One-pot synthesis of macrocyclic di-and tetralactones using [2+2] photocycloaddition reactions of di-2-pyrones with α,ω-diolefins

Article abstract of DOI:10.3987/COM-11-12378

Sensitized photocycloaddition reactions of 6,6'-dimethyl-4,4'-[1,4- bis(methylenoxy)phenylene]-di-pyrone (1) with poly(ethyleneglycol)divinyl ethers (2a, b) or 2,2'-dimethyltrimethylene dimethacrylate (4), together with the reactions of 6,6'-dimethyl-4,4'-polymethylenedioxy-2-pyrones (6a, b) with 4 were described. The reactions of 1 with 2a, b gave crown ether type macrocyclic compounds (3a and 3a' (isomer of 3a), 3b and 3b' (isomer of 3b)) possessing 19-and 22-membered rings across the C3-C4 and C3'-C4' double bonds in 1, respectively. Similar reactions of 1 with 4 and 6a, b with 4 afforded different types of macrocycles (5 and 5', 7a, b and 7a', b') having 19- to 21-membered rings across the C5-C6 and C5'-C6' double bonds in 2-pyrone ring. The stereochemical features of 3a' and 5 were determined by X-ray crystal analysis. The reaction mechanism was inferred by MO methods.

Full text of DOI:10.3987/COM-11-12378

HETEROCYCLES, Vol. 85, No. 2, 2012
333
HETEROCYCLES, Vol. 85, No. 2, 2012, pp. 333 - 343. © 2012 The Japan Institute of Heterocyclic Chemistry
Received, 26th October, 2011, Accepted, 8th December, 2011, Published online, 12th December, 2011
DOI: 10.3987/COM-11-12378
ONE-POT SYNTHESIS OF MACROCYCLIC DI- AND TETRA-
LACTONES USING [2+2] PHOTOCYCLOADDITION REACTIONS OF
DI-2-PYRONES WITH ,-DIOLEFINS
Hui Min Zhang, Kazuya Kawabata, Hideki Miyauchi, and Tetsuro Shimo*
Department of Chemistry, Biotechnology and Chemical Engineering, Graduate
School of Science and Engineering, Kagoshima University, Korimoto 1-21-40,
Kagoshima 890-0065, Japan
Abstract – Sensitized photocycloaddition reactions of 6,6’-dimethyl-4,4’-[1,4-
bis(methylenoxy)phenylene]-di-pyrone (1) with poly(ethyleneglycol)divinyl
ethers (2a, b) or 2,2’-dimethyltrimethylene dimethacrylate (4), together with the
reactions of 6,6’-dimethyl-4,4’-polymethylenedioxy-2-pyrones (6a, b) with 4
were described. The reactions of 1 with 2a, b gave crown ether type macrocyclic
compounds (3a and 3a’ (isomer of 3a), 3b and 3b’ (isomer of 3b)) possessing 19-
and 22-membered rings across the C3−C4 and C3’−C4’ double bonds in 1,
respectively. Similar reactions of 1 with 4 and 6a, b with 4 afforded different
types of macrocycles (5 and 5’, 7a, b and 7a’, b’) having 19- to 21-membered
rings across the C5−C6 and C5’−C6’ double bonds in 2-pyrone ring. The
stereochemical features of 3a’ and 5 were determined by X-ray crystal analysis.
The reaction mechanism was inferred by MO methods.
INTRODUCTION
The synthesis of macrocyclic ring systems is an important area in organic chemistry. There are several
strategies to prepare macrocyclic compounds, including cyclization, capping and condensation using
thermal reactions.1 Photochemical reactions are also an effective approach.2 Although the [2+2]
cycloaddition reaction is a useful method in the synthesis of a variety of macrocycles with one or two
cyclobutane rings,3 little attention has been paid to the synthesis of macrocyclic compounds from the
sequential inter- and intramolecular [2+2] photocycloaddition reactions between substrates possessing
two enones and , -diolefins, because of the predicted complications with several reactions. We have
recently succeeded in accomplishing a one-pot synthesis of macrocyclic compounds from the sequential
inter- and intramolecular [2+2] photocycloadditions of di-2-pyrones with ,-diolefins,4 together with an

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HETEROCYCLES, Vol. 85, No. 2, 2012
MO analysis that the origin of a remarkable change in regioselectivities of the inter- and intramolecular
photocycloadditions.5 We planned to extend the one-pot synthesis of macrocyclic compounds to
di-2-pyrone tethered by the p- position of the benzene ring (1) and polymethylenedioxy-di-2-pyrones (6a,
b) to investigate the generality of the sequential inter- and intramolecular photoreactions with
electron-rich and electron-poor ,-diolefins (2a, b and 4) .
