Synthesis and characterization of boronates derived from non-symmetric amino-bis-phenols

Article abstract of DOI:10.1016/j.jorganchem.2005.08.042

The condensation of 2-[[(2-hydroxyphenyl)amino]methyl]-phenols (1a-1e) with different arylboronic acids led to 12 new monomeric boronates of the type 2-aryl-dibenzo[d,h]-6-aza-1,3-dioxa-2-boracyclononene (2a-2l). The boronates were characterized by ¹

Full text of DOI:10.1016/j.jorganchem.2005.08.042

Journal of Organometallic Chemistry 691 (2006) 337–348
www.elsevier.com/locate/jorganchem
Synthesis and characterization of boronates derived
from non-symmetric amino-bis-phenols
a
a
b
a,
*
*
`
´
´
Arturo Abreu , S. Jesus Alas , Hiram I. Beltran , Rosa Santillan , Norberto Farfan
a
Departamento de Quı´mica, Centro de Investigacio´n y de Estudios Avanzados del Instituto Polite´cnico Nacional. Apdo. Postal 14-740,
07000 Me´xico, D. F., Me´xico
b
Instituto de Quı´mica-UNAM, Circuito Exterior, Ciudad Universitaria, Coyoaca´n, 04510, Me´xico, D. F., Me´xico
Received 15 August 2005; received in revised form 22 August 2005; accepted 22 August 2005
Available online 2 November 2005
Abstract
The condensation of 2-[[(2-hydroxyphenyl)amino]methyl]-phenols (1a–1e) with different arylboronic acids led to 12 new monomeric
1
boronates of the type 2-aryl-dibenzo[d,h]-6-aza-1,3-dioxa-2-boracyclononene (2a–2l). The boronates were characterized by H-, 13C-,
11B- and 2D-NMR experiments, FT infrared, mass spectra and elemental analyses. The stereochemistry of the H–N ! B–Ph fusion
is always cis, as established through the NMR spectra, as well as the X-ray structures of four boronates (2a, 2e, 2f and 2l). Hydrogen
bonds between the amine proton and the oxygen ester of the five- membered ring are present in three X-ray structures (2a, 2e and 2f),
while the supramolecular structure in the derivative possessing a primary amine (2l) is built up through the protons present in this moiety
instead of the proton from the H–N ! B–Ph fragment.
Ó 2005 Elsevier B.V. All rights reserved.
Keywords: Boron; Boronate; Tridentate ligand; X-ray crystallography; NMR; Supramolecular arrangement
1. Introduction
nic-salicylidene Schiff bases [21] (Scheme 1). All of these li-
gands have one nitrogen and two oxygen donor atoms with
strategic variations in the main skeleton that allowed eval-
uation 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; the characteristics of the dative bond as well
as the rigidity of the tridentate ligands employed gave rise
to monomeric molecules and, through a self-assembly pro-
cedure, to specific di-, tri- and tetrameric molecules. For
this particular construction, the oxygen atoms build up
mainly five- or six- membered rings as well as intermolecu-
lar boron-oxygen bonds to achieve the oligomeric-products
[22]. As previously mentioned, the structure of the product
is mainly determined by the nature of the ligand, however,
in some cases it can be modulated by varying the reaction
conditions.
In previous studies, we described the synthesis of a series
of mono-, di-, tri- and tetrameric boronates derived from
NO2 tridentate ligands such as N-alkyl-diethanolamines
[1],
N-methyl-N-(1-methyl-2-phenyl-2-hydroxyethyl)gly-
cines [2], 2-substituted pyridines [3], N-(2-hydroxybenzyl)-
a-aminoacids [4], N-alkyliminodiacetic acids [5], N-(2-
hydroxyethyl)-N-alkyl-glycines [6], N-alkyl-2-20-diphenol-
amines [7], 2,6-pyridinedimethanol and 2-salicylideneami-
noethanol [8–12], piperidine and piperazine alcohols [13],
a-aminoacids [14,15], N-alkylaminodiacetic acids [16],
ephedrine and pseudoephedrine derivatives [17], tridentate
azomethine ligands [18], ethanolamine derivatives [19],
aminodialcohols [20] as well as the self assembly of boro-
The geometrical change between planar trigonal to tet-
rahedral boron atoms due to donor ! acceptor coordina-
tion has been quantitatively evaluated by the TetraHedral
*
Corresponding authors. Tel.: +52 55 5061 3725; fax: +52 55 5747
7713/5061 3389 (R. Santillan).
E-mail address: rsantill@cinvestav.mx (R. Santillan).
0022-328X/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.08.042

338
A. Abreu et al. / Journal of Organometallic Chemistry 691 (2006) 337–348
R1
N
R1
H
R2
R
a
b
c
d
e
C(CH3)2CH(CH3)2
a
b
R= H
R= CH3
CH3 C(CH3)2CH(CH3)2
Ph
H
N
B
C(CH3)2CH(CH3)2
Ph
B
O
O
O
O
O
CH3 Ph
R2
Ph
R
H
CH3
R
H
N
B
R3
H
a
b
c
d
e
f
g
h
i
R1
H
H
C6H5
C6H5
H
R2
H
R3
H
R2
N
B
a
CH(CH3)CH3
CH2CH(CH3)2
CH(CH3)CH2CH3
CH2-C6H4-p-OH
CH2CH2SCH3
C6H5
1
O
b
c
d
e
H
C6H5
R
H
H
C6H5
CH3
C6H5
CH3
O
O
O
CH2C6H5
R1
H
Me
H
R2
Ph
Ph
R3
H
H
H
H
H
H
H
H
Me
O
O
a
R3
b
c
d
e
C(CH3)2CH(CH3)2
C(CH3)2CH(CH3)2
Ph
O
1
Me
R
N
B
R2
CH2-C6H4-o-CH2Br
CH2CO-C6H4-p-C6H5 Ph
CH2CONH2
CH2CH2OC6H5
Me
Me
Me
f
O
g
h
i
j
k
Ph
Ph
Ph
Ph
Ph
(CH2)3CH3
CH2C6H5
Scheme 1. Monomeric boronates derived from tridentate ligands.
Character (THCD ! A) [23]. As important structural evi-
dence, it is worth mentioning that for boron compounds
constructed from tridentate ligands, the N ! B bonds are
tivity [12]. The same behaviour was observed in the case of
the boronates derived from N-(2-hydroxybenzyl)-a-amino-
acids [4] (possessing a sp2 carbon atom at the five mem-
bered fused ring) and 2-((2-hydroxyethylamino) methyl)
phenols [25] (the five-membered fused ring has a sp3 carbon
atom) where the substituents are on the same side and only
the exo disastereoisomer is formed.
Continuing our investigations, we describe herein the
reactions of 2-[[(2-hydroxyphenyl)amino]methyl]-phenols,
nonsymmetric amino-bis-phenols, with different arylbo-
ronic acids with the aim to determine the preferred
arrangement of these new boronates. Additionally the fu-
sion preference was investigated by changing the design
of the tridentate ligands using compounds possessing two
phenolic units linked through a methylene-secondary
˚
between 1.6 and 1.7 A.
A literature search proved that the preferred stereo-
chemistry at the transannular fused rings involving the
N ! B bonds is cis [1–7,24]. Further studies revealed that
it is possible to carry out the stereoselective addition of ace-
tone to the C=N bond in a complete series of [4.3.0] boron
heterobicycles derived from salicylideniminophenols
(Scheme 2). In these compounds, the polarization, and
therefore the selective reactivity of this bond was evidenced
by acetolysis of the imine group to produce the correspond-
ing dioxaborocines with a cis fusion and the incoming
group placed also on the same side, with full diastereoselec-
O
R1
R1
O
R2
H
R2
N
B
N
R3
O
O
R3
B
6h, ∆
O
O
R1
R2
H
H
R3
H
H
a
b
c
d
e
NO2
CH3
Cl
H
H
CH3
H
H
CH3
CH3
H
Scheme 2. Synthesis of 2-phenyl-aryl[d]benzo[h]-6-aza-1,3-dioxa-2-boracyclonon-6-enes by acetolysis reaction.

A. Abreu et al. / Journal of Organometallic Chemistry 691 (2006) 337–348
339
2.1. Synthesis of 2-[[(2-hydroxyphenyl)amino]methyl]-
phenols
N
M
N
N
O
O
The synthetic route to prepare the 2-[[(2-hydroxyphe-
nyl)amino]methyl]-phenols 1a–1e involved the reaction
of 2-aminophenols with an equimolecular ratio of salicyl-
aldehyde or 3,5-di-tert-butyl-2-hydroxybenzaldehyde un-
O
O
O
Ti
O
N
N
der reflux of methanol during
6 h to give the
Ti (IV)
corresponding Schiff bases. This was followed by in situ
reduction of the imine fragment with sodium borohydride
and acidulation with hydrochloric acid. The resulting tri-
dentate ligands were obtained in yields ranging from 59%
to 91% (Scheme 4).
