Cyclooctapyrroles, novel macrocycles containing biladiene-a,c units

Article abstract of DOI:10.1016/S0040-4020(02)01592-2

Cyclooctapyrroles, novel macrocycles containing two biladiene-a,c units, were synthesized in high yield from the condensation of 3,3′-dipyrromethanes with 5,5′-diformyl-2,2′-dipyrromethane under acidic conditions. These macrocycles form dinuclear complexes with zinc(II).

Full text of DOI:10.1016/S0040-4020(02)01592-2

Tetrahedron 59 (2003) 871–875
Cyclooctapyrroles, novel macrocycles containing
biladiene-a,c units
*
Qingqi Chen and David Dolphin
Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1
Received 14 May 2002; revised 3 December 2002; accepted 3 December 2002
Abstract—Cyclooctapyrroles, novel macrocycles containing two biladiene-a,c units, were synthesized in high yield from the condensation
of 3,30-dipyrromethanes with 5,50-diformyl-2,20-dipyrromethane under acidic conditions. These macrocycles form dinuclear complexes with
zinc(II). q 2003 Elsevier Science Ltd. All rights reserved.
1. Introduction
simple materials is attractive as a synthetic method for
macrocycles containing pyrrolic units. To extend our work,
we were interested in preparing octacyclopyrroles 7–9,
whose structures are similar to that of compound 1c, but
where the sulfur bridge is replaced by one, two or three
carbon bridges. We describe here our findings and show that
novel macrocycles, 7–9, are formed in high yield 0by acidic
condensation of 5,50-diformyl-4,40-dimethyl-3,3 -d0iethyl-
2,2-dipyrromethane (6) with 5,50-biscarboxy-2,20,4,4 -tetra-
methyl-3,30-dipyrrolyl-methane (2), 1,2-bis(5-carboxy-2,4-
dimethylpyrrole-3-yl)ethane (3), and 1,3-bis(5-carboxy-2,4-
dimethyl-pyrrole-3-yl)propane (4).
Macrocycles containing polypyrrolic units have been
attracting considerable interest1–7 due to their applications
in theory,1,2 photodynamic therapy (PDT),1,2,8 neutral
substance binding, anion recognition9,10 and complexation
with metallic ions.10,11 Among these polypyrrolic macro-
cycles, cyclooctapyrroles are of particular interest because
of their figure-eight conformations,6,10,12 their ability to
form dinuclear complexes with metal ions such as Cu(II),
and Pd(II),10 and their anion binding properties.13
[32]Octaphyrin(1.0.1.0.1.0.1.0) 1a was synthesized by
Vogel’s group4 using an acid-catalyzed MacDonald14 type
[2þ2þ2þ2]0 condensation o0f 5,50-diformyl-2,20-bipyrrole
with a 5,5 -biscarboxy-2,2 -bipyrrole or by a [4þ4]
condensation of a tetrapyrrolic derivative in yields of
7–11%. meso-Tetraphenyl [32]octaphyrin[1.0.1.0.1.0.1.0]
was prepared via a Rothemund type15 synthesis from the
condensation of a 2,20-bipyrrole with benzaldehyde with a
yield of 7%.12 More recently [30]heptaphyrin
(1.1.1.1.1.0.0),16a cyclo[8]pyrrole,16b dioxa-[40]decaphyrin
(1.0.1.0.0.1.0.1.0.0),16c [64]hexadecaphyrin (1.0.1.0.
2. Results
The starting material (2, or 3, or 4 (0.95 mmol)) was stirred
in trifluoroacetic acid (TFA, 10 mL) at 408C until all solid
had dissolved, th0e mixture was0 then cooled down to room
temperature. 5,5 -Diformyl-4,4 -dimethyl-3,30-diethyl-2,20-
dipyrromethane (6) (0.95 mmol) was added at once,
followed by a mixture of hydrobromic acid (48% in glacial
acetic acid, 2 mL), methanol (20 mL) and dichloromethane
(20 mL). The mixture was left to stir for another 3 h at room
temperature. The product was precipitated by adding
anhydrous ether and collected by filtration. The yields of
7, 8, and 9 were 95, 90, and 90%, respectively. It is worth
noting that the condensation of compounds 5 and 6 under
similar acidic conditions resulted only in a [2þ2] product
10, in a yield of 72%. Compounds 7–10 were all isolated as
HBr salts.
