Controlled [3+2] and [2+2] Cycloadditions of 1,3-Bifunctional Allenes with C60 by Using a Flow Reaction System

Article abstract of DOI:10.1002/ejoc.201901072

The reaction of 1,2-diaryl-1,2-diketones, propiolic acid esters, and C₆₀ in the presence of Et₃N gave cyclopentene-annulated fullerenes through a [3+2] cycloaddition. They were formed in two Et₃N-promoted steps, namely, th

Full text of DOI:10.1002/ejoc.201901072

A Journal of
Accepted Article
Title: Controlled [3+2] and [2+2] Cycloadditions of 1,3-Bifunctional
Allenes with C60 by Using a Flow Reaction System
Authors: Mitsuhiro Ueda, Miho Hayama, Hiroyuki Hashishita, Aiko
Munechika, and Takahide Fukuyama
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10.1002/ejoc.201901072
European Journal of Organic Chemistry
COMMUNICATION
Controlled [3+2] and [2+2] Cycloadditions of 1,3-Bifunctional
Allenes with C60 by Using a Flow Reaction System
Mitsuhiro Ueda,*[a] Miho Hayama,[a] Hiroyuki Hashishita,[a] Aiko Munechika,[a] and Takahide
Fukuyama[a]
Dedication ((optional))
Abstract: The reaction of 1,2-diaryl-1,2-diketones, propiolic acid
esters, and C60 in the presence of Et3N gave cyclopentene-
annulated fullerenes via [3+2] cycloaddition. They were formed in
two Et3N-promoted steps, namely, the generation of 1,3-bifunctional
allenes and the cycloaddition of 1,3-bifunctional allenes with C60.
Interestingly, when a similar reaction was conducted using a flow
packed-bed reactor in combination with a silica-supported tertiary
amine, cyclobutane-annulated fullerenes were obtained via [2+2]
cycloaddition.
Results and Discussion
We commenced our next study by investigating the reaction of
1,3-bifunctional allenes, which are generated in situ by the Et3N-
catalyzed reaction of 1,2-diaryl-1,2-diketones with propiolic acid
esters6 and C60. Contrary to our expectation, cyclopentene-
annulated fullerene 4a was formed as the major product instead
of 3a (3a:4a = 4:96, Table 1, entry 1).7 A previous study has
reported the formation of mono- and di-substituted
cyclopentene-annulated fullerenes via phosphine-catalyzed
[3+2] cycloadditions of allenoates with C60 (Scheme 2).8 Our
present findings provide access to further variations of
functionalized cyclopentene-annulated fullerenes (Table 1).
Optimization of the reaction conditions suggested that 4a was
selectively formed by the reaction in o-dichlorobenzene (ODCB)
using 1 equiv Et3N at 27 °C for 20 min (entry 3).
Introduction
Ring-annulated fullerenes such as [6,6]-phenyl-C61-butyric acid
methyl ester (PCBM) exhibit outstanding performance as
materials for organic solar cells1 and organic-inorganic
perovskite solar cells.2 Their potential as materials for
photovoltaics (PV) has triggered the development of efficient
methods for the synthesis of novel ring-annulated fullerenes.3,4,5
In our previous work, we found that the allenol esters, which
were generated in situ by the Pt-catalyzed 1,3-acyloxy migration
of propargylic esters, reacted with C60 to give cyclobutane-
annulated fullerenes as [2+2] cycloaddition products (Scheme
1).3 The cyclobutane-annulated fullerenes were found to exhibit
excellent performances as materials for organic photovoltaics
(OPV) rather than PCBM-based devices. This inspired us to
investigate other multi-substituted ring-annulated fullerenes.
Table 1. Reaction of the In Situ Generated 1,3-Bifunctional Allene (from 1a
a
and 2a) with C60
Ph
O
Ph
O
O
O
Ph
O
O
Ph
NEt3
Ph
+
+
+
Ph
OMe
ODCB
27 °C, time
O
CO2Me
CO2Me
3a
1a (3 equiv) 2a (3 equiv)
0.02 M
4a
O
Ph
Ph
•
O
CO2Me
1,3-bifunctional allene
Scheme 1. [2+2] Cycloaddition of the In Situ Generated Allenol Ester with C60
Equiv of
NEt3
Entry
Time
HPLC area (%)b
(Previous Work)
3a
2
4a
53
Othersc
C60
40
20
62
Ph
Ph
Ph
Bu
TsOH
•
+
1
2
3
0.3
1
4 h
4 h
5
12
2
Bu
BocO Bu
PtCl2
O
BocO
(10 mol %)
4
60
higher Voc and FF
(compared to PC61BM)
Ph
: open-circuit voltage
: fill factor
* Voc
FF
BocO
1
20 min
0
36 (32)d
Bu
[a] Reaction conditions: C60 (0.15 mmol), 1a (3 equiv), 2a (3 equiv), ODCB
(7.5 mL), temperature: 27 °C. [b] Determined by the ratio of HPLC peak area.
[c] Multiple cycloaddition products. [d] Isolated yield of 4a.