M= Fe(III), Mo(VI)
Scheme 3. Application of 2-[[(2-hydroxyphenyl)amino]methyl]-phenols as
chelating agents for transition metals.
amine system. These new ligand prototypes are the 2-[[(2-
hydroxyphenyl)amino]methyl]-phenols, which were synthe-
sized by a method similar to that described in the literature
[26]. Moreover, it has been described that the tridentate li-
gands synthesized herein have found application as chelat-
ing agents for some transition metals [27–31] and as plant
growth regulators [32] (Scheme 3).
2.2. NMR data of 2-[[(2-hydroxyphenyl)amino]methyl]-
phenol hydrochlorides (1a–1e)
1
The H NMR spectra shows a phenolic OH between
10.42 and 10.79 ppm, followed by the hydrogen atoms
from the bridging nitrogen around 8.50 ppm. The cou-
pling system of the salicylidene fragment for compounds
1a–1c is of ABCD type. The 1d and 1e ligands show an
AM system for the 3,5-di-tert-butyl fragment and the pro-
tons corresponding to the di-tert-butyl groups appear in
1.36 and 1.16 for the 3 and 5 positions, respectively. The
protons at position 7 are observed between 4.36 and
4.43 ppm. The 13C NMR spectra present the following
trends, the resonance for C-2 shows chemical shifts be-
tween 152.4 and 156.9 ppm, for C-9 between 149.3 and
154.2 ppm, always appearing at high frequencies. The
chemical shifts for C-7 are between 47.4 and 49.7 ppm.
The chemical shifts for the di-tert-butyl groups appear
between 30.4 and 32.1 for the methyl (C(CH3)3) group
and appear between 34.5 and 35.7 ppm for the quaternary
carbon (C(CH3)3)).
The tridentate ligands and the monomeric boronates
1
were characterized by H, 13C, homo- and hetero-nuclear
2D-NMR experiments, FT-IR, mass spectra, and addition-
ally for the boronates, the 11B NMR spectra. Suitable
monocrystals of four boronates were obtained.
2. Results and discussion
The reaction between 2-[[(2-hydroxyphenyl)amino]-
methyl]phenols (1a–1e) and different aryl boronic acids
led to 12 new monomeric boronates (2a–2l). The stereo-
chemistry of the H–N ! B–Ph fusion is always cis, as
established from the NMR spectra, as well as the X-ray
structures of four boronates. The results of this contribu-
tion are resumed as follows.
R 2
R 2
R2
13
12
H2N
C6H6/EtOH
7
H
N
B
6
R1
8
5
11
∆ 12 hr
NaHCO3
R1
Cl
NH2+
1
9
10
HO
R 1
4
O
2
O
3
OH
OH
OH
1) MeOH, ∆ 1 hr
14
R1
+
OH
R 4
15
2) NaBH4
19
18
B
R1
3) HCl
R3
16
R 3
17
R1
H
H
R2
H
Cl
R 4
O
R3
H
R4
H
1a
1b
1c
R1
H
R2
H
H
H
H
R3
H
H
R4
H
1
R
OH
H
NO2
H
COMe
2a
COMe
NH2
H
H
2b
2c
2d
H
H
H
COMe
1d tBu
H
COMe
NH2
H
H
1e tBu Me
2e
2f
2g tBu
2h tBu
2i tBu
2j tBu
H
H
Cl
NO2
H
H
H
H
H
H
H
COMe
NH2
H
COMe
H
COMe
H
H
H
2k tBu
2l tBu
Me
Me
H
NH2
H
H
Scheme 4. Synthesis of 2-[[(2-hydroxyphenyl)-amino]-methyl]-phenols (1a–1e) and 6-aza-1,3-dioxa-2-bora-[d,h]-di-benzocylononenes (2a–2l).

340
A. Abreu et al. / Journal of Organometallic Chemistry 691 (2006) 337–348
2.3. IR and MS data of 2-[[(2-hydroxyphenyl)amino]-
methyl]-phenol hydrochlorides (1a–1e)
a range of 9.6–7.4 ppm, characteristic for tetracoordinated
boronate esters.
The IR spectra of compounds 1a–1e show strong N–H
and O–H stretching bands. The mass spectra show the
ion peak corresponding to loss of hydrochloric acid from
the M+. Cleavage at the CH2–NH bond, leads to the frag-
ment corresponding to the hydroxytropylium ion in 1a–1c,
while the base peak in 1d corresponds to the aminophenol
fragment and 1e to the di-tert-butylsalicylidene ion.
2.6. IR and MS data of 2-aryl-dibenzo[d,h]-6-aza-1,3-
dioxa-2-boracyclononenes
The IR spectra of compounds 2a–2l show the character-
istic N–H band. The mass spectra show the molecular ion
peak for the monomeric boronates and the loss of the aryl
groups from M+ to give tetracyclic structures with a cova-
lent bond between the boron and nitrogen atoms, charac-
teristic for this type of derivatives, as well as the
hydroxytropylium ion for 2a–2e and the di-tert-butylsalicy-
lidene ion for 2g–2l.
2.4. Synthesis of 2-aryl-dibenzo[d,h]-6-aza-1,3-dioxa-2-
boracyclononenes
The condensation of 2-[[(2-hydroxyphenyl)amino]-
methyl]-phenol hydrochlorides (1a–1e) with phenylboronic
acid, 3-aminophenylboronic acid, 3-acetylphenylboronic
acid and 4-acetylphenylboronic acid in the presence of
1.5 molar equivalents of sodium bicarbonate were carried
out at reflux in benzene–ethanol mixtures to give the corre-
sponding boronates (2a–2l) in yields ranging from 55% to
90%. These compounds show transannular N ! B bonds
with a tetrahedral geometry for both boron and nitrogen
atoms as well as five- and six-membered fused rings
(Scheme 4).
2.7. Molecular structures of 2a, 2e, 2f and 2l
Crystallographic data for boronates 2a, 2e, 2f and 2l are
listed in Table 1; selected bond lengths, bond and torsion
angles, as well as plane deviations are summarized in
Table 2. The corresponding molecular structures are shown
in Fig. 1.
Compound 2a crystallized in a non primitive space
group (C c m 21) which is indicative of the rh generated
due to disorder in the molecule, hence only half of the
molecular entity was refined. This kind of disorder is quite
unusual, since similar structures showed a disordered imine
fragment where boron and tin atoms are coordinated to the
Schiff base and the fused ring moieties remain asymmetric
[33]. Due to the high symmetry, in this case, the B(1),
C(14), C(17), H(1N), H(7A) and H(7B) atoms are placed
in special positions within the crystallographic cell. More
accurate models regarding the molecular disorder were per-
formed relative to two aromatic ring moieties with inde-
pendent occupation factors but were unstable approaches
during the refinement of the structure. Hence, the model
for the disordered structure presented herein represents
the one with better crystal and refinement data parameters.
The refinement of the crystal structure for 2l revealed
two sites of positional disorder, one regarding a chloro-
form molecule included in the crystallographic cell, and
the second one due to a tert-butyl moiety of the salicylid-
ene. When both disorders were neglected, the final R1
was equal to 10.29% with R2 (all data) equal to 31.48%.
When the disorder present at the chloroform molecule
was considered, the final indexes were those shown in Table
1, R1 was equal to 9.33% with R2 (all data) equal to
30.17%. Moreover, when both, the tert-butyl and the chlo-
roform were included as disordered moieties within the
model, no satisfactory solution was encountered and a full
anisotropic refinement was not possible. Thus, the latter
refinement scheme gave R1 equal to 11.45% with R2 (all
data) equal to 33.62%. Additionally, due to the obtained
R values, the trial of twinned refinement was performed,
but no significant gain was obtained with this approach.
Therefore, the disorder was mainly responsible for the
inaccurate statistical refinement of this structure. In any
2.5. NMR data of 2-aryl-dibenzo[d,h]-6-aza-1,3-dioxa-2-
boracyclononenes
All compounds show an AB system for the methylene at
1
position 7 in the H NMR spectra. The chemical shift dif-
ference for the AB system is in the range from 0.08 to
0.15 ppm for compounds 2b–2g and 2j, which were deter-
mined in DMSO-d6; while boronates 2a, 2h, 2i, 2k and 2l
were determined in CDCl3, and showed an ABX system.