1.0.1.0.1.0.1.0.1.0.1.0),17a
calix[n]furano[m]pyrroles
(n¼3,4,6,8) and (m¼2,4),17b and calix[m]pyrrole,17c have
been reported.
Recently, we 0 found that the condensation of a 5,500-
biscarboxy-3,3 -dipyrroyl sulfide with a 5,50-diformyl-3,3 -
dipyrrolyl sulfide or a 5,50-diformyl-2,20-dipyrromethane
under acidic conditions resulted in a [2þ2þ2þ2] cycliza-
tion to give the dicationic octacyclopyrrole 1b or 1c in
80–90% yields.18 This high yield condensation using
The 1H NMR, 13C NMR, FAB-MS spectra of 7–9 are
consistent with the proposed structures, in which there are
two biladiene-a,c units, linked by one, two or three carbon
bridges at their b,b0-positions. All these macrocycles have
limited solubility in dichloromethane, chloroform, acetone,
methanol, acetonitrile, acetic acid, pyridine, dimethyl
Keywords: cyclooctapyrrole; cyclopolypyrroles; biladiene-ac;
dipyrromethene; macrocycle.
*
Corresponding author. Tel.: þ1-604-822-4571; fax: þ1-604-822-9678;
e-mail: ddolphin@qltinc.com
0040–4020/03/$ - see front matter q 2003 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(02)01592-2

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Q. Chen, D. Dolphin / Tetrahedron 59 (2003) 871–875
these macrocycles (7–9) to their fully conjugated systems
using common oxidizing agents such as DDQ, Br2,
Pb(OAc)4, etc have so far failed in our hands.
Compounds 7–9 form binuclear complexes with Zn(II) in
high yield from the reaction with Zn(OAc)2.
3. Discussion
Although X-ray structures of 7–9 are not available, results
from molecular modeling19 showed that, unlike octapyrrin
1a, which adopted a ‘figure-eight’ conformation, they tend
to adopt a chair conformation (Fig. 1), while the zinc(II)
complexes adopt square-shaped conformations (Fig. 2).
These conformations presumably result from the greater
flexibility of 7–9 compared to 1a. Like biladienes the
dipyrrin units in our cyclooctapyrroles are flat and fully
conjugated and the optical spectra of compounds 7–10 are
very similar to those of biladienes-a,c. However, unlike
biladienes, where the pyrrolic rings in the dipyrromethene
units adopt a Z-conformation, an E-conformation is seen in
the cyclooctapyrroles. Modeling also suggests that the flat
formamide or dimethyl sulfoxide. They are, however,
soluble in TFA. Combustion analysis confirms that they
are tetracationic hydrobromide salts. Based on the 1H NMR
and UV–Vis spectra, macrocycles 7–9 showed, as
expected, no macrocyclic aromaticity. Attempts to oxidize
Figure 1. Lowest energy conformation of 7, obtained using Hyperchem
(Release 5.01).17 For clarity, all H atoms have been omitted, top view
(upper), and edge view (lower).

Q. Chen, D. Dolphin / Tetrahedron 59 (2003) 871–875
873
Figure 2. Lowest energy conformation of 7 complexed with Zn (II) obtained using Hyperchem (Release 5.01).17 For clarity, all H atoms have been omitted, top
view (upper), and edge view (lower).
‘aromatic’ systems are conformationally unstable and that
the peripheral alkyl groups play an important role in
by the departmental microanalytical laboratory. UV–Vis
spectra were recorded on an HP8452A photo diode array
spectrophotometer (instrumental precision^2 nm).
forming the twisted conformations. Upon metal [Zn2þ
]
binding the binuclear complexes exhibit dramatic confor-
mational changes where the biladiene units adopt a
‘porphyrin-like’ geometry. However, the two sets of four
pyrrolic rings are not coplanar, rather they adopt a helical
conformation.
The carboxylic acids 2–5 readily decarboxylate and
satisfactory combustion analyses were not obtained. The
macrocyclic zinc complex all showed very low solubility
and gave NMR spectra that were too broad to be of use.