Scheme 2. Phosphine-Catalyzed [3+2] Cycloaddition of Allenoates with C60
[a]
Dr. Mitsuhiro Ueda,* Miho Hayama, Hiroyuki Hashishita, Aiko
Munechika, Takahide Fukuyama
Department of Chemistry, Graduate School of Science,
Osaka Prefecture University
Sakai, Osaka 599-8531, Japan
E-mail: ueda@c.s.osakafu-u.ac.jp
R1
R1
PR3
•
+
CO2R2
CO2R2
R1 = H, Me, Et, iPr, Ph
R2 = Et, Bn
With the optimum conditions (entry 3, Table 1) in hand, we next
explored the scope of the Et3N-promoted [3+2] cycloaddition of 1
and 2 with C60 (Table 2). The reaction of 4,4’-dimethylbenzil (1b)
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10.1002/ejoc.201901072
European Journal of Organic Chemistry
COMMUNICATION
and 2a with C60 produced the corresponding product 4b in 27%
yield. The reaction of 4,4’-dimethoxybenzil (1c) and 2a with C60
also afforded the cyclopentene-annulated fullerene 4c, albeit in
a low yield (14%) due to the low solubility of 1c in ODCB.9 The
reaction of 3,3’-dimethoxybenzil (1d) and 2a with C60 gave the
corresponding [3+2] cycloaddition product 4d in 36% yield. The
reaction of 4,4’-difluorobenzil (1e) and 2a with C60 gave the
cyclopentene-annulated fullerene 4e in a good yield (46%). The
reactivity of 2,2’-thenil (1f) was higher than that of 1a, giving 4f
in 32% yield. Increasing the reaction time from 10 min to 20 min
generated multiple cycloaddition products with increased yields.
Scheme 3. Introduction of p-MeO-phenyl Group to 4a by Fe-Promoted
Friedel-Crafts Type γ-Addition
Ph
O
Ph
O
FeCl3 (1 equiv)
Ph
+
CO2Me
ODCB
110 °C, 2 h
OMe
CO2Me
4a (0.01 M)
OMe
5: 49% (72%)a
(10 equiv)
a Isolated yield of 5. The value in parenthesis is HPLC yield of 5.
A plausible mechanism for the present [3+2] cycloaddition is
illustrated in Scheme 4. The Et3N-promoted reaction of benzil
(1a) with methyl propiolate (2a) gives the 1,3-bifunctional allene
A. Allene A in the presence of Et3N is in equilibrium with the
zwitterionic intermediate B, which reacts with C60 to give D via C.
The subsequent 1,2-proton migration from D gives E. Finally, E
liberates Et3N to give 4a.
Table 2. NEt3-Promoted [3+2] Cycloaddition of the In Situ Generated 1,3-
a
Bifunctional Allene (from 1 and 2) with C60
Ar
O
O
O
O
NEt3 (1 equiv)
Ar
Scheme 4. Plausible Reaction Mechanism of the NEt3-Promoted [3+2]
Ar
+
+
Ar
OR
ODCB
27 °C, 20 min
Cycloaddition
O
CO2R
OBz
O
BzO Ph
Ph
0.02 M 1 (3 equiv)
1a : Ph
2 (3 equiv)
4
O
Ph
NEt3
+
2a: Me
2b: Et
•
Ph
OMe
1b : 4-Me-C6H4
1c : 4-MeO-C6H4
1d : 3-MeO-C6H4
1e : 4-F-C6H4
O
2c: tBu
A
CO2Me
CO2Me
4a
1a
2a
+
NEt3
BzO Ph
1f : thiophen-2-yl
OBz
Ph
NEt3
CO2Me
Et3N
Me
MeO
B
H
MeO
CO2Me
OMe
E
O
O
O
O
Me
OMe
C60
O
O
BzO
Ph
NEt3
CO2Me
OBz
Ph
CO2Me
CO2Me
CO2Me
C
NEt3
4b: 27% (91%)
4c: 14% (83%)c
4d: 36% (97%)
H CO2Me
F
D
S
In our previous study, allenol esters were found to react with
C60 to give [2+2] cycloaddition products (Scheme 1).3 In contrast,
the present reaction of 1,3-bifunctional allenes with C60 prefers
the [3+2] cycloaddition pathway. This can be attributed to the
rapid generation of the zwitterionic intermediate B by the
existing NEt3. We speculated that the reaction of 1,3-bifunctional
allene A with C60 would also give the [2+2] cycloaddition product
if we could design amine-free conditions. This led us to examine
the reaction on a flow packed-bed reactor using silica-supported
tertiary amine. Thus, the formed allene was introduced into a
batch reactor containing C60 (Scheme 5).11,12,13
O
O
S
O
O
O
F
O
O
O
CO2Me
CO2Me
CO2Et
CO2tBu
4h: 23% (76%)e
4e: 46% (87%)
4f: 32% (79%)d
4g: 29% (96%)
[a] Reaction conditions: C60 (0.15 mmol), 1 (3 equiv), 2 (3 equiv), NEt3 (1
equiv), ODCB (7.5 mL), temperature: 27 °C, reaction time: 20 min. [b] Yields of
4 are the isolated yield. The values in parentheses are based on the amount of
C60 consumed. [c] reaction time: 2 h. [d] reaction time: 10 min. [e] reaction
time: 16 h.
Scheme 5. [2+2] Cycloaddition of the Ex Situ Generated 1,3-Bifunctional
Allene with C60 in Amine-free Conditions
O
Ethyl propiolate (2b) and tertiary butyl propiolate (2c) showed
tolerance to the reaction conditions, furnishing the
corresponding cyclopentene-annulated fullerenes 4g and 4h in
29% and 23% yields, respectively.
The obtained cyclopentene-annulated fullerenes 4 bore aryl
carboxyl substituents, which could act as anionic leaving groups.