In chloroform, the chemical shift difference for the AB sys-
tem was 0.46 ppm and showed in all cases, a coupling con-
stant of 12.8 Hz and an additional coupling with the amine
proton with magnitudes between 3.6 and 1.5 Hz for the A–
X and B–X fragments, respectively. The recording of the
spectra in these two solvents was due to the lack of solubil-
ity depending on the substituents attached to the main bor-
onate skeleton.
The proton signal for the N–H proton is shifted
depending on the nature of the solvent employed; for
the compounds determined in DMSO-d6, the proton ap-
pears around 9.5 ppm, while for those obtained in CDCl3,
it is around 6.5 ppm. This significant difference in chemi-
cal shifts was attributed to the formation of hydrogen
bonds, of the type Ph–B N–Hꢀ ꢀ ꢀO = S(Me)2 (see Sec-
tion 2.7 for the crystalline solid state evidence of this
finding).
In 13C NMR, the boronates show chemical shifts similar
to the tridentate ligands; only carbons C-2 and C-9 are
slightly shifted by 4 and 7 ppm, respectively.
The construction of the tetracyclic-fused structure was
evidenced by the 11B chemical shift which appears within

A. Abreu et al. / Journal of Organometallic Chemistry 691 (2006) 337–348
341
Table 1
Collection data and refinement parameters for compounds 2a, 2e, 2f and 2l
Compound
2a
2e
2f
2l
Molecular formula
Molecular weight
Crystalline system
Space group
C18H16BNO2
301.14
Orthorhombic
Ccm21
C19H15BClNO2
335.58
Monoclinic
P21/n
C19H15BN2O4
346.14
Orthorhombic
Pcab
C28H35BN2O2 Æ CHCl3
561.76
Triclinic
ꢀ
P1
Unit cell dimensions
˚
a (A)
9.3521(3)
18.3953(7)
9.1534(3)
90
90
90
1574.70(9)
4
1.270
9.1036(4)
9.2801(5)
20.1784(13)
90
100.004(2)
90
1678.80(16)
4
1.328
10.0342(2)
11.0069(2)
31.1396(5)
90
90
90
3439.23(11)
8
1.337
7.6645(4)
13.7299(6)
16.2540(9)
112.226(2)
91.331(2)
106.195(2)
1504.51(13)
2
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
3
˚
Volume (A )
Z
q (mg mꢁ3
)
1.240
0.332
l (mmꢁ1
)
0.081
0.238
0.094
h Range (°)
3.97–27.47
5900
1776 [0.0412]
27.47° [99.3]
1776/43/147
1.049
3.44–27.52
5723
3617 [0.035]
27.52° [93.9]
3617/0/278
1.007
3.70–26.01
6201
3332 [0.0378]
26.01° [98.1]
3332/0/295
1.048
4.09–23.00
7608
4169 [0.0390]
23.00° [99.3]
4169/66/431
1.096
Collected reflections
Independent reflections [Rint
h Completeness [%]
Data/restrictions/parameters
Goodness-of-fit on F2
]
Final indices [I > r(I)]R1
Final indices (all data) wR2
0.0499
0.1414
ꢁ0.106
0.116
0.0534
0.1241
0.0528
0.1381
0.0933
0.3017
3
˚
Dqmin (e A )
ꢁ0.225
ꢁ0.217
ꢁ0.248
3
˚
Dqmax (e A )
0.148
0.231
0.435
˚
˚
case, the boronate moiety presents adequate geometrical
parameters and structure factors, allowing its further
discussion.
1.450(3) A for 2e, 1.680(3), 1.505(3), 1.450(3) A for 2f,
˚
and 1.690(8), 1.503(7), 1.420(7) A for 2l, in agreement
with the distances found in similar derivatives described
in the literature [1–31,33b]. The tetrahedral character
(THCD ! A) of the boron atoms has magnitudes of
The N ! B, B–O(1) and B–O(2) distances found are
˚
1.701(4), 1.453(3), 1.453(3) A for 2a, 1.665(3), 1.490(3),
Table 2
Selected geometrical parameters for compounds 2a, 2e, 2f and 2l
Compound
2a
2e
2f
2l
˚
Bond lengths (A)
N(1)–B(1)
C(14)–B(1)
1.701(4)
1.609(4)
1.665(3)
1.599(3)
1.680(3)
1.579(3)
1.690(8)
1.600(8)
Bond angles (°)
O(1)–B(1)–O(2)
N(1)–B(1)–C(14)
N(1)–B(1)–O(1)
N(1)–B(1)–O(2)
O(1)–B(1)–C(14)
O(2)–B(1)–C(14)
108.0(3)
108.9(2)
118.6(2)a
118.6(2)a
113.66(18)a
113.66(18)a
107.60(16)
110.33(15)
100.41(16)
109.71(18)
113.41(19)
114.44(18)
110.63(16)
112.13(16)
100.05(14)
108.54(16)
112.29(16)
111.96(17)
112.6(4)
111.8(4)
99.4(4)
109.4(4)
111.2(4)
111.8(4)
Dihedral angles (°)
H(1N)–N(1)–B(1)–C(14)
N(1)–C(6)–C(1)–O(1)
B(1)–O(1)–C(1)–C(2)
B(1)–O(2)–C(13)–C(12)
C(6)–N(1)–C(7)–C(8)
39.24(160)
13.89(19)
20.5(18)
20.5(18)
160.61(19)
ꢁ21.04(130)
ꢁ4.7(2)
0.72(142)
ꢁ1.4(2)
ꢁ8.38(506)
ꢁ0.9(6)
170.3(2)
ꢁ177.51(18)
133.8(2)
173.5(5)
136.0(5)
77.1(6)
ꢁ140.48(19)
163.33(17)
67.9(2)
˚
Deviation from mean C(7)–C(8)–C(9)–C(10)–C(11)–C(12)–C(13)–O(2) plane (A)
B(1)
N(1)
0.7125(49)
0.6931(48)
ꢁ0.7828(27)
ꢁ0.9458(28)
ꢁ1.0156(25)
0.9920(74)
0.8637(64)
ꢁ0.9601(23)
˚
Deviation from mean N(1)–C(6)–C(5)–C(4)–C(3)–C(2)–C(1)–O(1) plane (A)
B(1)
THC B (%)
0.2849(41)
68.20
ꢁ0.3057(28)
0.0230(26)
78.42
0.1655(69)
78.22
76.80
a
The values are the same due to the molecular symmetry.

342
A. Abreu et al. / Journal of Organometallic Chemistry 691 (2006) 337–348
2a
2e
2f
2l
Fig. 1. ORTEP diagrams of the molecular structures of compounds 2a, 2e, 2f and 2l.
68.20, 76.80, 78.42 and 78.22% for 2a, 2e, 2f and 2l. The
first value is diminished due to the crystallographic disor-
der present. For the THCD ! A measurement it is impor-
tant to mention that the lowest bond angle measured
corresponds to the O(1)–B–N angle with values of
118.6°, 100.41°, 100.05°, 99.4° for 2a, 2e, 2f and 2l; in this
case, the former value is incremented also due to the crys-
tallographic disorder. The decrease in bond angle can be
attributed to the ring fusion and strain in the 5-membered
ring. The structures possess dihedral angles of 39.24°,
21.04°, 0.72° and 8.38°, respectively for the H–N–B–Ph
fragment in 2a, 2e, 2f and 2l, whereby it is worth men-
tioning the significant variation of the disordered struc-
ture and thus the THCD ! A value was farther from the
mean value for this family of boronates. The five-mem-
bered ring containing the B–N–C(6)–C(1)–O(1) fragment
presents an almost flat conformation for 2a, 2e and 2l
with C(1), B(1) or B(1) slightly displaced from the plane;
in the case of 2f, the conformation of such fragment is the
one closer to planarity with a B(1) deviation of only
Compounds 2a, 2f and 2l crystallized in a roofed confor-
mation with respect to the boron nitrogen bond, while 2e
shows stepper conformation; for the roofed one a bigger
H–N–B–Ph dihedral angle is present in comparison to
the stepper arrangement.