Starting materials, 1,2-bis(5-benzoxycarbonyl-2,4-
dimethylpyrrole-3-yl)ethane, 1,3-bis(5-benzoxycarbonyl-
2,4-dimethylpyrrole-3-yl)propane and 1,4-bis(5-benzoxy-
carbonyl-2,4-dimethylpyrrole-3-yl)butane were prepared
according to literature procedures.20
4. Conclusion
It is clear from recent studies4,18 that [2þ2þ2þ2]
MacDonald type condensations can occur, under appro-
priate conditions, in preference to the more common [2þ2]
reactions. Unlike the fully conjugated octaphyrin (1a) the
macrocycles described here cannot be fully oxidized and
show no macrocyclic aromaticity. To a large extent this
reflects the inherent stability of the dipyrromethene units
themselves.
5.1.1. 5,50-Bisbenzoxycarbonyl-2,20,4,40-tetramethyl-3,30-
dipyrromethane. Paraformaldehyde (2.6 g, 86.7 mmol,
2.0 mol equiv.) was suspended in glacial acetic acid
(100 mL) containing conc. hydrochloric acid (33%, 5 mL).
The mixture was stirred with heating until the solid had
dissolved. After cooling to room temperature, 2-benzoxy-
carbonyl-3,5-dimethylpyrrole (9.9 g, 43.3 mmol) was
added. The mixture was allowed to stir at 408C for 3 h.
After removal of solvent, the residue was crystallized from
methanol. The product was obtained as white crystals
(9.10 g, 90%). Mp 282–2848C. 1H NMR (200 MHz,
DMSO-d6) d: 1.95 (s, 6H, 2 CH3), 2.05 (s, 6H, 2CH3),
3.25 (s, 2H, CH2), 5.25 (s, 4H, 2CH2), 7.25 (m, 10H, 2 Ph),
11.05 (s, 2H, 2NH) ppm. 13C NMR (50 MHz, DMSO-d6) d:
10.7 (CH3), 12.0 (CH3), 19.5 (CH2), 64.3 (OCH2) 115.4,
119.4, 126.7, 127.8, 128.5, 131.0, 137.1, 160.6 (COO) ppm.
Anal. calcd for C19H26N2O4: C 65.87; H 7.56; N 8.09;
found: C 65.45; H 7.51; N 7.58.
5. Experimental
5.1. General
All reagents and solvents were purchased and used as
received. Melting points were determined on a Thomas hot
stage or Buchi apparatus and are uncorrected. H and 13C
NMR spectra were recorded on a Bruker AC-200 or AMX-
300 instrument. The high and low-resolution mass spectra
were obtained by the departmental mass spectrometry
service laboratory. Combustion analyses were performed
1

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Q. Chen, D. Dolphin / Tetrahedron 59 (2003) 871–875
5.1.2. 1,1-Bis(5-carboxy-2,4-dimethylpyrrole-3-
yl)methane (2). 1,2-Bis(5-benzoxycarbonyl-2,4-dimethyl-
pyrrole-3-yl)methane (9.0 g, 19 mmol) was dissolved in
tetrahydofuran (150 mL). Palladium on carbon (10%, 0.1 g)
and a drop of triethylamine was then added. The mixture
was stirred for 20 h under a hydrogen atmosphere at room
temperature. The catalyst was removed by suction filtration.