RESULTS AND DISCUSSION
p-Di-2-pyrone (1) was prepared from dehydrochlorination of 4-hydroxy-6-methyl-2-pyrone with
1,4-bis(chloromethyl)benzene using 1,8-diazabicyclo[5.4.0]-7-undecene in 30% yield. Polymethylene-
dioxy-di-2-pyrones (6a, b) were prepared according to the method previously described in the literature.6
A solution of 1 (20 mM) with two equivalents of di(ethyleneglycol)divinyl ether (2a) in acetonitrile was
irradiated in the presence of benzophenone as a sensitizer with a 300 W high-pressure mercury lamp
using a UV cutoff filter under 320 nm and under a nitrogen atmosphere. The reaction was followed by
TLC and 24 h irradiation was required to fully convert the entire starting compound 1. An amount of two
equivalents of 2a was required because of the polymerization of 2a by irradiation. After removal of the
solvent, the oily residue was chromotographed by silica gel (eluent: ethyl acetate/hexane = 2:1, v/v) to
afford a mixture of 3a and 3a’ (1:1) (3,4-3,4-[2+2] cycloadducts) in 20% yield, which were the major
1
products from H NMR spectra of the reaction mixture, together with a complex mixture that we were
unable to isolate (Scheme 1).
Me
O
hv (>320nm)
O
O
O
+
3
O
Ph2C=O / MeCN
O
4
O
O
n
2a
2b
: n=2
: n=3
O
1
5
6
Me
10
Me
12Me
Me
O
Me
O
9
17
O
O
O
2
32(35) 33(36)
O
H
O
H
O
O
O
O
15
1
6
7
H
H
+
20
21
30(33)
31(34)
O
23O
O
O
H
H
H
H
O
O
24
3,4-3,4-[2+2]adducts
n-1
n-1
3a
3b
: n=2 (10%)
: n=3 (14%)
3a'
3b'
: n=2 (10%)
: n=3 (14%)
C2 symmetry
Cs symmetry
Me
Me
Me Me
hv (>320nm)
O
O
+
1
Ph2C=O / MeCN
O
O
4
10
12
9
O
O
O
O
O
O
O
13
16
30
31
O7
O
O
O
6
3
O
2
1
20 19
Me
H
H
Me
Me
H
H
Me
21
29
Me Me
Me Me
32
33
O
O
O
O
27
23
Me
Me
Me
Me
25
O
O
O
O
5,6-5,6-[2+2]adducts
5 (15%)
C2 symmetry
5' (15%)
Cs symmetry
Scheme 1

HETEROCYCLES, Vol. 85, No. 2, 2012
335
The isomers of 3a and 3a’, having C2 symmetry and Cs symmetry, respectively, were separated by
recrystallization from acetonitrile/chloroform (2:1, v/v). The structure of 3a’ was confirmed as the
regioselective
[2+2]
cycloadduct,
4,17-dimethyl-3,7,14,18,23,26,29-heptaoxahexacyclo-
[29.29,12.0.01,6.06,30.015,20.015,22]tritriaconta-4,9,11,16,32-pentaen-2,19-dione (22-exo, 30-exo adduct),
across the C3-C4 and C3’-C4’ double bonds in 1 with two olefin parts in 2a by X-ray crystallographic
analysis (Figure 1). The ORTEP drawing of 3a’ shows a 19-membered ring structure with two
cyclobutane rings. Another product 3a was estimated as the facial selective isomer at the C3−C4 and
1
C3’-C4’ double bonds in 1 with 2a because this compound gave similar H NMR spectral data as
acquired for 3a’. The stereochemistry of 3a’ in each cyclobutane ring was the exo conformation between
3,4-dihydropyrone ring and the alkoxy group, as determined from the X-ray structural analysis. The result
of the similar photoreaction of 1 with 2b is summarized in Table 1. The stereochemistry of each product
(3b, 3b’) was estimated to be C2 symmetry and Cs symmetry, respectively, from the comparison of the 1H
NMR data with those of 3a and 3a’.