The acidic nature of the N–H proton was evidenced
through NMR experiments realized with DMSO-d6 and
CDCl3 as solvents. For the former solvent, a significant dis-
1
placement for the H resonances is indicative of a strong
hydrogen bonding for the Ph–B N–Hꢀ ꢀ ꢀO@SMe2 inter-
action. The same behaviour is observed in the solid state
crystalline phase, where acid-base intermolecular interac-
tions between the Ph–B N–Hꢀ ꢀ ꢀO–B fragments take
place (Fig. 2). The observed values for the two interactions
˚
of 2a are d(Hꢀ ꢀ ꢀO) = 2.329 A, h(N–Hꢀ ꢀ ꢀO) = 164.08°,
h(Hꢀ ꢀ ꢀO–B) = 95.55°. The values for the two interactions
˚
for 2e are d(Hꢀ ꢀ ꢀO(1)) = 2.224 A, h(N–Hꢀ ꢀ ꢀO(1)) =
˚
155.68°, h(Hꢀ ꢀ ꢀO(1)–B) = 103.59°, d(Hꢀ ꢀ ꢀO(2)) = 2.573 A,
h(N–Hꢀ ꢀ ꢀO(2)) = 139.37°,
h(Hꢀ ꢀ ꢀO(2)–B) = 109.06°,
h(Hꢀ ꢀ ꢀO(2)–B) = 90.02° (Fig. 2).
˚
0.0230(26) A (Table 2). The six-membered ring containing
There are two other types of supramolecular arrange-
ments which depend on the type of substituent attached to
the boronate molecule. In the first one, compound 2f with
a NO2 group, presents a Ph–B N–Hꢀ ꢀ ꢀO(1)–B interaction
that involves the five member ring oxygen atom O(1)) with
the B–N–C(7)–C(8)–C(13)–O(2) fragment presents twisted
boat conformation for 2a and boat conformation for the
remaining derivatives, with the O(2) and C(7) placed be-
low the plane for 2e, and above for 2f and 2l, leading
to distinct conformations.
˚
values of d(Hꢀ ꢀ ꢀO(1)) = 2.321 A, h(N–Hꢀ ꢀ ꢀO(1)) = 149.90°,

A. Abreu et al. / Journal of Organometallic Chemistry 691 (2006) 337–348
343
2e
2a
2f
2l
Fig. 2. Intermolecular hydrogen bonds in compounds 2a, 2e, 2f and 2l (some fragments were omitted for clarity).
h(Hꢀ ꢀ ꢀO(1)–B) = 118.55°; and the Ph–B N–Hꢀ ꢀ ꢀO–N
CDCl3 solvents. In the former solvent, a significant shift
for the H resonances is indicative of a strong hydrogen
1
˚
interaction with values of d(Hꢀ ꢀ ꢀO) = 2.788 A, h(N–
Hꢀ ꢀ ꢀO) = 128.07°, h(Hꢀ ꢀ ꢀO–N) = 121.92° (Fig. 2). The sec-
ond arrangement is present in the X-ray structure of 2l; in
this case, the substituent was a primary amine which acted
as a bridging group between the normal Ph–B N–Hꢀ ꢀ ꢀ
O–B fragments to construct a more complex supramolecular
entity of the type Ph–B N–Hꢀ ꢀ ꢀN–Hꢀ ꢀ ꢀO–B (Fig. 2). The
bonding for the Ph–B N–Hꢀ ꢀ ꢀO@SMe2 interaction.
The difference in chemical shifts for the AB system var-
ies also depending on the solvent used, the Dd in CDCl3
around 0.45 ppm while in DMSO-d6 is 0.15 ppm, this effect
is also observed in the N–H proton.
The same behaviour is observed in the crystalline phase,
where acid-base intermolecular interactions between the
Ph–B N–Hꢀ ꢀ ꢀO–B fragments are present. The interac-
tions changed significantly when a primary amine is placed
within the molecular entity, since this substituent acted as a
bridging group between the normal Ph–B N–Hꢀ ꢀ ꢀO–B
fragments to construct a more complex supramolecular en-
tity of the type Ph–B N–Hꢀ ꢀ ꢀN–Hꢀ ꢀ ꢀO–B.
˚
values for the interaction in 2l are d(Hꢀ ꢀ ꢀN) = 2.214 A, h (N–
Hꢀ ꢀ ꢀN)= 153.83°, h(Hꢀ ꢀ ꢀN–H) = 98.66°, d(Hꢀ ꢀ ꢀO) = 2.526,
h(N–Hꢀ ꢀ ꢀO) = 156.38°,h(Hꢀ ꢀ ꢀO–B)= 109.06°.
3. Conclusions
The reaction between 2-[[(2-hydroxyphenyl)amino]-
methyl]-phenols with different aryl boronic acids led to 12
new monomeric boronates, in all cases.
4. Experimental
The stereochemistry of the H–N ! B–Ph moiety is al-
ways cis and was established through the NMR and the
X-ray structures of four boronates.
The acidic nature of the N–H proton was evidenced
through NMR experiments realized with DMSO-d6 and
All starting materials were commercial grade and were
used as received. Solvents were purchased from J.T. Baker
Co and used without further purification.

344
A. Abreu et al. / Journal of Organometallic Chemistry 691 (2006) 337–348
4.1. Instrumentation
(C-2), 151.2 (C-9), 132.2 (C-6), 130.8 (C-4), 129.8 (C-11),
124.5 (C-13), 124.0 (C-8), 119.6 (C-12), 119.2 (C-5), 118.8
(C-1), 117.1 (C-10), 115.9 (C-3), 48.4 (C-7) ppm. The
remaining tridentate ligands 1b–1e were prepared in analo-
gous ways.
NMR experiments were performed on Jeol ECLIPSE-
400, Jeol-GSX-270 and Bruker ADVANCE-300 spectrom-
1
eters. All H and 13C chemical shifts [ppm] are reported
relative to TMS (d1H = 0, d13C = 0). Coupling constants
are quoted in Hz. 11B spectra were obtained relative to
BF3 Æ OEt2 using DMSO-d6 or CDCl3 as solvent. Infrared
spectra were recorder as KBr pellets in a Perkin–Elmer
16F-PC FT-IR and Perkin–Elmer FT-IR System Spectrum
GX spectrometers. Mass spectra were recorded on a HP
5989A spectrometer at 20 eV electron impact.
4.1.1.2. 2-[[(2-Hydroxyphenyl)amino]methyl]-4-chlorophe-
nol hydrochloride (1b). White solid, yield 59% (1.38 g,
4.48 mmol) m.p. 196–198 °C. IR mmax (KBr): 3330, 3167,
2935, 1604, 1562, 1433, 1349, 1274, 1231, 1105, 774 cmꢁ1
.
MS (20 eV) m/z (%) 251 (M+ ꢁHCl, 5), 249 (14) 145
(37), 143 (100) 114 (11) 107 (37) 80 (26), 78 (13). 1H
NMR (300.13 MHz, DMSO-d6, d, ppm, J, Hz) 10.81
(OH, bs), 8.24 (NH, bs) 7.28 (1H, H-6, dd, Jo = 7.6,
Jm = 1.7), 7.15 (1H, H-4, m), 7.14 (1H, H-13, m), 7.07
(1H, H-10, m), 7.07 (1H, H-11, m), 6.92 (1H, H-3, dd,
Jo = 8.0, Jm = 1.0), 6.75 (1H, H-5, ddd, Jo = 8.0, 7.7,
Jm = 1.0), 4.36 (2H, H-7, s) ppm. 13C NMR (75.46 MHz,
DMSO-d6) d: 156.9 (C-2), 149.5 (C-9), 132.0 (C-6), 130.7
(C-4), 128.0 (C-11), 127.0 (C-13), 123.0 (C-8), 123.0 (C-
10), 120.0 (C-1), 119.6 (C-5), 118.1 (C-12), 116.0 (C-3),
47.4 (C-7) ppm.
Melting points were measured in open capillary tubes on
a Gallenkamp MFB-595 apparatus and have not been
corrected.
The X-ray crystal structure determinations for
compounds 2a, 2e, 2fand 2l were obtained on an Enraf
˚
Nonius-FR590 and Kappa-CCD (kMo Ka = 0.71073 A,
graphite monochromator, T = 293 K, x-2h and CCD
rotating images scan modes) respectively. When necessary,
absorption correction was performed within the SHELX-A
[34] program or by the semiempirical correction through
MULTISCAN procedure (PLATON) [35]. All reflection data
sets were corrected for Lorentz and polarization effects.
The first structure solution was obtained using the SHELX-
S-97 program and then SHELX-L-97ver. 34 program [34]
was applied for refinement and output data. All software
manipulations were done under the WIN-GX [36] environ-
ment program set. Molecular perspectives were drawn un-
der ORTEP 3 [37] drawing application. All heavier atoms
were found by Fourier map difference and refined aniso-
tropically. Some hydrogen atoms were found by Fourier
map difference and refined isotropically, the remaining
hydrogen atoms were geometrically modeled and calcu-
lated for the refinement.