After removal of solvent, the residue was dried under
vacuum. The product was obtained as a white powder
(5.40 g, 99%), which was used directly for the next step
synthesis without further purification. Mp 2208C (dec.). IR
(KBr), n¼3309, 3072, 2920, 1678, 1579, 1466, 1375, 1251,
(48% in acetic acid, 2 mL) were added. The red mixture was
left to stir overnight at room temperature. Anhydrous ether
(100 mL) was added. The suspension was allowed to stir for
another 30 min. The red solid was collected by suction
filtration and washed with anhydrous ether containing a few
drops of HBr (48% in glacial acetic acid). The crude product
was suspended in methanol (50 mL) containing a few drops
of HBr (48% in glacial acetic acid) and stirred at room
temperature for a period of 30 min. The solid was collected
by filtration to afford the product (800 mg, 95%). An
analytic sample was obtained by repeating the following
procedure three times: the crude product was dissolved in a
minimum amount of trifluoroacetic acid, then dichloro-
methane (1 mL), methanol (1 mL) and a few drops of HBr
(48% in glacial acetic acid) were added, followed by
anhydrous ether to precipitate the product. The red solid was
collected by centrifugation and dried in vacuo. Mp 2958C
(dec.). IR (KBr), n¼3460, 2933, 2854, 1610, 1512, 1452,
1377, 1236, 1168, 1097, 1051, 964, 914, 846, 681 cm21. 1H
NMR (200 MHz, CDCl3þ10% TFA-D, v/v), d: 0.75 (t,
J¼7.3 Hz, 6H, 2CH3), 1.10 (s, 6H, 2CH3), 2.20 (s, 24H,
8CH3), 2.30 (m, 8H, 4CH2), 2.55 (s, 12H, 4CH3), 3.75 (s,
4H, 2CH2 at b,b-position), 4.40 (s, 4H, 2CH2 at a,a-
position), 7.20 (s, 4H, 4-CHv), 9.25 (s, 1H, NH), 10.60
(brs, 1H, NH), 12.80–13.30 (m, 6H, 6 NH) ppm. 13C NMR
(CDCl3þ10% TFA-D, v/v, 75 MHz), d: 10.0, 13.8, 14.3,
14.5, 17.3, 19.4, 23.1, 120.9, 121.4, 126.9, 127.4, 131.1,
145.5, 147.2, 155.0, 156.3 ppm. UV–Vis (CHCl3þ1% of
TFA), lmax(1)¼370 (29800), 455 (111600), 490 (105900),
538 (79300) nm. MS: LRPþLSIMS (matrix: thioglycerol):
m/e¼905 (Mþþ1). HRMS (LSIMS, matrix: thioglycerolþ
CHCl3), found: 904.58818, [C60H72N8] requires:
904.58799. Anal. calcd for C60H72N8·4HBr: C 58.63; H
6.18; N 9.12; found: C 59.09; H 6.38; N 8.97.
1199, 1153, 1124, 1085, 982, 900, 767, 727, 642, 561 cm21
.
1H NMR (200 MHz, DMSO-d6) d: 1.90 (s, 6H, 2CH3), 2.10
(s, 6H, 2CH3), 3.20 (s, 2H, CH2), 10.95 (s, 2H, 2NH) ppm.
13C NMR (50 MHz, DMSO-d6) d: 11.2 (CH3), 11.3 (CH3),
19.5 (CH2), 121.3, 127.7, 130.3, 136.4, 161.5 (COOH) ppm.
5.1.3. 1,2-Bis(5-carboxy-2,4-dimethylpyrrole-3-yl)-
ethane (3). Prepared following the procedure for compound
2 using 1,2-bis(5-benzoxycarbonyl-2,4-dimethylpyrrole-3-
yl)ethane as starting material. Yield 99%. Mp 2338C (dec.).
IR (KBr), n¼3408, 2924, 2862, 1655, 1579, 1498, 1466,
1375, 1259, 1186, 1095, 1002, 903, 775, 752, 561 cm21. 1H
NMR (200 MHz, DMSO-d6) d: 1.90 (s, 6H, 2 CH3), 2.10 (s,
6H, 2CH3), 2.30 (s, 4H, 2CH2), 10.90 (s, 2H, 2NH) ppm.
13C NMR (50 MHz, DMSO-d6) d: 10.2 (CH3), 10.6 (CH3),
24.0 (CH2), 116.2, 120.3, 125.6, 130.0, 162.5 (COO) ppm.
5.1.4. 1,3-Bis(5-carboxy-2,4-dimethylpyrrole-3-yl)pro-
pane (4). Prepared following the procedure for compound
2 using 1,3-bis(5-benzoxycarbonyl-2,4-dimethylpyrrole-3-
yl)propane20 as starting material. Yield 98%. Mp 2308C
(dec.). IR (KBr), n¼3257, 2928, 2856, 1655, 1500, 1466,
1375, 1263, 1170, 1109, 1065, 962, 779, 729, 540 cm21. 1H
NMR (200 MHz, DMSO-d6) d: 1.45 (t, J¼7.3 Hz, 2H,
CH2), 2.05 (s, 6H, 2 CH3), 2.10 (s, 6H, 2CH3), 2.30 (t,
J¼7.3 Hz, 4H, 2CH2), 10.90 (s, 2H, 2NH) ppm. 13C NMR
(50 MHz, DMSO-d6) d: 10.1 (CH3), 10.4 (CH3), 22.1
(CH2), 24.1 (CH2), 117.2, 122.3, 130.6, 137.0, 161.3
(COO) ppm.
