Synthesis and crystal structure of a novel triangular macrocyclic molecule, tris(H2saloph), and its water complex

Article abstract of DOI:10.1016/S0040-4039(01)01943-8

Condensation of 2,3-dihydroxybenzene-1,4-dicarbaldehyde and 1,2-phenylenediamine afforded a novel 30-membered macrocyclic hexaimine bearing six hydroxyl groups, in which a water molecule is trapped in the crystalline state.

Full text of DOI:10.1016/S0040-4039(01)01943-8

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 42 (2001) 8861–8864
Synthesis and crystal structure of a novel triangular macrocyclic
†
molecule, tris(H saloph), and its water complex
2
Shigehisa Akine, Takanori Taniguchi and Tatsuya Nabeshima*
Department of Chemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
Received 6 August 2001; revised 9 October 2001; accepted 12 October 2001
Abstract—Condensation of 2,3-dihydroxybenzene-1,4-dicarbaldehyde and 1,2-phenylenediamine afforded a novel 30-membered
macrocyclic hexaimine bearing six hydroxyl groups, in which a water molecule is trapped in the crystalline state. © 2001 Elsevier
Science Ltd. All rights reserved.
Macrocyclic molecules containing a Schiff base and
hydroxyl moieties have attracted considerable attention
due to formation of a variety of multi-metal com-
N
N
1
plexes, which exhibit catalytic activity for epoxidation
2
3
of olefins, asymmetric ring-opening of epoxides, NLO
OH HO
OH HO
HO OH
4
behavior, etc. Application of the macrocycles to model
systems for active sites of metalloproteins and magnetic
materials may be expected. Furthermore, metallohosts
N
N
‡
bearing a salen analogue provide a unique and cooper-
5
ative binding site for both neutral guests and cations.
N
N
Hydrogen bonding through the hydroxyl groups of
salicylaldimine is also expected to be useful for molecu-
lar recognition, because a well-arranged, multi-hydro-
gen bonding network can be available. There is,
however, no example of host–guest systems by using
1
Synthesis of the cyclic hexaimine 1 is shown in Scheme
1. Dilithiation of 1,2-dimethoxybenzene (2) followed
by the reaction with N,N-dimethylformamide gave 2,3-
dimethoxybenzene-1,4-dicarbaldehyde (3). Treatment
of 3 with boron tribromide afforded 4 in 92% yield. The
macrocyclic compound 1 was obtained in a remarkably
high yield (91%) by condensation of 4 and 5 (4×10 M)
in acetonitrile (rt, 2 weeks). Under lower concentrations
2.5–4.0×10 M, rt, 1 month), the yield decreased
intermolecular hydrogen bonding of an oligo(H salen)
10
2
macrocyclic compound as a host, although interesting
synthetic applications of intramolecular hydrogen
bonds to cyclization of H salen analogues and the
2
absolutely template-dependent synthesis of bis- and
tris(H salen) ligands and their complexes were
−2
2
6
,7
reported. Cyclic oligo(H salen) derivatives possessing
2
8
a triangular arrangement of three salicylaldimine are
−3
(
very attractive and important target molecules, because
this arrangement is fit for the shape of guests with C3
considerably (19%). Pure compound 1 gradually precip-
itated during the reaction. The IR spectrum of 1 sug-
gested an imine functionality. The CꢀN stretching band
symmetry such as ammonium salts and spherical guests
7,9
such as alkali and alkaline earth metal ions. Here we
report synthesis of a triangular 30-membered macro-
cyclic oligo(H salen) analogue 1, tris(H saloph), with-
−1
appeared at 1620 cm , while the CꢀO absorption
−1
around 1660 cm of the dialdehyde 4 disappeared.
2
2
out a template and the crystal structure of a complex of
and a water molecule via multi-hydrogen bonds.
The structure of 1 was supported by NMR in DMF-d
7
1
§
and analytical data, and finally determined to be a 3:3
§
1
H NMR (400 MHz, DMF-d ) l 7.29 (s, 6H), 7.50–7.52 (m, 6H),
.62–7.64 (m, 6H), 9.07 (s, 6H), 13.54 (s, 6H); C NMR (100 MHz,
Keywords: imines; macrocycles; X-ray crystal structures.
7
1
3
7
*
Corresponding author. Tel.: +81-298-53-4507; fax: +81-298-53-6503;
e-mail: nabesima@chem.tsukuba.ac.jp
DMF-d ) l 119.74, 121.24, 121.69, 128.63, 142.51, 151.49, 164.61.
7
†
‡
Anal. calcd for C42H30N O ·2H O: C, 67.19; H, 4.56; N, 11.19.
H saloph=N,N%-disalicylidene-o-phenylenediamine.
6
6
2
2
Found: C, 67.51; H, 4.73; N, 11.15.
H salen=N,N%-disalicylideneethylenediamine.
2
0
040-4039/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(01)01943-8

