β-Perfluoroalkylated meso -aryl-substituted subporphyrins: Synthesis and properties

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PAPER

^pβ^a-^peP^rerfluoroalkylated meso-Aryl-Substituted Subporphyrins: Synthesis and

Properties

Peripheral Perfluoroalkylation of Subporphyrins

Shuai Zhao, Chao Liu, Yong Guo, Ji-Chang Xiao, Qing-Yun Chen*

Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road,

200032, Shanghai, P. R. of China

Fax +86(21)64166128; E-mail: chenqy@sioc.ac.cn

Received: 02.01.2014; Accepted after revision: 01.03.2014

periphery of porphyrins has great and special effect on the

Abstract: A convenient and effective synthesis of various novel β-

properties of the ligands.⁶Taking advantage of versatile

perfluoroalkylated subporphyrins has been developed. β-Trifluoro-

methods developed by our group for the introduction of

methylated subporphyrins were efficiently synthesized by the reac-

tion of brominated subporphyrins with FSO₂CF₂CO₂Me/CuI [with

perfluoroalkyl groups into the periphery of porphyrins,⁷

or without Pd(dba)₂]. Potentially valuable β-perfluoroalkylated, β- we synthesized and characterized perfluoroalkylated sub-

monotetrafluorobenzo, and β-monotrifluorobenzo subporphyrins

were successfully obtained by a modified sulfinatodehalogenation

reaction. Photophysical and electrochemical studies on several typ-

porphyrins and herein we present the results.

For the synthesis of the starting meso-triaryl subporphy-

rins, we utilized the synthetic protocol of the Osuka

group, which is based on the condensation of pyridine-tri-

N-pyrrolylborane (PPB) and an aromatic aldehyde.^2b,3c,g

ical perfluoroalkylated subporphyrins demonstrated that β-hexakis-

trifluoromethylated subporphyrins show an obviously red-shifted

UV/Vis absorption band that arises from macrocycle nonplanar dis-

tortion induced by trifluoromethyl groups, but this distortion is not

so severe as that of the corresponding β-octakis(trifluoromethyl)-

meso-tetraphenylporphyrin. This was supported by their redox po-

tential data. In addition, β-monotrifluorobenzo subporphyrin exhib-

its a special fluorescence spectrum of vibronic structure.

It should be mentioned that the separation and purification

of subporphyrins by this route are tedious and time-con-

suming owing to the complexity of the reaction and rela-

tively instability of subporphyrins. The introduction of a

suitable axial substituent to the center boron is crucial for

the successful isolation and characterization of subpor-

phyrins. As reported,^2bsubporphyrins are formed mainly

as boron–hydroxy forms during the condensation reac-

tion, which can be readily converted into their boron–

methoxy form. The boron–methoxy form is more stable than

the boron–hydroxy form and can be isolated. However, in

our hands, some boron–methoxy subporphyrins were still

not sufficiently stable for the common isolation condi-

tions, resulting in lower isolated yields. When treating an

axially hydroxy-substituted subporphyrin with boron

trifluoride–diethyl ether complex (20 equiv) in dichloro-

methane for five minutes, the boron–fluoride subporphy-

rin was produced in almost quantitative yield (Scheme 1),

which is consistent with the literature.^4bThis boron–fluo-

ride subporphyrin was more stable and less polar on silica

gel columns, making its isolation more convenient and ef-

ficient. In the following studies, all the subporphyrins

were transformed into the corresponding boron–fluoride

form as the starting material for easy isolation and charac-

Key words: subporphyrin, palladium, perfluoroalkyl, trifluoro-

methylation, sulfinatodehalogenation

In recent years, subporphyrin, as a genuine ring-contract-

ed porphyrin, has emerged as an interesting functional

pigment due to its unique properties, such as its intense

Soret-like absorption band, bright green fluorescence, C₃-

molecular symmetry, bowl-shaped 14π-electron aromatic

macrocycle.^1–4The groups of Osuka and Kobayashi re-

ported the synthesis of meso-aryl-substituted subporphy-

rins independently in 2007.²Intensive research has now

been performed on their functionalization and properties.³

Although much progress has been achieved, the chemistry

of subporphyrins remains greatly unexplored, compared

to that of subphthalocyanines.⁵

It is well-known that the properties of subporphyrins, like

porphyrins, can be conveniently tuned by peripheral fab-

rications.³Due to the small rotational barriers of meso-

aryl substituents in meso-aryl subporphyrins, they show

extremely substituent-dependent optical properties.^2bDe-

veloping new synthetic methods to introduce various

functional groups into the periphery of subporphyrins is

therefore important to study and understand the properties

of subporphyrins.^3g,hPerfluoroalkyl groups are a class of

unique electron-withdrawing substituent because they are

inert and strongly σ-electron withdrawing, but do not

function as π-electron donors. Their introduction into the

19

terization. In addition, F NMR spectra of these boron–

fluoride subporphyrins showed an obviously upfield-

shifted signal at δ = –157.1, compared to the common

boron–fluoride species, such as boron trifluoride–diethyl

ether complex (δ = –152.8), which may be due to the

shielding effect of the subporphyrin macrocycle.