5.1.7. Preparation of 7·Zn2. The ligand (,100 mg) was
dissolved in trifluoroacetic acid (5 mL) and dichloro-
methane (50 mL) was then added. To this mixture, a
solution of zinc acetate (,20 mg) in methanol (20 mL) was
added at once, followed by triethylamine (5 mL). The red
mixture was allowed to stir for 2 h at room temperature. The
solvent was removed under vacuum and the residue was
stirred with methanol (20 mL) for 2 h. The red dark solid
was collected and further purified by repeating this
procedure three times. IR (KBr), n¼3441, 2960, 2925,
2868, 1597, 1438, 1396, 1225, 1167, 1107, 972, 922, 856,
783, 733, 663 cm21. UV–Vis (CHCl3), lmax(1)¼360
(16800), 485 (68600), 545 (42600) nm. MS: LRPþLSIMS
(thioglycerol): m/e¼1033 (Mþþ1), C60H68N8Zn2 requires
1032. HRMS. (ESI) found: 1031.4163, [C60H68N8Zn2]
requires 1031.4197. Anal. calcd for C60H68N8Zn2: C
69.83; H 6.64; N 10.86; found: C 69.50; H 6.85; N 10.44.
5.1.5. 1,3-Bis(5-carboxy-2,4-dimethylpyrrole-3-yl)bu-
tane (5). Prepared following the procedure for compound
2 using 1,4-bis(5-benzoxycarbonyl-2,4-dimethylpyrrole-3-
yl)butane20 as starting material. Yield 98%. Mp 2458C
(dec.). IR (KBr), n¼3275, 2926, 2856, 1657, 1500, 1460,
1
1375, 1261, 1159, 1094, 1008, 893, 773 cm21. H NMR
(200 MHz, DMSO-d6) d: 1.20 (t, J¼7.3 Hz, 4H, 2CH2),
2.05 (s, 6H, 2CH3), 2.10 (s, 6H, 2CH3), 2.30 (t, J¼7.3 Hz,
4H, 2CH2), 10.90 (s, 2H, 2NH, 2COOH) ppm. 13C NMR
(50 MHz, DMSO-d6) d: 10.1 (CH3), 10.4 (CH3), 22.1
(CH2), 24.1 (CH2), 117.2, 122.3, 130.6, 137.0, 161.3
(COO) ppm.
5.1.8. Macrocycle 8·4HBr. Prepared according to the
procedure for compound 7. Yield 90%. Mp 3008C (dec.).
IR (KBr), n¼3441, 2921, 2853, 1612, 1512, 1453, 1378,
1261, 1168, 1050, 960, 915, 825, 678, 508 cm21. 1H NMR
(200 MHz, CDCl3þ10%TFA-d, v/v), d: 1.05 (t, J¼7.3 Hz,
12H, 4CH3), 2.00–2.80 (m, 52H, 12CH3, 8CH2), 4.40 (s,
4H, 2CH2), 7.20 (m, obscured by CHCl3 signal, 4-CHv),
11.60 (brs, obscured by TFA signal, NH) ppm. 13C NMR
(CDCl3þ10% TFA-d, v/v, 50 MHz), d: 9.8, 12.5, 14.4, 17.2,
17.3, 23.3, 23.7, 120.8, 121.3, 126.8, 127.7, 130.9, 144.0,
5.1.6. Macrocycle 7·4HBr. 1,2-Bis(5-carboxy-2,4-
dimethylpyrrole-3-yl)methane (2, 400 mg, 1.38 mmol) was
suspended in trifluoroacetic acid (10 mL), and stirred at
408C until all the solid had dissolved. The mixture was
cooled to 0room temperature and 5,50-diformyl-4,40-
dimethyl-3,3 -diethyl-dipyrromethane
(6,
394 mg,
1.38 mmol, 1.0 mol equiv.) and a mixture of dichloro-
methane (20 mL), methanol (20 mL) and hydrogen bromide

Q. Chen, D. Dolphin / Tetrahedron 59 (2003) 871–875
875
145.2, 155.6, 159.6 ppm. UV–Vis (CHCl3), lmax(1)¼372
Acknowledgements
(27500), 456 (171000), 494 (82600), 525 (68800) nm. MS:
LRPþLSIMS (thioglycerol): m/e¼933 (Mþþ1). HRMS
(LSIMS, matrix: thioglycerolþCHCl3), found: 933.62752,
[C62H77N8] requires 933.62712. Anal. calcd for
C62H77N8·4HBr: C 59.24; H 6.41; N 8.91; found: C 59.74;
H 6.57, N 8.67.
