Novel redox-active cyclophanes based on 3,3′-biindolizines: Synthesis and chirality

Article abstract of DOI:10.1021/jo951419o

The first compounds of a new series of redox-active cyclophanes were prepared by dehydrocyclization of bridged indolizines of type 1. The bridged dipyridino-compounds 2a and 2b obtained by reaction of 2 mol of lithiated α-picolines with dihalides were used as starting materials. Subsequent treatment of 2a,b with 2 mol of α-bromo ketones gave quaternary pyridinium halides. Ring closure in an alkaline medium (Chichibabin reaction) yielded the starting material for the synthesis of the macrocycles. Oxidative C-C coupling gave the diastereomeric cyclophanes of type 3. In all cases one pair of the enantiomers was obtained in excess. CV-investigations have shown that the main products are reversible redox systems. To clarify their conformations, compounds 3c , 3d/1, and 3d/2 were subjected to X-ray analysis.

Full text of DOI:10.1021/jo951419o

710
J . Org. Chem. 1996, 61, 710-714
Novel Red ox-Active Cyclop h a n es Ba sed on 3,3′-Biin d olizin es:
Syn th esis a n d Ch ir a lity
Helmut Sonnenschein,*,† Thomas Kreher,† Egon Gru¨ndemann,‡ Ralph-Peter Kru¨ger,‡
Annamarie Kunath,‡ and Volker Zabel‡
Institut fu¨r Angewandte Chemie BerlinsAdlershof, Abteilung Organische Synthese and Abteilung
Analytik, Rudower Chaussee 5, D-12484 Berlin, Germany
Received August 1, 1995X
The first compounds of a new series of redox-active cyclophanes were prepared by dehydrocyclization
of bridged indolizines of type 1. The bridged dipyridino-compounds 2a and 2b obtained by reaction
of 2 mol of lithiated R-picolines with dihalides were used as starting materials. Subsequent
treatment of 2a ,b with 2 mol of R-bromo ketones gave quaternary pyridinium halides. Ring closure
in an alkaline medium (Chichibabin reaction) yielded the starting material for the synthesis of the
macrocycles. Oxidative C-C coupling gave the diastereomeric cyclophanes of type 3. In all cases
one pair of the enantiomers was obtained in excess. CV-investigations have shown that the main
products are reversible redox systems. To clarify their conformations, compounds 3c , 3d /1, and
3d /2 were subjected to X-ray analysis.
In tr od u ction
Electroactive host or guest compounds are key com-
ponents for the formation of electrochemically control-
lable, self-assembled structures. For example, the syn-
thesis of switchable molecular shuttles based on a redox-
active guest were reported by A. E. Kaifer.1 We are
interested in the synthesis of switchable macrocyclic host
compounds using biindolizines as the electroactive unit.
As part of a study directed toward synthesis of such
cyclophanes, we recently reported the preparation of a
bridged indolizine of type 1.2 Upon oxidation, indolizines
easily undergo dimerization by C-C-bond formation at
their 3-positions.3 On oxidation of compound 1 (spacer
) 1,4-C6H4; R1 ) CH3), we observed mixtures of dehydro-
dimers and -trimers and higher dehydro-oligomers.4 The
tendency toward formation of higher oligomers is prob-
ably due to the rigid spacer group. Use of more flexible
spacer groups of sufficient lengths would possibly sup-
press oligomerization and favor intramolecular formation
of a monomer of the ansa-type 3.
F igu r e 1. Bridged indolizines.
ibabin5 yields the bridged indolizines 1a -d . Modeling
(Hyperchem) suggested that the spacers have sufficient
lengths to favor an intramolecular reaction.
In fact, subsequent treatment of 1a -d with potassium
hexacyanoferrate proceeds smoothly with intramolecular
oxidative coupling to give the desired products 3a -d
(Figure 3).
The new bond between the two indolizines in 3 displays
axial chirality due to hindered rotation around this bond.
Additionally, both indolizine-subunits in 3 define planes
of chirality due to the ansa character of the molecule.