Figure 1. ORTEP drawing of 3a'
Table 1. Photoreaction of di-2-pyrones (1, 6a, b) with electron-rich (2a, b) or electron-poor diolefins
(4)
Product (yield, %)
Conversion
of 1, 6a, b
(%)
Irradiation
time (h)
Di-2-pyrones
Diolefins
3,4-3,4-[2+2]
5,6-5,6-[2+2]
Adducts
Adducts
1
1
2a
2b
4
24
26
20
18
18
90a
99a
3a(10), 3a'(10)a
‐
3b(14), 3b'(14)a
‐
1
100b
77b
‐
‐
‐
5(15), 5'(15)b
7a(11.5),7a'(11.5)b
7b(12.5),7b'(12.5)b
6a
6b
4
4
75b
a Estimated from NMR spectral analyses using internal standard (benzophenone).
b Estimated from NMR spectral analyses using internal standard (fumaronitrile).

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HETEROCYCLES, Vol. 85, No. 2, 2012
Photoreaction of 1 with 2, 2’-dimethyltrimethylene dimethacrylate (4) was also carried out in the same
reaction conditions mentioned above. After removal of the solvent, the oily residue was chromatographed
by silica gel (eluent: ethyl acetate/hexane = 2:1, v/v) to afford a 1:1 mixture of 5 and 5’ (exo-exo
5,6-5,6-[2+2] cycloadducts) in 30% yield. Compounds 5 and 5’ were separated by fractional
recrystallization from acetonitrile. The structure of 5 was confirmed as the regioselective [2+2]
cycloadduct, 2,19,21,25,25,29-hexamethyl-3,7,14,18,23,27-hexaoxahexacyclo[27.230,31.12,29.119,21.0.01,6.
015,20]nonacosa-5,9,11,15,30-pentaen-4,17,22,28-tetraone (21-exo, 29-exo adduct, C2 symmetry), across
the C5−C6 and C5’−C6’-double bonds in 1 with two olefin parts in 4 by X-ray crystallographic analysis
(Figure 2).
Figure 2. ORTEP drawing of 5
The ORTEP drawing of 5 shows the 21-membered ring structure. Another product 5’ was estimated as the
facial selective isomer (Cs symmetry) at the C5−C6 and C5’−C6’ double bonds in 1 with 4 because these
compounds showed similar spectral properties to the NMR data of 5. The chemical shifts of the methyl
groups at the 25-position of 5 and 5’ showed  0.44 (5),  0.26 and 0.52 (5’), respectively, owing to the
shielding effect of the benzene ring in 5 and 5’. Photoreaction of 6a (n=5) with 4 was also carried out in
the same reaction conditions mentioned above. After removal of the solvent, the oily residue was
chromatographed by silica gel (eluent: ethyl acetate/hexane = 3:1, v/v) to afford a 1:1 mixture of 7a and
7a’ (exo-exo 5,6-5,6-[2+2] cycloadducts) in 23% yield (Scheme 2). Product 7a was isolated by
recrystallization from acetonitrile, but unfortunately it was hard to obtain as a single crystal. The structure
of 7a was estimated as the regioselective [2+2] cycloadduct, 2,18,20,24,24,28-hexamethyl-3,7,13,17,22,

HETEROCYCLES, Vol. 85, No. 2, 2012
337
26-hexaoxapenta-cyclo[26.12,28.118,20.0.01,6.014,19]octacosa-5,14-dien-4,16,21,27-tetraone (20-exo, 27-exo
adduct, C2 symmetry) from the comparison of the 1H-NMR spectral data with 5 and 5’. Another product
7a’ was estimated as the facial selective isomer (Cs symmetry). The result of the similar photoreaction of
6b (n=6) with 4 is summarized in Table 1. Unfortunately a mixture of [2+2] cycloadducts 7b and 7b’
were difficult to isolate despite many crystallization trials. Since the yields of the macrocyclic compounds
3, 5, 7 were relatively low (20−30%), we considered the formation of the other stereoisomers of the
macrocycles possessing two cyclobutane rings, oxetanes between di-2-pyrones and benzophenone
(sensitizer),7 and inter- or intramolecular [2+2] photocycloadducts of di-2-pyrones6 in this system.
