Narrow-rim functionalization of calix[4]arenes via Sonogashira coupling reactions

Article abstract of DOI:10.1021/jo050488s

The narrow (or "lower")-rim hydroxyl groups of calixarenes are known to be resistant to substitution/ displacement. The Sonogashira coupling reaction with TMSA and phenylacetylene, however, has now been extended to the bistriflate of p-tert-butylcalix[4]a

Full text of DOI:10.1021/jo050488s

Narrow-Rim Functionalization of Calix[4]arenes via Sonogashira
Coupling Reactions
Hassan Al-Saraierh, David O. Miller, and Paris E. Georghiou*
Department of Chemistry, Memorial University of Newfoundland, St. John’s, Newfoundland and
Labrador, A1B 3X7, Canada
parisg@mun.ca
Received March 10, 2005
The narrow (or “lower”)-rim hydroxyl groups of calixarenes are known to be resistant to substitution/
displacement. The Sonogashira coupling reaction with TMSA and phenylacetylene, however, has
now been extended to the bistriflate of p-tert-butylcalix[4]arene, previously known to be resistant
to Stille, Neigishi, or Suzuki-Miyaura reactions. Under some of the reaction conditions investigated,
the previously unknown narrow-rim mono- and diiodo-p-tert-butylcalix[4]arene products were also
produced, in addition to the narrow-rim mono- and dialkynyl products. Homocoupling of the narrow-
rim monoethynyl-p-tert-butyl-calix[4]arene produced a new narrow-rim rigid butadiyne-linked bis-
p-tert-butylcalix[4]arene.
Introduction
Many other research groups have demonstrated that
structural modifications of calix[4]arenes1 can lead to
significant changes in their chemical and physical prop-
erties, and this has resulted in much synthetic effort
being directed toward producing analogues and deriva-
tives of these versatile molecules. The great majority of
the modifications have involved narrow (or “lower”)-rim
functionalization of the phenolic hydroxy groups or, to a
lesser extent, wide (or “upper”)-rim modifications. The
latter have generally involved de-p-tert-butylation2 of the
readily accessible tetra-p-tert-butylcalix[4]arene (1) to
form 2, followed, for example, by either halogenation or
nitration at the positions para to the hydroxy groups, and
subsequent functional group interconversions via a broad
range of reaction types.3
Modifications of the narrow rim of calixarenes have
primarily involved aliphatic mono- to tetra-O-alkylation
(3) (a) van Loon, J.-D.; Arduini, A.; Verboom, W.; Ungaro, R.; van
Hummel, G. J.; Harkema, S.; Reinhoudt, D. N. Tetrahedron Lett. 1989,
30, 2681-2684. (b) Verboom, W.; Durie, A.; Egberink, R. J. M.; Asfari,
Z.; Reinhoudt, D. N. J. Org. Chem. 1992, 57, 1313-1316. (c) de
Mendoza, J.; Carramolino, M.; Cuevas, F.; Nieto, P. M.; Prados, P.;
Reinhoudt, D. N.; Verboom, W.; Ungaro, R.; Casnati, A. Synthesis 1994,
47-50. (d) Takeshita, M.; Nishio, S.; Shinkai, S. J. Org. Chem. 1994,
59, 4032-4034. (e) Arduini, A.; Fanni, S.; Manfredi, G.; Pochini, A.;
Ungaro, R.; Sicuri, A. R.; Ugozzoli, F. J. Org. Chem. 1995, 60, 1448-
1453. (f) Shokova, E.; Khomich, A. N.; Kovalev, V. V. Tetrahedron Lett.
1996, 37, 543-546.
(1) For general reviews on calixarenes, see: (a) Bo¨hmer, V. Angew.
Chem., Int. Ed. Engl. 1995, 34, 713-745. (b) Ikeda, A.; Shinkai, S.
Chem. Rev. 1997, 97, 1713-1734. (c) Gutsche, C. D. Calixarenes
Revisited; Royal Society of Chemistry: Cambridge, 1998. (d) Calix-
arenes 2001; Asfari, Z., Bo¨hmer, V., Harrowfield, J., Vicens J., Eds.;
Kluwer: Dordrecht, 2001.
(2) Rha, S. G.; Chang, S.-K. J. Org. Chem. 1998, 63, 2357-2359
and references therein.
10.1021/jo050488s CCC: $30.25 © 2005 American Chemical Society
Published on Web 09/16/2005
J. Org. Chem. 2005, 70, 8273-8280
8273

Al-Saraierh et al.
TABLE 1. Some Typical Reaction Conditions Employed and Products (7-10) Obtained for the Pd-Catalyzed Reactions
of Bistriflate 3 with Trimethylsilylacetylene (6a) in Refluxing Toluene Solution
entry
6a molar equiv
base/molar equiv
CuI mol %
catalyst/mol %
time (h)
7
8
9
10
1
2
3
4
5
1.4
1.4
2.0
2.5
DBU/4
DBU/2
DBU/4
DBU/2
DBU/2
500
240
1
200
600
Pd(PPh3)2Cl2/10
Pd(PPh3)2Cl2/10
Pd(PPh3)2Cl2/1
Pd(PPh3)2Cl2/1
Pd(PPh3)2Cl2/10
1.5
4.0
1.0
1.0
4.0
19
8
tr
43
12
tr
51
44
8
17
0
tr
14
25
64
tr
tr
64
(e.g., with groups such as Me, Et, Bn, -CH2CO2CH2CH3,
etc.) or mono- to tetra-O-esterification (e.g., using
CH3COCl, PhCOCl, etc.) and O-arylation.4 There are far
fewer reported instances of hydroxy group substitution
reactions on calix[4]arenes such as 1 by, for example,
hydrogen atoms,5 amino,6 or sulfhydryl groups.7
certain conditions, an unusual aromatic substitution of
the narrow-rim triflates by iodide was also observed. This
paper therefore reports the first successful Sonogashira
reaction mediated narrow-rim functionalizations of a
calix[4]arene.