Next, we attempted to prepare various brominated subpor-

phyrins. For monobromosubporphyrins, N-bromosuccin-

imide was chosen as the brominating reagent.^3hIt was

found that the conversion and yield were quite sensitive to

the reaction conditions (Table 1). As can be seen in Table

1, with 1.1 equivalents of N-bromosuccinimide in a mix-

ture solvent 1,2-dichloromethane–methanol at reflux for

SYNTHESIS 2014, 46, 1674–1688

Advanced online publication: 03.04.2014

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DOI: 10.1055/s-0033-1341055; Art ID: SS-2014-H0004-OP

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Peripheral Perfluoroalkylation of Subporphyrins

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Scheme 1 Axial substituent exchange from B–OH to B–F

two hours (entry 6), the desired subporphyrin 3a was ob- trifluoromethylation of brominated porphyrins, demon-

tained in good yield (91%), the other meso-aryl subpor- strating that the carbon–bromine bond in porphyrins is

phyrins can also be monobrominated under the optimized more inert than that of normal aromatic bromides, proba-

conditions to give 3b,d in good yields (Scheme 2). The β- bly due to higher steric hindrance.^7b

hexabrominated subporphyrins 4a–c were prepared ac-

As shown in Table 2, the trifluoromethylation reactions of

subporphyrins were conducted under various conditions.

It was found that monobromosubporphyrin 3a was more

easily trifluoromethylated than its porphyrin counterpart,

cording to the literature.^3gTreatment of meso-triarylsub-

porphyrins 2a–c with bromine at room temperature for ca.

2–3 hours afforded 4a in 95%, 4b in 82%, and 4c in quan-

titative yields, respectively (Scheme 2).

but harder than bromobenzene. In the absence of a palla-

dium catalyst, monotrifluoromethylated subporphyrin 5a

was generated in moderate yield, although a longer reac-

Table 1 Monobromination Reaction of 2a under Various Conditions^a

F

tion time was required (entries 1 and 2). As a comparison,

bromobenzene was smoothly trifluoromethylated with

methyl 2,2-difluoro-2-(fluorosulfonyl)acetate and cop-

per(I) iodide at 80 °C⁸and monobromoporphyrin could

not be trifluoromethylated without a palladium catalyst

under the similar conditions.^7bAn elevated temperature

and using 20 equivalents of methyl 2,2-difluoro-2-(fluo-

Ph

T (°C), t (h)

Ph

+

N

B

N

B

O

N

Br

N

Br

solvent

O

Ph

3a

2a

Entry NBS Solvent

(equiv)

Temp

r.t.

Time Conv. Yield

^b(%)

Table 2 Trifluoromethylation of β-Monobromosubporphyrin under

(h)

(%)

Various Conditions^a

1

2

3

4

5

6

1.1

1.5

1.1

CHCl₃

2.5

2

50

60

40

50

68

83

73^c

91

F

Ph

FSO₂CF₂CO₂Me, CuI

Ph

CHCl₃–MeOH (9:1) r.t.

N

B

N

B

catalyst, DMF

CHCl₃

reflux

2

82

N

CF₃

Br

DCE

reflux

2

85

Ph

DCE

2

100

95

3a

5a

DCE–MeOH (9:1)

2

Entry FSO₂CF₂CO₂Me/

CuI (equiv)

Catalyst

Temp Time Yield^b

^aReaction conditions: subporphyrin 2a (20 mg, 40.9 mmol), NBS, sol-

vent (8 mL), stirring, N₂.

(°C)

(h)

(%)

^bIsolated yields based on consumed starting subporphyrin.

^c20% of dibrominated product was observed.

1

2

3

4

5

6

7

5:5

none

100

80

6

8

3

4

3

8

2

60

72

81

74

80

55

94

10:10

5:5

none

Pd(dba)₂

Pd(PPh₃)₄

Pd(dba)₂

With monobrominated and hexabrominated subporphy-

rins in hand, we examined their trifluoromethylation reac-

tions. Methyl 2,2-difluoro-2-(fluorosulfonyl)acetate

(FSO₂CF₂CO₂Me), a general trifluoromethylation reagent

developed by our group,⁸was used for the trifluorometh-

ylation of brominated subporphyrins; it has been shown to

be an excellent trifluoromethylation reagent for the syn-

thesis of various trifluoromethyl-substituted porphyrins in

good-to-excellent yields.^7bIt should be noted that a cata-

lytic amount of palladium is necessary for the successful

10:10

20:20

100

^aReaction conditions: 3a (20 mg, 35 mmol), FSO₂CF₂COOMe/CuI,

catalyst (5 mol%), DMF (4 mL), N₂.

^bIsolated yields.

Synthesis 2014, 46, 1674–1688

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S. Zhao et al.

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F

Ar

O

N

B

CH₂ClCH₂Cl–MeOH

(9:1 v/v)

N

B

N

+

Br

N

Br

N

reflux, N₂

O

(1.1 equiv)

Ar

3a (91%)

3b (89%)

3d (95%)

2a Ar = Ph

2b Ar = 4-F₃CC₆H₄

2d Ar = 4-MeOC₆H₄

Br

F

Ar

CHCl₃

r.t., N₂

N

B

N

B

+

Br₂

N

Br

Ar

2a Ar = Ph

2b Ar = 4-F₃CC₆H₄

2c Ar = 4-t-BuC₆H₄

4a (95%)

4b (82%)

4c (quant.)