Thus, 4a was subjected to Friedel-Crafts type γ-addition with
anisole and FeCl3. As a result, the benzoyloxy group was
successfully replaced by p-anisyl group to give 1,3-diaryl
SiO2
O
Si
N
O
(ca. 380 mg)
O
BzO Ph
•
O
Ph
+
Ph
OMe
2a (0.1 M)
ODCB
O
i.d. = 4 mm
CO2Me
A
1a (0.1 M)
length = 50 mm
RTa = 3 min
0.5 mL/min
27 °C
1.5 mL
OBz
Ph
C60 (0.03 mmol)
ODCB (1 mL)
80 °C, 1 h
cyclopentene-annulated fullerene
(Scheme 3).10
5 in 49% isolated yield
CO2Me
3a
HPLC area (%)
3a / 4a / othersb / C60
a RT = residence time
b Multiple cycloaddition products
31 /
0
/
4
/ 65
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10.1002/ejoc.201901072
European Journal of Organic Chemistry
COMMUNICATION
This worked quite well, and we then examined a serial flow
reactor system consisting of a similar packed-bed reactor for
allene generation and a flow tubular reactor for the subsequent
[2+2] cycloaddition. To our delight, the ex situ generated allene
A in the first column by silica-supported tertiary amine reacted
with C60 in the second tubular reactor to give cyclobutane-
annulated fullerene 3a in a 32% yield (Scheme 6).14 This
continuous flow system could be extremely useful for the
synthesis of other cyclobutane-annulated fullerenes 3.
Scheme 7. [2+2] Cycloaddition of 1c, 2a, and C60 Using a Flow Packed-bed
Reactor in Combination with Silica-Supported Tertiary Amine
O
MeO
SiO2
O
Si
N
O
(ca. 380 mg)
O
O
Ar
+
Ar
O
OMe
BPR
(6 atm)
O
i.d. = 400 mm
O
1c (0.5 M) 2a (0.5 M)
CHCl3
i.d. = 4 mm
OMe
length = 50 mm
RTa = 3 min
0.17 mL/min
27 °C
CO2Me
C60 (0.02 M)
ODCB
i.d. = 1 mm
3c
12% (60%)b
0.85 mL/min
length = 2.5 m
RTa = 3 min
110 °C
Ar =
Scheme 6. [2+2] Cycloaddition of 1, 2a, and C60 Using a Flow Packed-bed
Reactor in Combination with Silica-Supported Tertiary Amine15,16
MeO
a RT = residence time
O
b Isolated yield of 3c. The value in parenthesis is based on the amount of C60 consumed.
SiO2
O
Si
N
O
(ca. 380 mg)
O
O
Ar
Ar
+
Ar
Scheme 8. Plausible Reaction Mechanism of [2+2] Cycloaddition
OMe
i.d. = 400 mm
O
O
O
Ar
i.d. = 4 mm
O
1 (0.5 M) 2a (0.5 M)
length = 50 mm
RTa = 3 min
0.17 mL/min
27 °C
SiO2
O
Si
N
ODCB
O
O
O
BzO
CO2Me
Ph
+
C60 (0.02 M)
ODCB
Ph
OMe
2a
•
i.d. = 1 mm
length = 2.5 m
RTa = 3 min
110 °C
3
O
0.85 mL/min
1a
CO2Me
A
1a : C6H5
1b: 4-Me-C6H4
1d: 3-MeO-C6H4
1e : 4-F-C6H4
1f : thiophen-2-yl
OBz
C60
SET
OBz
BzO
+
•
Me
O
CO2Me
CO2Me
CO2Me
3a
MeO
F
A plausible mechanism for the [2+2] cycloaddition is illustrated
in Scheme 8. The reaction of 1a with 2a by silica-supported
tertiary amine generates the 1,3-bifunctional allene A. Under
amine-free conditions, a single-electron transfer from the aryl
group of A to C60 occurs to give a radical ion-pair consisting of
the radical anion C60•– and a radical cation of A. C60•– reacts with
the radical cation of A to give the [2+2] cycloaddition product 3a
via the zwitterionic intermediate F.3
O
O
O
O
O
Me
OMe
CO2Me
CO2Me
CO2Me
3a
3b
3d
32% (78%)b
26% (88%)b
41% (77%)b
F
S
O
O
S
O
O
F
Conclusions
CO2Me
CO2Me
3f
3e
23% (74%)b
31% (95%)b
In conclusion, we have developed the [3+2] cycloaddition of in
situ generated 1,3-bifunctional allenes with C60 in the presence
of Et3N. In addition, the [2+2] cycloaddition of the same in situ
a RT = residence time
b Isolated yields of 3. The values in parentheses are based on the amount of C60 consumed.
