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Efficient Synthesis of Nanoscale Macrocyclic Hydrocarbons.

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The ' H and 13C{1H)NMR spectra of 2 show resonances
due only to the aryloxide substituents, while the
27A1{'H) NMR contains a single resonance (6 = 3.2). Although this 27AlNMR signal is in a region normally associated with six-coordinate aluminum centers,['] it follows the
general trend observed for monomeric three-coordinate aryloxide derivatives : R,AI(OAr*) compounds have 6("AI) resonance, signals around 190, while those for RAI(OAr*), are
found at about 100 ppm.['"' The medium-resolution mass
spectrum (70 eV, EI) of 2 exhibits a parent ion (mi. 684)
consistent with a monomeric structure in the gas phase.
Compound 2 is also monomeric in the solid state, as evident
from an X-ray crystal structure analysis.["'
The molecular structure of 2 (Fig. 1) consists of discrete
molecules with no unusual intermolecular distances. The
aluminum is three-coordinate trigonal planar [C 0-A1-0 =
359.9(3)"].The average AIL0 distance and AI-0-C angle are
1.648(7) A and 177.2(5)", respectively. The arene rings form
Fig. 1. Molecular structure of 2.
%
a propeller-like arrangement around the aluminum, and are
canted approximately 56" from the A10, plane. Two molecules of the solvent of recrystallization, CH,CI,, are present
in the asymmetric unit. The short A1-0 distances are undoubtedly a consequence of three factors. First, the aluminum atom is sp2 hybridized, whereas sp3 hybridization is
observed in the more common four-coordinate complexes.
Second, there is increased s character in the AI-0 bond as a
result of the near linear A1-0-C bond angle. Third, a pn-pn:
interaction is present between the vacant A1 3pz orbital (z
perpendicular to the A10, plane) and the lone pairs on the
aryloxide oxygen centers. This latter interaction may also
account for the highly shielded aluminum center, as evident
from the upfield resonance signal in the 27AlNMR spectrum.
Experimental Procedure
1 : To a suspension of LiAIH, (5.00 g, 0.125 mol) in Et,O (400 mL) at -78 "C
was added solid HOAr* (82.50 g. 0.375 mol). Caution: hydrogen gas is liberated. The reaction mixture was slowly warmed to room temperature and stirred
for 32 h. Filtration. followed by fractional crystallization allows for the isolation of I . Note that compound 1 is more soluble in Et,O than Li(OAr*)(OEt,)
and is thus the second compound to crystallize. Isolated yield: ca. 70%; m.p.
136-140°C; 'H NMR (250 MHz, C,D,, TMS ext.): 6 =7.22 (4H. s, C,H,),
3.68 (4H, m, OCH,), 2.30 (6H, s, CH,), 1.59 (36H, s, C(CH,),), 0.64 (6H, in,
OCH,CH,); at -52'C, 6 = 4.53 (br, s, AI-H); I3C{'H} NMR (100MHz,
C,D,, TMS ext.): S = 154.21 (0-C). 138.80(o-C), 126.48(m-CH), 126.28 @-C),
66.06 (0-CH,), 35.39 [C(CH,),], 31.89 [C(CH,),], 21.36 (CH,), 11.67
(OCH,CH,); "AI{'H) NMR (78 MHz, C,H,Me, [AI(H,0),13+ ext.) 6 = 59
= 5470 Hz); IR (KBr, Nujol): i. [cm-'1 =1896 (s), 1460 (vs), 1421 (s),
1387 (m), 1318 (w), 1258 (s), 1203 (m), 1147 (w), 1124 (w). 1088 (m), 1022 (m).
994 (m), 953 (w). 901 (s), 899 (m). 793 (m), 763 (m). 722 (w). 692 (m).
922
0 VCH
Verlugs~esellschqft
mbH, W-6940 Weinheim, 1992
2: To a toluene solution of 1 (4.00 g, 7.40 mmol) was added HOAr* (1.63 g.