Scheme 2 Mono- and hexabromination of various subporphyrins

rosulfonyl)acetate and copper(I) iodide seemed to be nec- alents of methyl 2,2-difluoro-2-(fluorosulfonyl)acetate

essary for effective transformation, because lower yields and copper(I) iodide as the trifluoromethylation reagent

of the desired product were produced at low temperatures (entry 5). With 20 equivalents of methyl 2,2-difluoro-2-

even after a longer time (entry 6) or with only five equiv- (fluorosulfonyl)acetate and copper(I) iodide and Pd(dba)₂

F

FSO₂CF₂CO₂Me (20 equiv)

CuI (20 equiv)

Ar

N

B

N

B

Pd(dba)₂(5 mol%)

N

Br

CF₃

DMF, 100 °C

Ar

5a (2 h, 94%)

5b (4 h, 86%)

5d (2 h, 95%)

3a Ar = Ph

3b Ar = 4-F₃CC₆H₄

3d Ar = 4-MeOC₆H₄

Pd(dba)₂

(5 mol%)

F₃C

Br

CF₃

F

Br

F

Ph

FSO₂CF₂CO₂Me (30 equiv)

N

B

N

B

CuI (30 equiv)

N

DMF, 100 °C, 1 h

CF₃

Br

F₃C

Br

no Pd(dba)₂

F₃C

CF₃

Br

Ph

4a

6a (90%)

F₃C

Br

F

CF₃

F

Ar

N

B

N

B

FSO₂CF₂CO₂Me (30 equiv)

CuI (30 equiv)

N

Br

CF₃

F₃C

Br

DMF, 100 °C

Br

F₃C

CF₃

Br

Ar

4b Ar = 4-F₃CC₆H₄

4c Ar = 4-t-BuC₆H₄

6b (2 h, 85%)

6c (2 h, 87%)

Scheme 3 Synthesis of various β-trifluoromethylated subporphyrins

Synthesis 2014, 46, 1674–1688

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Peripheral Perfluoroalkylation of Subporphyrins

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1

as the catalyst at 100 °C for only two hours, the monotri- room temperature, the H NMR spectrum of β-hexabro-

fluoromethylsubporphyrin 5a was effectively produced in mosubporphyrin 4a shows that the β-protons disappear

excellent yield (entry 7).

and rotation of the meso-phenyl substituents are restricted.

The ortho-phenyl protons (δ = 8.10 and 7.31) and meta-

phenyl protons (δ = 7.72 and 7.52) exhibit broad, but dis-

tinctly split, signals. However, at –40 °C, a pair of sharp

doublets at δ = 8.12 and 7.25 (o-H_Ph) and a pair of triplets

at δ = 7.75 and 7.51 (m-H_Ph) are observed. These results

are consistent to those in the recent report.^3gTo our sur-

prise, the ortho- and meta-phenyl protons of β-hexakistri-

fluoromethylated subporphyrin 6a exhibit a sharp doublet

(δ = 7.79) and a triplet (δ = 7.62) at room temperature, al-

though the trifluoromethyl group has larger steric hin-

drance than bromine atom. We propose that macrocycle

nonplanar distortion stemming from steric congestion of

the trifluoromethyl groups might create more spatial spac-

es for meso-phenyl substituents, which lets the meso-phe-

nyl substituents rotate more freely.

Under the optimized conditions, various monobromosub-

porphyrins were subjected to trifluoromethylation, lead-

ing to good yields of the desired products (Scheme 3).

When β-hexabromosubporphyrins were used as the sub-

strates under the optimized conditions, the corresponding

β-hexakistrifluoromethylated subporphyrins 6a–c were

obtained in good yields. It is worth mentioning that in this

case, the use of a palladium catalyst was not necessary,

since the same yield of the desired product was obtained

in the absence of a palladium catalyst (Scheme 3). This

shows that it is easier to break C–Br bonds in β-hexabro-

mosubporphyrins, which might be due to the unique

bowl-shaped structure of subporphyrins. In addition, the

introduction of a strong electron-withdrawing trifluoro-

methyl group is beneficial to the breaking of residual C–

Br bonds as well. As a result, β-hexabromosubporphyrins For the synthesis of β-perfluoroalkylated subporphyrins,

were readily trifluoromethylated even without a palladi- the sulfinatodehalogenation was found to be a suitable

um catalyst.

method, by which various monoperfluoroalkylated por-

phyrins were prepared.^7c,dTreatment of subporphyrin 2a

with 4-chloroperfluorobutyl iodide (7b) in the presence of

sodium dithionite and sodium bicarbonate in a solvent

mixture of dimethyl sulfoxide–dichloromethane (1:1) at

35 °C for six hours, successfully afforded the correspond-

ing β-monoperfluoroalkylate subporphyrin 8b, despite its

relatively low yield (Table 3, entry 1). Elevated tempera-

Figure 1 displays ¹H NMR spectra of starting subporphy-

rin 2a, β-hexabromosubporphyrin 4a, and β-hexakis(tri-

fluoromethyl)subporphyrin 6a. The ¹H NMR spectrum of

meso-triphenylsubporphyrin 2a exhibits an obvious sin-

glet of β-protons at δ = 8.20 and ortho-, meta-, and para-

phenyl protons at δ = 8.09, 7.73, and 7.64, respectively. At

Figure 1 Variable-temperature ¹H NMR spectra of 2a, 4a, and 6a in CDCl₃

Synthesis 2014, 46, 1674–1688

1678

S. Zhao et al.

PAPER

tures was beneficial to the reaction, and higher yield of the

desired product was obtained even with a lower amount of

initiator (entries 4–6). Finally, a combination of 10 equiv-

alents of 7b and 15 equivalents of sodium dithionite and

sodium bicarbonate in dimethyl sulfoxide–dichlorometh-

ane (1:1) at 60 °C for two hours were the optimal condi-

tions for the monoperfluoroalkylation of subporphyrins.

Too much perfluoroalkyl iodide or sodium dithionite and

sodium bicarbonate may be harmful and result in lower

yields because of polyperfluoroalkylated byproducts are

produced (entries 2 and 3).