Results and Discussion
We have been interested for some time in the potential
for functionalizing the narrow rim of calix[4]arenes using
metal-assisted coupling reactions such as the Stille8 and
Suzuki-Miyaura9 reactions on the corresponding calix-
[4]arene triflates or mesylates. Gonza´lez et al.10 reported
that an attempted Pd-catalyzed Stille reaction with 1,3-
bistriflate 3 or 1,3-bismesylate 4 resulted instead in
intermolecular migration of the sulfonyl groups and that
no narrow-rim substitution occurred with these sub-
stances. In our own hands,11 the following reactions,
using the mono- to tetrakistriflates of 1, failed to afford
any of the desired products, affording only unexpected
products. For example, a Pd-catalyzed carbonylative
Suzuki-Miyaura-type reaction12 with the 1,3-bistriflate
3 and phenylboronic acid resulted only in the formation
of an unprecedented stable 1:1 supramolecular complex
of benzophenone and the monotriflate 5,11 with no evi-
dence of triflate displacement. Also an attempted deoxy-
genation of 3 using Snieckus Pd-catalyzed conditions13
with 3 also failed, affording instead a different 1:1
supramolecular complex between triethylamine and 5.11
We have now found, however, that Pd-catalyzed reac-
tions of 3 under Sonogashira coupling14 conditions, using
trimethylsilylacetylene (TMSA, 6a) and a few other
representative terminal acetylenes to demonstrate the
generality of the reaction conditions, produces the desired
narrow-rim substitution and coupling products. The
aliphatic terminal alkynes 3-butyn-1-ol (6b), 5-hexyn-
1-ol (6c), and the phenyl-containing terminal alkyne
phenylacetylene (6d) were used in this study. Under
To the best of our knowledge, there are only six
published reports in which the Sonogashira reaction has
been employed with calixarenes, and five of these involve
functionalization of the wide rim.15-19 The other involves
conversion of tetrakis-p-iodobenzyloxycalix[4]arene to
form the corresponding tetrakis-p-(mannopyranosyl)-
benzyloxycalix[4]arene,20 but the reactions described do
not involve displacement of the phenolic oxygen atoms
on the narrow rim. Our initial experiments with the
Sonogashira reaction conditions and 1,3-bistriflate calix-
[4[arene (3)14,21 were conducted with TMSA since we were
also interested in the synthesis of rigid, alkynyl-bridged
biscalixarenes (see below). During these experiments,
several different bases, for example, triethylamine, 2,6-
lutidine, ammonium hydroxide, and 1,5-diazabicyclo-
[5.4.0]undec-5-ene (DBU), and different solvents, for
example, benzene, THF, dioxane, DMF, and toluene,
were evaluated. DBU and toluene were found to be the
best base and solvent combination to use (e.g., see Table
1). It was also found to be necessary to use refluxing
temperatures for any reaction to occur between 3 and
TMSA. In one of these experiments, four new calix[4]-
arene products 7-10 were formed (Scheme 1, reaction
conditions a; Table 1, entries 1 and 2) in addition to the
formation of some of the homocoupling product of TMSA
itself, namely, 1,4-bis(trimethylsilyl)-1,3-butadiyne (which
was also formed in all of the reactions evaluated).
The structures of 7 and 8 were established by
NMR and single-crystal X-ray crystallography to be the
narrow-rim functionalized iodo- and trimethylsilyl-
ethynyl-substituted calix[4]arene (7) and the monotri-
methylsilylethynyl-substituted monotriflate, 8. The X-ray
structure of 7 (Figure 1) reveals it to be in a pinched-
cone conformation in which the two distal aryl rings
containing the iodo and the trimethylsilylethynyl groups
are parallel to each other. The X-ray structure of 8 (not
shown), which has two molecules in the asymmetric unit,
(4) Chowdhury, S.; Georghiou, P. E. J. Org. Chem. 2001, 66, 6257-
6262.
(5) For narrow-rim functionalization via calixarene spirodienone
intermediates, see: Biali, S. E. Synlett, 2003, 1, 1-11 and references
therein.
(6) Ohseto, F.; Murakami, H.; Araki, K.; Shinkai, S. Tetrahedron
Lett. 1992, 33, 1217-1220.
(7) Gibbs, C. G.; Sujeeth, P. K.; Rogers, J. S.; Stanley, G. G.; Krawiec,
M.; Watson, W. H.; Gutsche, C. D. J. Org. Chem. 1995, 60, 8394-
8402.
(8) Stille, J. K. Angew. Chem., Int. Ed. Engl. 1986, 25, 508-523.
(9) Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457-2483.
(10) Gonza´lez, J. J.; Nieto, P. M.; Echavarren, A. M.; de Mendoza,
J. Org. Chem. 1995, 60, 7419-7423.
(15) Xu, B.; Miao, Y.-J.; Swager T. M., J. Org. Chem. 1998, 63,
8561-8564.
(16) Bo¨hmer, V.; Brusko, V.; Rissanen, K. Synthesis 2002, 1898-
1902.
(11) Chowdhury, S.; Bridson, J. N.; Georghiou, P. E. J. Org. Chem.
2000, 65, 3299-3302.
(17) Jokic, D.; Asfari, Z.; Weiss, J. Org. Lett. 2002, 4, 2129-2132.
(18) Armaroli, N.; Accorsi, G.; Rio, Y.; Ceroni, P.; Vicinelli, V.;
Welter, R.; Gu, T.; Saddik, M.; Holler, M.; Nierengarten, J.-F. New J.
Chem. 2004, 28, 1627-1637.
(19) Hennrich, G.; Murillo, M. T.; Prados, P.; Song, K.; Asselberghs,
I.; Clays, K.; Persoons, A.; Benet-Buchholz, J.; de Mendoza, J. Chem.
Commun. 2005, 2747-2749.
(20) Perez-Balderas, F.; Santoyo-Gonza´lez, F. Synlett 2001, 1699-
1702.
(12) Ishiyama, T.; Kizaki, H.; Hayashi, T.; Suzuki, A.; Miyaura, N.
J. Org. Chem. 1998, 63, 4726-4731.
(13) Chowdhury, S.; Zhao, B.; Snieckus, V. J. Polycyclic Aromat.
Compd. 1994, 5, 27.
(14) (a) Sonogashira, K.; Todha, Y.; Hagihara, N. Tetrahedron Lett.
1975, 16, 4467-4470. (b) For a general review, see: Sonogashira, K.
In Metal Catalyzed Cross-Coupling Reactions; Diederich, F., Stang, P.
J., Eds.; Wiley-VCH: Weinheim, 1998; Chapter 5.
8274 J. Org. Chem., Vol. 70, No. 21, 2005

Narrow-Rim Functionalization of Calix[4]arenes
SCHEME 1a
a Conditions: (a) see Table 1; (b and c) PdCl2(PPh3)2 (5 mol %), CuI (5 mol %), toluene, DBU (2 equiv), reflux, 6d, 3 h.