Thus, the question arises, to what degree is the
geometry of the two indolizines fixed in 3? Provided that
free rotation around the central bond is sufficiently
hindered, compounds 3a -d should contain three inde-
pendent elements of chirality (one axis, two planes); so
we looked first for axial chirality of unbridged 3,3′-
biindolizines. It was in fact possible to resolve 3,3′-bi-
(1,2-diphenylindolizine) and 3,3′-bi(2-methyl-1-phenyl-
indolizine) by means of chiral HPLC. This observation
was surprising in the case of the latter compound, which
bears only methyl groups near the axis of chirality.
Optical activity was retained even after 1 h heating in
boiling xylene.
Three elements of chirality could give rise to four
diastereomers. In the case of the bridged compound 3,
this number is reduced to three due to the equivalency
of two of them. Crude cyclophane 3d could be separated
by flash chromatography to give two crystalline diaster-
eomers. Both pairs of enantiomers were characterized
by X-ray analysis (structures 3d /1 and 3d /2). Compound
It appeared necessary to work out a new synthesis
which would allow preparation of biindolizines with
broad variation of the spacer group. We wish to report
here on the synthesis and dehydrocyclizations of bridged
indolizines linked by dodecamethylene and by 3,6,9-
trioxaundecamethylene groups.
Resu lts a n d Discu ssion
The bridged indolizines 1 were prepared in the follow-
ing way: 2 mol of lithiated R-picoline was reacted with
1,12-dibromododecane or bis[2-(2-chloroethoxy)ethyl] ether
to give the bis-pyridines 2a and 2b, respectively (Figure
2). Subsequent reaction of the crude 2a or 2b with either
bromoacetone or ω-bromoacetophenone according to Chich-
† Abteilung Organische Synthese.
‡ Abteilung Analytik.
X Abstract published in Advance ACS Abstracts, December 15, 1995.
(1) Co´rdova, E.; Bissell, R. A.; Kaifer, A. E. J . Org. Chem. 1995, 60,
1033.
(2) Hu¨nig, S.; Sonnenschein, H. J . Prakt. Chem. 1994, 336, 38.
(3) Hu¨nig, S.; Linhart, F. Liebigs Ann. Chem. 1976, 317.
(4) Kreher, T.; Sonnenschein, H.; Schmidt, L.; Hu¨nig, S. Liebigs Ann.
Chem. 1994, 1173.
(5) Chichibabin, A. E. Chem. Ber. 1927, 60, 1607.
(6) Cardellini, L; Carloni, P.; Greci, L.; Tosi, G.; Andruzzi, R.;
Marrosu, G.; Trazza, A. J . Chem. Soc., Perkin Trans. 2 1990, 2117.
0022-3263/96/1961-0710$12.00/0 © 1996 American Chemical Society

Novel Redox-Active Cyclophanes
J . Org. Chem., Vol. 61, No. 2, 1996 711
F igu r e 2. Synthesis of bridged indolizines.
The different geometry of the diastereomers is impor-
tant for the redox behavior of the ansa-compounds. We
expected that the oxidative formation of a central double
bond, which would orient both indolizine systems into a
common plane, should be possible only in the E-form. The
angle between the two indolizines is 62° in 3d /1 according
to X-ray analysis and thus corresponds to the calculated
angle of simple, unbridged 3,3′-biindolizines. Cyclic
voltammetry revealed 3d /1 to be a stable and reversible
redox system similar to unbridged biindolizines.2,4,6 The
torsion angle between the two indolizines in 3d /2 is 108°
in the crystal. Formation of the E-isomer is impossible
because of the location of the bridge in 3d /2. In fact,
there is a quite different redox system found by cyclic
voltammetry (Figure 5). This suggests that simple,
unbridged oxidized 3,3′-biindolizines should exist also in
the E-form only.
In all cases, mass spectroscopy revealed that a inter-
molecular dehydrocyclization involving two molecules of
1a -d takes place as a side reaction. Repeated flash
chromatography of crude cyclized 1a and 1c leads to
isolation of the dehydro-dimers 4a and 4b (Figure 6).