Table 3 Trifluoromethylation of β-Monobromosubporphyrin under

Various Conditions^a

F

Ph

I(CF ) Cl

Ph

N

B

N

B

Na₂S₂O₄/NaHCO₃

+

2 4

N

CH₂Cl₂–DMSO

(1:1 v/v)

N

7b

C₄F₈Cl

Ph

2a

8b

Entry I(CF₂)₄Cl

(equiv)

Na₂S₂O₄/NaHCO₃Temp

Time Yield^b

(equiv)

(°C)

(h)

(%)

As illustrated in Table 4, under the optimal conditions, a

broad spectrum of subporphyrins and perfluoroalkyl io-

dides were examined. A variety of β-monoperfluoroalkyl-

ated subporphyrins were generated in acceptable yields.

1

2

3

4

5

6

7

10

30

50

20

5

15:15

45:45

75:75

30:30

7.5:7.5

15:15

35

55

60

6

3

2

23

10^c

<5^c

38

With various β-mono(ω-chloroperfluorobutyl)subpor-

phyrins in hand, their intramolecular cyclization and re-

ductive defluorinative aromatization reactions were

further investigated. Under the modified sulfinatodeha-

logenation conditions,^7c,9the carbon–chloride bond of β-

monoperfluoroalkylated subporphyrin was activated and

the subsequent intramolecular cyclization reductive de-

fluorinative aromatization reaction occurred successfully

(Scheme 4). As expected, treatment of subporphyrin 11b

with 10 equivalents of sodium dithionite and sodium bi-

carbonate in dimethyl sulfoxide at 100 °C afforded β-

monotetrafluorobenzo subporphyrin 15a in good yield. In

the case of subporphyrin 10a, due to the shorter perfluo-

roalkyl chain, the corresponding subporphyrin β-perfluo-

roalkyl radical preferred to attack the ortho-carbon of the

34

10

35

41^d

^aReaction conditions: subporphyrin 2a (20 mg, 40.9 mmol), R^FI 7b,

Na₂S₂O₄/NaHCO₃, CH₂Cl₂–DMSO (1:1, 6 mL), N₂.

^bIsolated yield.

^cPolyperfluoroalkylated subporphyrins were generated.

^dConversion of substrate 2a is 91%.

Table 4 Synthesis of β-Perfluoroalkylated Subporphyrins

F

Ar

F

Ar

N

B

Na₂S₂O₄, NaHCO₃

R^FI

B

+

R^F

N

CH₂Cl₂–DMSO (1:1 v/v)

60 °C

N

7a–e

Ar

8–11

2

Entry

Substrate

R^FI

Product

Yield (%)

2

Ar

7

R^F

1

2

2a

2b

2c

2d

Ph

7a

7b

7c

7b

7a

7b

7c

7d

7e

(CF₂)₂Cl

8a

31

41

34

46

35

40

53

35

42

39

Ph

(CF₂)₄Cl

8b

3

Ph

(CF₂)₆Cl

8c

4

4-F₃CC₆H₄

4-t-BuC₆H₄

4-MeOC₆H₄

(CF₂)₄Cl

9b

5

(CF₂)₂Cl

10a

10b

11b

11c

11d

11e

6

(CF₂)₄Cl

7

(CF₂)₄Cl

8

(CF₂)₆Cl

9

(CF₂)₄O(CF₂)₂SO₂F

(CF₂)₈F

10

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Peripheral Perfluoroalkylation of Subporphyrins

1679

phenyl ring on the adjacent meso-position rather than the the corresponding subporphyrins are not influenced obvi-

adjacent β-position. Subsequent reductive defluorinative ously. However, when six trifluoromethyl groups are in-

aromatization produced the fluorinated seven-member- stalled into the periphery of subporphyrin, both the Soret-

fused subporphyrin 14 in good yield. Interestingly, when like band (396 nm) and the Q-like band (488, 518 nm) of

subporphyrins 8b and 9b were utilized as the substrates, β-hexakis(trifluoromethyl)subporphyrin 6a are signifi-

partial reduction products β-monotrifluorobenzo subpor- cantly red-shifted compared to those of 2a, and the Soret-

phyrin 12a and 13a were generated, respectively. In all like band of subporphyrin 6a has a shoulder-like peak at

these cases, intramolecular cyclization subchlorins were 377 nm. Moreover, the shape of the Q-like band is signif-

obtained as minor byproducts simultaneously.

icantly altered from that of 2a. Namely, the Q (0,0) bands

are intensified and the Q (0,1) bands are weakened. All of

these results might be attributed to severe macrocycle

nonplanar distortion induced by trifluoromethyl groups

and the electronic interaction of periphery substituents

with meso-aryl groups.^3g,10

A possible mechanism for the intramolecular cyclization

reductive defluorinative aromatization reaction is illus-

trated in Scheme 5, which is similar to that of the corre-

sponding porphyrins.^7cHowever, the mechanism for the

different products of the reactions according to the meso-

aryl groups is not very clear and requires further study.

