LETTER
A Novel Platform for Molecular Receptors
2029
(6) and 1,3,5-triiodobenzene (3) gave triamine 1 in excel-
lent isolated yield (Table 1, entry 4). Nevertheless, when
we use the commercially available 1,3,5-tribromobenzene
2 rather than triiodobenzene 3 the yield of 1 was signifi-
cantly reduced to 35% (Table 1, entry 5).
References and Notes
(1) (a) Vögtle, F.; Atwood, J. L. Comprehensive
Supramolecular Chemistry, Vol. 2; Atwood, J. L.; Davies, J.
E. D.; MacNicol, D. D.; Vögtle, F., Eds.; Pergamon/Elsevier
Science: Oxford, 1996, 439–473. (b) Vögtle, F.; Atwood, J.
L. Comprehensive Supramolecular Chemistry, Vol. 2;
Atwood, J. L.; Davies, J. E. D.; MacNicol, D. D.; Vögtle, F.,
Eds.; Pergamon/Elsevier Science: Oxford, 1996, 525–549.
(c) Anslyn, E. V.; Dougherty, D. A. Modern Physical
Organic Chemistry; University Science Books: Sausalito,
California, 2006, 228–232. (d) Steed, J. W.; Atwood, J. L.
Supramolecular Chemistry; J. Wiley and Sons: Chichester,
2000, 233–234. (e) Steed, J. W.; Atwood, J. L.
Although boronic acids are commonly used as nucleo-
philic components for the Suzuki–Miyaura reaction, they
posses some drawbacks, such as structural ambiguity
(e.g., dimers, trimers) and the purification difficulty.
These drawbacks can be overcome by use of boronate
esters. To ensure that the purity of the 2-aminophenylbo-
ronic acid (6) did not alter the efficiency of the cross-cou-
pling reaction we synthesized the corresponding pinacol
boronate 8.17 The coupling of 2-aminophenylboronic acid
pinacol ester (8) with triiodobenzene 3 afforded 1 in
nearly the same yield as in the reaction of the analogous
boronic acid (Table 1, entry 6 vs. entry 4). Thus, the purity
of 6 is sufficient for effective coupling with haloarenes 2
and 3.
Supramolecular Chemistry; J. Wiley and Sons: Chichester,
2000, 334–337.
(2) (a) Collman, J. P.; Zhang, X. Comprehensive
Supramolecular Chemistry; Atwood, J. L.; Davies, J. E. D.;
MacNicol, D. D.; Vögtle, F., Eds.; Pergamon/Elsevier
Science: Oxford, 1996, 1–32. (b) Rusin, O.; Kral, V. Chem.
Commun. 1999, 2367. (c) Lee, C.; Lee, D. H.; Hong, J.-I.
Tetrahedron Lett. 2001, 42, 8665. (d) Kim, Y.-H.; Hong, J.-
I. Angew. Chem. Int. Ed. 2002, 41, 2947.
During the course of our search for synthetic procedures
for the preparation of pinacol boronate 8, we came across
a very interesting account by Baudoin and co-workers.18
They prepared compound 8 via palladium-catalyzed bory-
lation of 2-bromoaniline with pinacolborane in the pres-
ence of phosphine ligand 7. In turn, boronate ester 8 was
cross-coupled in a one-pot process with 2-iodophenylace-
tonitrile derivatives to afford sterically hindered 2,2¢-bi-
phenyls. Thus, the reaction of 2-bromoaniline with
pinacolborane produced pinacol boronate 8 which, with-
out isolation, was treated with 1,3,5-triiodobenzene 3 in
the presence of water and Ba(OH)2 gave triamine 1 in
65% isolated yield (Table 1, entry 7).
(3) (a) Davis, A. P.; Lawless, L. J. Chem. Commun. 1999, 9.
(b) Baragana, B.; Blackburn, A. G.; Breccia, P.; Davis, A. P.;
de Mendoza, J.; Padron-Carrillo, J. M.; Prados, P.; Riedner,
J.; de Vries, J. G. Chem. Eur. J. 2002, 8, 2931. (c)Davis, A.
P.; Perry, J. J.; Williams, R. P. J. Am. Chem. Soc. 1997, 119,
1793. (d) Ayling, A. J.; Perez-Payan, M. N.; Davis, A. P. J.
Am. Chem. Soc. 2001, 123, 12716.
(4) (a) Valiyaveettil, S.; Engbersen, J. F. J.; Verboom, W.;
Reinhoudt, D. N. Angew. Chem., Int. Ed. Engl. 1993, 32,
900. (b) Xie, H.; Yi, S.; Wu, S. J. Chem. Soc., Perkin Trans.