This work was supported by the Natural Sciences and
Engineering Council of Canada.
References
5.1.9. Compound 8·Zn2. Prepared following the procedure
for compound 7·Zn2. IR (KBr), n¼3440, 2958, 2930, 2871,
1561, 1439, 1396, 1224, 1677, 1108, 972, 923, 865, 783,
732, 662 cm21. UV–Vis (CHCl3), lmax(1)¼365 (17900),
488 (78600), 546 (39800) nm. MS (FAB): m/e¼1061
(Mþþ1), C62H72N8Zn2 requires 1060. HRMS (ESI)
found: 1059.4501, [C60H68N8Zn2] requires 1059.4510.
Anal. calcd for C: C 70.25; H 6.85; N 10.57: found: C
69.92; H 6.51; N 10.43.
1. Jasat, A.; Dolphin, D. Chem. Rev. 1997, 97, 2267.
2. Sessler, J. L.; Weghorn, S. T. Expanded, Contracted &
Isomeric Porphyrins; Pergmon: New York, 1997.
3. (a) Neves, M. G. P. M. S.; Martin, R. M.; Tome, A. C.;
Silvestre, A. J. D.; Silva, A. M. S.; Felix, V.; Drew, M. G. B.;
Cavaleiro, J. A. S. Chem. Commun. 1999, 385. (b) Bruckner,
C.; Sternberg, E. D.; Boyle, R. W.; Dolphin, D. Chem.
Commun. 1997, 1689. (c) Narayanan, S. J.; Sridevi, B.;
Chandrashekar, T. K.; Vij, A.; Roy, R. Angew. Chem. Int. Ed.
Engl. 1998, 37, 3394.
5.1.10. Macrocycle 9·4HBr. Prepared following the
procedure for compound 7. Yield 90%. Mp 2858C (dec.).
IR (KBr), n¼3400, 2930, 2872, 1610, 1566, 1510, 1444,
1390, 1238, 1163, 1097, 1061, 953, 922, 899, 685 cm21. 1H
NMR (200 MHz, CDCl3þ10%TFA-d, v/v), d: 1.05 (t,
J¼7.3 Hz, 12H, 4CH3), 2.65 (brs, 4H, 2CH2), 2.20–2.80
(m, 52H, 12CH3, 8CH2), 4.40 (s, 4H, 2CH2), 7.20 (s,
obscured by CHCl3 signal, 4-CHv), 11.00 (brs, obscured
by TFA signal, NH) ppm. 13C NMR (CDCl3þ10% TFA,
75 MHz), d: 10.0, 13.1, 14.6, 17.4, 22.8, 23.8, 24.4, 30.3,
120.4, 126.6, 127.8, 130.2, 130.2, 143.0, 145.2, 145.3,
157.2 ppm. UV–Vis (CHCl3), lmax(1)¼375 (29000), 454
(186000), 525 (88600) nm. MS: LRPþLSIMS (matrix:
thioglycerol): m/e¼961 (Mþþ1). HRMS (LSIMS, matrix:
thioglycerolþCHCl3); found: 961.65689, [C64H81N8]
requires 961.65842. Anal. calcd for C64H80N8·4HBr·4H2O:
C 56.64; H 6.78 N 8.25; found: C 56.89; H 6.67; N 8.37.
4. (a) Vogel, E.; Broring, M.; Fink, J.; Rosen, D.; Schmickler, H.;
Lex, J.; Chan, K. W. K.; Wu, Y.-D.; Plattner, D. A.; Nendel,
M.; Houk, K. N. Angew. Chem. Int. Ed. Engl. 1995, 34, 2511.