4.1.1.3. 2-[[(2-Hydroxyphenyl)amino]methyl]-4-nitrophe-
nol hydrochloride (1c). White solid, yield 76% (1.85 g,
6.23 mmol) m.p. 176–179 °C. IR mmax (KBr, cmꢁ1) 3330,
3167, 2935, 1604, 1562, 1433, 1349, 1274, 1231, 1105,
774 cmꢁ1. MS (20 eV) m/z (%) 260 (M+ ꢁ HCl, 16), 154
(97), 124 (10), 107 (100), 85 (45), 78 (47). 1H NMR
(300.13 MHz, DMSO-d6, d, ppm, J, Hz) 11.98 (OH, bs),
8.62 (NH, bs) 7.77 (1H, H-11, dd, Jo = 8.8, Jm = 2.7),
7.65 (1H, H-13, d, Jm = 2.7), 7.25 (1H, H-6, dd, Jo = 7.5,
Jm = 1.4), 7.10-7.16 (1H, H-5, m), 7.10–7.16 (1H, H-10,
m), 6.92 (1H, H-3, dd, Jo = 7.5, Jm = 0.6), 6.76 (1H, H-4,
ddd, Jo = 7.5, Jm = 0.6), 4.41 (2H, H-7, s). 13C NMR
(75.46 MHz, DMSO-d6, d, ppm) 155.8 (C-2), 154.2 (C-9),
139.8 (C-12), 131.7 (C-8), 129.9 (C-6), 129.1 (C-4), 121.8
(C-1), 119.0 (C-5), 118.7 (C-11), 115.2 (C-3), 114.2 (C-
10), 110.9 (C-13), 44.1 (C-7).
4.1.1. Preparation of 2-[[(2-hydroxyphenyl)amino]-
methyl]-phenol hydrochlorides (1a–1e)
4.1.1.1. 2-[[(2-Hydroxyphenyl)amino]methyl]-phenol hydro-
chloride (1a). Compound 1a was prepared from 0.89 g
(8.18 mmol) of 2-aminophenol and 1.00 g (8.18 mmol) of
salicylaldehyde under reflux in a THF–MeOH mixture
for 6 h to give 3a, followed by reduction with 0.62 g
(16.36 mmol) of sodium borohydride, and subsequent
addition of 3.4 mL of hydrochloric acid, to obtain a white
solid, characterized as 1a in 91% yield (1.90 g, 7.71 mmol)
m.p. 210–213 °C. IR mmax (KBr): 3313, 3218, 2840, 2784,
1605, 1564, 1507, 1445, 1270, 1235, 753, 591 cmꢁ1. MS
(20 eV) m/z (%) 215 (M+ ꢁ HCl, 19), 109 (100), 80 (26),
77 (21), 51 (13). 1H NMR (399.78 MHz, DMSO-d6, d,
ppm, J, Hz) 11.04 (OH, bs), 10.27 (NH, bs) 7.28 (1H, H-
6, dd, Jo = 7.7, Jm = 1.5), 7.25 (1H, H-13, d, Jo = 7.7),
7.10–7.16 (1H, H-4, m), 7.10–7.16 (1H, H-10, m), 7.10–
7.16 (1H, H-11, m), 6.96 (1H, H-3, dd, Jo = 8.1,
Jm =;1.1), 6.77 (1H, H-12, ddd, Jo = 8.0, 7.4, Jm = 1.4),
6.74 (1H, H-5, ddd, Jo = 8.1, 7.7, Jm = 1.1), 4.38 (2H, H-
7, s) ppm. 13C NMR (100.53 MHz, DMSO-d6) d: 156.8
4.1.1.4.
methyl]-phenol hydrochloride (1d). White solid, yield 90%
(2.78 g, 7.66 mmol) m.p. 194–198 °C. IR mmax (KBr, cmꢁ1
2-[[(2-Hydroxy-3,5-di-tertbutylphenyl)amino]-
)
3202, 2958, 2770, 1625, 1565, 1508, 1360, 1282, 1213, 754.
MS (20 eV) m/z (%) 327 (M+ ꢁ HCl, 10), 219 (40), 203 (38),
161 (15), 109 (100), 91 (10), 80 (21). 1H NMR (399.78 MHz,
DMSO-d6, d, ppm, J, Hz) 11.05 (OH, bs), 8.62 (NH, bs)
7.31 (1H, H-13, d, Jo = 7.7), 7.21 (1H, H-11, dd, Jo = 8.2,
Jm = 1.1), 7.20 (1H, H-4, d, Jm = 2.6), 7.10 (1H, H-10, dd,
Jo = 8.2, Jm = 1.1), 6.97 (1H, H-6, d, Jo = 2.6), 6.79 (1H, H-
12, ddd, Jo = 8.2, 7.7, Jm = 1.1), 4.43 (2H, H-7, s), 1.36 (9H,
tBu-C-3, s), 1.16 (9H, tBu-C-5, s). 13C NMR (75.47 MHz,
DMSO-d6, d, ppm) 152.4 (C-2), 151.3 (C-9), 142.4 (C-5),
139.6 (C-3), 130.2 (C-11), 127.3 (C-3), 124.8 (C-13), 124.6
(C-4), 123.4 (C-8), 121.9 (C-1), 119.7 (C-12), 117.1 (C-10),
49.2 (C-7), 35.3 (C-tBut-C-3), 34.4 (C-tBu-C-5), 31.8 (CH3-
tBu-C-5) 30.4 (CH3-tBu-C-3).

A. Abreu et al. / Journal of Organometallic Chemistry 691 (2006) 337–348
345
4.1.1.5.
2-[[(2-Hydroxy-3,5-di-tertbutylphenyl)amino]-
(1H, H-5, m), 6.70-6.77 (1H, H-10, m), 6.70–6.77 (1H, H-
12, m), 4.45 (1H, H-7A, d, JAB = 13.8), 4.29 (1H, H-7B,
d, JAB = 13.8), 2.56 (3H, H–COCH3, s). 13C NMR (67.94
DMSO-d6, d, ppm) 198.6 (C@O), 159.1 (C-9), 157.1 (C-
2), 150.1 (C-14), 136.6 (C-16), 132.6 (C-15, C-19), 130.0
(C-4), 129.9 (C-8), 129.7 (C-11), 129.0 (C-6), 127.5 (C-16,
C-18), 122.2 (C-1) 121.4 (C-13), 120.3 (C-12), 119.0 (C-3),
118.7 (C-5), 112.5 (C-10), 48.7 (C-7), 27.2 (COCH3). 11B
NMR (86.68 MHz, CDCl3, d, ppm) 7.5.
methyl]-4-methylphenol (1e). White solid, yield 70%
(2.24 g, 5.93 mmol) m.p. 228–232 °C. IR mmax (KBr,
cmꢁ1) 3202, 2958, 2770, 1625, 1565, 1508, 1360, 1282,
1213, 754 cmꢁ1. MS m/z (%) 327 (M+ ꢁ HCl, 10), 218
(27) (100), 161(29), 123 (90). 1H NMR (399.78 MHz,
DMSO-d6, d, ppm, J, Hz) 10.79 (OH, bs), 8.61 (NH, bs)
7.31 (1H, H-13, d, Jo = 7.7), 7.21 (1H, H-11, dd, Jo = 8.2,
Jm = 1.1), 7.20 (1H, H-4, d, Jm = 2.6), 7.10 (1H, H-10,
dd, Jo = 8.2), 6.97 (1H, H-6, d, Jo = 2.6), 6.79 (1H, H-12,
ddd, Jo = 8.2, 7.7, Jm = 1.1), 4.43 (2H, H-7, s), 1.36 (9H,
tBu-C-3, s), 1.16 (9H, tBu-C-5, s). 13C NMR (75.47
MHz, DMSO-d6, d, ppm) 152.4 (C-2), 151.3 (C-9), 142.4
(C-5), 139.6 (C-3), 130.2 (C-11), 127.3 (C-3), 124.8 (C-
13), 124.6 (C-4), 123.4 (C-8), 121.9 (C-1), 119.7 (C-12),
117.1 (C-10), 49.2 (C-7), 35.3 (C-tBu-C-3), 34.4 (C-tBu-C-
5), 31.8 (CH3-tBu-C-5) 30.4, (CH3-tBu-C-3).