7.41 mmol). The reaction mixture was heated at reflux for 3 2 h. Caution: hydrogen gas is liberated. The solution was then cooled, the solvent removed under
vacuum, and the residue crysrallized from pentane (- 20 "C). Crystals suitable
for X-ray analysis were obtained from CH,CI, solution. Yield: ca. 90%; m.p.
116-124°C; 'H NMR (250MHz, C,D,, TMS ext.): 6 =7.11 (2H. s, C,H,),
2.19 (3H, S, CH,), 1.51 (18H. s, C(CH,),); 13C('HJ NMR (100MHz. C,D,,
TMS ext.): 6 =151.71 (0-C). 138.51 (0-C), 128.64 (m-C), 126.77 @-C), 35.45
[C(CH,),I, 32.49 [C(CH,),], 21.25 (CH,); *'AI{'H) NMR (78 MHr, C,H,Me
= 585 Hz); 1R (KBr, Nujol): i. [cm-'1 = 1422
[AI(H,0),l3' ext.) 6 = 3.2
(s), 1390 (m), 1363 (m), 1295 (m), 1265 (s), 1209 (m), 1184 (w). 1157 (w), 1125
(in), 1081 (w). 1026 (w), 977 (s), 941 (m), 909 (w), 889 (w). 859 (m), 810 (w), 802
(w), 768 (m), 727 (w). 659 (m), 634 (w).
(
~
z
~
~
~
Received: January 15, 1992 [Z 5124 IE]
German version: Angew. Chem. 1992, 104, 939
CAS Registry numbers:
1, 141635-57-6; 2. 141635-58-7; 2.2CHzCIz, 141635-59-8; LiAIH,, 1685385-3.
[I] D. C. Bradley, Adv. Chem Ser. 1959, 23, 10.
[2] a) R. A. Anderson, G. E. Coates. J. Chem. Soc. Dalton Trans. 1972,2153;
b) A. G. Goel, R. C. Mehrotra, Indian J Chem. Sect. A . 1978, 16, 428;
c) P. B. Hitchcock, M. F. Lappert, A. Singh, J. Chem. Soc. Chem. Commun. 1983, 1499; d) P. B. Hitchcock, M. F. Lappert, R. G. Smith, Inorg.
Chim. Aczu 1987, 27, 183; e) J. Calabrese, M. A. Cushing. Jr., S. D. Ittel,
Inorg. Chum. 1988,27.867; f ) H. A. Stecher, A. Sen, A. L. Rheingold, ibid.
1988, 27, 1132; g) M. F. Lappert, A. Singh, R. G. Smith, Inor,q. Synth.
1990, 27, 164; h) K. H. Whitmire, H. W. Roesky, S. Brooker, G. M.
Sheldrick, J. Organomet. Chem. 1991, 402, C4.
[ 3 ] B. Cetinkaya, I. Giimriik$ii, M. F. Lappert, J. L. Atwood, R. D. Rogers,
M. J. Zaworotko, J An?. Chein. So?. 1980,102.2089; M. Scbolz, M. Noltemeyer, H. W. Roesky, Angew. ChPm. 1989. 101. 1419, Angew,. Chem. h i .
Ed. Engl. 1989.28, 1383.
[4] a) M. D. Hedly, D. A. Wierda, A. R. Barron, OrgunometuNics 1988, 7,
2543; b) M. D. Healy, J. W. Ziller, A. R. Barron, J. Am. Chem. Soc. 1990,
112. 2949.
[5] a) M. Skowronskd-Ptasinska, K. B. Starowieyski, S. Pasynkiewicz, M.
Carewska, J ; Orgunomel. Chrm. 1978, 160, 403; b) A. P. Streve, R. Mulhaupt, W. Fultz, J. Calabrese, W Robhins, S. D. Ittel, Orgunomerullics
1988.7.409; c) R. Benn, E. Janssen, H. Lehmkuhl, A. Rufinska, K. Angermund, P. Betz, R. Goddard, C. Kriiger, J Orgunomet. Chem. 1991,4f 1,37.