SCHEME 2a
FIGURE 1. X-ray single-crystal PLUTO stereoview of 7 in a
pinched-cone conformation and a molecule of CHCl3 (all of the
a Conditions: PdCl2(PPh3)2 (2 mol %), CuI (5 mol %), toluene,
DBU (2 equiv), reflux, 3 h. For 11 (32% yield), compound 6b was
used; for 12 (20% yield), compound 6c was used.
H atoms have been removed for clarity).
also reveals it to be in a similar pinched-cone conforma-
tion, in which the two distal aryl rings bearing the triflate
and trimethylsilylethynyl groups are parallel to each
other, by analogy with the structure of 7.
Although crystals of 9 or 10 suitable for X-ray analysis
were not forthcoming, their NMR and mass spectra were
in agreement with the structures depicted. In solution,
as ascertained by the NMR spectra, their conformations
are pinched-cone and 1,3-alternate, respectively, as pre-
dicted using deMendoza’s criteria.22
The incorporation of the trimethylsilylethynyl groups
onto the narrow rim of calix[4]arene in 7 and 8 are the
first examples to be reported of a metal-assisted direct
coupling of an alkyne moiety, by displacement of the
phenolic functionality on the narrow rim of a calixarene.
The presence of the iodine atoms in 7, 9, and 10, however,
was unexpected. These compounds are also the first
examples to be reported in which a direct metal-assisted
substitution by a halide has occurred on the narrow rim
of a calix[4]arene.
To determine whether the iodo compounds were formed
as intermediates or byproducts of the reaction, conditions
were evaluated in order to optimize the yields of these
iodo products. Using similar Pd-catalyzed conditions as
were used above but excluding the terminal acetylenes,
the monoiodo- and diiodocalixarenes 9 and 10, respec-
tively, could be formed in reproducible and synthetically
useful yields of 14% and 64%, respectively (Table 1, entry
5). However, with synthetically useful yields of both 9
and 10 in hand, attempts to effect the coupling reaction
of TMSA directly on either of these compounds, under
the same Sonogashira reaction conditions used previ-
ously, failed to produce any TMSA-coupled products. Only
1,4-bis(trimethylsilyl)-1,3-butadiyne and unreacted start-
ing material were recovered. These results suggest that
the iodo compounds were therefore not formed as inter-
mediates in the reactions of 3 with TMSA that produced
7 and/or 8 but that they were formed as byproducts
instead.
The optimal conditions that were found for synthesiz-
ing 8 (in 51% isolated yields) required 1 mol % of both
the Pd catalyst and the CuI cocatalyst and 4 molar equiv
of DBU, in refluxing toluene (Table 1, entry 3). However,
when a higher molar ratio of the CuI was used, together
with a more concentrated solution of reactants (Table 1,
entry 4), a mixture containing both 7 and 8 in 43% and
44% yields, respectively, was obtained. To test the
generality of these reaction conditions for other potential
narrow-rim substitutions, 3 was reacted with some other
readily available terminal alkynes. The reactions of 3
with, for example, 3-butyn-1-ol (6b) or 5-hexyn-1-ol (6c),
under the optimal conditions found for TMSA, gave the
corresponding monosubstituted products 11 and 12,
respectively (Scheme 2). However, as was also found with
(21) Csok, Z.; Szalontai, G.; Czira, G.; Kollar, L. Supramol. Chem.
1998, 10, 69-77.
(22) Jaime, C.; de Mendoza, J.; Prados, P.; Nieto, P. M.; Sa´nchez,
C. J. Org. Chem. 1991, 56, 3372-3376.
J. Org. Chem, Vol. 70, No. 21, 2005 8275

Al-Saraierh et al.
SCHEME 3a
FIGURE 2. X-ray single-crystal PLUTO stereoview of 1,3-
bis(phenylethynyl)calix[4]arenes, 14 (all of the H atoms have
been removed for clarity).
a Conditions: (a) PdCl2(PPh3)2 (10 mol %), CuI (5 mol %), DBU
(4 equiv), 6d, toluene, reflux, 4 h; (b) PdCl2(PPh3)2 (10 mol %),
CuI (5.7 mol equiv), DBU (2 equiv), toluene, reflux, rt, 3 h; (c)
PdCl2(PPh3)2 (10 mol %), CuI (5 mol %), DBU (4 equiv), 6a, toluene,
reflux, 4 h.
the reactions of 3 with TMSA, none of the corresponding
disubstituted products were obtained.
Sonogahira catalytic cycle,14b leading to the formation of
7a in this case.
With phenylacetylene (6d), on the other hand, Pd-
catalyzed coupling with 3 afforded both the expected
mono- and 1,3-bis(phenylethynyl)calix[4]arenes 13 and
14, respectively. A single-crystal X-ray determination of
14 (Figure 2) showed the two aryl groups that bear the
phenylethynyl groups to be parallel to each other, in a
pinched-cone conformation, analogous to those observed
for 7 and 8. The conformation of 14 is similar to that of
the wide-rim-substituted tetrakis-p-nitrophenylethynyl-
calix[4]arene compound recently described by Hennrich
and co-workers.20 As determined by X-ray crystallogra-
phy, the two pendant-type p-nitrophenylethynyl groups
in their compound and in our narrow-rim-substituted 14
are similarly oriented, having approximate “edge-to-face”
types of interactions, in which the twist angles in 14 are
80.8° as compared with the approximately 60° angle in
their compound.
The best yields of 13 and 14 (11% and 64%, respec-
tively) that we obtained required the use of 5 mol % of
both the Pd catalyst and the cocatalyst CuI, with 3 molar
equiv of DBU, in refluxing toluene. When several other
reaction condition modifications recently described by
others23 were tried with bistriflate 3 and 6d, they all
failed to produce any of the desired calixarene coupling
products, affording instead only 1,4-diphenyl-1,3-butadiyne
and recovered unreacted 3. However, in contrast to the
reactions of TMSA or 6b or 6c with 10, phenylacetylene
did produce 14 as the major product with 1,3-diiodo calix-
[4]arene 10 under the coupling conditions (Scheme 3).
Pd-CuI-catalyzed coupling reaction of 7 with phenyl-
acetylene (6d) (Scheme 1, reaction b) produced the
corresponding mixed bisethynyl product 7a in 54% yield.
