Origins of selectivity for the [2+2] cycloaddition
of α,β-unsaturated ketones within a porous
self-assembled organic framework.
Jun Yang,a Mahender B. Dewal,a Salvatore Profeta Jr.,a Mark D. Smith,a Youyong Li,b
and Linda S. Shimizua*.
a
Department of Chemistry and Biochemistry, University of South Carolina, Columbia,
SC 29208,
b
Materials and Process Simulation Center, California Institute of Technology, CA 91125.
[email protected]
Supporting Information
S1
1
UV-Visible absorbance study of host 1 and enone guest.
To test if the host 1 absorbs UV light in the same range as the guest enones, we measured the
UV-Visible absorbance of host and guest. A comparison of the UV absorbance of the bis-urea
macrocycle (host 1) and 2-cyclohexenone in DMSO is shown in Figure S1. The host 1 shows only
weak absorbance in the 300-380 nm range, typically used to facilitate [2+2] cycloadditions.
UV-Visible absorbance
0.20
bis-urea macrocycle (1 mM)
A
0.15
2-cyclohexenone (1 mM)
0.10
0.05
0.00
300.0
350.0
400.0
450.0
wavelength (nm)
Figure S1. Comparison of UV-Visible absorbance of host 1 in DMSO versus 2-cyclohexenone in
DMSO.
2
Characterization of [2+2] cycloaddition of 2-cyclohexenone 5 in the presence of host 1.
For enones, the intersystem crossing is efficient and [2+2] cycloaddition of enones was believed
to occur through triplet excited state and the exo had-to-head and exo head-to-tail products were the
major products.1 We also characterized [2+2] cycloaddition products of other enones based on
literature reports, 1H NMR, molecular weight and the order of elution in GC-MS.2
Scheme S1. Photodimerization of 2-cyclohexenone 5 in the presence and absence of host 1.
O
O
H
H
H
H
O
H H
hv
5
O
two minor products
5a
H H
O
5b
major pproducts exo
without host 1:
with host 1:
35%
96%
49%
3%
16%
1%
[2+2] cycloaddition of neat liquid of 2-cyclohexenone 5 (control) and 2-cyclohexenone in the
presence of host 1 were carried out using a Hanovia medium-pressure 450 W mercury arc lamp cooled
in a borosilicate immersion well, and the entire apparatus was placed in a UV shielded and
refrigerated reaction chamber. After the irradiation, the control was dissolved in CDCl3. A small
amount of the solution was taken and characterized by GC-MS. There are 4 peaks for dimeric
products, displaying molecular weight 192. No starting material was observed. The remainder of the
solution was purified via column chromatography with EtOAc/Hexane (1:4) and 3 products were
isolated. These three products were further characterized by 1H NMR, 13C NMR and GC-MS. The
S2
host 1•2-cyclohexenone crystals were shaken with 1 mL of CDCl3 for 1 h. Analysis of the CDCl3
filtrate by GC-MS showed that the exo HT product 5a was the major product. The structure of
standard HT dimer 5a was confirmed as cis-anti-cis-tricyclo (6.4.0.02.7)dodecane-3,9-dione by X-ray
crystallography.3 A small sample of the complex was also dissolved directly in d6-DMSO for
comparison. The HT dimer 5a had shorter retention time by GC-MS (Figure S3) than exo HH product
5b because of their difference on the dipole moment. The HH product 5b was reported to be the major
product when 2-cyclohexenone 5 is irradiated in polar solvent or with inorganic zeolites.4
photolysis product
with host 1
Ha
O
Hb
Ha Hb
5a
Hb Ha
Ha
O
Hb
Ha Ha
O
O
5b
Hb Hb
Figure S2. 1H NMR of photolysis product of 2-cyclohexenone 5 with the presence of host 1 and two
isolated major dimers from the control.