As compared to subporphyrin 2a, both Soret-like band

and Q-like band of subporphyrin 12a are obviously red-

shifted, and the intensity of the Q-like band is greatly en-

hanced, which might originate from the effective π-conju-

gation with the fluorinated benzo group. These trends are

similar to that of the corresponding porphyrins.^7c

Figure 2 and Table 5 show the UV/Vis absorption and

fluorescence emission spectra and data of typical perfluo-

roalkylated subporphyrins. Subporphyrin 2a shows a

Soret-like band at 368 nm and Q-like bands at 456 and 480

nm. β-Hexabromosubporphyrin 4a shows a slightly more

red-shifted Soret-like band at 370 nm which can be com- Along with these changes, the fluorescence spectra show

pared to that of 2a, which demonstrated that macrocycle the same trend, with peak positions of 2a, 5a, 8b, 6a at

nonplanar distortion aroused by peripheral bromide sub- 510, 515, 517, and 540 nm, respectively. Influenced by

stituents is not serious.^3g,10When a trifluoromethyl group peripheral hexakis(trifluoromethyl) substituents, fluores-

is introduced into the β-position, the absorption spectra of cence spectrum of 6a is distinctly red-shifted. In contrast

F

F₂C CF₂

H

F

F₂C

CF₂

H

Ar

H

N

B

Na₂S₂O₄(10 equiv)

K₂CO₃(10 equiv)

F

Ar

N

B

N

B

+

N

C₄F₈Cl

F

DMSO, 100 °C

N

Ar

8b Ar = Ph

Ar

9b Ar = 4-F₃CC₆H₄

12a (85%)

13a (80%)

12b (5%)

13b (5%)

t-Bu

Ar

N

F

N

Na₂S₂O₄(3 equiv)

K₂CO₃(3 equiv)

F

B

N

C₂F₄Cl

DMSO, 100 °C

F

Ar

10a Ar = 4-t-BuC₆H₄

Ar

14 (78%)

F

F₂C CF₂

F

F₂C

CF₂

H

Ar

N

B

Na₂S₂O₄(10 equiv)

K₂CO₃(10 equiv)

F

+

N

B

N

B

F

N

C₄F₈Cl

N

DMSO, 100 °C

Ar

11b Ar = 4-MeOC₆H₄

15a (85%)

15b (5%)

Scheme 4 Intramolecular cyclization and reductive defluorinative aromatization reaction of various β-(chloroperfluoroalkyl)subporphyrins

Synthesis 2014, 46, 1674–1688

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S. Zhao et al.

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F₂

C

F₂C

CF₂

F₂C CF₂

CF₂

F₂C CF₂

CF₂

F₂C

C₄F₈Cl

•

H

[H]

•–

SO₂

Cl^–

Ar

N

B

N

B

N

B

N

B

F

N

Ar

•

H

F₂C CF₂

CF₂

•–

•

–

SO₂

CF₂

F^–

CF₂

F₂C

F

•–

– F^–

(2)

SO₂

Ar

Ph

N

B

N

B

F

(1)

B

N

Ar

[H]

– F^–

(3)

F

F₂C CF₂

CF₂

H

CF₂

F

H

F

repeat

steps 1–3

repeat

steps 1–3

Ar

N

B

N

B

N

F

B

N

Ar

Scheme 5 Proposed mechanism of intramolecular cyclization and reductive defluorinative aromatization reaction of β-mono(ω-chloroper-

fluorobutyl) subporphyrins

to the broad fluorescence spectra of 2a, 5a, and 6a, sub- ing substitution by trifluoromethyl groups. The observed

porphyrin 12a exhibit a fluorescence spectrum of vibronic electrochemical potential shift can be understood by the β-

structure. This vibronic structure fluorescence may be as- substituent effects, namely, the strong electron-withdraw-

cribed to the benzo-structure and restricted meso-phenyl ing property of trifluoromethyl group could stabilize both

substituents.^3g

LUMO and HOMO levels, thus reduce the first-reduction

potential and enhance first-oxidation potential.^3gAs a

sharp comparison, the first oxidation and reduction poten-

tials of the corresponding porphyrin CuTPP and

CuTPP(CF₃)₈are 1.04 and –1.19 V and 0.99 and –0.39 V,

respectively (Table 6). These data demonstrate that

CuTPP(CF₃)₈is both more readily reduced and oxidized

than CuTPP. This trend can be explained as follows: both

inductive effect and macrocycle distortion affect the level

of HOMOs and LUMOs, and govern redox potentials.

Electron-withdrawing substituents stabilize more the

LUMOs than the HOMOs, while macrocycle distortion

destabilizes the HOMOs and the LUMOs relatively un-

changed.¹²In severely distorted porphyrins, the destabi-

lizing effect on the HOMOs induce by macrocycle

distortion predominates, which greatly elevate the HOMO

level and lowers the first-oxidation potential.^7bHowever,

Similar to porphyrins, the redox potentials of subporphy-

rins track their energy levels of HOMOs and LUMOs. Ne-

glecting solvent effects, the differences between the first

oxidation and reduction potential indicate the energy of

the first absorption band of the subporphyrin, because this

transition is principally a HOMO to LUMO excita-

tion.^11,12The oxidation and reduction potentials of substi-

tuted subporphyrins 5b, 6b, 9b, 13a were measured by

cyclic voltammetry in dichloromethane containing 1 × 10^–4

M tetrabutylammonium hexafluorophosphate as a sup-

porting electrolyte in order to find out the influence of β-

substituents on the electronic properties of subporphyrins.

Subporphyrins 2b, 5b, and 6b exhibited the first oxidation

potential and reduction potential at 1.20 and –1.60 V, 1.35

and –1.36 V, and 2.11 and –0.55 V, respectively. These

data show that the trifluoromethylated subporphyrins are

more readily reduced and harder to oxidize with increas-

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Peripheral Perfluoroalkylation of Subporphyrins

1681

steric congesting effects are not severe for subporphyrin time. Various mono- and hexakistrifluoromethylated sub-

aromatic macrocycles, and the electronic inductive effects porphyrins could be successfully generated with methyl

of β-trifluoromethyl substituents take the dominant posi- 2,2-difluoro-2-(fluorosulfonyl)acetate and copper(I) io-

tion for the electrochemical potentials.

dide. A palladium catalyst is beneficial to the reaction, but

not essential. Under modified sulfinatodehalogenation

conditions, a variety of β-perfluoroalkylated subporphy-

rins were produced smoothly. The subsequent intramolec-

ular cyclization reductive defluorinative aromatization of

β-(ω-chloroperfluorobutyl)subporphyrins afforded valu-

able β-monotetrafluorobenzo and β-monotrifluorobenzo

subporphyrins in good yield. The photophysical and elec-

trochemical studies on several typical subporphyrins and

porphyrins indicated the intensive influence of various

perfluoroalkyl groups on the properties of subporphyrins.