In a similar manner, the flow reaction of 4,4’-dimethylbenzil
(1b), methyl propiolate (2a), and C60 using a silica-supported
tertiary amine charged packed-bed reactor gave the desired
cyclobutane-annulated fullerene 3b in 26% yield. The reactivity
of 3,3’-dimethoxybenzil (1d) and 2a was higher than that of 1a
and 2a (3d, 41%). The reaction of 4,4’-difluorobenzil (1e) and 2a
with C60 proceeded to form the cyclobutane-annulated fullerene
3e in 23% yield. 2,2’-Thenil (1f) showed higher reactivity
compared with 1a, and a large amount of multiple cycloaddition
products was formed at 110 °C. However, the yield of 3f could
be increased (31%) at a lower reaction temperature (60 °C).17
Due to the poor solubility of 4,4’-dimethoxybenzil (1c) in o-
dichlorobenzene, the solvent was changed to CHCl3 in the case
of 1c and 2a.9 This required a back-pressure regulator (6 atm) to
suppress the gas evolution. In this way, the flow reaction of 4,4’-
dimethoxybenzil (1c), methyl propiolate (2a), and C60 gave the
desired cyclobutane-annulated fullerene 3c, albeit in 12% yield
(Scheme 7).
generated 1,3-bifunctional allenes was achieved using
a
continuous flow packed-bed reactor and silica-supported tertiary
amine. It is expected that the flow protocol developed in this
work would prove to be a powerful tool for the synthesis of other
ring-annulated fullerenes. Further studies on the application of
these products in the field of materials science are currently in
progress.
Experimental Section
Typical Procedure for NEt3-Promoted [3+2] Cycloaddition of in-situ
Generated 1,3-Bifunctional Allene with C60
To a 50 mL screw capped test tube, C60 (0.15 mmol, 0.360 g), benzil (1a,
0.45 mmol, 3 equiv), methyl propiolate (2a, 0.45 mmol, 3 equiv), NEt3
(0.15 mmol, 1 equiv), and ODCB (7.5 mL) were added. The mixture was
stirred for 20 min at 27 °C. The reaction was monitored by analytical
HPLC. After 20 min, MeOH was added to the reaction mixture, and the
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10.1002/ejoc.201901072
European Journal of Organic Chemistry
COMMUNICATION
143.15, 143.22, 143.30, 143.32, 144.35, 144.65, 144.74, 145.00,
sediment was filtered and washed with MeOH. The residue was purified
by silica gel column chromatography eluting first with hexane to remove
C60, and then with toluene (Rf = 0.7 with toluene). The combined fractions
were concentrated under reduced pressure giving the desired
cyclopentene-annulated fullerene derivatives 4a as a solid.
145.32,145.46, 145.52, 145.63, 145.67, 145.79, 145.82, 145.88, 146.00,
146.23, 146.34, 146.38, 146.41, 146.59, 146.61, 147.49, 147.67, 148.35,
151.32, 152.26, 152.84, 153.42, 162.81 (d, JCF = 247.2 Hz), 163.84,
163.91, 166.39 (d, JCF = 253.0 Hz).
HRMS (ESI) m/z calcd for C78H12O4F2 [M + Na+]: 1073.0596, found
1073.0592.
4a: Brown solid (47.6 mg, 32% yield).
1H NMR (400 MHz, CDCl3): δ 4.03 (3H, s), 7.34-7.38 (1H, m), 7.45-7.54
(4H, m), 7.61-7.67 (1H, m), 7.81 (2H, d, J = 7.2 Hz), 8.13 (2H, d, J = 7.6
Hz), 8.61 (1H, s).
4f: Brown solid (49.3 mg, 32% yield).
1H NMR (400 MHz, CDCl3): δ 3.92 (3H, s), 7.12-7.17 (2H, m), 7.45 (1H, d,
J = 5.2 Hz), 7.49 (1H, s), 7.64 (1H, dd, J = 4.4, 0.8 Hz Hz), 7.73 (1H, dd,
J = 3.6, 0.8 Hz), 7.92 (1H, dd, J = 3.6, 1.2 Hz).
13C NMR (100 MHz, CDCl3): δ 52.79, 74.77, 80.75, 98.58, 126.22,
127.66, 127.86, 128.95, 129.04, 129.31, 129.93, 130.07, 130.18, 130.23,
130.69, 132.73, 133.88, 134.36, 134.43, 134.57, 135.02, 135.50, 135.17,
139.21, 139.47, 140.06, 140.53, 141.88, 141.91, 142.01, 142.13, 142.55,
142.85, 142.97, 143.05, 144.80, 145.30, 145.89, 146.00, 146.16, 146.22,
146.33, 146.39, 146.63, 147.50, 147.67, 147.81, 148.43, 151.60, 152.50,
153.21, 153.75, 164.09, 164.83.
13C NMR (100 MHz, CDCl3): δ 53.56, 78.83, 81.14, 95.71, 127.56,
127.72, 127.86, 128.29, 129.24, 132.72, 134.06, 135.01, 135.64, 135.83,
136.10, 136.71, 137.06, 139.48, 139.55, 139.86, 140.07, 141.71, 141.75,
141.82, 141.88, 141.95, 142.17, 142.26, 142.60, 142.77, 142.89, 143.08,
143.20, 143.38, 144.51, 144.69, 144.92, 145.49, 145.55, 145.67, 145.81,
145.84, 146.28, 146.33, 146.62, 146.68, 147.20, 147.25, 147.56, 147.64,
147.69, 150.87, 151.67, 152.07, 153.22, 161.28, 169.34.
HRMS (ESI) m/z calcd for C78H14O4 [M + Na+]: 1037.0784, found:
1037.0761.
HRMS (ESI) m/z calcd for C74H10O4S2 [M + H+]: 1027.0093, found
1027.6360.
4b: Brown solid (42.2 mg, 27% yield).
1H NMR (400 MHz, CDCl3): δ 2.34 (3H, s), 2.43 (3H, s), 4.02 (3H, s),
7.24-7.26 (2H, m), 7.28-7.31 (2H, m), 7.67 (2H, d, J = 8.4 Hz), 8.01 (2H,
d, J = 6.4 Hz), 8.59 (1H, s).