Me
O
O
n
Me
hv (>320nm)
4
+
Ph2C=O / MeCN
O
O
O
O
6a : n=5
6b : n=6
O
O
O
3O
O
5
7
13(14)
17(18)
O
O
O
n
O
O
O
n
O
2
6
19(20)
1
Me
Me
Me
Me
H
H
H
H
29(30)
30(31)
20(21)
28(29)
Me
O
Me
O
Me
Me
24(25)
O
O
O
O
O
O
Me Me 22(23)
5,6-5,6-[2+2]adducts
Me Me
7a'
7b'
: n=5 (11.5%)
: n=6 (12.5%)
7a
7b
: n=5 (11.5%)
: n=6 (12.5%)
C2 symmetry
Cs symmetry
Scheme 2
We next describe the photocycloaddition mechanism using the PM5 level.8 Figure 3 shows energies and
coefficients of the higher singly occupied molecular orbital (HSOMO) and lower ones (LSOMO) of the
triplet states by means of the PM5 level, and those of the LUMO and HOMO of the ground states of two
,-diolefins, 2 and 4, by means of the PM5 level. Since these photoadditions were sensitized by a triplet
sensitizer (benzophenone), they were inferred to proceed via a two-step radical path, and that the first
steps were mainly influenced by the energies and coefficients of the two frontier orbitals, respectively.
The reasonable processes via radical intermediates (I and II in Figure 4) are inferred from the narrow gap
() of the energies and the large coefficients (Ci and Cr) between two substrates are quantitatively
confirmed by the large two-center frontier orbital interactions in Table 2.

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HETEROCYCLES, Vol. 85, No. 2, 2012
Me
5
6
Me
O
Et
O
Me
eV
4
O
Et
-0.69
O
0.16
1.0
O
-0.65
3
O
LUMO
0
-0.3
HSOMO
-3.7
-6.4
-5
LSOMO
-9.2
-10
-10.9
HOMO
5
6
Me
O
Me
Me
4
O
Et
O
3
Et
O
-0.69
O
-0.64
0.63
O
Figure 3. Estimated energies and coefficients of triplet 2-pyrones and
ground state olefins by means of PM5 level5
O-R2
O
3a,b , 3a',b'
O
R1
Me
O
R1
O
5,5' and 7a,b , 7a',b'
Me
OR3
O
Figure 4.
Two types of intermediate structures

HETEROCYCLES, Vol. 85, No. 2, 2012
339
Table 2. Estimated frontier orbital interactions between 2-pyrones and olefins by the PM5
calculation (γ2/eV)
2
4
Position
C3 -Cβ a
C6 - Cβ b
4.7
C3 -Cβ
4.5
C6 - Cβ
3.4
2.8
2-pyrone 
(CiCr)2/
0.067
0.003
0.043
0.059
a Left : LSOMO (2-pyrone) - HOMO (2 or 4) interaction.
b Right: HSOMO (2-pyrone) - LUMO (2 or 4) interaction.
Interactions, (CiCr)2/(in 2/eV), have a tendency to be larger between C3 (2-pyrone) and C(olefin 2),
or C6 (2-pyrone) and C(olefin 4) than others. In the concrete, with 2 having an electron-donating group,
the C3-C interactions between the LSOMO and HOMO are larger than others, and with 4 having an
electron-withdrawing group, the C6-C interactions between the HSOMO and LUMO are relatively large.