[6] K. Ruhlandt-Senge, P. P. Power, Inorg. Chem. 1991, 30, 2633.
[7] B. Cetinkaya, I. Giimriik$ii, M. E Lappert, J. L. Atwood, R. Shakir, J
A m . Cliem. Sor. 1980, 102, 2086.
[XI A. R. Barron, G. Wilkinson, Polyhedron 1986, 5, 1897.
191 A. W Apblett, A. C. Warren, A. R. Barron, Chem. Mulei-. 1992, 4, 167.
[lo] X-ray structure analysis of 2 . 2CH2C1,: space group PT, a =12.903(9),
b =13.911(8),~= 1 6 . 2 0 1 ( 9 ) a , ~= 99.71(5),0 =103.16(5),;~=114.63(6)",
V = 2457(3)
pLrlrll=1.155 g ~ m - ~p(MoKm)
,
= 0.295 mm-',
6348
unique reflections, 3758 observed ( I z 6u(1)), R = 0.083, R, = 0.085. Further details of the crystal structure investigation may be obtained from the
Fachinformationszentrum Karlsruhe, Gesellschaft fur wissenschaftlichtechnische Information mbH, D-W-7514 Eggenstein-Leopoldshafen 2
(FRG) on quoting the depository number CSD-56189, the names of the
authors, and the journal citation.
a3,
Efficient Synthesis of Nanoscale Macrocyclic
Hydrocarbons**
By Jejfrey S. Moore* and Jinshan Zhang
Structurally well-defined macrocycles"] have long attracted the interest of many research groups, especially those
studying recognition and selective cornplexati~n.[~~
Our in[*] Prof. J. S. Moore, J. Zhang
The Willard H. Dow Laboratories, The University of Michigan
Ann Arbor, MI 48109-1055 (USA)
[**I Nanoarchitectures, Part 2. This research was supported in part by the
Donors of the Petroleum Research Fund, administered by the American
S. M. wishes to thank the 3M company for support
Chemical Society. .I.
through their awards program for untenured faculty. We also thank Prof.
Steven Dierker for stimulating discussions regarding this work. Part 1:
-
PI.
OS70-0833/92/0707-0922$3.50+ ,2510
Angew. Chem. Int. Ed. Engi. 1992, 31. N o . 7
terest in these compounds is as a class of large molecular
building blocksr31that can be used to assemble new materials
by a “modular” approach. Rigid toroids constructed from
phenylacetylene monomers are ideally suited for this since
both the position and orientation (endo vs. exo) of pendant
groups are well defined. Here we describe the efficient synthesis of very large macrocyclic hydrocarbons having internal diameters up to 22 A.
Our synthesis involves macrocy~lization[~~
of a,w-unsymmetrically difunctionalized phenylacetylene sequences. We
recently described an efficient preparation of these oligomers
in which the chain length, the sequence order of monomers,
and end-group functionality can be precisely c ~ n t r o l l e d . ~ ~ ]
These sequences are cyclized by intramolecular palladiumcatalyzed couplingt6]by slow addition of the oligomer to
solution of the active catalyst. As shown in Scheme 1, both
the products with six (1) and twelve (2) arene units were
obtained in high yield (75 YOand 70 YO,respectively). In each
case, only a single cyclic product was observed. The tertbutyl groups were required to maintain adequate solubility.