4g: Brown solid (44.8 mg, 29% yield).
1H NMR (400 MHz, CDCl3): δ 1.46 (3H, t, J = 7.6 Hz), 4.48 (2H, q, J = 7.6
Hz), 7.36 (1H, t, J = 7.2 Hz), 7.45-7.51 (4H, m), 7.63 (1H, t, J = 8.0 Hz),
7.81 (2H, d, J = 7.2 Hz), 8.14 (2H, dd, J = 8.4, 1.6 Hz), 8.60 (1H, s).
13C NMR (100 MHz, CDCl3): δ 14.42, 62.16, 74.73, 80.74, 98.52, 126.16,
128.94, 129.29, 130.21, 133.86, 134.97, 135.43, 135.91, 137.12, 139.15,
139.32, 140.03, 140.54, 141.51, 141.62, 141.81, 141.97, 142.08, 142.42,
142.50, 142.54, 142.60, 142.68, 142.80, 142.93, 143.08, 143.24, 143.31,
144.34, 144.62, 144.71, 144.75, 145.26, 145.39, 145.45, 145.45, 145.58,
145.71, 145.82, 145.94, 146.13, 146.27, 146.31, 146.27, 146.31, 146.52,
146.58, 147.44, 147.62, 147.87, 147.49, 151.62, 152.51, 153.24, 153.80,
163.62, 164.78.
13C NMR (100 MHz, CDCl3): δ 21.45, 21.90, 52.76, 74.72, 80.84, 98.39,
125.44, 126.07, 127.47, 128.37, 128.48, 129.18, 129.64, 130.00, 130.25,
134.99, 135.39, 135.97, 137.18, 137.66, 138.74, 139.25, 139.39, 139.43,
140.01, 141.63, 141.85, 142.01, 142.45, 142.53, 142.62, 142.81, 142.95,
143.26, 143.45, 144.70, 144.75, 145.25, 145.36, 145.76, 145.86, 146.19,
146.30, 146.34, 146.53, 146.60, 147.47, 147.64, 147.83, 148.47, 151.66,
152.62, 152.62, 153.42, 153.97, 164.16, 164.93.
HRMS (ESI) m/z calcd for C80H18O4 [M + Na+]: 1065.1097, found
1065.1094.
HRMS (ESI) m/z calcd for C79H16O4 [M + Na+]: 1051.0941, found
1051.0924.
4c: Brown solid (22.6 mg, 14% yield).
1H NMR (400 MHz, CDCl3): δ 3.81 (3H, s), 3.87 (3H, s), 4.02 (3H, s),
6.97 (4H, m), 7.71 (2H, d, J = 9.2 Hz), 8.06 (2H, d, J = 8.8 Hz), 8.59 (1H,
s).
4h: Brown solid (36.5 mg, 23% yield).
1H NMR (400 MHz, CDCl3): δ 1.63 (9H, s), 7.36 (1H, q, J = 7.6 Hz), 7.44-
7.54 (4H, m), 7.61-7.67 (1H, m), 7.81 (2H, d, J = 7.6 Hz), 8.15 (2H, d, J =
7.6 Hz), 8.48 (1H, s).
13C NMR (100 MHz, CDCl3): δ 52.77, 55.39, 55.71, 74.65, 81.04, 98.14,
113.74, 114.20, 114.42, 114.58, 114.87, 122.44, 127.45, 127.86, 128.46,
132.28, 132.53, 133.00, 133.88, 133.95, 134.08, 134.90, 135.33, 135.91,
137.20, 139.33, 139.39, 139.44, 140.07, 141.65, 141.85, 141.88, 142.09,
142.13, 142.36, 142.47, 142.62, 142.81, 142.95, 143.11, 143.25, 144.56,
144.74, 145.24, 145.35, 145.40, 145.49, 145.61, 145.75, 145.85, 145.95,
146.19, 146.26, 146.34, 46.51, 146.59, 147.48, 147.64, 147.79, 148.48,
151.64, 152.69, 152.86, 153.51, 153.74, 154.03, 159.73, 164.09, 164.19,
164.60.
13C NMR (100 MHz, CDCl3): δ 21.61, 28.43, 83.72, 85.38, 98.42, 125.44,
127.85, 128.37, 128.91, 129.17, 129.24, 130.06, 130.23, 130.28, 130.68,
133.12, 133.80, 135.03, 135.46, 135.89, 137.11, 138.01, 139.14, 139.21,
139.28, 140.04, 140.70, 141.54, 141.64, 141.67, 141.71, 141.80, 141.86,
141.99, 142.10, 142.18, 142.46, 142.50, 142.60, 142.80, 142.95, 143.11,
143.22, 144.18, 144.39, 144.63, 144.72, 144.82, 145.18, 145.27, 145.43,
145.47, 145.59, 145.71, 145.75, 145.81, 145.91, 145.96, 146.20, 146.29,
146.33, 146.37, 146.54, 146.61, 147.47, 147.63, 147.89, 148.70, 149.38,
151.89, 152.76, 153.42, 154.05, 162.84, 164.73,
HRMS (ESI) m/z calcd for C80H18O6 [M + Na+]: 1097.0996, found
1097.1035.
HRMS (ESI) m/z calcd for C81H20O4 [M + Na+] 1079.1254, found
1079.1243.
4d: Brown solid (58.1 mg, 36% yield).