8
862
S. Akine et al. / Tetrahedron Letters 42 (2001) 8861–8864
NH2
NH2
CHO
CHO
OMe
OMe
OMe
OMe
OH
OH
5
i
ii
1
iii
91%
CHO
CHO
2
3 27%
4
92%
Scheme 1. Reagents and conditions: (i) (1) n-BuLi, TMEDA, ether, (2) DMF then H O; (ii) BBr , dichloromethane, then H O; (iii)
2
3
2
acetonitrile.
¶
macrocycle by X-ray crystallographic analysis (Fig. 1).
least-square plane of whole non-hydrogen atoms of 1),
the dihedral angles between the catechol rings and the
average plane are about 30°. Thus, four of the six
hydroxyl groups (O(1)*, O(2)*, O(3), and O(4)) stick
out to one side of the molecular plane and the other
two (O(1) and O(2)) to the opposite side.
This is the first example of X-ray crystallographic iden-
tification of a tris(H saloph) derivative. Compound 1
has a triangular shape with three apexes of the
phenylenediamine moieties and was located on the crys-
tallographic two-fold axis. Each hydroxyl group points
to a nitrogen atom of the imine moieties with O–N
2
distance of ca. 2.6 A
,
, indicating existence of a strong
Interestingly, a hydrate, 1·H O·MeCN, was also
2
intramolecular hydrogen-bond network. However, no
intermolecular hydrogen bond was observed. While the
three benzene rings of the phenylenediamine moieties
lie on the average plane of the molecule (defined as the
obtained from the reaction mixture. X-Ray crystallog-
¶
raphy revealed that a water molecule is captured in the
11
cavity of the cyclic compound 1 (Fig. 2). The two
hydrogen atoms of the water molecule make effective
Figure 1. Crystal structure of 1·3MeCN (ORTEP, 50% probability). Disordered atoms and solvent molecules are omitted. Selected
interatomic distances (A): N(1)ꢁO(1) 2.597(3), N(2)ꢁO(2) 2.593(3), N(3)ꢁO(3) 2.568(4), N(3)*ꢁO(4) 2.603(4), O(1)ꢁO(1)* 3.376(4),
O(1)ꢁO(2) 2.647(3), O(2)ꢁO(3) 3.165(4), O(3)ꢁO(4) 2.677(5), O(4)ꢁO(2)* 2.930(4).
,
¶
3
Crystallographic analysis of 1·3MeCN: deep red prism (0.40×0.40×0.30 mm ), C48H39N O (M=837.88), trigonal, a=18.2013(6), c=10.7814(4)
9
6
3
3
−1
A
,
, V=3093.2(2) A
,
, space group, P3 21 (No. 152) or P3 21 (No. 154), Z=3, z
=1.349 g/cm , T=120 K, v(MoKa)=0.092 mm , collected
13
1
2
calcd
reflections, 22827, unique, 4725 (Rint=0.0682), R =0.0527 (I>2|(I)), wR =0.1342 (all data). The chirality of the crystal was not reliably
1
2
determined by the refinement, which left ambiguity in the determination of the space group. In the crystal of 1·3MeCN, the cavity of 1
surrounded by the six oxygen atoms was partially filled by the methyl groups of two acetonitrile molecules.
3
Crystallographic analysis of 1·H O·MeCN: deep red needle (0.40×0.10×0.05 mm ), C44H35N O (M=773.79), monoclinic, a=9.646(3), b=
2
7
7
3
3
1
8.910(2), c=21.032(9) A
,
, i=95.519(3)°, V=3819(2) A
,
, space group, P2 /c (No. 14), Z=4, z
mm , collected reflections, 22311, unique, 6671 (Rint=0.1898), R =0.0935 (I>2|(I)), wR =0.2472 (all data).
=1.346 g/cm , T=120 K, v(MoKa)=0.093
1
calcd
−
1
13
1
2
Crystallographic data (excluding structure factors) for the structures in this paper have been deposited with the Cambridge Crystallographic Data
Centre as supplementary publication numbers CCDC 166254 (1·3MeCN) and 166255 (1·H O·MeCN).
2