Detection of diastereomers of 4a and 4b has been
unsuccessful so far due to low solubility.
F igu r e 3. Synthesis of cyclophanes by intramolecular dehy-
drocyclization.
3d /1 is favored by a factor of 5:1. The bridge is positioned
between the two phenyl groups in 3d /1, while it is
positioned between the phenyl group and the indolizine
group of the second part of the molecule in the diaste-
reomer 3d /2.
Con clu sion
The synthesis of new electroactive cyclophanes by
intramolecular C-C coupling of bridged indolizines was
successful. The cyclization of 1a -d leads to mixtures of
diastereomeric macrocycles. One pair of the enantiomers
was obtained in excess. We have demonstrated that the
main products of the reactions are reversible redox
systems. It was shown by X-ray analysis of 3d /1 that
the indolizine-indolizine bond and the oxygen O15 in the
middle of the polyether bridge are separated by only 4.8
Å. It seems that for inclusion complexation of organic
guests, cyclophanes with longer spacers are necessary.
Therefore, we are involved in the synthesis of indolizines
bridged by chains with more than 12 atoms. Subsequent
cyclization of these compounds should lead to interesting
host compounds.
Further evidence for the geometry of these compounds
has been obtained by NMR-spectroscopy. In contrast to
the situation of the main product 3d /1, the two indolizine
systems in 3d /2 differ in their spacial relation to the
spacer bridge of the cyclophane system. On the central
C-C-bond, also, a half-rotation is impossible. Therefore
the indolizine systems in 3d /2 are not equivalent. Due
to this, 3d /2 shows twice as many signals in the 13C-NMR
as does 3d /1. The enantiomers of the cyclophanes 3d /1
and 3d /2 were separated by HPLC using Chiralcel OD
columns. The CD spectra of the M and P enantiomers
of 3d /1 and 3d /2 are shown in Figure 4. The spectra
confirm the existence of enantiomers of the same chiral
molecule. The third possible diastereomer 3d /3 was
detected only by HPLC and shows a similar UV-spectrum
in comparison to 3d /1.
Exp er im en ta l Section
According to preliminary experiments, an analogous
situation can be expected for 3a -c. Each of them could
be separated into enantiomers on a chiral column.
Compound 3c, the main product of cyclization of 1c, was
also subjected to X-ray analysis. It was shown that the
geometry of 3c corresponds to that of 3d /1. Only one
diastereomer could be found upon cyclization of 1a .
Gen er a l. Experimental data were collected as described in
references 2 and 4. The working electrode in the CV experi-
ments was a Pt electrode tip, and a glassy carbon electrode
was used as auxiliary electrode. The reference electrode was
a silver electrode immersed in a 3 M AgCl solution. The
experiments were run at room temperature under a dry argon

712 J . Org. Chem., Vol. 61, No. 2, 1996
Sonnenschein et al.
F igu r e 4. UV and CD spectra of (-)- and (+)-isomers of componds 3d /1 and 3d /2.
atmosphere. All voltammograms were recorded in CH2Cl2
containing 0.01 M TBAPF6. Melting points are uncorrected.
Separation of enantiomers was performed on HPLC with
Chiralcel OD.
Syn th eses of th e Br id ged In d olizin es 1a -d . Gen er a l
P r oced u r e. A mixture of the crude bridged pyridines (ca. 40
mmol) and some crystals of KI in acetone (100 mL) was
refluxed under stirring and an acetone (50 mL) solution of the
bromo ketone (50 mmol) was added slowly (2 h). The mixture
was refluxed for an additional 4 h. After removing the solvent
at a rotary evaporator, the pyridinium bromide was obtained
as a semisolid compound. The crude bromide was suspended
in 150 mL water containing NaHCO3 (13 g, 155 mmol) and
refluxed under stirring for 2 h. The reaction mixture was
cooled and extracted with toluene (3 × 30 mL). The organic
layer was washed with water (3 × 10 mL), dried over MgSO4,
and concentrated under reduced pressure. The oily residue
was purified by flash chromatography on silica gel with toluene
(1c) or hexane/EtOAc 1:1 (1a , 1b, 1d ) as eluents.