1H NMR (400 MHz, CDCl3): δ 3.80 (6H, s), 4.02 (3H, s), 6.87-6.90 (1H,
m), 7.15-7.19 (2H, m), 7.33-7.34 (1H, m), 7.37-7.42 (2H, m), 7.68 (1H, dd,
J = 2.8, 1.6 Hz), 7.74 (1H, dt, J = 7.6, 1.2 Hz), 8.60 (1H, s).
5: Brown solid (24.5 mg, 49% yield).
1H NMR (400 MHz, CDCl3): δ 3.84 (3H, s), 3.99 (3H, s), 6.93 (1H, s),
7.01 (2H, dt, J = 8.8, 3.2 Hz), 7.43-7.52 (3H, m), 7.83 (2H, dt, J =6.4, 1.6
Hz), 8.02 (2H, dt, J = 9.2, 3.2 Hz)
13C NMR (100 MHz, CDCl3): δ 52.81, 55.59 (two peaks overlap), 74.73,
80.61, 98.41, 112.89, 113.51, 121.39, 122.08, 122.78, 123.41, 127.85,
129.95, 130.18, 130.49, 130.67, 131.24, 134.35, 135.93, 137.03, 139.17,
139.43, 139.99, 141.61, 141.86, 141.94, 142.04, 142.12, 142.44, 142.53,
142.61, 142.83, 142.88, 142.93, 143.10, 143.21, 143.30, 144.37, 144.64,
144.76, 144.18, 145.26, 145.32, 145.41, 145.50, 145.50, 145.59, 145.74,
145.87, 145.97, 146.21, 146.30, 146.30, 146.52, 146.59, 147.46, 147.77,
148.40, 151.58, 152.40, 152.97, 152.83, 159.84, 160.18, 164.03, 164.64.
13C NMR (100 MHz, CDCl3): δ 53.26, 55.44, 74.12, 78.52, 80.29, 114.32,
128.59, 128.78, 129.89, 130.16, 132.16, 132.95, 134.42, 134.77, 135.70,
135.99, 136.33, 139.09, 139.13, 139.80, 140.02, 141.59, 141.76, 141.86,
141.90, 142.03, 142.71, 142.86, 143.07, 143.20, 144.35, 144.75, 144.51,
144.70, 145.03, 145.23, 145.31, 145.41, 145.46, 145.69, 145.88, 145.06,
146.11, 146.18, 146.21, 146.26, 146.39, 146.41, 146.44, 146.93, 147.39,
147.57, 148.85, 152.41, 153.65, 154.72, 155.53, 159.47, 173.05
HRMS (ESI) m/z calcd for C78H16O3 [M + Na+]: 1023.0992, found
1023.1000.
HRMS (ESI) m/z calcd for C80H18O6 [M + Na+]: 1097.0996, found
1097.0995.
The structure of 5 was determined by HMBC, HMQC, and NOESY
analysis.
4e: Brown solid (72.5 mg, 46% yield).
1H NMR (400 MHz, CDCl3): δ 4.02 (3H, s), 7.16 (4H, t, J = 8.0 Hz), 7.77
(2H, dd, J = 8.8, 5.2 Hz), 8.13 (2H, dd, J = 8.8, 5.6 Hz), 8.56 (1H, s).
13C NMR (100 MHz, CDCl3) δ 52.88, 74.69, 80.62, 98.18, 116.23 (d, JCF
= 22.0 Hz), 116.45 (d, JCF = 21.0 Hz), 126.20, 126.23, 127.97, 128.02,
132.82 (d, JCF = 9.5 Hz), 135.01, 135.40, 135.79, 136.50, 136.53, 137.04,
139.35, 139.48, 140.09, 141.54, 141.60, 141.66, 141.86, 141.90, 141.92,
142.09, 142.12, 142.43, 142.52, 142,63, 142.84, 142.86, 142.89, 143.01,
Typical Procedure for [2+2] Cycloaddition of 1, 2a and C60 by Using
a Flow Packed-Bed Reactor in Combination with Silica-Supported
Tertiary Amine
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10.1002/ejoc.201901072
European Journal of Organic Chemistry
COMMUNICATION
HRMS (ESI) m/z calcd for C80H18O6 [M + Na+]: 1097.0996, found
1097.0995.
The E/Z configuration of 3d was determined by HMBC, HMQC, and
NOESY analysis.
Silica-supported tertiary amine (380 mg) was packed into a stainless
steel column (i.d. = 4 mm, length = 2.5 m). An o-dichlorobenzene solution
of 1a (0.5 M) and 2a (0.5 M) was feed into a column reactor at 27 °C to
form 1,3-bifunctional allene (0.17 mL/min, RT = 3 min), and the resultant
mixture was mixed with an o-dichlorobenzene solution of C60 (0.02 M,
0.85 mL/min) using a T-shaped micromixer (stainless-steel made, 400
µm channel diameter). The reaction mixture was passed through a
residence time unit (110 °C, i.d. = 1 mm, length = 2.5 m, RT = 3 min).
Consequently, we obtained the [2+2] cycloaddition product 3a in 32%
yield after the purification by silica gel column chromatography eluting
first with hexane to remove C60, and then with toluene (Rf = 0.7 with
toluene).
3e: Brown solid (23% yield).
1H NMR (400 MHz, CDCl3): δ 3.82 (3H, s), 5.53 (1H, s), 7.24-7.32 (4H,
m), 8.16-8.23 (4H, m).