When the same conditions were used with 8 and 6d
(Scheme 1, reaction c), product 7a was not formed,
affording only 1,4-diphenyl-1,3-butadiyne and unreacted
8. The reasons for this result can only be conjectured
upon at this stage, but a possible explanation is that
the steric hindrance due to the presence of both the
bulky TMS with the triflate groups on the same sub-
strate inhbits the formation of an intermediate in
When the monotriflate 5 instead was employed to effect
the same Pd-assisted Sonogashira coupling with TMSA,
none of the desired monocoupling product 17 was ob-
tained, producing only 1,4-bis(trimethylsilyl)-1,3-butadiyne
and 1. With 5 and phenylacetylene only 1,4-diphenyl-
1,3-butadiyne and 1 was formed. As a result of these
findings, subsequent narrow-rim transformations were
carried out via the synthetically more accessible bistri-
flate 3.
With synthetically useful amounts of 8 available,
removal of the TMS group was easily achieved using 1
equiv of tetrabutylammonium fluoride (TBAF) followed
by mild acid workup, to afford 15 (Scheme 4). Its 1H NMR
spectrum revealed, in addition to other signals due to a
minor component (see discussion below), two sets of AB
quartets centered at δ 3.87 and 4.02 ppm due to the
bridging methylene groups and three singlets at δ 0.90,
0.98 and 1.35 in a ratio of 1:1:2, respectively, due to the
tert-butyl groups. This is consistent for a structure that
is in a pinched-cone conformation similar to those ob-
served for 7, 8, and 14. A single-crystal X-ray structure,
however, showed a distinct unusual partial-cone (paco)
1
conformation (Figure 3). The H NMR spectrum of this
compound would be expected to have revealed four
singlets for the tert-butyl groups, which is not the case.
It is therefore possible that 15 crystallizes out in a
different conformation (i.e., paco-15) than that which
predominantly exists in solution, since the difference in
computed (MMFF) free energies between the paco and
pinched-cone conformations is only 1.2 kcal mol-1. The
mass and NMR spectra of a trace minor component
formed along with 15 is consistent with the 1,3-alternate
conformational isomer, 16.
Treatment of 8 with 2 equiv of TBAF, followed by mild
acid workup, resulted in both the removal of the TMS
group and cleavage of the triflate group to afford the
1
trihydroxy-ethynyl compound 17. The H NMR spectra
of 17 showed similarities to those of all of the other major
products formed in this study; however, no crystals
suitable for X-ray analysis could be obtained. This
compound was next subjected to Glaser homocoupling
(23) (a) Elangovan, A.; Wang, Y.; Ho, T. Org. Lett. 2003, 5, 1841-
1844. (b) Bhattacharya, S.; Sengupta, S. Tetrahedron Lett. 2004, 45,
8733-8736. (c) Liang, B.; Dai, M.; Chen, J.; Yang, Z. J. Org. Chem.
2005, 70, 391-393.
8276 J. Org. Chem., Vol. 70, No. 21, 2005

Narrow-Rim Functionalization of Calix[4]arenes
SCHEME 4a
a Conditions: (a) 1 equiv TBAF, THF, rt, 15 min; (b) 2 equiv TBAF, THF, rt, 15 min; (c) CuI (5 equiv), DBU (2.4 equiv), toluene, rt, 15
min.
determined by 1H NMR spectroscopy, no significant
complexation have yet been discerned with any of these
cationic or neutral guests.
Conclusions
We have shown for the first time that the Pd-catalyzed
Sonogashira reaction can now be extended to the direct
functionalization of the narrow rim of calix[4]arene.
While undoubtedly modifications in the future might lead
to better synthetic yields, the reactions demonstrated in
this paper show that reasonably useful synthetic yields
FIGURE 3. X-ray single-crystal PLUTO stereoview of paco-
15 in a partial cone conformation in which one pair of distal
of the narrow-rim alkynyl derivatives can be obtained.
Phenylacetylene is the most reactive of the terminal
alkynes examined in this study and also appears to be
the most robust toward the reaction conditions. Despite
the fact that preliminary studies have thus far failed to
reveal any significant complexation properties for this
biscalix[4]arene, this compound represents the first
example of a biscalixarene that has been formed by
directly linking two calixarenes at their narrow rims via
potentially modifiable hydrocarbon groups. Thus, the
molecular architectures of calixarenes can now be further
elaborated using the synthetic route that has been
opened up and described in this paper. Experiments are
currently underway to develop and extend the Sonogash-
ira coupling conditions to these and other calix[n]arenes
for further applications and studies, especially in the
context of the nonlinear optical (NLO) properties of
similar but wide-rim-substituted calix[4]arene com-
pounds recently demonstated by Hennrich and co-
workers.20
phenolic groups are anti to each other
conditions24 to produce the desired narrow-rim mono-
butadiyne-bridged biscalix[4]arene 18. The spectroscopic
and mass properties of 18 are consistent with the
proposed structure (Scheme 3). In particular, the 1H
NMR reveals signals that are consistent for each calix-
arene unit being in a cone-like conformation. The lowest
energy conformation predicted by MMFF molecular
modeling calculations25 is one in which the two calix-
arenes, each of which is in a pinched-cone conformation,
are situated directly above (eclipse) each other, most
likely as a result of hydrogen-bonding that can occur
between the hydroxy groups of each calixarene unit. The
intracalixarene O‚‚‚H bond distances are 1.67 and 1.73
Å, with the closest O‚‚‚H and O‚‚‚O bond distances
between the two calixarene units being 2.53 and 2.84 Å,
respectively. The rigid butadiyne linkage provides a near-
linear “spine” connecting the two calixarene units (Figure
4).
Complexation Studies
Experimental Section
Preliminary complexation tests with 18 were conducted
individually with NaI, KI, RbI, and HgCl2 in 1:1 methanol-
d4/CDCl3; with tetramethylammonium chloride or
CF3CO2Ag in neat CDCl3; with AgBF4 or AgClO4 in
CDCl3/acetone-d6; with CH3CN or hexamethylbenzene in
CDCl3; or with C60 in CS2 or toluene-d8 solutions. As
General Methods. For general experimental methods, see
ref 11. All of the 1H and 13C NMR spectra reported herein and
presented in Supporting Information were recorded at 500 and
125 MHz and in CDCl3.
(Trimethylsilyl)ethynyl-p-tert-butylcalix[4]arene Io-
dide 7 and (Trimethylsilyl)ethynyl-p-tert-butylcalix[4]-
arene Triflate 8. To a mixture of PdCl2(PPh3)2 (0.77 mg,
0.0011 mmol), CuI (42 mg, 0.22 mmol), and 3 (100 mg, 0.11
mmol) heated at reflux in toluene (10 mL) and with stirring
was added a solution of DBU (30 mg, 0.20 mmol) and 6a (26
mg, 0.26 mmol) in toluene (5 mL). The reaction mixture was
(24) (a) Glaser, C. Ber. Dtsch. Chem. Ges. 1869, 2, 422. (b) Glaser,
C. Ann. Chem. Pharm. 1870, 154, 137.
(25) Molecular modeling calculations were performed using Spartan
′04 for Windows.