5a cis-anti-cis-tricyclo(6.4.0.02.7)dodecane-3,9-dione: pale yellow solid; 1H NMR (300 MHz,
CDCl3): δ 1.67, (m, 2H), 1.88-1.96, (m, 6H), 2.24, (m, 2H), 2.40, (m, 2H), 2.64, (t, J = 7.2, 7.5 Hz,
2H), 3.02 ppm, (m, 2H); 13C NMR (75 M Hz, CDCl3): δ 21.7, 27.3, 38.6, 40.4, 47.8, 213.4; MS (m/z)
192 (42) [M+], 68 (100), 96 (35), 150 (34); HRMS calcd for C12H16O2 192.1150, found 192.1146.
Photolysis product from
host 1
5b
5a
photolysis of liquid
2-cyclohexenone control
dimer 5a isolated by column
chromatography
5a
Figure S3. GC-MS spectra of photolysis product of 2-cyclohexenone 5 with the presence of host 1
and isolated major dimer 5a from the control.
S3
3
Characterization of [2+2] cycloaddition reaction of 3-methyl-2-cyclopentenone 6 in the
presence of host 1.
[2+2] cycloaddition of 3-methyl-2-cyclopentenone in the presence of host 1 was carried out using
a Hanovia medium-pressure 450 W mercury arc lamp cooled in a borosilicate immersion well, and the
entire apparatus was placed in a UV shielded and refrigerated reaction chamber. After the irradiation,
the complex, crystals were either dissolved directly into d6-DMSO or shaken with 1 mL of CDCl3 for
1 h. Analysis of the CDCl3 filtrate by GC-MS showed that the exo head-to-tail product was the only
major product. A small amount of starting enone (20%) was also observed.
Scheme S2. Photodimerization of 3-methyl-2-cyclopenenone 6 in the presence and absence of host 1.
O
O
H
O
H H
O
O
H
O
H H
O
O
O
O
hv
H
24 h
6
O
6a
H
6b
6c
O
O
a
6d
a
6e
a
6f
a
4 minor products
major products
without host 1:
(30% conversion)
27%
52%
13%
with host 1:
(80% conversion)
98%
2.0%
<1%
a:
H
4 minor products were cited from literature.5
6a 1,6-dimethyl-cis-anti-cis-tricyclo[5.3.0.02,6]decane-3,8-dione: 1H NMR (300 MHz, CDCl3): δ
1.16, (m, 6H), 1.87-1.97, (m, 2H), 2.10-2.20, (m, 2H), 2.34, (s, 2H), 2.42-2.49 ppm, (m, 4H); 13C
NMR (75 MHz, CDCl3): δ 22.8, 37.4, 39.3, 41.0, 59.7, 219.3; MS (m/z) 192 (15) [M+], 96 (100), 97
(85), 81 (25), 108 (20).
O
O
H CH3
CH3
H3C H
O
a
b
Figure S4. 1H NMR of the host 1•3-methyl-2-cyclopentenone 6 inclusion complex a) before UV
irradiation and b) after 24 hours of UV irradiation.
S4
O
O
H CH3
H3C H
O
Figure S5. GC-MS spectra of cycloaddition products of 3-methyl-2-cyclopentenone 6 from the host 1
complex after UV irradiation and extraction.
X-ray crystal structure of 6a 1,6-dimethyl-cis-anti-cis-tricyclo[5.3.0.02,6]decane-3,8-dione: X-ray
diffraction intensity data from a colorless prism crystal were measured at 150(1) K using a Bruker
SMART APEX diffractometer (Mo Kα radiation, λ = 0.71073 Å).6 Several crystals were surveyed,
all of which were found to be twinned. The crystal selected for data collection was composed of two
domains. Identification of the twinning and derivation of the twin law which transforms the indices
of one domain into those of the other was performed with the Bruker program Cell_Now.6 The twin
law is
0
⎛ −1
⎜
−1
0
⎜
⎜ − 0.476 − 0.827
⎝
0⎞
⎟
0⎟
1 ⎟⎠
which corresponds to a 180° rotation about the reciprocal [001] axis. Integration of the twinned raw
data frames was performed with SAINT+.6 Reflection files for structure solution (SHELX HKLF 4
format) and twin refinement (SHELX HKLF 5 format) were created with TWINABS.6 Final unit
cell parameters were determined by least-squares refinement of 2043 strong reflections from the major
domain. Direct methods structure solution, difference Fourier calculations and full-matrix
least-squares refinement against F2 were performed with SHELXTL.7 The major twin fraction
refined to 0.730(1).