Molecular models show that the inner diameter (hydrogen to
hydrogen) of 1 is 8.4 A while that of 2 is slightly greater than
22 A. The high yields and absence of other cyclic products
for these large ring systems are probably a consequence of
the assembly of the rigid,”] a,w-difunctionalized sequences
prior to the cyclization reaction.
oligomerization and cyclization in the same reaction flask
(i.e. “one-pot” process). Although the one-pot reaction can
potentially generate products in a single step, the yield depends strongly on ring
As an example, the one-pot
synthesis of the parent coumpound of 1 proceeds in only
4.6 %
The overall yield for 1 by our route including
the synthesis of sequence is nearly an order of magnitude
higher. Besides giving low yield, the one-pot process is also
limited to products of certain structural types. For example,
only cyclic geometries that result from a single type of
monomer can easily be realized. Thus, toroidal hydrocarbon
2 could not be prepared from a one-pot reaction but instead
would require prior synthesis of the mera-para dimer. For
these same reasons, products with specific placement of
functional groups are not easily prepared by the one-pot
process. However, cyclization of a properly functionalized
sequence will provide macrocycles with groups positioned
according to the sequence order of monomers. The arrangement of tert-butyl groups on alternate rings in 1 illustrates
this point. Finally, we have recently shown that high yields
of large three-dimensional cage molecules can be realized by
double cyclization of branched sequences.I8I These structures could probably not be realized using the one-pot approach.
The efficient cyclizations described here, in combination
with our phenylacetylene sequence synthesis, offer enormous
possibilities for preparing large and well-defined organic
structures. The geometric possibilities that can be obtained
by cyclization of sequences of phenylacetylene monomer
units (combinations of 60”, 120”, and 180” angles) are essentially any framework that lies on the trigonal lattice. Table 1
shows the number of unique planar cyclic geometries that
can be obtained from sequences containing three to ten
phenylacetylene units.[’’ These molecular frameworks
Fable 1. Relationship between monomer units to be linked and the resulting
structure.
Number ofmonomer
units [a]
Number of possible
cyclic geometries [b]
175%
3
4
5
6
7
8
9
10
1
1
1
4
5
16
37
120
[a] Monomers are ortho-, mela-, and para-phenylacetylenes. [b] Defined as a
“closed path” on a two-dimensional trigonal lattice.
.I
should be useful for constructing novel mesogens or building
blocks for self-assembled monolayers or rationally designed
organic crystals.
Experimental Procedure
1
2
Scheme I . Synthesis of nanoscale macrocyclic hydrocarbons. Reaction conditions: [Pd(dba),]. PPh,, CuI, triethylamine, 70°C.
There are a number of advantages in using preassembled
sequences to synthesize large cyclic structures. The method
we describe here should be compared to the more common
approach used to prepare macrocycles which involves
A n p w . C h t w Inr. Ed. Ennl. 1992, 31, No. 7
0 VCH
2 : A septum-stoppered flask charged with [Pd(dba),] [lo] (0.15 g, 0.26 mmol),
triphenylphosphine (0.41 g, 1.56 mmol), copper(1) iodide (0.05 g, 0.26 mmol)
was evacuated and back-filled with nitrogen. Anhydrous triethylamine (75 mL)
was added, and the solution was heated to 70°C. The a-iodo-oi-ethynyl-dodecameric sequence (0.50 g, 3.0 mmol) was taken up in a mixture of triethylamine
(25 mL) and benzene (25 mL) and added to the catalyst by a syringe pump at
arateof2.5 mLh-’. At theendoftheaddition, thesolution wasstirredat 90°C
for another five h and then diluted with dichloromethane. The solution was
washed with 1 N aqueous HCI, brine, and water and dried over sodium sulfate.
After the solvent was removed the residue was purified by flash chromatography (eluting with CH,CI,) and recrystallized (first from MeOH/CH,C12, then
toluene) to afford a colorless crystalline solid ( 2 ) in 70% (0.324 g).
Characterization data for (2): ‘ H NMR (200 MHz. [DJbenzene): 6 = 7.84 (t.