The photoreactions of 1 with 2, and 1 or 6 with 4 are strongly supported to go through the respective
intermediates (I and II) in Figure 4. In summary, sensitized photocycloaddition reactions of p-di-2-pyrone
(1) with electron-rich ,-diolefins (2a, b) gave crown ether-type macrocyclic compounds (3a, b) across
the C3-C4 and C3’-C4’ double bonds in 1 with two olefin parts in 2a, b, having 19- and 22-memered
rings. On the other hand, similar photoreactions of 1 or polymethylene dioxy-di-2-pyrones (6a, b) with
electron-poor ,-diolefin (4) afforded macrocyclic dioxatetralactones (5 and 7) across the C5-C6 and
C5’-C6’ double bonds in 1 or 6 with two olefin parts in 4 having 19- to 21-membered rings. A sequential
inter- and intramolecular [2+2] photocycloaddition mechanism in this system was reasonably interpreted
by an MO analysis.
EXPERIMENTAL
All melting points were measured on Yanagimoto Melt-tem apparatus and uncorrected. NMR spectra
were measured at 400MHz on the JNM GSX-400 (TMS as an internal standard). IR spectra were
recorded with a JASCO IR Report-100spectrometer. Mass spectra were recorded with a JEOL
JMS-HX110A (FABMS) using m-nitrobenzyl alcohol as matrix. Elemental analysis was made using a
Yanaco MT-5. Single crystal X-ray diffraction analyses of 3a’, 5, and 7a were performed on a Rigaku
RAXIS-RAPID imaging plate diffractometer with graphite monochromated Mo K radiation. Lorentz
and polarization corrections were applied to the intensity data. The structures were solved by direct
methods using SHELX-979 or SIR 9210 and refined by a full-matrix least-squares method. The
non-hydrogen atoms were refined anisotopically. All calculations were performed using the teXsan11
crystallographic soft ware package. Photoirradiations were carried out in the Pyrex tube using 300 W
high-pressure mercury lamp. Wakogel C200 was used for preparative column chromatography.

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HETEROCYCLES, Vol. 85, No. 2, 2012
6,6’-Dimethyl-4,4’-[1,4-bis(methylenoxy)phenylene]-di-2-pyrone (1) ….. To a refluxing MeCN (200
mL) solution of 4-hydroxy-6-methyl-2-pyrone (20.0 g, 160 mmol) and DBU (26.2 g, 170 mmol) was
slowly added 1,4-bis(chloromethyl)benzene 14.0 g, 80 mmol) and refluxing was continued for 72 h. After
cooling to room temperature, the reaction mixture was evaporated in vacuo and the resulting oily residue
was dissolved in CHCl3 (200 mL). To the concentrate was added acetic acid and water, and the mixture
was stirred for 1 h at room temperature. The mixture was washed with brine, dried with anhydrous
magnesium sulfate, and filtered. The filtrate was concentrated to dryness under reduced pressure, and the
residue was recrystallized from MeCN to give 1 (8.21 g, 30%).
1
1: mp 210−212 ºC. H NMR (CDCl3) 2.22 (6H, s, Me), 5.03 (4H, s, CH2), 5.48, 5.85 (each 2H, d, J =
1.6 Hz, CH), 7.41 (4H, s, Ar-H). IR (KBr) 1710, 1640 cm-1. LR MS m/z 355 (MH+). Anal. Calcd for
C20H18O6: C, 67.79, H, 5.12. Found: C, 67.66, H, 5.16).
4,17-Dimethyl-3,7,14,18,23,26,29-heptaoxahexacyclo[29.29,12.0.01,6.06,30.015,20.015,22]tritriaconta-
4,9,11,16,32-pentaen-2,19-dione (22-exo, 30-exo adduct) (3a) (C2 symmetry) and (3a’) (Cs
symmetry) ….. To a solution of 1 (1.42 g, 4.00 mmol) with di(ethyleneglycol)divinyl ether (2a) (1.22 g,
8.02 mmol) in MeCN (200 mL) was irradiated in the presence of benzophenone (0.327 g, 1.80 mmol) for
24 h. After removal of the solvent, the oily residue was chromatographed by silica gel (eluent:
EtOAc/hexane = 2:1, v/v) to give a mixture of 3a and 3a’ (1:1) (369 mg, 20% yield). Compound 3a’ was
separated by recrystallization from a mixture of MeCN and CHCl3 (2:1).