S. Akine et al. / Tetrahedron Letters 42 (2001) 8861–8864
8863
Figure 2. Crystal structure of 1·H O·MeCN (ORTEP, 30% probability). Disordered atoms and acetonitrile molecules are omitted.
2
Selected interatomic distances (A
.657(7), N(6)ꢁO(6) 2.655(7), O(1)ꢁO(2) 2.671(6), O(2)ꢁO(3) 3.006(6), O(3)ꢁO(4) 2.640(6), O(4)ꢁO(5) 3.053(6), O(5)ꢁO(6) 2.646(6),
,
): N(1)ꢁO(1) 2.645(8), N(2)ꢁO(2) 2.628(7), N(3)ꢁO(3) 2.573(6), N(4)ꢁO(4) 2.590(6), N(5)ꢁO(5)
2
O(6)ꢁO(1) 3.032(6), O(1)ꢁO(7) 2.940(6), O(2)ꢁO(7) 2.939(6), O(3)ꢁO(7) 2.975(6), O(4)ꢁO(7) 3.023(6), O(5)ꢁO(7) 2.997(6),
O(6)ꢁO(7) 2.947(6).
N
O
NH2
NH2
H
N
×
2
4
+ 5
OH
OH
O
N H
H O
O H
N
O
CHO
6
7
N
O
N
H H
+
6
O
1
(precipitates)
O
N H
H O
O
H N
O H
H N
N
2
CHO
8
Scheme 2. Plausible mechanism for the formation of 1.