J. Org. Chem, Vol. 70, No. 21, 2005 8277

Al-Saraierh et al.
FIGURE 4. Computer-generated (MMFF-minimized) structure of butadiyne-bridged biscalix[4]arene 18 showing the relative
orientation of the two calixarene units which are joined by the butadiyne backbone. Left: H atoms have been omitted from the
structure for clarity. Right: space-filling representation of the same minimized structure.
stirred for a further 0.5 h at the reflux temperature. The
solvent was evaporated on a rotary evaporator and the
resulting crude product was dissolved in CH2Cl2 (20 mL) and
washed with aqueous saturated NH4Cl (10 mL) and with H2O
(10 mL). The CH2Cl2 extracts was dried (MgSO4) and the
solvent was removed on a rotary evaporator to give the crude
product, which was purified by PLC (1:9 acetonitrile/hexanes)
to give the following compounds in order of increasing polarity.
7 (40 mg, 43%): 1H NMR δ 0.37 (s, 9H), 0.74 (s, 9H), 0.94 (s,
9H),1.34 (s, 18H), 3.54 (d, J ) 13.5 Hz, 2H), 3.65 (d, J ) 13.5
Hz, 2H), 4.49 (dd, J ) 14.5, 14.5 Hz, 4H), 5.18 (s, 2H, OH),
6.51 (s, 2H), 6.76 (s, 2H), 7.12 (s, 4H); 13C NMR δ 0.41, 30.85,
30.89, 31.99, 33.79, 34.18, 34.51, 36.95, 44.52, 60.61, 103.47,
104.51, 105.87, 118.32, 124.14, 125.51, 125.60, 125.82, 128.10,
129.95, 141.60, 142.47, 143.25, 149.44, 151.60; MS (APCI+) m/z
839.3 (M+), calcd for C49H63O2ISi 839.03. 8 (41 mg, 44%): 1H
NMR δ 0.39 (s, 9H), 0.78 (s, 9H), 0.93 (s, 9H),1.34 (s, 18H),
3.38 (d, J ) 13.5 Hz, 2H), 3.61 (d, J ) 14.0 Hz, 2H), 4.34 (d,
J ) 13.5 Hz, 2H), 4.40 (d, J ) 14.0 Hz, 2H), 5.41 (s, 2H, OH),
6.61 (s, 2H), 6.80 (s, 2H), 7.13 (s, 2H), 7.15 (s, 2H); 13C NMR
δ -0.11, 30.80, 30.93, 31.94, 32.07, 34.07, 34.18, 34.56, 36.72,
60.61, 103.15, 106.08, 117.13, 124.44, 125.57, 125.61, 126.51,
127.10, 129.10, 132.92, 141.44, 142.54, 142.73, 149.31, 150.78,
152.35; MS (APCI+) m/z 861.3 (M+), calcd for C50H63O5SiF3S
861.18.
X-ray Crystal Data for 7. Colorless crystal (MeOH/CHCl3),
mp 274-276 °C, C50H64O2ISiCl3, triclinic, space group P-1 (No.
2), Z ) 2, a ) 13.1511(9) Å, b ) 14.402(1) Å, c ) 15.419(1) Å,
R ) 87.811(1)°, â ) 76.823(1)°, γ ) 62.993(1)°. V ) 2526.3(3)
Å3, Dcalc ) 1.26 g cm 3, crystal size ) 0.60 × 0.28 × 0.05 mm3.
Intensity data were measured at 193 ( 1 K on a Bruker P4/
CCD diffractometer with graphite monochromated Mo KR (λ
) 0.71073 Å) radiation 2θmax ) 52.8°; 17987 reflections
converged to a final Rint of 0.035 for 10245 unique reflections
and 514 variable parameters and converged with unweighted
and weighted factors of R1 and wR2. Final R1 and wR2 values
were 0.064 and 0.180, respectively, and GOF ) 1.04.
X-ray Crystal Data for 8. Colorless crystal (MeOH/CHCl3),
mp 285-287 °C, C50H63O5SiF3S, triclinic space group P-1 (No.
2), Z ) 4, a ) 13.218(1) Å, b ) 18.086(1) Å, c ) 22.432(2) Å, R
) 106.191(1)°, â ) 90.743(1)°, γ ) 101.502(2)°. V ) 5033.1(6)
Å3. Dcalc ) 1.147 g cm-3, crystal size ) 0.42 × 0.21 × 0.19 mm3.
Intensity data were measured at 193 ( 1 K on a Bruker P4/
CCD diffractometer with graphite monochromated Mo KR (λ
) 0.71073 Å) radiation 2θmax ) 52.8°; 39051 reflections
converged to a final Rint of 0.048 for 20502 unique reflections
and 1108 variable parameters and converged with unweighted
and weighted factors of R1 and wR2. Final R1 and wR2 values
were 0.070 and 0.221, respectively, and GOF ) 1.03.