4.1.2.3. 2-(3-Acetylphenyl)-benzo[d]-benzo[h]-6-aza-1,3-
dioxa-2-boracyclononene (2c). Yellow solid, 62%
(0.576 g, 1.73 mmol), m.p. 201–204 °C. IR mmax (KBr,
cmꢁ1) 3446, 3076, 1661, 1610, 1490, 1281, 1247, 1037, 968,
751. MS (m/z) 343 (M+, 19), 237 (23), 224 (45), 223 (66),
1
222 (100), 221 (23), 194 (8), 120 (19), 105 (21), 77 (15). H
NMR (300.13 MHz, DMSO-d6, d, ppm, J, Hz) 9.37 (1H,
NH, s), 8.15 (1H, H-15, d, Jm = 1.4), 7.89 (1H, H-17, ddd,
Jo = 7.5, Jm = 1.1, 1.4), 7.81 (1H, H-19, ddd, Jo = 7.5,
Jm = 1.1, 1.4), 7.45 (1H, H-18, t, Jo = 7.5), 7.31 (1H, H-13,
d, Jo = 7.4), 7.14 (1H, H-4, dd, Jo = 7.9, Jm = 1.4), 7.03–
7.07 (1H, H-6, m), 7.03–7.07 (1H, H-11, m), 6.85 (1H, H-3,
d, Jo = 7.9), 6.69-6.72 (3H, H-5, H-10, H-12, m), 4.47 (1H,
H-7A, d, JAB = 13.9), 4.33 (1H, H-7B, d, JAB = 13.9), 2.57
(3H, COCH3, s). 13C NMR (75.46 MHz, DMSO-d6, d,
ppm) 198.6 (C@O), 158.5 (C-9), 156.7 (C-2), 137.0 (C-19),
135.9 (C-16), 131.5 (C-15), 129.4 (C-4), 128.8 (C-11), 128.5
(C-6), 128.5 (C-8), 127.6 (C-17), 127.6 (C-18), 121.9 (C-13),
121.8 (C-1), 120.8 (C-12), 118.5 (C-3), 118.2 (C-5), 111.9
(C-10), 47.9 (C-7), 26.8 (COCH3). 11B NMR (128.26 MHz,
CDCl3, d, ppm) 8.2.
4.1.2. General synthesis of 2-aryl-dibenzo[d,h]-6-aza-1,3-
dioxa-2-boracyclononenes
4.1.2.1. 2-Phenyl-benzo[d]-benzo[h]-6-aza-1,3-dioxa-2-bora-
cyclononene (2a). Compound 2a was prepared by the
reaction of 0.50 g (1.98 mmol) of 1a, 0.283 g (1.98 mmol)
phenylboronic acid, and (0.29 g, 2.98 mmol) of sodium
bicarbonate in 120 mL of 4:1 benzene: ethanol mixture
for 12 h, to give a yellow solid in 80.0% yield (0.56 g,
1.59 mmol) m.p. 210–214 °C. IR mmax (KBr, cmꢁ1) 3116,
1610, 1490, 1460, 1280, 1254, 1230, 1214, 1042, 748. MS
(m/z) 301 (M+, 35), 224 (57), 223 (82), 222 (81), 195
1
(100), 194 (26), 78 (10). H NMR (399.78 MHz, CDCl3,
d, ppm, J, Hz) 8.53 (1H, NH, s),7.59 (2H, H-15, d, Jo =
7.0), 7.16-7.22 (2H, H-16, m), 7.16-7.22 (2H, H-17, m),
7.09 (1H, H-4, t, Jo = 8.8), 7.28 (1H, H-13, d, Jo = 7.7),
6.99 (1H, H-11, t, Jo = 7.7), 6.91 (1H, H-3, d, Jo = 7.1),
7.08 (1H, H-6, d, Jo = 7.3), 6.70 (1H, H-10, d, Jo = 8.0),
6.67 (1H, H-12, t, Jo = 7.3), 6.62 (1H, H-5, t, Jo = 7.7),
4.41 (1H, H-7A, dd, JAB = 13.5, JAX = 3.7), 3.95 (1H, H-
7B, dd, JAB = 13.5, JBX = 2.0). 13C NMR (100.53 MHz,
CDCl3, d, ppm) 159.2 (C-9), 157.0 (C-2), 132.0 (C-15, C-
19), 129.9 (C-4), 129.8 (C-11), 129.2 (C-8), 127.7 (C-17),
127.6 (C-6), 127.6 (C-16, C-18), 121.2 (C-1), 120.6 (C-13),
120.1 (C-12), 119.4 (C-3), 118.1 (C-5), 112.9 (C-10), 50.2
(C-7). 11B NMR (128.26 MHz, CDCl3, d, ppm) 7.6. The
remaining boronates were prepared using the same
procedure.
4.1.2.4. 2-(3-Aminophenyl)-benzo[d]-benzo[h]-6-aza-1,3-
dioxa-2-boracyclononene (2d). Yellow solid, 69%
(0.47 g, 1.40 mmol), m.p. 224–226 °C. IR mmax (KBr,
cmꢁ1) 3427, 3162, 3066, 1608, 1486, 1464, 1248, 1236,
1204, 1076, 1050, 936, 756. EM (m/z, %) 337 (M+ + 2,
13), 336 (11), 335 (37), 258 (55), 257 (66), 256 (66), 231
(35), 229 (100), 228 (26), 107 (16), 78 (14). 1H NMR
(300.18 MHz, DMSO-d6, d, ppm, J, Hz) 9.12 (1H, NH,
s), 7.58 (2H, H-15, H-19, dd, Jo = 7.5), 7.29–7.35 (3H, H-
16, H-18, H-17, m), 7.30 (1H, H-13, dd, Jo = 7.4), 7.12
(1H, H-4, t, Jo = 7.4), 6.99–7.04 (1H, H-6, H-11, m), 6.90
(1H, H-3, d, Jo = 7.37), 6.73 (1H, H-5, m,), 6.69 (1H, H-
12, t, Jo = 7.4), 6.68-6.72 (1H, H-10, H,12, m), 4.39 (1H,
H-7A, d, JAB = 14.0), 4.24 (1H, H-7B, d, JAB = 14.0).
13C NMR (75.47 MHz, DMSO-d6, d, ppm) 159.5 (C-9),
157.4 (C-2), 148.1 (C-16), 129.9 (C-8), 129.9 (C-4), 129.0
(C-11), 129.0 (C-18), 128.6 (C-6), 121.8 (C-1), 121.4 (C-
13), 120.3 (C-12), 120.0 (C-15), 119.0 (C-3), 118.4 (C-19),
118.3 (C-5), 113.8 (C-17), 112.4 (C-10), 48.7 (C-7). 11B
NMR (96.29 MHz, DMSO-d6, d, ppm) 9.0.
4.1.2.2. 2-(4-Acetylphenyl)-benzo[d]-benzo[h]-6-aza-1,3-
dioxa-2-boracyclononene (2b). Pale yellow solid, 80.2%
(0.767 g, 1.73 mmol), m.p. 208–211 °C. IR mmax (KBr,
cmꢁ1) 3430, 3221, 2762, 2560, 1566, 1481, 1449, 1116.
MS (m/z) 343 (M+, 7), 237 (13), 334 (23), 224 (28), 223
(52), 222 (100), 221 (24), 193 (11), 120 (20), 105 (27), 77
1
(41). H NMR (270.16 MHz, DMSO-d6, d, ppm, J, Hz)
9.36 (1H, NH, s), 7.89 (2H, H-16, d, Jo = 7.8), 7.70 (2H,
H-15, d, Jo = 7.8), 7.33 (1H, H-13, d, Jo = 7.9), 7.14 (1H,
H-4, t, Jo = 7.9), 7.06 (1H, H-11, t, Jo = 8.8), 7.04 (1H,
H-6, d, Jo = 8.8), 6.85 (1H, H-3, d, Jo = 7.9), 6.70-6.77
4.1.2.5.