The compound crystallizes in the triclinic system. The space group P⎯1 was confirmed by the
successful solution and refinement of the data. The asymmetric unit consists of one complete
molecule. All non-hydrogen atoms were refined with anisotropic displacement parameters.
Hydrogen atoms were located in difference maps before being placed in geometrically idealized
positions and included as riding atoms with refined isotropic displacement parameters.
S5
Crystal data and structure refinement for 1,6-dimethyl-cis-anti-cis-tricyclo[5.3.0.02,6]-
Table S1.
decane-3,8-dione 6a.
Identification code
6a
Empirical formula
C12 H16 O2
Formula weight
192.25
Temperature
150(1) K
Wavelength
0.71073 Å
Crystal system
Triclinic
Space group
P⎯1
Unit cell dimensions
a = 6.4403(12) Å
α= 74.611(3)°.
b = 6.8554(12) Å
β= 78.455(3)°.
γ = 67.987(3)°.
Volume
c = 12.826(2) Å
502.97(16) Å3
Z
2
Density (calculated)
Absorption coefficient
1.269 Mg/m3
0.085 mm-1
F(000)
208
Crystal size
0.32 x 0.14 x 0.10 mm3
Theta range for data collection
1.66 to 24.15°.
Index ranges
-7<=h<=7, -7<=k<=7, 0<=l<=14
Reflections collected
1899
Independent reflections
1899 [R(int) = 0.0000]
Completeness to theta = 24.15°
99.7 %
Absorption correction
None
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
Goodness-of-fit on F2
1899 / 0 / 146
1.151
Final R indices [I>2sigma(I)]
R1 = 0.0452, wR2 = 0.1183
R indices (all data)
R1 = 0.0502, wR2 = 0.1213
0.313 and -0.181 e.Å-3
Largest diff. peak and hole
S6
4
Characterization of [2+2] cycloaddition reactions of 2-methyl-2-cyclopentenone 7 in the
presence of host 1.
[2+2] cycloaddition of 2-methyl-2-cyclopentenone in the presence of host 1 was carried out using
a Hanovia medium-pressure 450 W mercury arc lamp cooled in a borosilicate immersion well, and the
entire apparatus was placed in a UV shielded and refrigerated reaction chamber. After the irradiation,
the complex, crystals were either dissolved directly into d6-DMSO or shaken with 1 mL of CDCl3 for
1 h. The CDCl3 filtrate was used for GC-MS. The analysis shown that the [2+2] cycloaddition of
2-methyl-2-cyclopentenone 7 in the presence of host 1 resulted in the mixture of 80% of exo HT
product 7a and 20% of exo HH product 7b.
Scheme S3. Photodimerization of 2-methyl-2-cyclopentenone 7 in the presence and absence of host 1.
O
O
O
H
O
hv
24 h
H
7
O
H H
7a
7b
without host 1:
(27% conversion)
28%
72%
with host 1:
(95% conversion)
80%
20%
7a 2,7-dimethyl-cis-anti-cis-tricyclo[5.3.0.02,6]decane-3,8-dione: 1H NMR (300 MHz, CDCl3): δ
1.26, (m, 6H), 1.97-2.02, (m, 4H), 2.33-2.38, (m, 4H), 2.48-2.52 ppm, (m, 2H); MS (m/z) 192 (25)
[M+], 97 (100), 96 (65), 164 (25), 107 (20).
7b 1,2-dimethyl-cis-anti-cis-tricyclo[5.3.0.02,6]decane-3,10-dione: 1H NMR (300 MHz, CDCl3): δ
1.12, (m, 6H), 2.02-2.07, (m, 4H), 2.34-2.44, (m, 4H), 2.55-2.58 ppm, (m, 2H); MS (m/z) 192 (88)
[M+], 96 (100), 97 (58), 68 (44), 107 (25).