3a: oil. 1H NMR (CDCl3)  2.04 (2H, m, CH2), 2.05 (6H, s, Me), 2.16 (2H, t, J =12.8 Hz, CH2), 3.28-3.40
(2H, m, CH2), 3.48 (2H, t, J = 9.6Hz, CH), 3.59-3.73 (2H, m, CH2), 3.70 (2H, d, J = 5.2 Hz, CH), 4.19
(2H, d, J = 10.8 Hz, CH2), 4.47 (2H, d, J = 10.8 Hz, CH2), 5.06 (2H, s, CH), 7.32 (4H, Ar-H). IR (neat)
1760, 1685 cm-1. LR MS m/z 513 (MH+). HR MS (MH+) calcd for C28H33O9 513.2125. found: 513.2094.
1
3a’: mp 231−233 ºC. H NMR (CDCl3) 2.04 (6H, s, Me), 2.09 (2H, ddd, J = 12.4, 9.6, 5.6 Hz, CH2),
2.19 (2H, dd, J = 12.4, 9.6 Hz, CH2), 3.17 (2H, ddd, J = 13.2, 7.6, 5.2 Hz, CH2), 3.28 (2H, ddd, J = 13.2,
7.6, 6.0 Hz, CH2), 3.39 (2H, dt, J = 7.6, 5.2 Hz, CH2), 3.45 (2H, dt, J = 7.6, 6.0 Hz, CH2), 3.59 (2H, t, J =
9.6 Hz, CH), 3.77 (2H, d, J = 5.6 Hz, CH), 4.15 (2H, d, J = 10.0 Hz, CH2), 4.36 (2H, d, J = 10.0 Hz, CH2),
4.95 (2H, s, CH), 7.33 (4H,s, Ar-H). IR (KBr) 1760, 1695 cm-1. LR MS m/z 513 (MH+). Anal. Calcd for
C28H32O9: C, 65.61, H, 6.29. Found: C, 65.59, H, 6.15.
X-Ray crystal data for 3a’ (C28H32O9): M = 512.54, crystal dimensions 0.54x0.42x0.38 mm3,
orthorhombic, space group Pnma, a = 8.32670(10) Å, b = 31.8091(4) Å, c = 10.0349(2) Å,  = 90 º,  =
90 º,  = 90 º, V = 2657.89(7) Å3, Z = 4, calc = 1.281 mg/m3, 2max = 55.0 º, T = 113(2) K, R = 0.0417, Rw
= 0.1190, GOF = 1.162.
4,17-Dimethyl-3,7,14,18,23,26,29,32-octaoxahexacyclo[32.29,12.0.01,6.06,33.015,20.015,22]hexatriaconta-
4,9,11,16,35-pentaen-2,19-dione (22-exo, 33-exo adduct) (3b) (C2 symmetry) and (3b’) (Cs
symmetry) ….. To a solution of 1 (0.708 g, 2.00 mmol) with tri(ethyleneglycol)divinyl ether (2b) (0.724

HETEROCYCLES, Vol. 85, No. 2, 2012
341
g, 3.58 mmol) in MeCN (200 mL) was irradiated in the presence of benzophenone (0.364 g, 2.00 mmol)
for 7 h. After removal of the solvent, the oily residue was chromatographed by silica gel (eluent:
EtOAc/hexane = 2:1, v/v) to give a mixture of 3b and 3b’ (1:1) (308 mg, 28% yield). Compounds 3b and
3b’ were separated by recrystallized from a mixture of MeCN and CHCl3 (2:1).
1
3b: mp 196−199 ºC. H NMR (CDCl3) 2.04 (6H, s, Me), 2.16 (2H, ddd, J = 12.8, 10.4, 5.6 Hz, CH2),
2.31 (2H, t, J = 12.8 Hz, CH2), 3.40-3.62 (8H, m, CH2), 3.56 (2H, dd, J = 12.8, 10.4 Hz, CH), 3.74 (2H,
m, CH2), 3.88 (2H, d, J = 5.6 Hz, CH), 3.99 (2H, m, CH2), 4.12 (2H, d, J = 11.2 Hz, CH2), 4.42 (2H, d, J
= 11.2 Hz, CH2), 4.98 (2H, s, CH), 7.33 (4H,s, Ar-H). IR (KBr) 1763, 1689 cm-1. LR MS m/z 557 (MH+).