2-Phenyl-4-chlorobenzo[d]-benzo[h]-6-aza-1,3-
dioxa-2-boracyclononene (2e). Yellow pale solid, 70.0%
(0.56 g, 1.59 mmol), m.p. 243–246 °C. IR mmax (KBr,
cmꢁ1) 3116, 1610, 1490, 1460, 1280, 1254, 1230, 1214,

346
A. Abreu et al. / Journal of Organometallic Chemistry 691 (2006) 337–348
1042, 748. MS (m/z, %) 301 (M+, 35), 224 (57), 223 (82),
222 (81), 195 (100), 194 (26), 78 (10). 1H NMR
(300.18 MHz, DMSO-d6, d, ppm, J, Hz) 9.49 (1H, NH,
s), 7.58 (2H, H-15, H-19, dd, Jo = 7.5, Jm = 2.4), 7.29–
7.35 (3H, H-16, H-18, H-17, m), 7.16 (1H, H-4, t,
Jo = 7.4), 7.07 (1H, H-6, d, Jo = 7.6 ), 6.90 (1H, H-3, d,
Jo = 7.4), 6.73–6.79 (1H, H-5, m,), 6.92 (2H, H-11, H-12,
d, Jo = 7.5 ), 6.40 (1H, H-13, d, Jm = 2.4), 4.45 (1H, H-
7A, d, JAB = 14.0), 4.38 (1H, H-7B, d, JAB = 14.0). 13C
NMR (75.47 MHz, DMSO-d6, d, ppm) 157.9 (C-9), 156.9
(C-2), 134.2 (C-8), 131.9 (C-15, C-19), 129.7 (C-11), 129.5
(C-4), 128.6 (C-6), 127.8 (C-12), 127.5 (C-17), 127.4 (C-
16, C-18) 121.6 (C-13), 121.8 (C-1), 120.0 (C-3), 118.6 (C-
5), 113.2 (C-10), 48.1 (C-7). 11B NMR (96.29 MHz,
DMSO-d6, d, ppm) 9.0.
5) 29.7 (CH3-tBu-C-3). 11B NMR (86.68 MHz, DMSO-
d6, d, ppm) 8.1.
4.1.2.8. 2-(4-Acetylphenyl)-benzo[d]-3,5-ditertbutylbenzo-
[h]-6-aza-1,3-dioxa-2-boracyclononene (2h). Yellow so-
lid, 55% (0.48 g, 1.06 mmol), m.p. 204–207 °C. FW = 455.
IR mmax (KBr, cmꢁ1) 3449, 3139, 2593, 1648, 1610, 1492,
1281, 1241, 1047, 993, 743. MS (m/z, %) 455 (M+, 28),
440 (13), 339(14), 336 (19), 335 (34), 320 (38), 237 (100),
222 (19), 203 (55), 57 (21). 1H NMR (300.18 MHz, CDCl3,
d, ppm, J, Hz) 7.92 (2H, H-16, H-18, d, Jo = 7.9), 7.74 (2H,
H-15, H-19, d, Jo = 7.9), 7.27 (1H, H-13, d, Jo = 7.6) 7.27
(1H, H-4, d, Jm = 1.8), 7.14 (1H, H-11, t, Jo = 7.7), 6.84
(1H, H-10, d, Jo = 7.7), 6.80 (1H, H-6, d, Jm = 1.8), 6.74
(1H, NH, s), 6.73 (1H, H-12, t, Jo = 7.7), 4.65 (1H, H-
7A, dd, JAB = 13.7, JAX = 3.6), 4.20 (1H, H-7B, dd,
JAB = 13.7, JBX= 1.4), 2.58 (3H, COCH3, s), 1.45 (9H,
tBu-C-3, s), 1.24 (9H, tBu-C-5, s). 13C NMR
(75.47 MHz, CDCl3, d, ppm) 199.1 (C@O), 159.9 (C-9),
153.6 (C-2), 141.7 (C-5), 138.1 (C-3), 136.9 (C-17), 132.9
(C-15, C-19), 130.3 (C-11), 129.8 (C-8), 124.0 (C-6), 123.8
(C-4), 121.8 (C-13), 112.7 (C-1), 118.8 (C-12), 112.8 (C-
10), 49.9 (C-7), 35.2 (C-tBu-C-3), 34.7 (C-tBu-C-5), 32.3
(CH3-tBu-C-5) 30.5 (CH3-tBu-C-3), 27.4 (COCH3). 11B
NMR (96.29 MHz, CDCl3, d, ppm) 7.4.
4.1.2.6. 2-Phenyl-4-nitrobenzo[d]-benzo[h]-6-aza-1,3-dioxa-
2-boracyclononene (2f). Yellow pale solid, 75.0% (0.50 g,
1.44 mmol), m.p. 236–238 °C. IR mmax (KBr, cmꢁ1) 3448,
3178, 1604, 1490, 1512, 1494, 1342, 1310, 1286, 1274,
1236, 1050, 1042, 1022, 742. MS (m/z, %) 346 (M+, 16),
269 (72), 268 (100), 267 (79), 240 (45), 222 (18), 221 (34),
210 (14), 194 (21), 107 (25), 78 (18). 1H NMR
(399.78 MHz, DMSO-d6, d, ppm, J, Hz) 9.85 (1H, NH,
s), 8.38 (1H, H-13, d, Jm = 2.4), 8.08 (1H, H-11, dd,
Jo = 8.9, Jm = 2.4), 7.59 (2H, H-15, H-19, dd, Jo = 7.2,
Jm = 2.6), 7.32–7.36 (3H, H-16, H-18, H-17, m), 7.16
(1H, H-4, t, Jo = 7.4), 7.11 (1H, H-6, d, Jo = 7.4), 6.89
(2H, H-3, H-10, m), 6.79 (1H, H-5, t, Jo = 7.4), 4.60 (1H,
H-7A, d, JAB = 13.6), 4.52 (1H, H-7B, d, JAB = 13.6).
13C NMR (100.53 MHz, DMSO-d6, d, ppm) 165.2 (C-9),
156.7 (C-2), 139.4 (C-12), 134.6 (C-8), 132 (C-15, C-19),
130.5 (C-4), 130.1 (C-6), 127.8 (C-16, C-18), 127.8 (C-17),
122.2 (C-1), 120.6 (C-3), 119.4 (C-5), 119.1 (C-11), 112.5
(C-13), 112.5 (C-10), 48.5 (C-7). 11B NMR (128.26 MHz,
DMSO-d6, d, ppm) 8.4.
4.1.2.9. 2-(3-Acetylphenyl)-benzo[d]-3,5-ditertbutylbenzo-
[h]-6-aza-1,3-dioxa-2-boracyclononene (2i). Yellow so-
lid, 89.8% (0.48 g, 1.06 mmol), m.p. 237–239 °C.
FW = 455. IR mmax (KBr, cmꢁ1) 3449, 3139, 2593, 1648,
1610, 1492, 1281, 1241, 1047, 993, 743. MS (m/z, %) 455
(M+, 38), 440 (13), 335 (23), 334 (23), 320 (23), 237 (100),
222 (23), 203 (63), 161 (13), 57 (16). 1H NMR
(300.18 MHz, CDCl3, d, ppm, J, Hz) 8.08 (1H, H-15, s),
7.92 (1H, H-17, d, Jo = 7.2), 7.23 (1H, H-19, d, Jo = 7.9),
7.36 (1H, H-18, dd, Jo = 7.9, 7.2) 7.27 (1H, H-4, d,
Jm = 2.3), 7.27 (1H, H-13, d, Jo = 7.6), 7.13 (1H, H-11,
dd, Jo = 7.6, Jm = 1.2), 6.84 (1H, H-10, d, Jo = 7.6), 6.81
(1H, H-6, d, Jm = 2.3), 6.77 (1H, H-12, td, Jo = 7.6,
Jm = 1.2), 6.71 (1H, N–H, s), 4.65 (1H, H-7A, dd,
JAB = 12.9, JAX = 3.6), 4.20 (1H, H-7B, dd, JAB = 12.9,
JAX = 1.5), 2.32 (3H, COCH3, s), 1.45 (9H, tBu-C-3, s),
1.24 (9H, tBu-C-5, s). 13C NMR (75.47 MHz, CDCl3, d,
ppm) 200.7 (C@O), 159.8 (C-9), 153.1 (C-2), 142.5 (C-5),
139.2 (C-3), 137.5 (C-19), 136.5 (C-16), 132.4 (C-15),
130.6 (C-11), 128.2 (C-18), 128.0 (C-8), 127.9 (C-17),
124.6 (C-6), 123.2 (C-4), 120.8 (C-13), 119.8 (C-1), 118.6
(C-12), 113.6 (C-10), 51.2 (C-7), 35.1 (C-tBu-C-3), 34.4
(C-tBu-C-5), 31.8 (CH3-tBu-C-5) 30.0 (CH3-tBu-C-3),
26.8 (COCH3). 11B NMR (96.29 MHz, CDCl3, d, ppm) 8.6.
4.1.2.7. 2-Phenyl-benzo[d]-3,5-ditertbutylbenzo[h]-6-aza-
1,3-dioxa-2-boracyclononene (2g). Yellow pale solid,
88.0% (0.50 g, 1.21 mmol), m.p. 208–211 °C. FW = 413.