2 1999, 2751. (c) Beer, P. D.; Hopkins, P. K.; McKinney, J.
D. Chem. Commun. 1999, 1273. (d) Amendola, V.;
Fabbrizzi, L.; Mangano, C.; Lanfredi, A. M.; Pallavicini, P.;
Perotti, A.; Ugozzoli, F. J. Chem. Soc., Dalton Trans. 2000,
1155. (e) Fabbrizzi, L.; Leone, A.; Taglietti, A. Angew.
Chem. Int. Ed. 2001, 40, 3066.
In summary, different approaches to the preparation of
1,3,5-tris(2¢-aminophenyl)benzene 1 were investigated.
All attempts to cross-couple of 2-nitro or 2-N-Boc phenyl-
boronic acid derivatives with 1,3,5-haloarenes failed.
However, the coupling of unprotected 2-aminophenylbo-
ronic acid and 1,3,5-triiodobenzene using Pd(OAc)2,
Ba(OH)2 and (2-biphenyl)dicyclohexylphosphine pro-
vides 1,3,5-tris(2¢-aminophenyl)benzene (1) in 87% iso-
lated yield. Alternatively, triamine 1 can be prepared via
a one-pot procedure from commercially available 2-bro-
moaniline. These methods represent efficient pathways to
1,3,5-tris(2¢-aminophenyl)benzene (1) which could serve
as novel versatile platform for the synthesis of diverse
novel acyclic molecular receptors. As an example, we
used triamine 1 as molecular scaffold and synthesized a
series of anion receptors. Studies concerning the ability of
these receptors to bind different anionic species are cur-
rently under investigation in our laboratory. The details of
those studies will be reported in due course.
(5) (a) Gunther, H.; Anslyn, E. V. Chem. Eur. J. 2002, 8, 2218.
(b) Ihm, H.; Yun, S.; Kim, H. G.; Kim, J. K.; Kim, K. S. Org.
Lett. 2002, 4, 2897. (c) Bai, Y.; Zhang, B.-G.; Xu, J.; Duan,
C.-Y.; Dang, D.-B.; Liu, D.-J.; Meng, Q.-J. New J. Chem.
2005, 29, 777. (d) Wallace, K. J.; Belcher, W. J.; Turner, D.
R.; Syed, K. F.; Steed, J. W. J. Am. Chem. Soc. 2003, 125,
9699. (e) Turner, D. R.; Paterson, M. J.; Steed, J. W. J. Org.
Chem. 2006, 71, 1598.
(6) Manabe, K.; Okamura, K.; Date, T.; Konga, K. J. Am. Chem.
Soc. 1993, 58, 6692.
(7) Abe, H.; Aoyagi, Y.; Inouye, M. Org. Lett. 2005, 7, 59.
(8) Horiuchi, N.; Huff, J.; Rebek, J. Jr. Tetrahedron Lett. 1990,
31, 5121.
(9) Seaman, W.; Johnson, J. R. J. Am. Chem. Soc. 1931, 53, 711.
(10) Collibee, S. E.; Yu, J. Tetrahedron Lett. 2005, 46, 4453.
(11) Barder, T. E.; Walker, S. D.; Martinelli, J. R.; Buchwald, S.
L. J. Am. Chem. Soc. 2005, 127, 4685.
(12) Welti, R.; Abel, Y.; Gramlich, V.; Diederich, F. Helv. Chim.
Acta 2003, 86, 548.
(13) Lamba, J. J. S.; Tour, J. M. J. Am. Chem. Soc. 1994, 116,
11723.
(14) (a) Bryant, J. A.; Helgeson, R. C.; Knoblez, C. B.;
deGrandpre, M. P.; Cram, D. J. J. Org. Chem. 1990, 55,
4622. (b) Unrau, C. M.; Campbell, M. G.; Snieckus, V.
Tetrahedron Lett. 1992, 33, 2773. (c) Burk, M. J.; Lee, J.
R.; Martinez, J. P. J. Am. Chem. Soc. 1994, 116, 10847.
(d) Miura, Y.; Momoki, M.; Fuchikami, T. J. Org. Chem.
1996, 61, 4300. (e) Zuideveld, M. A.; Wehrmann, P.; Röhr,
C.; Mecking, S. Angew. Chem. Int. Ed. 2004, 43, 869.
Acknowledgment
We would like to thank Professor Janusz Jurczak for helpful discus-
sions. We are grateful for financial support from Warsaw Univer-
sity Department of Chemistry (grant BW1681/13/05).
Synlett 2006, No. 13, 2027–2030 © Thieme Stuttgart · New York