Syn th eses of th e Br id ged P yr id in es 2a a n d 2b. Gen -
er a l P r oced u r e. To an ice-cooled solution of R-picoline (5 mL,
50.6 mmol) in 50 mL of THF was added n-BuLi (32 mL, 51.2
mmol, 1.6 M in hexane). Lithiation was completed after 60
min at the same temperature, and 25 mmol of dihalide in 40
mL of THF was quickly added. The reaction mixture was
stirred for an additional 4 h and then quenched by addition of
water, washed (3 × 10 mL) with water, and dried over MgSO4.
After the solvent was evaporated, the crude residue was pure
enough for further operations. A part of the product was
purified by flash chromatography on silica gel (eluted with
hexane:ethylacetate 1:1) or by recrystallization (diethylether:
hexane:pentane 1:1:1).
1,12-Bis(2-m eth ylin d olizin -1-yl)d od eca n e (1a ): yield
1
18%, brown oil; H NMR δ 1.24 (m, 16 H), 1.53 (quintet, J )
7.5 Hz, 4 H), 2.24 (s, 6 H), 2.66 (t, J ) 7.5 Hz, 4 H), 6.29 (m,
2 H), 6.52 (m, 2 H), 7.02 (s, 2 H), 7.20 (d, J ) 8.3 Hz, 2 H),
7.73 (d, J ) 6.9 Hz, 2 H); 13C NMR δ 10.6, 23.9, 29.6, 29.6,
29.6, 29.6, 31.4, 108.9, 110.3, 112.4, 115.0, 116.8, 123.2, 124.5,
130.0; MS (FAB) m/ e 429 (M + H+, 20%), 144 (100%) for
C30H40N2 (428).
1,14-Bis(p yr id -2-yl)tetr a d eca n e (2a ): yield ca. 80%, mp
47-50 °C, colorless needles (ether, pentane, hexane 1:1:1);
1H NMR δ 1.29 (m, 20H), 1.72 (quintet, J ) 7.8 Hz, 4H), 2.79
(t, J ) 7.8 Hz, 4H), 7.10 (m, 4H), 7.57 (td, J ) 7.7 Hz, J ) 1.8
Hz, 2H), 8.52 (d, J ) 4.8 Hz, 2H); 13C NMR δ 29.39 (t), 29.47
(t), 29.53(t), 29.6 (t), 29.6 (t), 29.9 (t), 38.5 (t), 120.8 (d), 122.6
(d), 136.2 (d), 149.2 (d), 162.6 (s); MS (FAB) m/e 353 (M + H+,
100%), 260 (7%). Anal. Calcd for C24H36N2 (352.56): C, 81.76;
H, 10.29; N 7.95 . Found: C, 81.51; H, 10.42; N 7.55.
1,13-Bis(p yr id -2-yl)-4,7,10-tr ioxa tr id eca n e (2b): yield
1,11-B is (2-m e t h y lin d o lizin -1-y l)-3,6,9-t r io x a u n d e -
ca n e (1b): yield 27%, orange oil; 1H NMR δ 2.25 (s, 6 H),
3.01 (t, J ) 7.7 Hz, 4 H), 3.56 (t, J ) 7.7 Hz, 4H), 3.64 (m, 8
H), 6.31 (td, J ) 6.8 Hz, J ) 1.3 Hz, 2 H), 6.53 (ddd, J ) 9.0
Hz, J ) 6.5 Hz, J ) 1.1 Hz, 2 H), 7.05 (s, 2 H), 7.25 (d, J ) 8.7
Hz, 2 H), 7.73 (dt, J ) 7.0 Hz, J ) 1.1 Hz, 2 H); 13C NMR δ
10.6 (q), 24.7 (t), 70.2 (t), 70,7 (t), 71.9 (t), 107.6 (s), 109.2 (d),
110.5 (d), 115.6 (d), 116.6 (d), 123.6 (s), 124.5 (d), 130.6 (s);
MS (MALDI) m/ e 421 ((M + H)+, 100%) for C26H32N2O3 (420).
