
37. Hopfl, H. J. Organomet. Chem. 1999, 581, 129e149.