O
O
O
H
H
O
O
H H
Figure S6. 1H NMR (d6-DMSO) of the host 1•2-methyl-2-cyclopentenone 7 inclusion complex a)
before UV irradiation and b) after 24 hours of UV irradiation.
S7
O
H
H
O
O
O
O
H H
Figure S7. GC-MS spectra of cycloaddition products of 2-methyl-2-cyclopentenone 7 from the host 1
complex after UV irradiation and extraction.
X-ray crystal structure of 7a 2,7-dimethyl-cis-anti-cis-tricyclo[5.3.0.02,6]decane-3,8-dione: X-ray
diffraction intensity data from a colorless plate crystal were measured at 150(1) K using a Bruker
SMART APEX diffractometer (Mo Kα radiation, λ = 0.71073 Å).4 Raw area detector data frame
integration was performed with SAINT+.6 Final unit cell parameters were determined by least-squares
refinement of 2964 strong reflections from the data set. Direct methods structure solution, difference
Fourier calculations and full-matrix least-squares refinement against F2 were performed with
SHELXTL.7
The compound crystallizes in the space group P21/n as determined uniquely by the pattern of
systematic absences in the intensity data. The asymmetric unit consists of half of one molecule
located on a crystallographic inversion center. All non-hydrogen atoms were refined with
anisotropic displacement parameters. Hydrogen atoms were located in difference maps before being
placed in geometrically idealized positions and included as riding atoms with refined isotropic
displacement parameters.
S8
Crystal data and structure refinement for 2,7-dimethyl-cis-anti-cis-tricyclo[5.3.0.02,6]-
Table S2.
decane-3,8-dione 7a.
Identification code
7a
Empirical formula
C12 H16 O2
Formula weight
192.25
Temperature
150(1) K
Wavelength
0.71073 Å
Crystal system
Monoclinic
Space group
P21/n
Unit cell dimensions
a = 7.0223(7) Å
α= 90°.
b = 6.4259(7) Å
β= 99.693(2)°.
γ = 90°.
Volume
c = 10.9846(11) Å
488.60(9) Å3
Z
2
Density (calculated)
Absorption coefficient
1.307 Mg/m3
0.087 mm-1
F(000)
208
Crystal size
0.48 x 0.30 x 0.12 mm3
Theta range for data collection
3.22 to 25.00°.
Index ranges
-8<=h<=8, -7<=k<=7, -13<=l<=13
Reflections collected
4987
Independent reflections
867 [R(int) = 0.0578]
Completeness to theta = 25.00°
100.0 %
Absorption correction
None
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
Goodness-of-fit on F2
867 / 0 / 73
1.062
Final R indices [I>2sigma(I)]
R1 = 0.0400, wR2 = 0.1037
R indices (all data)
R1 = 0.0431, wR2 = 0.1068
0.307 and -0.181 e.Å-3
Largest diff. peak and hole
S9
5
Characterization of [2+2] cycloaddition reactions of small enones in the presence of host 1.
a.
Host 1 was treated with acrylic acid 2 vapor for 24 hours forming host 1•acrylic acid
complex (3:2 stoichiometry). The host•guest complex was irradiated under UV lamp for
24 h and 1H NMR showed only peaks corresponding to host 1 and acrylic acid 2,
indicating that no reaction occurred.
O
HO
a
b
Figure S8. 1H NMR of the host 1•acrylic acid inclusion complex a) before UV irradiation and b) after
24 hours of UV irradiation.
b.
Host 1 was treated with methylvinyl ketone for 24 hours forming host 1•MVK complex
(5:2 stoichiometry). The host•guest complex was irradiated under UV lamp for 24 hours
and 1H NMR showed only peaks corresponding to host 1 and MVK 3, indicating that no
reaction occurred.
O
a
b
Figure S9. 1H NMR of the host 1•methylvinyl ketone inclusion complex a) before UV irradiation and
b) after 24 hours of UV irradiation.
S 10
c.