1,12-Bis(2-p h en ylin d olizin -1-yl)d od eca n e (1c): yield
1
ca. 80%, yellow oil; H NMR δ 2.03 (m, 4H), 2.85 (t, J ) 7.6
Hz, 4H), 3.50 (t, J ) 6.5 Hz, 4 H), 3.62 (m, 8H), 7.11 (m, 4H),
7.56 (td, J ) 7.7 Hz, J ) 1.9 Hz, 2 H), 8.50 (d, J ) 4.9 Hz,
2H); 13C NMR δ 29.5(t), 34.8 (t); 70.1 (t), 70.5 (t), 70.6 (t), 121.0
(d), 122.9 (d), 136.3 (d), 149.2 (d), 161.7 (s). MS (FAB) m/e
345 (M + H+, 100%), 288 (26%). Anal. Calcd for C20H28N2O3
(344.45): C, 69.74; H, 8.19; N, 8.13. Found: C, 69.97; H, 8.37;
N, 8.29.
1
26%, greenish crystals mp 81-85 °C; H NMR δ 1.24 (m, 16
H), 1.55 (quintet, J ) 7.7 Hz, 4 H), 2.83 (t, J ) 7.7 Hz, 4 H),

Novel Redox-Active Cyclophanes
J . Org. Chem., Vol. 61, No. 2, 1996 713
(493 mg, 1.5 mmol) was added to a solution of N(Et)3 × HClO4
(0.1 g, 0.5 mmol) in 100 mL of ethanol. The suspension was
stirred for 10 min and then treated with a solution of the
bridged indolizine (0.7 mmol) in 50 mL of toluene. After
stirring at rt for 20 h the solvent was evaporated under
reduced pressure. The mixture was taken up with toluene and
water. The organic layer was separated and dried (MgSO4),
and the solvent was evaporated under reduced pressure.
Purification by column chromatography (hexane/ethyl acetate
6:1) yielded the pure cyclophanes.
1,1′-Dod eca m et h ylen e-2,2′-d im et h yl-3,3′-b iin d olizin e
1
(3a ): yield 14%, yellow oil; H NMR δ 0.54-1.50 (m, 16 H),
1.71 (s, 6 H), 2.46 (s, 2 H), 2.65 (m, 2 H), 2.96 (m, 2H), 3.25
(m, 2 H), 6.42 (m, 2 H), 6.60 (m, 2 H), 7.38 (d, J ) 7.1 Hz, 2
H), 7.61 (d, J ) 8.9 Hz, 2 H); 13C NMR δ 10.6, 23.3, 28.1, 28.1,
28.3, 28.7, 29.7, 109.7, 111.8, 112.0, 115.6, 116.9, 123.0, 124.6,
130.1; MS (FAB) m/ e 427 (M + H+, 100%). Anal. Calcd for
C30H38N2 (426.65): C, 84.46; H, 8.89; N, 6.57. Found: C, 84.13;
H, 8.59; N, 6.02.
1,1′-(3,6,9-Tr ioxa u n d eca m eth ylen e)-2,2′-d im eth yl-3,3′-
biin d olizin e (3b): yield 44%, yellow crystals mp 164-70 °C;
1H NMR δ 1.86 (s, 6 H), 2.68 (t, J ) 8.1 Hz, 2 H), 3.07 (m, 12
H), 4.08 (m, 2 H), 6.40 (t, J ) 6.6 Hz, 2 H), 6.63 (t, J ) 6.6 Hz,
2 H), 7.31 (d, J ) 8.7 Hz, 2 H), 7.80 (d, J ) 7.0 Hz, 2 H); 13C
NMR δ 10.8, 25.2, 71.2, 72.0, 72.7, 109.2, 110.1, 113.0, 115.4,
116.1, 123.3, 129.6, 129.7; MS (FAB) m/ e 419 (M + H+, 100%).