IR mmax (KBr, cmꢁ1) 3221, 2762, 2560, 1566, 1481, 1449,
1116. MS (m/z, %) 413 (M+, 11), 398 (6), 336 (5), 320
(11), 203 (18), 195 (100), 146 (7), 91 (5), 57 (23). 1H
NMR (300.18 MHz, DMSO-d6, d, ppm, J, Hz) 9.16 (1H,
NH, s), 7.59 (2H, H-15, H-19, dd, Jo = 7.5, Jm = 2.1),
7.24–7.33 (2H, H-16, H-18, m ), 7.24–7.33 (1H, H-17, m),
7.24–7.33 (1H, H-13, m), 7.12 (1H, H-4, d, Jm = 2.0),
7.04 (1H, H-11, ddd, Jo = 8.0, 7.5, Jm = 1.1), 6.90 (1H,
H-6, d, Jo = 2.0), 6.70 (1H, H-12, dd, Jo = 8.0, Jo = 7.54),
6.68 (1H, H-10, d, Jo = 7.95), 4.37 (1H, H-7A, d, JAB
=
13.7), 4.22 (1H, H-7B, d, JAB = 13.7), 1.37 (9H, tBu-C-3,
s), 1.18 (9H, tBu-C-5, s). 13C NMR (75.47 MHz, DMSO-
d6, d, ppm) 159.2 (C-9), 152.9 (C-2), 140.7 (C-5), 137.2
(C-3), 131.8 (C-15, C-19), 129.4 (C-8), 129.3 (C-11), 127.2
(C-16, C-18), 127.2 (C-17), 123.0 (C-6), 122.8 (C-4), 121.4
(C-13), 120.9 (C-1), 117.7 (C-12), 111.8 (C-10), 49.1 (C-
7), 34.6 (C-tBu-C-3), 33.8 (C-tBu-C-5), 31.4 (CH3-tBu-C-
4.1.2.10. 2-(3-Aminophenyl)-benzo[d]-3,5-ditertbutylbenzo-
[h]-6-aza-1,3-dioxa-2- boracyclononene (2j). Yellow solid,
82.0% (0.48 g, 1.06 mmol), m.p. 237–239 °C. FW = 428. IR
(m) (KBr, cmꢁ1) 3351, 3184, 2958, 1610, 1490, 1441, 1242,
1041, 771. MS (m/z, %) 428 (M+, 20), 335 (60), 334 (23),
1
320 (50), 210 (100), 209 (25), 93 (21), 57 (14). H NMR

A. Abreu et al. / Journal of Organometallic Chemistry 691 (2006) 337–348
347
(300.18 MHz, DMSO-d6, d, ppm, J, Hz) 9.12 (1H, NH, s),
7.30 (1H, H-13, d, Jo = 7.5), 7.12 (1H, H-4, d, Jm = 1.3),
7.03 (1H, H-11, t, Jo = 7.7), 6.98 (1H, H-18, t, Jo = 7.5),
6.88 (1H, H-6, d, Jm = 1.3), 6.83 (1H, H-15, m), 6.83 (1H,
H-19, m), 6.68 (1H, H-12, t, Jo = 7.7), 6.61 (1H, H10, d,
Jo = 7.7), 6.50 (1H, H-17, d, Jo = 7.4), 4.77 (2H, NH2, s),
4.32 (1H, H-7A, d, JAB = 13.6), 4.19 (1H, H-7B, d,
JAB = 13.6), 1.38 (9H, tBu-C-3, s), 1.18 (9H, tBu-C-5, s).
13C NMR (75.47 MHz, DMSO-d6, d, ppm) 159.4 (C-9),
153.1 (C-2), 147.5 (C-16), 145.0 (C-14), 140.6 (C-5), 137.2
(C-3), 129.3 (C-11), 129.3 (C-8), 127.8 (C-18), 123.3 (C-6),
123.0 (C-4) 121.4 (C-13), 121.0 (C-1), 119.9 (C-15), 117.9
(C-19), 117.5 (C-12), 113.3 (C-17), 111.8 (C-10), 49.1 (C-
7), 34.5 (C-tBu-C-3), 33.9 (C-tBu-C-5), 31.5 (CH3-tBu-C-5)
29.8 (CH3-tBu-C-3). 11B NMR (86.68 MHz, DMSO-d6, d,
ppm) 9.0.
JAB = 13.6, JAX = 3.6), 3.95 (1H, H-7B, d, JAB = 13.6,
JBX = 1.7), 1.33 (9H, tBu-C-3, s), 1.18 (9H, tBu-C-5, s).
13C NMR (75.47 MHz, CDCl3, d, ppm) 158.1 (C-9), 154.0
(C-2), 148.4 (C-16), 146.1 (C-14), 141.3 (C-5), 138.0 (C-3),
130.4 (C-11), 130.1 (C-8), 128.6 (C-18), 127.1 (C-12), 123.9
(C-6) 123.6 (C-4), 122.4 (C-13), 121.7 (C-1), 120.7 (C-15),
118.7 (C-19), 114.0 (C-17),113.2 (C-10), 49.9 (C-7), 34.7
(C-tBu-C-3), 34.3 (C-tBu-C-5), 32.3 (CH3-tBu-C-5) 30.6
(CH3-tBu-C-3), 21.2 (C-Me). 11B NMR (96.29 MHz,
CDCl3, d, ppm) 9.6.
5. Supplementary material
For compounds 2a, 2e, 2f and 2l full crystallographic
data were submitted as CIF files with the Cambridge Crys-
tallographic Data Center, CCDC Nos. 280252-280255.
CCDC, 12 Union Road, Cambridge CB21EZ, UK (Fax:
+44 1223 336033; e-mail: deposit@ccdc.cam.ac.uk or
www: http://www.ccdc.cam.ac.uk).
4.1.2.11. 2-Phenyl-4-methylbenzo[d]-3,5-ditertbutylbenzo-
[h]-6-aza-1,3-dioxa-2-boracyclononene (2k). Compound
2k was prepared by the reaction of 0.51 g (1.35 mmol) of
1e, 0.165 g (1.35 mmol) phenylboronic acid, and (0.243 g,
1.925 mmol) of sodium bicarbonate to give 2k as a yellow
solid 80.0% (0.46 g, 1.08 mmol) m.p. 227–231 °C.
FW = 428. IR mmax (KBr, cmꢁ1) 3221, 2762, 2560, 1566,
1481, 1449, 1116. MS (m/z, %) 427 (M+1, 11), 349 (8),
209 (100), 153 (7), 57 (14). 1H NMR (270.16 MHz, CDCl3,
d, ppm, J, Hz) 7.67 (2H, H-15, H-17, dd, Jo = 6.30,
Jm = 2.2), 7.29–7.33 (2H, H-16, H-18, m), 7.29–7.33 (1H,
H-17, m), 7.25 (1H, H-4, d, Jm = 2.2), 6.92 (1H, H-13, s),
6.91 (1H, H-11, d, Jo = 7.9), 6.74 (1H, H-6, d, Jo = 2.2),
6.65 (1H, H-10, d, Jo = 7.9), 5.47 (1H, NH, s), 4.48 (1H,
H-7A, dd, JAB = 12.6, JAX = 3.7), 4.02 (1H, H-7B, dd,
JAB = 12.6, JAX = 1.7), 2.23 (3H, CH3-C12, s), 1.44 (9H,
tBu-C-3, s), 1.23 (9H, tBu-C-5, s). 13C NMR (67.94
MHz, CDCl3, d, ppm) 157.8 (C-9), 153.3 (C-2), 142.2 (C-
5), 139.2 (C-3), 132.1 (C-15, C-19), 131.2 (C-11), 128.3
(C-17), 128.1 (C-16, C-18), 127.8 (C-12), 127.2 (C-8),
124.6 (C-6), 123.2 (C-4), 121.1 (C-13), 119.5 (C-1), 113.2
(C-10), 50.8 (C-7), 35.1 (C-tBu-C-3), 34.4 (C-tBu-C-5),
30.1 (CH3-tBu-C-5) 29.3 (CH3-tBu-C-3). 11B NMR
(86.68 MHz, DMSO-d6, d, ppm) 8.7.
Acknowledgements
The authors thank CONACYT for financial support
and the fellowship granted to A. Abreu during the Ph.D.
research. Thanks are given to Consejo Superior de la Inves-
´
´
tigacion Cientıfica in Spain for the Cambridge Crystallo-
´
graphic Data Base license, to V. Gonzalez, G. Uribe and
´
Ma. L. Rodrıguez, for NMR spectra, D. Castillo for IR
´
spectra and G. Cuellar for MS.
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