13C NMR (100 MHz, CDCl3): δ 51.70, 77.36, 90.98, 96.42, 100.13,
113.83, 114.66, 116.07 (d, JCF = 21.9 Hz), 116.62 (d, JCF = 22.0 Hz),
116.68, 117.34, 122.83, 123.43, 127.63, 127.81, 128.53 (d, JCF = 8.6 Hz),
129.23 (d, JCF = 8.6 Hz), 129.55, 129.65, 129.68, 129.76, 130.07, 132.00,
132.07, 132.88, 133.02, 133.18, 136.21, 136.76, 136.80, 138.18, 139.05,
139.80, 141.79, 142.09. 142.24, 142.39, 143.15, 144.49, 145.40, 145.79,
146.09, 146.15, 146.29, 146.45, 146.60, 147.30, 148.00, 148.50, 148.62,
149.08, 149.45, 149.60, 152.22, 152.30, 156.19, 156.74, 157.86, 160.37,
160.80, 162.24, 163.99 (d, JCF = 250.1 Hz), 164.94 (d, JCF = 259.6 Hz),
166.85.
3a: Brown solid (32% yield).
1H NMR (400 MHz, CDCl3): δ 3.79 (3H, s), 5.55 (1H, s), 7.48-7.60 (6H,
m), 8.16-8.20 (4H, m).
13C NMR (100 MHz, CDCl3): δ 51.46, 78.03, 83.46, 90.73, 96.64, 126.54,
127.03, 128.31, 128.72, 129.10, 129.29, 129.57, 130.38, 130.74, 131.24,
131.69, 137.30, 139.11, 139.38, 139.59, 139.72, 140.08, 140.18, 140.61,
141.79, 141.94, 142.10, 142.20, 142.38, 142.45, 142.59, 142.76, 142.89,
143.04, 143.32, 143.40, 143.98, 144.23, 144.41, 144.49, 145.30, 145.34,
145.46, 145.54, 145.56, 145.61, 145.66, 145.77, 145.97, 146.04, 146.17,
146.19, 146.28, 146.33, 146.38, 146.49, 146.61, 146.92, 147.15, 147.30,
148.29, 148.91, 149.39, 149.87, 150.74, 151.28, 153.12, 154.95, 165.14,
165.42.
HRMS (ESI) m/z calcd for C78H12O4F2 [M + Na+]: 1073.0596, found
1073.0560.
3f: Brown solid (31% yield).
1H NMR (400 MHz, CDCl3): δ 3.74 (3H, s), 5.54 (1H, t, J = 2.0 Hz), 6.54
(1H, dd, J = 6.0, 2.4 Hz), 6.66 (1H, dd, J = 6.0, 1.6 Hz), 6.99 (1H, s),
7.16-7.20 (1H, m), 7.68 (1H, d, J = 4.8 Hz), 8.03 (1H, d, J = 3.6 Hz).
13C NMR (100 MHz, CDCl3): δ 52.33, 62.83, 67.91, 71.11, 108.16,
111.58, 112.75, 116.09, 116.37, 118.67, 124.27, 128.26, 128.68, 129.17,
132.13, 133.84, 135.30, 135.87, 136.73, 139.42, 139.62, 139.77, 139.96,
140.21, 141.52, 141.68, 141.74, 141.78, 141.85, 141.99, 142.03, 142.35,
142.38, 142.50, 142.61, 142.89, 142.92, 143.04, 143.14, 143.21, 143.25,
143.80, 144.68, 144.76, 144.88, 144.91, 144.97, 145.53, 145.58, 145.66,
145.73, 145.82, 145.88, 146.08, 146.34, 146.45, 146.53, 146.58, 146.75,
146.79, 146.82, 147.02, 147.75, 147.83, 147.85, 150.99, 151.03, 151.17,
151.24, 154.82, 155.54, 157.23, 165.57 (two peaks over-lap).
HRMS (ESI) m/z calcd for C78H14O4 [M + Na+]: 1037.0784, found:
1037.0777.
3b: Brown solid (26% yield).
1H NMR (400 MHz, CDCl3): δ 2.42 (6H, s), 3.79 (3H, s), 5.54 (1H, s),
7.37 (4H, t, J = 6.8 Hz), 8.06 (4H, t, J = 8.0 Hz).
13C NMR (100 MHz, CDCl3): δ 21.68, 22.09, 51.57, 78.21, 83.47, 90.54,
92.00, 96.72, 115.13, 121.59, 126.51, 127.01, 127.66, 128.37, 128.87,
129.18, 129.45, 129.53, 129.85, 130.01, 130.17, 130.48, 130.81, 134.36,
136.06, 136.73, 137.32, 138.98, 139.14, 139.50, 139.65, 139.71, 140.12,
140.20, 140.46, 141.74, 141.85, 141.99, 142.50, 142.81, 142.94, 144.31,
144.48, 144.57, 145.18, 145.30, 145.36, 145.41, 145.45, 145.53, 145.59,
145.68, 146.03, 146.10, 146.24, 146.38, 146.54, 146.77, 146.97, 147.13,
147.22, 147.36, 148.60, 149.23, 149.77, 150.28, 151.23, 151.80, 165.51,
166.00.
HRMS (ESI) m/z calcd for C74H10O4S2 [M + Na+]: 1048.9913, found
1048.9915.
Acknowledgments
HRMS (ESI) m/z calcd for C80H18O4 [M + Na+]: 1065.1097, found
1065.1093.