Host 1 was treated with 2-cyclopentenone 4 vapor for 7 days forming host
1•2-cyclopetenone complex (1:2 stoichiometry). The host•guest complex was irradiated
under UV lamp for 24 hours and 1H NMR showed only peaks corresponding to host 1 and
2-cyclopentenone 4, indicating that no reaction occurred.
O
a
b
Figure S10. 1H NMR of the host 1•2-cyclopentenone inclusion complex a) before UV irradiation and
b) after 24 hours of UV irradiation.
6
Characterization of [2+2] cycloaddition reactions of large enones in the presence of host 1.
a.
Mesityl oxide 8 has the calculated molecular volume of 107 Å3. Host 1 was treated with
mesityl oxide vapor for 24 hours forming host 1•mesityl oxide complex (5:1 stoichiometry).
The host•guest complex was irradiated under UV lamp for 24 hours and 1H NMR showed
only peaks corresponding to host 1 and mesityl oxide 8, indicating that no reaction
occurred.
O
a
b
Figure S11. 1H NMR of the host 1•mesityl oxide inclusion complex a) before UV irradiation and b)
after 24 hours of UV irradiation.
S 11
b.
2,3-dimethyl-2-cyclopentenone 9 has the calculated molecular volume of 114 Å3. Host 1
was treated with 2,3-dimethyl-2-cyclopentenone 9 for 7 days forming host
1•2,3-dimethyl-2-cyclopentenone complex (2:3 stoichiometry). The host•guest complex
was irradiated under UV lamp for 24 hours and 1H NMR showed a complex mixture of
isomers was obtained. Further GC-MS analysis showed that the mixture contained 8
isomers with the expected molecular weight (220 g/mol).
O
a
b
Figure S12. 1H NMR of the host 1•2,3-dimethyl-2-cyclopetenone inclusion complex a) before UV
irradiation and b) after 24 hours of UV irradiation.
products extracted from host 1
Control
O
O
O
O
Figure S13. GC-MS spectra of cycloaddition products of 2,3-dimethyl-2-cyclopentenone 9 from the
host 1 complex after UV irradiation and extraction.2
S 12
7
haracterization of [2+2] cycloaddition reactions of large enones with the presence of host 1,
which were not able to be bound with host 1.
a.
TGA study of host 1 after soaking in 3-methyl-2-cyclohexenone 6.
Large size cyclic enones were not bound by vapor treatment of the host 1. We tested if the host
would absorb these enones from the liquid state. For example host 1 was immersed in
3-methyl-2-cyclohexenone 6 liquid for 2 hours. After filtration and air dry for 5 minutes, the resulted
solid were used for TGA study. TGA desorption curve showed that the weight loss was observed
immediately at room temperature and was dependent on the air drying time, indicating that no stable
inclusion complex was formed. This result suggested that the enone molecules are coated on the outer
surface of the microporous crystals instead of filled inside the cavities.
1
0.9
Weight loss (%)
0.8
0.7
0.6
0.5
0.4
0.3
20
40
60
80
100
120
Temperature (°C)
Figure S14. TGA desorption of host 1•3-methyl-2-cyclohexenone 6 mixture.
b.
3-methyl-2-cyclohexenone 10 has calculated molecular volume as 114 Å3 and was not
able to form host•guest complex by vapor treatment with the empty host. The crystalline
host 1 was soaked in 3-methyl-2-cyclohexenone liquid for 2 h then recovered by filtration
and air dried. The host•guest mixture was irradiated under UV for 24 hours. After
irradiation, 1H NMR of the mixture showed mixture of isomers had been obtained. Further
GC-MS analysis indicated that the percentage of each isomer is similar to the control.8
O
a
b
Figure S15. 1H NMR of the host 1•3-methyl-2-cyclohexenone mixture 10 a) before UV irradiation
and b) after 24 hours of UV irradiation.
S 13
O
O
H
H
H H
O
O
O
Figure S16. GC-MS spectra of cycloaddition products of 3-methyl-2-cyclohexenone 10 from the host
1•3-methyl-2-cyclohexenone mixture after UV irradiation and extraction.
c.