With these oxidation and reduction potential data in hand,

we can estimate the electrochemical HOMO–LUMO gaps

of various subporphyrins. The HOMO–LUMO gaps of

2b, 5b, and 6b are 2.80, 2.71, and 2.66 V, respectively. As

a result, the red-shifted Q-like absorption bands for 5b and

6b were observed (Table 6).

A series of novel fluorinated subporphyrins have been ef-

ficiently synthesized by our trifluoromethylation reagent

and modified sulfinatodehalogenation method for the first

Figure 2 UV/Vis absorption and fluorescence emission spectra of 2a, 4a, 5a, 6a, 12a

Synthesis 2014, 46, 1674–1688

1682

S. Zhao et al.

PAPER

like band caused mainly by extensive π-conjugation,

which also exhibit a fluorescence spectrum of vibronic

structure. The redox potentials of several typical subpor-

phyrins were measured by cyclic voltammetry, and the

HOMO–LUMO gap of β-hexakistrifluoromethylated sub-

porphyrins illustrate that its macrocycle nonplanar distor-

tion is not as serious as that of porphyrin, which can be

supported by its ¹H NMR spectrum as well. Further stud-

ies on the synthesis of various fluorinated subporphyrin

are now in progress in our laboratory.

Table 5 UV/Vis Absorption and Fluorescence Emission Spectra

Data for Various Subporphyrins (CH₂Cl₂, 25 °C)

Subporphyrins Soret-like bands Q-like bands

Fluorescence

(nm)

2a

4a

368

456, 480

456, 478

458, 476

488, 518

458, 480

464, 488

456, 476

456, 478

456, 476

482, 508

458, 476

466, 490

458

510

–

370

5a

370

515

540

517

505, 534

504

–

6a

396 (377^a)

370

1

8b

NMR spectra were recorded at 400 MHz for H and 376 MHz for

¹⁹F NMR spectra. All spectra were obtained at r.t. in CDCl₃, except

subporphyrins 4a–c which were obtained at –40 °C; TMS was used

as an internal standard (δ_TMS= 0) for ¹H NMR spectra and CFCl₃as

an external standard (negative for upfield) for ¹⁹F NMR spectra.

Relative fluorescence quantum yields were determined with refer-

ence to that of 9,10-diphenylanthracene [Φ_F= 0.95 (EtOH)]. Elec-

trochemical properties of the compounds were investigated by

cyclic voltammetry (CV) using a three-electrode cell with a glass

carbon working electrode, a Pt wire counter electrode and an

Ag/AgNO₃reference electrode. Pure CH₂Cl₂was used as solvent.

The concentrations of the compounds were in the range of 10^–6M,

and TBAF (10^–4M) was used as supporting electrolyte. Solution

was purged with argon gas prior to measurements, and all measure-

ment were made at 25 °C. TLC analysis was performed on silica gel

plate and flash column chromatography over silica gel (300–400

mesh) (Huanghai Chemicals). DMSO and DMF were distilled from

CaH₂. All the other solvents and chemicals were reagent grade, pur-

chased commercially, and used without further purification if not

noted.

12a

2b

378

368

4b

368

5b

368

508

525

508

511

–

6b

390

9b

370

13a

4c

376

374

6c

402

494, 525

464, 494

466, 494

468, 496

466, 488

537

546

557

549

537

2d

378

5d

379

meso-Triphenylsubporphyrin (2a); Typical Procedure

To a solution of subporphyrin 1a (49 mg, 0.1 mmol) in CH₂Cl₂(10

mL), BF₃·OEt₂(0.25 mL, 2 mmol, 20 equiv) was added, and the re-

sulting mixture was stirred at r.t. for 5 min; TLC indicated that the

substrate was exhausted. The solvent was concentrated to dryness,

the resulting residue was purified by column chromatography (sili-

ca gel, CH₂Cl₂–PE–Et₂O, 1:4:1) and recrystallization (CH₂Cl₂–

MeOH) gave pure subporphyrin 2a (45.6 mg, 95%) as an orange

solid.

¹H NMR (400 MHz, CDCl₃): δ = 8.20 (s, 6 H, β-H), 8.09 (d, 6 H, o-

H_Ph), 7.73 (t, 6 H, m-H_Ph), 7.64 (t, 3 H, p-H_Ph).

¹⁹F NMR (376 MHz, CDCl₃): δ = –157.11 (m, 1 F, BF).

11b

15a

378

384

^aShoulder absorption.