(Trimethylsilyl)ethynyl-phenylethynyl-p-tert-butyl-
calix[4]arene 7a. To a mixture of PdCl2(PPh3)2 (1.68 mg,
0.0024 mmol), CuI (0.45 mg, 0.0024 mmol), and 7 (40 mg, 0.048
mmol) heated at reflux in toluene (3.0 mL) and with stirring
was added a solution of DBU (14.6 mL, 0.096 mmol) and 6d
(6.0 mL, 0.055 mmol) in toluene (2.0 mL). The reaction mixture
was stirred for a further 3.0 h at the reflux temperature. The
solvent was evaporated on a rotary evaporator and the
resulting crude product was dissolved in CH2Cl2 (5.0 mL) and
washed with aqueous saturated NH4Cl (5.0 mL) and with H2O
(5.0 mL). The CH2Cl2 extracts were dried (MgSO4) and the
solvent was removed on a rotary evaporator to give the crude
product was purified by PLC (CH2Cl2/petroleum ether 3:7) to
give 7a (21 mg, 54%): 1H NMR δ 0.035 (s, 9H), 0.84 (s, 9H),
0.86 (s, 9H), 1.35 (s, 18H), 3.49 (d, J ) 14.5 Hz, 2H), 3.57 (d,
J ) 14.0 Hz, 2H), 4.55 (d, J ) 14.0, 2H), 4.72 (d, J ) 13.0,
2H), 5.46 (s, 2H, OH), 6.65 (s, 2H), 6.66 (s, 2H), 7.13 (s, 2H),
7.16 (s, 2H), 7.31 (m, 3H), 7.61 (dd, 2H); 13C NMR δ 0.22, 30.85,
31.99, 34.16, 34.34, 34.37, 36.71, 87.49, 97.41, 103.28, 119.03,
119.12, 123.99, 124.06, 124.23, 125.52, 128.20, 128.52, 128.64,
128.94, 131.83, 139.81, 141.43, 141.60, 142.29, 150.76, 150.99,
151.43 (one carbon is missing); MS (APCI+) m/z 813.6 (M+),
calcd for C57H68O2Si 813.25.
Iodo-p-tert-butylcalix[4]arene Triflate 9 and Diiodo-
p-tert-butylcalix[4]arene 10. To a stirred mixture of PdCl2-
(PPh3) (8.0 mg, 0.011 mmol), CuI (120 mg, 0.63 mmol), and
DBU (30 mg, 0.20 mmol) in toluene (25 mL) was added a
solution of 3 (100 mg, 0.11 mmol) in toluene (15 mL) over a
period of 1.0 h. The reaction mixture was then stirred for a
further 3.0 h at room temperature. The solvent was evaporated
on a rotary evaporator and the resulting crude product was
dissolved in CH2Cl2 (40 mL) and washed with aqueous
saturated NH4Cl (15 mL) and with H2O (20 mL). The CH2Cl2
extracts was dried (MgSO4) and the solvent was removed on
a rotary evaporator to give the crude product which was
purified by PLC (1:9 acetonitrile/hexane) to give the following
compounds in order of increasing polarity. 10 (60 mg, 64%):
1
mp 235-238 °C; H NMR δ 1.05 (s, 18H), 1.33 (s, 18H), 3.87
(d, J ) 14.0 Hz, 4H), 4.02 (s, 2H, OH), 4.10 (d, J ) 14.0 Hz,
4H), 6.92 (s, 4H), 7.20 (s, 4H); 13C NMR δ31.14, 31.85, 34.15,
45.64, 103.09, 126.37, 127.42, 128.61, 141.98, 143.87, 150.43,
151.85; MS (APCI+) m/z 868.0 (M+), calcd for C44H54O2I2
1
868.72. 9 (14 mg, 14%): mp 298-300 °C; H NMR δ 0.91 (s,
9H), 0.98 (s, 9H), 1.35(s, 18H), 3.49 (d, J ) 14.0 Hz, 2H), 3.82
(d, J ) 14.5 Hz, 2H), 4.06 (s, 2H, OH), 4.19(d, J ) 14.0 Hz,
2H), 4.29 (d, J ) 14.5 Hz, 2H), 6.76 (s, 2H), 6.85 (s, 2H), 7.18
(s, 2H), 7.19 (s, 2H); 13C NMR δ 30.93, 31.10, 31.85, 33.43,
34.06, 34.21, 34.35, 45.08, 104.07, 125.91, 126.16, 127.16,
127.50, 127.89, 128.17132.15, 133.26, 142.15, 142.99, 143.31,
150.59, 150.73, 151.00; MS (APCI+) m/z 890.3 (M+), calcd for
C44H54F3IO5S 890.88.
4-Hydroxybutynyl-p-tert-butylcalix[4]arene Triflate
11. To a stirred mixture of 3 (50 mg, 0.055 mmol), CuI (0.52
mg, 0.003 mmol), and PdCl2(PPh3)2 (0.77 mg, 0.0011 mmol)
in toluene (5 mL) was added a solution of 3-butyn-1-ol (6b)
(8.4 mg, 0.12 mmol) and DBU (30 mg, 0.20 mmol) in toluene
(5 mL) at reflux temperature in toluene (5 mL). The reaction
mixture was stirred for a further 2 h at the reflux temperature.
The solvent was evaporated on a rotary evaporator and the
resulting crude product was dissolved in CH2Cl2 (10 mL) and
washed with aqueous saturated NH4Cl (5 mL) and with H2O
(5 mL). The CH2Cl2 extracts was dried (MgSO4) and the solvent
was removed under vacuum to give the crude product which
8278 J. Org. Chem., Vol. 70, No. 21, 2005

Narrow-Rim Functionalization of Calix[4]arenes
was purified by PLC (6:1 petroleum ether/THF) to give 11 (14.5
monochromated Mo KR (λ ) 0.71073 Å) radiation 2θmax )
1
mg, 32%): mp 206-209 °C; H NMR δ 0.82 (s, 9H), 0.95 (s,
53.5°; 19123 reflections converged to a final Rint of 0.062 for
10209 unique reflections and 613 variable parameters and
converged with unweighted and weighted factors of R1 and
wR2. Final R1 and wR2 values were 0.070 and 0.205, respec-
tively, and GOF ) 1.01.
9H), 1.35 (s, 18H), 2.82(t, 2H), 3.00 (t, 1H, OH), 3.44 (d, J )
13.5 Hz, 2H), 3.62 (d, J ) 14.5 Hz, 2H), 3.94 (q, 2H), 4.29 (d,
J ) 13.5 Hz, 2H), 3.43 (d, J ) 14.5 Hz, 2H), 5.10 (s, 2H, OH),
6.68 (s, 2H), 6.82 (s, 2H), 7.15 (s, 2H), 7.17 (s, 2H); 13C NMR
δ24.59, 30.87, 30.94, 31.90, 31.94, 32.54, 34.24, 37.09, 34.50,
61.26, 98.93, 117.75, 124.45, 124.58, 125.65, 125.84, 125.92,
126.86, 128.34, 129.31, 132.96, 141.37, 142.55, 143.54, 150.30,
151.69; MS (APCI+) m/z 833.2 (M+), calcd for C49H59O6F3S
833.06.
Ethynyl-p-tert-butylcalix[4]arene Triflates 15 and 16.