(b) Broring, M.; Jendrny, J.; Zander, L.; Schmickler, H.; Lex,
J.; Wu, Y. D.; Nendel, M.; Chen, J. G.; Plattner, D. A.; Houk,
K. N.; Vogel, E. Angew. Chem. Int. Ed. 1995, 34, 2515.
5. Lash, T. D. Angew. Chem. Int. Ed. Engl. 2000, 39, 1763.
6. Sessler, J. L.; Weghorn, S. J.; Lynch, V.; Johnson, M. R.
Angew. Chem. Int. Ed. Engl. 1994, 33, 1509.
7. Sternberg, E.; Dolphin, D.; Bruckner, C. Tetrahedron 1998,
54, 4151.
8. Turn, B.; Botoshansky, M.; Eichen, Y. Angew. Chem. Int. Ed.
Engl. 1998, 37, 2475.
9. Sessler, J. L.; Seidel, D.; Lynch, V. J. Am. Chem. Soc. 1999,
121, 11257.
10. Werner, A.; Michels, M.; Zander, L.; Lex, J.; Vogel, E. Angew.
Chem. Int. Ed. Engl. 1999, 38, 3650.
5.1.11. Compound 9·Zn2. Prepared following the pro-
cedure for compound 7·Zn2. IR (KBr), n¼3440, 2926, 2864,
1597, 1439, 1396, 1230, 1164, 1107, 956, 931, 887, 781,
733, 669 cm21. UV–Vis (CHCl3), lmax(1)¼370 (18900),
475 (81200), 539 (40200) nm. MS (ESI) m/e¼1089
(Mþþ1), [C64H76N8Zn2] requires 1088. HRMS (ESI)
found: 1085.4841, [C64H76N8Zn2] requires: 1085.4854.
Anal. calcd for C64H76N8Zn2: C 70.64; H 7.04; N 10.30,
found: C 70.20; H 6.85; N 9.90.
11. Gerasimchuk, N. N.; Gerges, A.; Clifford, T.; Danby, A.;
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16. (a) Bucher, C.; Seidel, D.; Lynch, V.; Sessler, J. L. Chem.
Commun. 2002, 328. (b) Seidel, D.; Lynch, V.; Sessler, J. L.
Angew. Chem. Int. Ed. Engl. 2002, 41, 1422. (c) Sessler, D.;
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5.1.12. Macrocycle 10·2HBr. Prepared following the
procedure for compound 7. Yield 72%. Mp 2468C (dec.).
IR (KBr), n¼3440, 2930, 2869, 1610, 1568, 1510, 1443,
1389, 1238, 1164, 1097, 1074, 960, 922, 685, 663 cm21. 1H
NMR (200 MHz, CDCl3þ10% TFA-d), d: 1.05 (t,
J¼7.3 Hz, 6H, 2CH3), 1.54 (brs, 4H, 2CH2), 2.25 (s, 12H,
4CH3), 2.40–2.80 (m, 14H, 4CH2, 2CH3), 4.20 (s, 2H,
CH2), 7.24 (s, obscured by CHCl3 signal, –CHv), 11.05
(brs, obscured by TFA signal, NH) ppm. UV–Vis (CDCl3),
17. (a) Setsune, J.; Maeda, S. J. Am. Chem. Soc. 2000, 122, 12405.
(b) Arumugan, N.; Jang, Y. S.; Lee, C. H. Org. Lett. 2000, 2,
3115. (c) Nagarajan, A.; Ka, J. W.; Lee, C. H. Tetrahedron
2001, 57, 7323.
lmax(1)¼375 (12500), 455 (58600), 535 (82000) nm. MS:
LRPþLSIMS (matrix: thioglycerol): m/e¼495 (Mþþ1).
HRMS (ESI) found: 495.3483, [C33H42N4] requires:
495.3488. Anal. calcd for C33H42N4·2HBr·H2O: C 58.76;
H 6.87; N 8.31%; found: C 58.54; H 6.39, N 7.90.
18. Chen, Q.; Dolphin, D. Can. J. Chem. In press.
19. Hyperchem Release 5.01, MMþ force field optimized by
Polak-Ribiere.
20. Paine, J. B.; Dolphin, D. Can. J. Chem. 1978, 56, 1710.