J=1.3Hz,1H,H-Cl),7.67(d,J=1.3Hz,2H,H-C2),7.42(s,4H,H-CI’),
1.10 (s, 9H, (CH,),C-); 13C NMR (90 MHz, CDCI,): 6 = 151.8 (C2a), 132.4
(Cl). 131.6 (Cl’), 128.7 (C2). 123.1 (Cla and Cl’a), 91.0 (C=C). 89.2 (C=C),
34.7 (CH,),C-, 31.2 (CH,),C-; MS (FAB) mir 1539 [(M H)]? Correct elemental analysis.
Verlugs~esellschuftmhH. W-6940 Weinheim, 1992
+
0570-OX33/92/0707-0923$3.50+.25/0
923
Characterization data for 1: 'H NMR (200 MHz, [DJbenzene): 6 = 8.09 (t,
J = 1 . 6 H Z , 1H,H-C1'), 7 . 9 8 ( t , J = 1 . 4 H ~ ,lH,H-CI), 7 . 7 0 ( d , J = 1 . 4 H ~ ,
l H , H-C2), 7.42 (dd, J = 1.6, 7.9Hz, 2H, H-CT), 6.86 (t, J = 7 . 9 H z , l H ,
H-C3'), 1.10 (s, 9H, (CH,),C-); I3C NMR (75 MHz, CDCI,): b = 151.7 (C2a),
135.3(C1'), 132.4(C l), 131.0(C T ) , 128.6(C 2), 128.4(C3'), 123.6(Cl'a), 123.1
(Cla), 89.8 (CsC), 88.6 (C=C), 34.8 (CH,),C-), 31.1 (CH,)3C-); HR MS
(70 eV, El) m/z C,,H,,: calc. 768.3756, found 768.3774. Correct elemental analysis. Crystals of 1 have not provided useful diffraction data.
Received: February 5, 1992 [Z 5168 IE]
German Version: Angew. Chem. 1992, 104, 873
CAS Registry numbers:
1, 141928-18-9; 2, 141903-36-8; 3. 141903-37-9; 4, 141903-38-0
For examples of macrocyclic hydrocarbons see: a) Annulenes: I. D.
Campbell, G. Eglinton, W Henderson, R . A . Raphael, J. Chem. Sor.
Chem. Commun. 1966,87-89; b) H. A. Staab, K. Neunhoeffer. Synthesis
1974, 424; c) Coronaphenes: F. Diederich, H. A. Staab, Angew. Chem.
1978, 90,383-385; Angew. Chem. Int. Ed. Engl. 1978, 17, 372-374; d) F.
Vogtle, K. Kadei, Chem. Ber. 1991, 124, 903-907; e) K. Kadei, F. Vogtle,
ibid. 1991, 124, 909-913; f) Cyclynes: A. de Meijere, F. Jaekel, A. Simon,
H. Borrmann, J. Kohler, D. Johnels, L. T. Scott, J Am. Chem. SOC.
1991,
113, 3935-3941.
For example: a) T. W. Bell, F. Guzzo, M. G. B. Drew, J. Am. Chem. SOC.
1991, fl3,3115-3122; b)T. W. Bell, A. Firestone, ibid. 1986, 108, 81098111; c) R. C. Helgeson, J.-P. Mazaleyrat, D. J. Cram, ibid. 1981, 103,
3929-3931; d ) G . R. Newkome, H.-W. Lee, ibid. 1983, f05,5956-5957;
e) J. L. Toner, Tetrahedron Left. 1983, 24, 2707-2710; f) J. E. B. Ransohoff, H. A. Staab, ibid. 1985,26,6179-6182; g) M. Dobler, M. Dumic, M.
Egli, V. Prelog, Angew. Chem. 1985, 97, 793-795; Angew. Chem. Int. Ed.
Engl. 1985,24, 792 794.
A "nanoscale structural unit" was recently described: T. H. Webb, C. S.
Wilcox, J. Org. Chem. 1990,55, 363-365.
For reviews on macrocyclization see: a) L. Rosa, F. Vogtle, Top. Curr.