To a stirred solution of 8 (20 mg, 0.023 mmol) in THF (2.0
mL) was added Bu4NF (6.1 mg, 0.023 mmol), and the reaction
mixture stirred, in a flask open to the air, for a further 15
min at room temperature. The solvent was evaporated on a
rotary evaporator and the resulting crude product was dis-
solved in CH2Cl2 (10 mL) and washed with aqueous 10% HCl
(5 mL). The CH2Cl2 extracts were dried (MgSO4) and the
solvent was removed on a rotary evaporator to give the crude
product which was purified by PLC (3:7 CH2Cl2 /petroleum
ether) to give the following compounds. 15 (9.0 mg, 49%): mp
156-157 °C; 1H NMR δ 0.88 (s, 9H), 0.97 (s, 9H), 1.34 (s, 18H),
3.45 (d, J ) 13.5 Hz, 2H), 3.65 (d, J ) 14.5 Hz, 2H), 3.68 (s,
1H), 4.24 (d, J ) 14.0 Hz, 2H), 4.35 (d, J ) 14.0 Hz, 2H), 4.65
(s, 2H, OH), 6.75 (s, 2H), 6.85 (s, 2H), 7.16 (s, 2H), 7.17 (s,
2H); 13C NMR δ 30.90, 31.04, 31.88, 31.93, 33.11, 34.18, 37.31,
34.59, 81.24, 87.30, 116.96, 120.14, 124.72, 125.85, 126.68,
126.96, 127.44, 128.28, 133.19, 142.29, 142.61, 142.80, 149.96,
150.70, 152.29; MS (APCI+) m/z 789.3 (M+), calcd for
C47H55F3O5S 789.01. 16 (traces): 1H NMR δ 0.89 (s, 9H), 1.02
(s, 9H), 1.35 (s, 18H), 3.56 (s, 1H), 3.63 (d, J ) 14.5 Hz, 2H),
3.76 (d, J ) 14 Hz, 2H), 4.33(m, 4H), 4.59 (s, 2H, OH), 6.72 (s,
2H), 6.87 (s, 2H), 7.14 (s, 2H), 7.19 (s, 2H); 13C NMR δ 30.98,
31.00, 31.92, 33.98, 34.15, 34.56, 37.69, 44.79, 57.55, 81.36,
86.76, 104.94, 117.13, 124.71, 125.88, 126.64, 127.21, 128.65,
142.23, 142.54,143.58, 149.95, 151.45, 151.70; MS (APCI+) m/z
789.5 (M+), calcd for C47H55F3O5S 789.01.
6-Hydroxybutynyl-p-tert-butylcalix[4]arene Triflate
12. To a stirred mixture of 3 (50 mg, 0.055 mmol), CuI (0.52
mg, 0.003 mmol), and PdCl2(PPh3)2 (0.77 mg, 0.001 mmol) in
toluene (5 mL) was added a solution of hexyn-1-ol (6c) (11.8
mg, 0.12 mmol) and DBU (30 mg, 0.20 mmol) in toluene (5
mL) at reflux temperature in toluene (5 mL). The reaction
mixture was stirred for a further 2 h at the reflux temperature.
The solvent was evaporated on a rotary evaporator and the
resulting crude product was dissolved in CH2Cl2 (10 mL) and
washed with aqueous saturated NH4Cl (5 mL) and with H2O
(5 mL). The CH2Cl2 extracts was dried (MgSO4) and the solvent
was removed under vacuum to give the crude product which
was purified by PLC (9:1 petroleum ether/THF) to give 12 (9.5
1
mg, 20%): mp 193-195 °C; H NMR δ 0.78 (s, 9H), 1.04 (s,
9H), 1.31 (s, 18H), 1.90(m, 2H), 2.21(m, 2H), 2.39 (m, 2H), 3.36
(d, J ) 13.0 Hz, 2H), 3.47 (d, J ) 14.0 Hz, 2H), 3.94 (d, J )
14.0 Hz, 2H), 4.16 (t, 2H), 4.39 (d, J ) 13 Hz, 2H), 6.64 (s,
2H), 6.66 (s, 2H), 6.92 (s, 2H, OH), 7.05 (s, 2H), 7.15 (s, 2H);
13C NMR δ 18.37, 24.86, 28.95, 30.89, 31.20, 31.92, 32.23,
32.32, 34.08, 34.38, 69.40, 83.62, 99.81, 117.84, 120.48, 124.99,
125.68, 125.92, 126.35, 126.54, 129.03, 132.24, 132.30, 133.29,
142.33, 142.43, 149.09, 149.10, 150.70; MS (APCI+) m/z 861.3
(M+), calcd for C51H63F3O6S 886.11.
X-ray Crystal Data for 16. Colorless crystal (MeOH/
CHCl3), C47H55O5F3S, monoclinic, space group P21/c (No. 14),
Z ) 4, a ) 14.056(1) Å, b ) 24.827(2) Å, c ) 12.300(1) Å, â)
92.362(2)°. V ) 4288.6(6) Å3, Dcalc ) 1.22 g cm-3, crystal size
) 0.34 × 0.34 × 0.16 mm3. Intensity data were measured at
193 ( 1 K on a Bruker P4/CCD diffractometer with graphite
Phenylethynyl-p-tert-butylcalix[4]arene Triflate 13
and Bis(phenylethynyl)-p-tert-butylcalix[4]arene 14. To
a stirred mixture of PdCl2(PPh3)2 (8.0 mg, 0.011 mmol), CuI
(100 mg, 0.53 mmol), DBU (70 mg, 0.46 mmol), and phenyl-
acetylene (6d) (26 mg, 0.26 mmol) in toluene (30 mL) was
added a solution of 3 (100 mg, 0.11 mmol) in toluene (10 mL)
at reflux temperature. The reaction mixture was stirred for a
further 4 h at the reflux temperature. The solvent was
evaporated on a rotary evaporator and the resulting crude
product was dissolved in CH2Cl2 (40 mL) and washed with
aqueous saturated NH4Cl (15 mL) and with H2O (20 mL). The
CH2Cl2 extracts was dried (MgSO4) and the solvent was
removed under vacuum to give the crude product which was
purified by PLC (3:7 CH2Cl2/petroleum ether) to give the
following compounds. 14 (55.0 mg, 61%): mp 241-244 °C; 1H
NMR δ 0.90 (s, 18H), 1.32 (s, 18H), 3.58(d, J ) 13.5 Hz, 4H),
4.61 (d, J ) 13.5 Hz, 4H), 5.50 (s, 2H, OH), 6.75 (s, 4H), 7.09
monochromated Mo KR (λ ) 0.71073 Å) radiation 2θmax
)
52.9°; 30523 reflections converged to a final Rint of 0.058 for
8789 unique reflections and 509 variable parameters and
converged with unweighted and weighted factors of R1 and
wR2. Final R1 and wR2 values were 0.106 and 0.294, respec-
tively, and GOF ) 1.13.