Anal. Calcd for C26H30N2O3 (418.54): C, 74.61; H, 7.22; N,
6.69. Found: 74.51; H, 7.44; N 6.23.
1,1′-Dod eca m et h ylen e-2,2′-d ip h en yl-3,3′-b iin d olizin e
(3c): yield 22%, yellow crystals mp 214-25 °C; 1H NMR
(DMSO-d6, 100 °C) δ 0.72 -0.97 (m, 16 H), 1.42 (m, 4 H), 3.04
(m, 4 H), 5.95 (td, J ) 6.8 Hz, J ) 1.3 Hz, 2H), 6.46 (ddd, J )
9.0 Hz, J ) 6.7 Hz, J ) 1.0 Hz, 2 H), 6.84 (m, 4 H), 7.03 (m,
6 H), 7.25 (d, J ) 7.2 Hz, 2 H), 7.37 (dt, J ) 9.0 Hz, J ) 1.3
Hz, 2 H); 13C NMR (DMSO-d6, 100 °C) δ 22.3, 26.6, 28.2, 28.4,
28.5, 28.5, 109.0, 110.7, 111.0, 115.6, 116.2, 122.3, 125.5, 127.1,
127.8, 127.9, 130.7, 135.2; MS (CI) m/ e 551 (M+ + 1, 100%).
Anal. Calcd for C40H42N2 (550.79): C, 87.23; H, 7.69; N, 5.09.
Found: C, 86.94; H, 7.50; N, 4.71.
F igu r e 5. Cyclic voltammograms of 3d /1 and 3d /2 in CH2Cl2
containing 0.01 M TBAPF6.
1,1′-(3,6,9-Tr ioxa u n d eca m eth ylen e)-2,2′-d ip h en yl-3,3′-
biin d olizin es (3d /1 a n d 3d /2). 3d /1: yield 26%, yellow
crystals mp 260-70 °C; 1H NMR (DMSO d6, 80 °C) δ 2.83 (m,
4 H), 2.99-3.17 (m, 12 H), 5.85 (td, J ) 7.3 Hz, J ) 1.3 Hz, 2
H), 6.33 (m, 2 H), 6.75-6.89 (m, 10 H), 7.24 (m, 4 H); 13C NMR
(DMSO-d6, 80 °C) δ 24.0, 69.9, 70.2, 70.4, 108.7, 109.0, 111.9,
115.5, 116.5, 122.8, 125.2, 126.8, 129.2, 130.5, 132.2, 136.1;
MS (MALDI) 543 ((M + H)+, 100%). Anal. Calcd for
C36H34N2O3 (542.68): C, 79.68; H, 6.31; N, 5.16. Found: C,
79.39; H, 6.33; N 4.83. CD for (+)-3d /1 (n-hexane) λ (∆θ) 405
(5.426 x 104), 350 (-3.061 x 104), 302 (1.413 x 105), 266 (1.519
x 105), 223 (-3.948 x 105).
1
3d /2: yield 5%, yellow crystals mp 222-27 °C; H NMR δ
2.02 (m, 1H), 2.46-2.98 (m, 10 H), 3.24 (m, 2 H), 3.37 (m, 1
H), 3.51 (m, 1 H), 4.00 (m, 1 H), 6.26 (td, J ) 6.7 Hz, J ) 1.2
Hz, 1 H), 6.46 (d, J ) 6.7 Hz, 1 H), 6.59 (m, 1 H), 6.64 (t, J )
6.4 Hz, 1 H), 6.71 (m, 1 H), 6.78-6.96 (m, 10 H), 7.40 (d, J )
8.9 Hz, 1 H), 7.44 (d, J ) 8.8 Hz, 1 H), 7.67 (d, J ) 5.8 Hz, 1
H); 13C NMR 24.9 (t), 25.5 (t), 69.4 (t), 71.0 (t), 71.4 (t), 71.6
(t), 71.8 (t), 72.4(t), 109.1 (s), 110.2 (d), 111.1(d), 111.2(s), 111.5
(s), 115.3 (d), 115.6 (s), 115.7 (d), 115.8 (d), 119.7 (d), 124.4(d),
124.6(d), 125.2 (d), 125.5 (d), 126.6(d), 127.7 (d), 128.5 (s), 129.5
(s), 130.0 (d), 131.6 (d), 134.6 (s), 135.3 (s), 136.0 (s), 136.2 (s);
MS (FAB) 543 (M + H+, 12%), 485 (20%), 261 (100%). Anal.