HR MS (MH+) calcd for C30H37O10 557.2387. found: 557.2354. Anal. Calcd for C30H36O10: C, 64.74, H,
6.52. Found: C, 64.56, H, 6.57.
1
3b’: mp 222−226 º. H NMR (CDCl3) 2.04 (6H, s, Me), 2.17 (2H, ddd, J = 12.8, 10.4, 5.6 Hz, CH2),
2.31 (2H, t, J = 12.8 Hz, CH2), 3.40-3.63 (8H, m, CH2), 3.59 (2H, dd, J = 12.8, 10.4 Hz, CH), 3.74 (2H,
m, CH2), 3.89 (2H, d, J = 5.6 Hz, CH), 3.99 (2H, m, CH2), 4.19 (2H, d, J = 11.2 Hz, CH2), 4.37 (2H, d, J
= 11.2 Hz, CH2), 4.94 (2H, s, CH), 7.35 (4H,s, Ar-H). IR (KBr) 1757, 1684 cm-1. LR MS m/z 557 (MH+).
HR MS (MH+) calcd for C30H37O10 557.2387. found: 557.2390. Anal. Calcd for C30H36O10: C, 64.74, H,
6.52. Found: C, 64.24, H, 6.62.
2,19,21,25,25,29-Hexamethyl-3,7,14,18,23,27-hexaoxahexacyclo[27.230,31.12,29.119,21.0.01,6.015,20]nona-
cosa-5,9,11,15,30-pentaen-4,17,22,28-tetraone (21-exo, 29-exo adduct) (5) C2 symmetry) and (5’) (Cs
symmetry) ….. To a solution of 1 (0.893 g, 2.52 mmol) with 2,2’-dimethyltrimethylene dimethacrylate
(4) (1.01 g, 4.21 mmol) in MeCN (200 mL) was irradiated in the presence of benzophenone (0.204 g,
1.12 mmol) for 18 h. After removal of the solvent, the oily residue was chromatographed by silica gel
(eluent: EtOAc/hexane = 2:1, v/v) to give a mixture of 5 and 5’ (1:1) (449 mg, 30% yield). A mixture of
compounds 5 and 5’ was separated by recrystallized from a mixture of MeCN and CHCl3 (1:1).
5: mp 251−254 ºC. 1H NMR (CDCl3) 0.44, 1.37, 1.53 (each 6H, s, Me), 2.25 (2H, d, J = 13.2 Hz, CH2),
2.83 (2H, d, J = 13.2 Hz, CH2), 3.18 (2H, s, CH), 3.57, 3.75 (each 2H, d, J = 10.8 Hz), 4.84, 4.93 (each
2H, d, J = 10.4 Hz), 5.49 (2H, s, CH). IR (KBr) 1730, 1703, 1628 cm-1. LR MS m/z 595 (MH+), Anal.
Calcd for C33H38O10·CH3CN: C, 65.79, H, 6.53, N, 1.99. Found: C, 66.10, H, 6.51, N, 2.20.
X-Ray crystal data for 5 (C33H38O10·CH3CN) : M = 635.70, crystal dimensions 0.20 x 0.10 x 0.10 mm3,
monoclinic, space group C2/c (#15), a = 33.161(10) Å, b = 9.219(3) Å, c = 11.998(4) Å,  = 108.6990
(19) º, V = 3474.5(18) Å3, Z = 5, calc = 1.454 g/cm3, 2max = 55.0 º, T = 123 K, R = 0.0817, Rw = 0.2257,
GOF = 1.057.
5’: oil. 1H NMR (CDCl3) 0.26 , 0.52 (each 3H, s, Me), 1.41, 1.53 (each 6H, s, Me), 2.26, 2.83 (each 2H,
d, J = 13.6 Hz, CH2), 3.16 (2H, s, CH), 3.54, 3.76 (each 2H, d, J = 10.8 Hz, CH2), 4.84, 4.89 (each 2H, d,
J = 9.6 Hz, CH2), 5.50 (2H, s, CH), 7.42 (4H, s, Ar-H). IR (KBr) 1720, 1703, 1622 cm-1. LR MS m/z 595
(MH+). HR MS (MH+) calcd for C33H39O10 595.2543. found: 595.2520.