Ethynyl-p-tert-butylcalix[4]arene 17. To a stirred solu-
tion of 8 (20 mg, 0.023 mmol) in THF (5 mL) was added Bu4NF
(12.2 mg, 0.047 mmol) and the reaction stirred for a further
15 min at room temperature in a flask open to the air. The
solvent was evaporated on a rotary evaporator and the
resulting crude product was dissolved in CH2Cl2 (10 mL) and
washed with 10% HCl (5 mL). The CH2Cl2 extract was dried
(MgSO4) and the solvent was removed on a rotary evaporator
to give the crude product which was purified by PLC (3:7
CH2Cl2/petroleum ether) to give 17 (13 mg, 85%): mp 215-
217 °C; 1H NMR δ 1.07 (s, 9H), 1.18 (s, 9H), 1.25 (s, 18H),
3.46 (d, J ) 14.0 Hz, 2H), 3.64 (d, J ) 13.5 Hz, 2H), 3.78 (s,
1H, OH), 4.16 (d, J ) 14.0 Hz, 2H), 4.58 (d, J ) 13.5 Hz, 2H),
6.99 (s, 2H), 7.01 (s, 4H), 7.13 (s, 2H), 7.83 (s, 2H, OH); 13C
NMR δ 30.93, 31.59, 31.78, 32.79, 34.15, 34.21, 34.70, 36.62,
83.17, 85.15, 116.21, 125.13, 125.78, 125.91, 126.17, 126.91,
127.92, 128.19, 143.21, 143.36; MS (APCI+) m/z 657.3 (M+),
calcd for C46H56O3 656.95
Biscalix[4]arene 18. To a stirred solution of 17 (25 mg,
0.038 mmol) and CuI (30 mg, 0.16 mmol) in toluene (10 mL)
was added a solution of DBU (14 mg, 0.091 mmol) in toluene
(2 mL) at room temperature. The reaction mixture was stirred
for a further 15 min at room temperature temperature. The
solvent was evaporated on a rotary evaporator and the
resulting crude product was dissolved in CH2Cl2 (15 mL) and
washed with aqueous 10% HCl (5 mL). The CH2Cl2 extracts
(t, 4H), 7.14 (s, 4H), 7.23 (t, 2H), 7.45 (d, J ) 8.00 Hz, 4H); 13
C
NMR δ 30.92, 31.95, 34.15, 34.41, 37.06, 87.31, 97.55, 118.99,
123.51, 124.34, 125.64, 128.17, 128.43, 128.63, 131.74, 141.67,
142.35, 150.95, 151.37; MS (APCI+) m/z 817.5 (M+), calcd for
C60H64O2 817.16. 13 (10.1 mg, 11%): mp >310 °C; 1H NMR δ
0.91 (s, 9H), 1.01(s, 9H), 1.27(s, 18H), 3.55 (d, J ) 14.0 Hz,
2H), 3.65 (d, J ) 14.5 Hz, 2H), 4.36 (d, J ) 14.0 Hz, 2H), 4.45
(d, J ) 14.5 Hz, 2H), 4.91 (s, 2H, OH), 6.78 (s, 2H), 6.88 (s,
2H), 7.12(s, 2H), 7.13 (s, 2H), 7.33 (m, 3H), 7.54 (t, 2H), 13C
NMR δ 31.01, 31.06, 31.68, 31.84, 34.07, 34.09, 34.54, 36.55,
37.73, 86.76,118.65, 120.04, 122.31, 123.30, 124.61, 125.98,
126.39, 126.44, 12.85, 128.35, 128.57, 130.68, 131.91, 137.83,
141.99, 142.36, 148.53, 151.18, 151.38; MS (APCI+) m/z 865.4
(M+), calcd for C53H59F3O5S 865.10.
X-ray Crystal Data for 14. Colorless prism crystal (MeOH/
CHCl3), C60H64O2, I-centered monoclinic, space group Ia (No.
9), Z ) 4, a ) 11.757(4) Å, b ) 46.19(1) Å, c ) 9.611(3) Å, â )
106.585(5)°. V ) 5002(2) Å3, Dcalc ) 1.08 g cm-3, crystal size )
0.56 × 0.52 × 0.17 mm3. Intensity data were measured at 193
( 1 K on a Bruker P4/CCD diffractometer with graphite
J. Org. Chem, Vol. 70, No. 21, 2005 8279

Al-Saraierh et al.
was dried (MgSO4) and the solvent was removed on a rotary
evaporator to give the crude product which was purified by
PLC (1:1 CH2Cl2/petroleum ether) to give 18 (17 mg, 68%):
Acknowledgment. Financial support by the
Natural Sciences and Engineering Research Council
of Canada (NSERC) and Memorial University of
Newfoundland is gratefully acknowledged.
1
mp 161-164 °C. H NMR δ 1.09(s, 9H), 1.18 (s, 9H), 1.24(s,
18H), 3.38 (d, J ) 13.0 Hz, 2H), 3.69 (d, J ) 14.0 Hz, 2H),
4.26 (d, J ) 14.0 Hz, 2H), 4.74 (d, J ) 14.0 Hz, 2H), 6.99 (s,
4H), 7.03 (s, 2H), 7.14, 8.11(s, 2H, OH), 9.55 (s, 2H, OH); 13C
NMR δ 30.95, 31.62, 31.00, 32.89, 34.17, 34.19, 34.85, 36.66,
81.06, 116.25, 125.18, 125.78, 125.95, 125.99, 127.19, 128.10,
128.12, 133.85, 143.36, 143.61, 144.45, 147.61, 149.32, 152.77;
MS (APCI+) m/z 1312.7 (M+), calcd for C92H110O6 1311.88.
Supporting Information Available: Spectral data for all
new compounds and X-ray crystallographic data in CIF format
for 7, 8, 14, and 16. This material is available free of charge
via the Internet at http://pubs.acs.org.
JO050488S
8280 J. Org. Chem., Vol. 70, No. 21, 2005