Calcd for C36H34N2O3 (542.68): C, 79.68; H, 6.31; N, 5.16.
Found: C, 79.55; H, 6.27; N, 4.85. CD for (-)-3d /2 (n-hexane)
λ (∆θ) 390 (-4.125 x 104), 329 (-9.965 x 103), 301 (2.874 x
104), 280 (2.029 x 104), 256 (-4.339 x 104), 228 (1.531 x 105),
202 (2.595 x 105).
1,14(1,1′)-Di(2,2′-d im e t h yl-3,3′-b iin d olizin o)h e xa e -
icosa p h a n e (4a ): yield 3%, oily crystals, decomposition 150-
70 °C; 1H NMR δ 1.17 - 1.39 (m, 32 H), 1.63 (m, 8 H), 2.07 (s,
12 H), 2.78 (broadened m, 8 H), 6.27 (broadened t, 4 H), 6.59
(broadened m, 4 H), 7.08 (broadened m, 4 H), 7.35 (d, J ) 9.0
Hz, 4 H); 13C NMR δ 10.4, 24.1, 29.1, 29.2, 29.3, 29.4, 31.0,
109.1, 111.8, 112.4, 115.5, 116.8, 123.0, 125.2, 130.7; MS (FAB)
F igu r e 6. Cyclophanes obtained by dimerization of bridged
indolizines.
6.40 (td, J ) 7.0 Hz, J ) 1.6 Hz, 2 H), 6.58 (ddd, J ) 9.0 Hz,
J ) 7.0 Hz, J ) 1.4 Hz, 2 H), 7.24 - 7.49 (m, 14 H), 7.82 (d, J
) 7.0 Hz, 2 H); 13C NMR δ 24.1 (t), 29.4 (t), 29.60 (t), 29.62 (t),
29.7 (t), 31.6 (t), 110.1 (d), 110.1 (d), 111.5 (s), 115.3 (d), 117.7
(d), 124.8 (d), 126.3 (d), 128.4 (d), 128.8 (d), 128.9 (s), 130.6
(s), 136.2 (s); MS (MALDI) 554 ((M + H)+, 100%), 309.2 (40%).
Anal. Calcd for C40H44N2 (552.80): C, 86.91; H, 8.02; N, 5.07.
Found: C, 86.79; H, 7.81; N, 4.72.
1,11-B is (2-p h e n y lin d o lizin -1-y l)-3,6,9-t r io x a u n d e -
1
ca n e (1d ): yield 24%, yellow-brown oil; H NMR δ 3.09 (t, J
) 7.5 Hz, 4 H), 3.49 (m, 12 H), 6.34 (td, J ) 7.0 Hz, J ) 1.2
Hz, 2 H), 6.53 (ddd, J ) 9.0 Hz, J ) 6.5 Hz, J ) 1.0 Hz, 2 H),
7.19 -7.42 (m, 14 H), 7.75 (dt, J ) 7.0 Hz, J ) 1.1 Hz, 2 H);
13C NMR δ 24.7 (t), 70.1 (t), 70.6 (t), 71.9 (t), 106.6 (s), 110.3
(d), 116.1 (d), 117.6 (d), 124.8 (d), 126.4 (d), 128.2 (d), 128.4
(d), 128.8 (d), 129.3 (s), 131.2 (s), 135.8 (s); MS (EI) m/ e 544
(M+, 24%), 206 (100%) for C36H36N2O3 (544).
Cycliza tion of th e Br id ged In d olizin es. K3[Fe(CN)6]

714 J . Org. Chem., Vol. 61, No. 2, 1996
Sonnenschein et al.