Chem. 1983,113,l-86; b) L. Mandolini Adv. Phys. Org. Chem. 1986,22,
tion number (CN) of X is always nip times that of M:
CN(X) = nip CN(M). Hence when CN(M) is high, CN(X)
will be very large and the subsequent coordination polyhedra
will also be correspondingly large. Here we would like to
introduce a new class of space-filling polyhedra which can be
utilized in describing structures in which a small number of
linear molecules, large atoms, or large ions are coordinated
by many monoatomic units. These polyhedra are obtained
by the successive interpenetration of cubes along a threefold
axis.
First we would like to consider the condensation of two
cubes to form a structural unit having common corners. This
can be achieved in five different ways, as shown in Figure 1 a<. The first four cases yield nothing significantly new.
They are generated by fusing one, two, four, or eight corners
of each cube, leading to shared corners, edges, faces, and
finally to a complete overlap. In contrast, the fifth possibility
(Fig. 1e) is of greater interest. In this situation, the cubes are
interpentrated so that three corners of each cube are fused
together.
-
1-110.
J. Zhang, J. S. Moore, Z. Xu, R. Aguirre, J Am. Chem. SOL..1992, 114,
2273-2274.
a) K. Sonogashira, Y. Tohda, N. Hagihara, Tetrahedron Lett. 1975,44674470; b) L. Cassar, J. Orgunomel. Chem. 1975, 93, 253-257; c) H. A.
Dieck, R. F. Heck, ibid. 1975, 93, 259-263.
For a discussion of the advantages of rigid structural units in the synthesis
of large rings see reference [4a].
Z. Wu, J. S. Moore, unpublished results.
Combinatorial analysis was used to enumerate planar cyclic geometries
derived from sequences of ortho-, melu-, and para-phenylacetylene
monomers. This was accomplished by performing a systematic n-step walk
on a two-dimensional trigonal lattice. As an example, the four isomers that
can be obtained from sequences contaming six monomer units are shown
below.
M. F. Rettig, P. M. Maitlis, Inorg. Synth. 1977, 17, 134-137.
Generalized Edshammar Polyhedra for the
Description of a Family of Solid-state Structures
i
ii
e
Fig. 1 . Two cubes with a) one, b) two, c) four, d) eight, e) three common corners.
A corner of each cube now lies inside the other cube and
a structure emerges that is reminiscent of a body-centered
cube (bcc). However, the centering is far from perfect; the
enclosed point is located closer to the position (1/3, 1/3, 1/3)
than to the position (1/2, 112, 1/2) of the surrounding cube.
The original cubes each possess eight corners, thus sixteen in
total. After condensation, only thirteen corners are available. Of these thirteen, two are enclosed by eleven, thus
building a new space-filling polyhedron, the Edshammar
polyhedron,"] which will be denoted henceforth by the symbol "E and the configuration 4636 (Fig. 2a).
The latter designation indicates that the polyhedron is
assembled from six squares and six triangles.['] Certainly this
process can be extended further. The condensation of three
cubes along a common threefold axis leads to a polyhedron
By Sven Lidin,* Thomas Popp, Mehmet Somer,
and Hans Georg von Schnering
In compounds with the general composition M,X, with
n 9 p , component X, which can be a single atom, ion, or
molecule, must build discrete units which are to a certain
extent embedded in a continuous medium M. The coordinaa
['I
Dr. S. Lidin
Dept. Inorganic Chemistry 2
Chemical Centre, P.O. Box 124
S-22100 Lund (Schweden)
Dr. T. Popp, Dr. M. Somer, Prof. Dr. H. G. von Schnenng
Max-Planck-Institut fur Festkorperforschung, Stuttgart
924
0 VCH
Ver/ugsgese//schujtmbH, W-6940 Weinheim, 1992
b
Fig. 2. a) The Edshammar ("E) polyhedron. b) The I4E polyhedron.
0570-0833192/0707-0924$3.50+ .25/0
Angew. Chem. Int. Ed. Engl. 1992, 31, No. 7
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