As the number of β-perfluoroalkyl substituents increas-

ing, both Soret-like band and Q-like band of subporphy-

rins are significantly red-shifted due to macrocycle

nonplanar distortion. β-Monotrifluorobenzo subporphy-

rins show a red-shifted Soret-like band and enhanced Q-

Table 6 Oxidation and Reduction Potentials of Subporphyrin 2b, 5b, 6b, 9b, and 13a (CH₂Cl₂; V vs Ferrocene/Ferrocenium Ion Pair)^a

Subporphyrin

Oxidation (V)

Reduction (V)

HOMO–LUMO Gap (V) Q-like band λ_max(nm)

E¹

E²

E³

1/2ox

1/2red

2b

1.20

1.35

2.11

1.44

1.24

1.04

0.99

–1.60

–1.36

–0.55

–1.37

–1.45

–1.19

–0.39

–

2.80

2.71

2.66

2.81

2.69

2.23

1.38

476

508

476

490

647^b

721^b

5b

–1.67

–1.10

–1.85

–1.73

–

6b

–1.62

––

9b

13a

CuTPP^b

–2.09

–

b

CuTPP(CF₃)₈

–

^aMeasured by cyclic voltammetry, supporting electrolyte, Bu₄NPF₆(10^–4M); working electrode, glassy carbon; counter electrode, Pt wire; ref-

erence electrode, Ag/AgNO₃(scan rate: 0.1 V/s).

^bSee ref.7c; TPP = meso-tetraphenylporphyrin, TPP(CF₃)₈= β-octakis(trifluoromethyl)-meso-tetraphenylporphyrin.

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Peripheral Perfluoroalkylation of Subporphyrins

1683

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₃H₂₁BN₃:

469.1859; found: 469.1856.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₃H₂₀BN₃Br:

547.0946; found: 547.0965.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 368 (20.6), 456 (1.6), 480

nm (1).

UV/Vis (CH₂Cl₂): λ (relative intensity) = 370 (11.7), 456 nm (1).

Fluorescence (CH₂Cl₂, λ_ex= 370 nm): λ_max= 511 nm, Φ_F= 0.03.

Fluorescence (CH₂Cl₂, λ_ex= 368 nm): λ_max= 510 nm.

β-Monobromo-meso-tris[4-(trifluoromethyl)phenyl]subpor-

phyrin (3b)

From subporphyrin 2b, chromatography (CH₂Cl₂–PE–Et₂O,

1:10:1), to give 3b (28 mg, 89%) as a yellow solid.

meso-Tris[4-(trifluoromethyl)phenyl]subporphyrin (2b)

From subporphyrin 1b, chromatography (CH₂Cl₂–PE–Et₂O, 1:8:1),

to give 2b (64.8 mg, 97%) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ = 8.19–8.21 (m, 5 H, β-H), 8.15–

8.17 (m, 4 H, o-H_Ph), 7.95–8.02 (m, 8 H, o,m-H_Ph).

¹H NMR (400 MHz, CDCl₃): δ = 8.19 (s, 6 H, β-H), 8.18 (d, 6 H, o-

H_Ph), 8.00 (d, 6 H, m-H_Ph).

¹³C NMR (100 MHz, CDCl₃): δ = 141.18, 140.96, 140.59, 140.57,

139.92, 139.77, 139.13, 138.22, 135.80, 133.22, 133.17, 131.01,

130.69, 130.40, 130.34, 125.82, 125.79, 125.63, 125.55, 124.89,

124.86, 124.48, 123.51, 123.35, 123.02, 122.83, 119.99, 119.87,

119.09, 113.08.

¹⁹F NMR (376 MHz, CDCl₃): δ = –62.31 (s, 3 F, CF₃), –62.40 (s, 3

F, CF₃), –62.44 (s, 3 F, CF₃), –157.2 (m, 1 F, BF).

¹⁹F NMR (376 MHz, CDCl₃): δ = –62.41 (s, 9 F, CF₃), –157.20 (m,

1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₆H₁₈BN₃F₉:

673.1481; found: 673.1482.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 368 (24), 456 (2.1), 476

nm (1).

Fluorescence (CH₂Cl₂, λ_ex= 368 nm): λ_max= 504 nm, Φ_F= 0.09.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₆H₁₇BN₃F₉Br:

751.0606; found: 751.0586.

meso-Tris(4-tert-butylphenyl)subporphyrin (2c)

From subporphyrin 1c, chromatography (CH₂Cl₂–PE–Et₂O, 1:8:1),

to give 2c (64 mg, 98%) as an orange solid.

¹H NMR (400 MHz, CDCl₃): δ = 8.21 (s, 6 H, β-H), 8.03 (d, 6 H, o-

H_Ph), 7.74 (d, 6 H, m-H_Ph), 1.52 (s, 27 H, t-Bu).

UV/Vis (CH₂Cl₂): λ (relative intensity) = 368 (10.6), 456 nm (1).

Fluorescence (CH₂Cl₂, λ_ex= 368 nm): λ_max= 508, 529 nm, Φ_F=

0.03.

β-Monobromo-meso-tris(4-methoxyphenyl)subporphyrin (3d)

From subporphyrin 2d, chromatography (PE–EtOAc, 2:1), to give

3d (25.6 mg, 95%) as an orange solid.

¹H NMR (400 MHz, CDCl₃): δ = 8.16 (d, J = 5.6 Hz, 4 H, β-H), 8.11

(s, 1 H, β-H), 7.95–8.00 (m, 4 H, o-H_Ph), 7.79 (br s, 2 H, o-H_Ph),

7.19–7.28 (m, 6 H, m-H_Ph), 4.01 (s, 6 H, OMe), 4.00 (s, 3 H, OMe).

¹³C NMR (100 MHz, CDCl₃): δ = 150.85, 140.18, 134.10, 132.83,

125.73, 122.70, 120.60, 34.79, 31.50.

¹⁹F NMR (376 MHz, CDCl₃): δ = –157.09 (m, 1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₅H₄₅BN₃:

637.3737; found: 637.3735.