854 (M + H+, 100%), 427 (10%). Anal. Calcd for C60H76N4
(853.29): C, 84.46; H, 8.98; N, 6.57. Found: C, 84.14; H, 8.71;
N, 6.39.
group P1; crystal size 0.7 × 0.5 × 0.5 mm, unit cell dimensions
a ) 11.210(5), b ) 11.285(4), c ) 12.175(3) Å; R ) 80.60 (3)°,
â ) 72.45(4)°, γ ) 71.48 (3)°; V ) 1388.6 (9) Å3; 5429 refs, 749
< 2σ(F); R ) 4.5%; Rw ) 5.0%; all hydrogen atoms are
included and refined.
The structures were solved by direct methods with the
SHELXS-86 program7 and refined anisotropically using
SHELXL-938 and XTAL3.2.9 The coordinates of structures 3c,
3d /1, and 3d /2 have been deposited with the Cambridge Data
Centre. The coordinates can be obtained from the Director,
Cambridge Data Centre, 12 Union Road, Cambridge, CB2 1
BZ, U.K.
1,14(1,1′)-Di(2,2′-d ip h e n yl-3,3′-b iin d olizin o)h e xa e -
icosa p h a n e (4b): yield 7%, bright yellow crystals mp 194-
1
99 °C; H NMR (CDCl3, 40 °C) δ 1.11 (broadened m, 32 H),
1.49 (broadened m, 8 H), 2.79 (broadened m, 8 H), 6.29
(broadened t, 4 H), 6.61 (broadened t, 4 H), 6.80 (broadened
m, 8 H), 7.03 (broadened m, 12 H), 7.25 (broadened m, 4 H),
7.39 (d, J ) 9.2 Hz, 4 H); 13C NMR δ 23.7, 28.7, 29.1, 29.2,
29.3, 30.9, 110.2, 112.1, 116.2, 117.5, 123.0, 125.9, 127.7, 129.2,
129.3, 130.9, 131.0, 135.6; MS (MALDI) 1102 ((M + H)+, 100%).
Anal. Calcd for C80H84N4 (1101.57): C, 87.23; H, 7.69; N, 5.09.
Found: C, 86.88; H, 7.50; N, 5.04.
Ack n ow led gm en t. We thank Prof. Dr. S. Hu¨nig for
helpful discussions and suggestions. This work was
supported by the Fonds der Chemischen Industrie.
X-r a y Diffr a ction An a lysis. Suitable crystals for the
X-ray study were grown from a toluene/ethyl acetate mixture.
Crystal data:
3c (C40H42N2, fw 550.79): The crystals are monoclinic, space
group P21/n; crystal size 0.3 × 0.3 × 0.2 mm, with very poor
quality. Unit cell dimensions a ) 13.635(4), b ) 18.317(12), c
) 12.684(6) Å, R ) 90.0°, â ) 90.64(4)°, γ ) 90.0°; V ) 3168(3)
Å3; 6201 unique reflections, 3617 < 2σ(F)!; R ) 12.9%; Rw
13.9%, some calculated hydrogen atoms are included but not
refined.
Su p p or tin g In for m a tion Ava ila ble: Plots of 3d /1, 3d /2,
and 3c according to the X-ray analysis; stereochemistry of the
ansa-compounds 3d (5 pages). This material is contained in
libraries on microfiche, immediately follows this article in the
microfilm version of this journal, and can be ordered from the
ACS; see any current masthead page for ordering information.
3d /1 (C36H34N2O3, fw 542.68): crystals are monoclinic: space
group P21/n; crystal size 0.5 × 0.5 × 0.2 mm, unit cell
dimensions a ) 13.302(3), b ) 17.869(3), c ) 12.278 (4) Å; R )
90.0°, â ) 91.91(3)°, γ ) 90.0°; V ) 2921 (1) Å3; 5127 unique
reflections, 1181 < 2σ(F); R ) 6.0%; Rw ) 6.2%; all hydrogen
atoms are included and refined.
J O951419O
(7) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467
(8) Sheldrick, G. M. SHELXL-93. A program for the refinement of
crystal structures. Universita¨t Go¨ttingen, Germany.
(9) Hall, S. R.; Stewart, J . M., Eds. XTAL 3.2 Reference Manual;
University of Western Australia and University of Maryland, 1992.
3d /2 (C36H34N2O3, fw 542.68): crystals are triclinic, space