8
864
S. Akine et al. / Tetrahedron Letters 42 (2001) 8861–8864
hydrogen bonding to four oxygen atoms of 1 because
of complementary geometrical fit. Compound
2. Li, Z.; Jablonski, C. Chem. Commun. 1999, 1531.
3. Ready, J. M.; Jacobsen, E. N. J. Am. Chem. Soc. 2001,
123, 2687.
4. Korupoju, S. R.; Mangayarkarasi, N.; Ameerunisha, S.;
Valente, E. J.; Zacharias, P. S. J. Chem. Soc., Dalton
Trans. 2000, 2845.
5. (a) van Staveren, C. J.; van Eerden, J.; van Veggel, F.
C. J. M.; Harkema, S.; Reinhoudt, D. N. J. Am. Chem.
Soc. 1988, 110, 4994; (b) van Doorn, A. R.; Schaafstra,
R.; Bos, M.; Harkema, S.; van Eerden, J.; Verboom,
W.; Reinhoudt, D. N. J. Org. Chem. 1991, 56, 6083.
1
adopted a shallow bowl conformation with all the six
hydroxyl groups sticking out to the same side. Rather
long O(water)–O(catechol) distances (2.94–3.02 A) sug-
,
gest delocalization of protons in ways like O···H···N
and O···H···O.
Selective formation of cyclic compound 1 is probably
explained by stabilization of the favorable conforma-
tion of the transition state and/or intermediates in the
cyclization due to intramolecular hydrogen bonds.
6
. For macrocyclic bis(H salen) or bis(H saloph) deriva-
2 2
1
The initial cyclization process was monitored by H
tives reported so far, see: (a) Moneta, W.; Baret, P.;
Pierre, J.-L. J. Chem. Soc., Chem. Commun. 1985, 899;
NMR spectroscopy in CD CN. Only two compounds
3
(
major and minor, 4:1) were formed (Scheme 2). The
(
b) Moneta, W.; Baret, P.; Pierre, J.-L. Bull. Soc. Chim.
major component was easily assigned to be 1:1 adduct
6
Fr. 1988, 995; (c) van Veggel, F. C. J. M.; Bos, M.;
Harkema, S.; Verboom, W.; Reinhoudt, D. N. Angew.
Chem., Int. Ed. Engl. 1989, 28, 746; (d) van Veggel, F.
C. J. M.; Bos, M.; Harkema, S.; van de Bovenkamp, H.;
Verboom, W.; Reedijk, J.; Reinhoudt, D. N. J. Org.
Chem. 1991, 56, 225; (e) P e´ rez, M. A.; Bermejo, J. M. J.
Org. Chem. 1993, 58, 2628; (f) Houjou, H.; Lee, S.-K.;
Hishikawa, Y.; Nagawa, Y.; Hiratani, K. Chem. Com-
mun. 2000, 2197.
ꢀꢀ
, and the minor component was considered to be a
linear 2:2 adduct 7. It is noteworthy that hydroxyl
protons of the salicylaldimine moieties were observed
at 13.5 and 13.2 ppm during the course of the reac-
tion, indicating existence of strong hydrogen bonds.
The conformation of the precursor 8 is restricted by
multiple hydrogen bonds in such a way that the amino
group can easily attack the formyl group. The driving
force for formation of the cyclic trimer is considered
to be the extremely low solubility of the product in
acetonitrile,** as well as the multiple hydrogen bonds
as mentioned above.
7. Huck, W. T. S.; van Veggel, F. C. J. M.; Reinhoudt, D.
N. Recl. Trav. Chim. Pays-Bas 1995, 114, 273.
8. Recently,
a chiral triangular macrocyclic hexaimine
without a hydroxyl group has been reported, see:
Gawronski, J.; Kolbon, H.; Kwit, M.; Katrusiak, A. J.
Org. Chem. 2000, 65, 5768.
It is well known that the oxygen atoms of metal com-
plexes of salen-type ligands have anionic character,
which sometimes enhances coordination strength to
9
. Macrocyclic tris(catechol) derivatives with C symmetry
3
1
2
bind Fe(III), see: Rodgers, S. J.; Ng, C. Y.; Raymond,
K. N. J. Am. Chem. Soc. 1985, 107, 4094.
other metal ions. We are currently investigating the
synthesis of transition metal complexes of 1 and
10. Crowther, G. P.; Sundberg, R. J.; Sarpeshkar, A. M. J.
Org. Chem. 1984, 49, 4657.
preparing more soluble tris(H saloph) as a sophisti-
2
cated host molecule by introducing hydrophobic
groups such as an alkyl chain into the benzene rings
of 1.
1
1. A number of macrocyclic compounds carrying water
molecules have been reported so far, for example:
Gokel, G. W.; Garcia, B. J. Tetrahedron Lett. 1977, 18,
317.
1
2. For example, see: Cunningham, D.; McArdle, P.;
Mitchell, M.; Chonchubhair, N. N.; O’Gara, M.;
Franceschi, F.; Floriani, C. Inorg. Chem. 2000, 39, 1639.
References
1
. (a) Guerriero, P.; Tamburini, S.; Vigato, P. A. Coord.
Chem. Rev. 1995, 139, 17; (b) Pilkington, N. H.; Rob-
son, R. Aust. J. Chem. 1970, 23, 2225.
13. Sheldrick, G. M. SHELXL-97. Program for crystal
structure refinement, University of G o¨ ttingen, 1997.
ꢀꢀ 1
H NMR signals assigned to intermediate 6 are as follows (400
MHz, CD CN): l=4.4 (brs, 2H), 6.74 (td, J=7.6, 1.2 Hz, 1H),
3
6
.82 (dd, J=7.6, 1.2 Hz, 1H), 7.10 (td, J=7.6, 1.2 Hz, 1H), 7.17
(
dd, J=7.6, 1.2 Hz, 1H), 7.20 (d, J=8.4 Hz, 1H), 7.27 (d, J=8.4
Hz, 1H), 8.78 (s, 1H), 10.02 (s, 1H), 10.5 (brs, 1H), 13.5 (brs, 1H).
* The product was also insoluble in chloroform, methanol, and
water.
*