4,4-dimethyl-2-cyclohexenone 11 has calculated molecular volume as 130 Å3 and was not
able to form host•guest complex by vapor treatment with the empty host. The crystalline
host 1 was soaked in 4,4-dimethyl-2-cyclohexenone liquid for 2 h then recovered by
filtration and air dried. The host•guest mixture was irradiated under UV for 24 hours.
After irradiation, 1H NMR of the mixture showed mixture of isomers had been obtained.
Further GC-MS analysis indicated that the percentage of each isomer is similar to the
control.9
O
a
b
Figure S17. 1H NMR of the host 1•4,4-dimethyl-2-cyclohexenone 11 mixture a) before UV
irradiation and b) after 24 hours of UV irradiation.
S 14
O
O
H H
H H
O
O
H H
O
H H
Figure S18. GC-MS spectra of cycloaddition products of 4,4-dimethyl-2-cyclohexenone 11 from the
host 1•4,4-dimethyl-2-cyclohexenone mixture after UV irradiation and extraction.
d.
3,5-dimethyl-2-cyclohexenone 12 has calculated molecular volume as 131 Å3 and was not
able to form host•guest complex by vapor treatment with the empty host. The crystalline
host 1 was soaked in 3,5-dimethyl-2-cyclohexenone liquid for 2 hours then recovered by
filtration and air dried. The host•guest mixture was irradiated under UV for 24 hours.
After irradiation, 1H NMR of the mixture showed mixture of isomers had been obtained.
Further GC-MS analysis indicated that the percentage of each isomer is similar to the
control.8,10
O
a
b
Figure S19. 1H NMR of the host 1•3,5-dimethyl-2-cyclohexenone 12 mixture a) before UV
irradiation and b) after 24 hours of UV irradiation.
S 15
O
H
H
O
O
O
H H
O
Figure S20. GC-MS spectra of cycloaddition products of 3,5-dimethyl-2-cyclohexenone 12 from the
host 1•3,5-dimethyl-2-cyclohexenone mixture after UV irradiation and extraction.
8
Table of indexes and d spacing of powder X-ray diffraction of the host 1•enone guest
complexes before [2+2] cycloaddition reactions.
S 16
9
Powder X-ray diffraction of the host 1•enone guest complexes after [2+2] cycloaddition
reactions.
After irradiation of host 1•enone inclusion complexes, the resulted solids were investigated by
powder X-ray diffraction. The irradiated host 1•2-cyclohexenone complex showed a well defined
powder patterns, which are distinct from the complex before irradiation, indicative of well ordered and
highly crystalline form.
Figure S21. Powder X-ray diffraction of host 1•2-cyclohexenone complex before reaction and after
24 hours of UV irradiation.
The irradiated complex host 1•3-methyl-2-cyclopentenone showed a well defined powder
patterns indicative of well ordered and highly crystalline form.
Figure S22. Powder X-ray diffraction of host 1•3-methyl-2-cyclopentenone complex before reaction
and after 24 hours of UV irradiation.
S 17
10 he relationship between TGA data and physical properties of guest molecules.
We compared the TGA data (temperature at half guest is lost, T1/2) with some physical properties
of the guest molecules by plotting T1/2 vs dipole moment of guest molecule (Figure S23a) and T1/2 vs
boiling point of guest molecule (Figure S23b). T1/2 appeared to be loosely correlated with the dipole
moments of the guest molecules. No correlation was apparent between T1/2 and the boiling points of
the enone guests. These results suggest that the dipole-dipole interaction is an important driving force
for guest binding.
Table S3. Correlation between T1/2 with guest dipole moment and guest boiling point.11-13
a
b
T 1/2 vs guest boiling point
T 1/2 vs guest dipole moment
100
100
7
95
4
4
90
90
6
85
T 1/2 ( C)
3
80
5
8
75
6
85
3
o
T 1/2 (oC)
7
95
2
80
5
8
75
2
70
70
65
65
60
60
1
2
3
4
50
5
100
150
200
o
Boiling point ( C)
dipole moment of enones (D)
Figure S23. a) Plot of T1/2 versus guest dipole moment; b) Plot of T1/2 versus guest boiling point.
S 18
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