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HETEROCYCLES, Vol. 85, No. 2, 2012
2,18,20,24,24,28-Hexamethyl-3,7,13,17,22,26-hexaoxapentacyclo[26.12,28.118,20.0.01,6.014,19]octacosa-
5,14-dien-4,16,21,27-tetraone (20-exo, 27-exo adduct) (7a) (C2 symmetry) and (7a’) (Cs symmetry)
….. To a solution of 6a (0.640 g, 2.00 mmol) with 4 (0.724 g, 3.00 mmol) in MeCN (100 mL) was
irradiated in the presence of benzophenone (0.182 g, 1.00 mmol) for 10 h. After removal of the solvent,
the oily residue was chromatographed by silica gel (eluent: EtOAc/hexane = 1:1, v/v) to give a mixture of
7a and 7a’ (1:1) (198 mg, 23% yield). Compound 7a was separated by fractional recrystallization from
MeCN.
7a: mp 272−274 ºC. 1H NMR (CDCl3) 1.01 (2H, m, CH2), 1.04, 1.33, 1.52 (each 6H, s, Me), 1.76 (4H,
m, CH2), 2.32 (2H, d, J = 13.2 Hz, CH2), 2.64 (2H, dd, J = 13.2, 1.2 Hz, CH2), 3.45 (2H, s, CH), 3.80 (2H,
d, J = 11.2 Hz, CH2), 3.92 (4H, m, CH2), 4.14 (2H, d, J = 11.2 Hz, CH2), 5.28 (2H, s, CH). IR (KBr) 1731,
1705, 1627 cm-1. LR MS m/z 561 (MH+). HR MS (MH+) calcd for C30H41O10 561.2700. found: 561.2690.
Anal. Calcd for C30H40O10: C, 64.23, H, 7.14. Found: C, 64.51, H, 6.95.
7a’: mixture with 7a. 1H NMR (CDCl3) 1.01 (2H, m, CH2), 1.04, 1.32, 1.54 (each 6H, s, Me), 1.76 (4H,
m, CH2), 2.29 (2H, d, J = 13.2 Hz, CH2), 2.74 (2H, dd, J = 13.2, 1.2 Hz, CH2), 3.37 (2H, s, CH), 3.90 (2H,
d, J = 10.8 Hz, CH2), 3.95 (4H, m, CH2), 4.06 (2H, d, J = 10.8 Hz, CH2), 5.28 (2H, s, CH).
2,19,21,25,25,29-Hexamethyl-3,7,14,18,23,27-hexaoxapentacyclo[27.12,29.119,21.0.01,6.015,20]nonacosa-
5,15-dien-4,17,22,28-tetraone (21-exo, 28-exo adduct) (7b) (C2 symmetry) and (7b’) (Cs symmetry)
….. To a solution of 6b (0.670 g, 2.00 mmol) with 4 (0.723 g, 3.00 mmol) in MeCN (100 mL) was
irradiated in the presence of benzophenone (0.180 g, 1.00 mmol) for 24 h. After removal of the solvent,
the oily residue was chromatographed by silica gel (eluent: EtOAc/hexane = 1:1, v/v) to give a mixture
of 7b and 7b’ (1:1) (215 mg, 25% yield), whose compounds were difficult to separate each other by
recrystallization.
7b and 7b’ (1:1 mixture): 1H NMR (CDCl3) 1.00 (4H, m, CH2), 1.04, 1.36, 1.53 (each 6H, s, Me), 1.73
(4H, m, CH2), 2.27 (2H, d, J = 13.2 Hz, CH2), 2.78 (2H, d, J = 13.2 Hz, CH2), 2.80 (2H, d, J = 13.2 Hz,
CH2), 3.30 (2H, s, CH), 3.90 (4H, m, CH2), 4.05, 4.07 (4H, d, J = 11.2 Hz, CH2), 5.29 (2H, s, CH). IR
(KBr) 1713, 1631 cm-1. LR MS m/z 575 (MH+). HR MS (MH+) calcd for C31H43O10 575.2856. found:
575.2845.
ACKNOWLEDGEMENT
The authors are grateful to Professor Shinmyozu (Institute for Materials Chemistry and Engineering,
Kyushu University) for the measurements of the single crystal X-ray diffraction.
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