This work was supported by Grant-in-Aid for Young Scientists
(B) (17K14487) from JSPS and Scientific Research on
Innovative Areas 2707 Middle Molecular Strategy (JP15H05850)
from JSPS.
3c: Brown solid (12% yield).
1H NMR (400 MHz, CDCl3): δ 3.81 (3H, s), 3.88(3H, s), 3.89 (3H, s), 5.61
(1H, s), 7.02-7.07 (2H, m), 7.49 (2H, dt, J = 8.4, 2.0 Hz), 7.70-7.74 (3H,
m), 7.79 (1H, dq, J = 7.6, 1.2 Hz).
13C NMR (100 MHz, CDCl3): δ 51.60, 55.51, 55.77, 77.36, 83.55, 90.45,
96.65, 114.14, 114.42, 114.47, 114.72, 115.07, 123.59, 123.86, 125.43,
126.43, 127.95, 128.35, 128.58, 129.16, 132.50, 136.71, 137.23, 137.99,
138.97, 139.12, 139.67, 139.74, 140.14, 140.21, 141.73, 141.76, 141.86,
141.99, 142.15, 142.20, 142.26, 142.39, 142.50, 142.59, 142.69, 142.80,
142.93, 143.03, 143.10, 144.28, 144.47, 144.55, 144.62, 145.34, 145.44,
145.51, 145.57, 145.68, 146.07, 146.20, 146.39, 146.52, 146.86, 147.07,
147.21, 147.36, 148.57, 149.21, 149.82, 150.38, 160.38, 161.16, 165.49,
166.19,
Keywords: [3+2] cycloaddition • [2+2] cycloaddition • 1,3-
bifunctional allene • flow packed-bed reactor • silica-supported
tertiary amine
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HRMS (ESI) m/z calcd for C80H18O6 [M + Na+]: 1097.0996, found
1097.0994.
3d: Brown solid (41% yield).
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5.61 (1H, s), 7.02-7.07 (2H, m), 7.49 (2H, dt, J = 8.4, 2.0 Hz), 7.72-7.74
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13C NMR (100 MHz, CDCl3): δ 51.60, 55.62, 55.74, 78.05, 83.29, 90.84,
96.55, 112.88, 112.94, 114.68, 114.77, 115.92, 119.04, 119.58, 130.04,
130.39, 132.63, 133.08, 136.65, 137.39, 138.95, 139.16, 139.62, 139.67,
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142.41, 142.47, 142.51, 142.65, 142.82, 142.94, 143.03, 143.11, 144.28,
144.46, 144.54, 145.25, 145.36, 145.45, 145.50, 145.58, 145.62, 145.67,
145.72, 146.03, 146.10, 146.18, 146.20, 146.23, 146.39, 146.44, 146.54,
146.90, 147.08, 147.21, 147.35, 148.33, 148.94, 149.50, 149.83, 159.73,
160.25, 165.32, 165.40, 165.46.
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COMMUNICATION
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As the results of checking the solubility of 1c in organic solvents, we
found the high solubility of 1c in CHCl3. However, the yield of 4c was
not improved by the use of ODCB:CHCl3 (2:1) as solvent.
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it would be difficult to form the sterically congested quaternary carbon.
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Cyclobutane-annulated fullerene 3a and cyclopentene-annulated
fullerene 4a are clearly distinguishable by signals for vinyl protones in
1H NMR analysis (3a: 5.55 ppm, 4a: 8.61 ppm).
[14] The mixture of 1a, 2a, C60 and silica-supported tertiary amine in batch
system gave cyclopentene-annulated fullerene 4a selectively.
[15] Silica-supported tertiary amine: 380 mg (amine: ca. 0.27 mmol, see: ref.
10-f). Catalyst loading: 106 mol % for 1a (RT = 3 min, flow rate = 0.17
mL/min).
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a) J. Marco-Martínez, V. Marcos, S. Reboredo, S. Filippone, N. Martín,
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[16] The lower temperature conditions (80 °C) in a residence time unit
occurred to decrease the conversion.
[17] The flow reaction of 1e, 2a and C60 at 60 °C gave 3e in lower yield due
to the low conversion.
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COMMUNICATION
Entry for the Table of Contents (Please choose one layout)
Layout 1:
COMMUNICATION
Ar
O
The reaction of 1,2-diaryl-1,2-
Silica-supported tertiary-
O
O
O
Ar
diketones, propiolic acid esters,
and C60 in the presence of Et3N
gave cyclopentene-annulated
amine*
Ar
Et3N
Ar
OMe
O
[3+2]
Mitsuhiro Ueda,* Miho Hayama,
Hiroyuki Hashishita, Aiko
Munechika, Takahide Fukuyama
batch system
C60
CO2Me
fullerenes
cycloaddition.
cyclobutane-annulated
fullerenes were obtained via
via
[3+2]
Interestingly,
O
SiO2
Ar
O Si
O
N
Page No. – Page No.
O
O
Silica-supported tertiary amine
[2+2] cycloaddition when
a
Controlled [3+2] and [2+2]
Cycloadditions of 1,3-
Bifunctional Allenes with C60
by Using a Flow Reaction
System
Ar
similar reaction was conducted
using a flow packed-bed reactor
in combination with a silica-
supported tertiary amine.
[2+2]
flow reaction system
CO2Me
*one or two words that highlight the emphasis of the paper or the field of the study
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