¹³C NMR (100 MHz, CDCl₃): δ = 159.87, 159.78, 140.65, 140.50,

140.03, 138.67, 135.92, 134.34, 134.01, 133.95, 128.98, 128.78,

126.98, 124.29, 122.97, 122.77, 122.40, 122.30, 120.82, 120.32,

120.03, 119.83, 114.31, 113.37, 113.28, 112.22.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 374 (13.4), 459 (1), 488

nm (1).

Fluorescence (CH₂Cl₂, λ_ex= 374 nm): λ_max= 518 nm.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₆H₂₆BN₃O₃Br:

637.1281; found: 637.1281.

meso-Tris(4-methoxyphenyl)subporphyrin (2d)

From subporphyrin 1d, chromatography (CH₂Cl₂–PE–EtOAc,

1:5:1), to give 2d (54.5 mg, 94%) as an orange-reddish solid.

¹H NMR (400 MHz, CDCl₃): δ = 8.15 (s, 6 H, β-H), 8.00 (d, 6 H, o-

H_Ph), 7.26 (d, 6 H, m-H_Ph), 4.00 (s, 9 H, OMe).

¹⁹F NMR (376 MHz, CDCl₃): δ = –157.10 (m, 1 F, BF).

UV/Vis (CH₂Cl₂): λ (relative intensity) = 378 (12), 462 (1), 490 nm

(1).

Fluorescence (CH₂Cl₂, λ_ex= 378 nm): λ_max= 539 nm, Φ_F= 0.004.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₆H₂₇BN₃O₃:

559.2176; found: 559.2170.

β-Hexabromo-meso-triphenylsubporphyrin (4a)

From subporphyrin 2a (25 mg, 50 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:4:1), to give 4a (45.7 mg, 95%) as a yellow

solid.

¹H NMR (500 MHz, CDCl₃, –40 °C): δ = 8.12 (d, J = 7.80 Hz, 3 H,

o-H_Ph), 7.75 (t, J = 7.80 Hz, 3 H, m-H_Ph), 7.70 (t, J = 7.80 Hz, 3 H,

p-H_Ph), 7.51 (t, J = 7.80 Hz, 3 H, m-H_Ph), 7.25 (d, J = 7.80 Hz, 3 H,

o-H_Ph).

¹³C NMR (100 MHz, CDCl₃): δ = 134.38, 133.08, 132.50, 131.86,

129.34, 127.65, 120.14, 118.42.

¹⁹F NMR (376 MHz, CDCl₃): δ = –157.17 (m, 1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₃H₁₅BN₃Br₆:

UV/Vis (CH₂Cl₂): λ (relative intensity) = 378 (13.1), 464 (1), 494

nm (1.42).

Fluorescence (CH₂Cl₂, λ_ex= 378 nm): λ_max= 546 nm, Φ_F= 0.12.

β-Monobromo-meso-triphenylsubporphyrin (3a); Typical Pro-

cedure

Compound 2a (20 mg, 41 μmol) was dissolved in a mixture of

DCE–MeOH (9:1, 8 mL), then NBS (8.0 mg, 45 μmol) was added,

the resulting solution was heated to reflux and stirred for 2–3 h un-

der N₂atmosphere (monitored by TLC). The mixture was cooled to

r.t., and then directly concentrated in vacuo; the residue was puri-

fied by column chromatography (silica gel, CH₂Cl₂–hexane–Et₂O,

1:5:1) to give 3a (21 mg, 91%) as a yellow solid.

936.6490; found: 936.6522.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 370 (23), 456 (3), 478 nm

(1).

¹H NMR (400 MHz, CDCl₃): δ = 8.17–8.23 (m, 5 H, β-H), 8.05–

8.10 (m, 4 H, o-H_Ph), 7.91 (br s, 2 H, o-H_Ph), 7.66–7.76 (m, 9 H, m,p-

H_Ph).

Fluorescence (CH₂Cl₂, λ_ex= 370 nm): λ_max= 518 nm, Φ_F= 0.002.

¹³C NMR (100 MHz, CDCl₃): δ = 141.98, 141.81, 141.42, 141.33,

139.92, 137.59, 137.41, 136.79, 135.74, 134.11, 134.04, 129.75,

129.34, 129.17, 129.10, 128.83, 125.50, 124.30, 124.13, 123.75,

123.61, 122.25, 121.97, 121.34, 113.51.

β-Hexabromo-meso-tris[4-(trifluoromethyl)phenyl]subporphy-

rin (4b)

From subporphyrin 2b (30 mg, 43 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:20:1), to give 4b (41 mg, 82%) as a yellow

solid.

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S. Zhao et al.

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¹H NMR (500 MHz, CDCl₃, –40 °C): δ = 8.28 (d, J = 7.80 Hz, 3 H,

o-H_Ph), 8.04 (d, J = 7.80 Hz, 3 H, m-H_Ph), 7.78 (d, J = 7.80 Hz, 3 H,

m-H_Ph), 7.41 (d, J = 7.80 Hz, 3 H, o-H_Ph).

¹³C NMR (100 MHz, CDCl₃): δ = 135.51, 134.44, 133.48, 132.87,

132.44, 132.11, 131.79, 131.46, 128.22, 125.50, 125.10, 124.53,

122.79, 120.08, 118.75, 118.65.

¹⁹F NMR (376 MHz, CDCl₃): δ = –62.30 (s, 9 F, CF₃), –156.83 (m,

1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₆H₁₂BN₃F₉Br₆:

1140.6190; found: 1140.6163.

β-Mono(trifluoromethyl)-meso-tris[4-(trifluoromethyl)phe-

nyl]subporphyrin (5b)

From subporphyrin 3b (13 mg, 16.8 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:15:1) to give 5b (11 mg, 86%) as a yellow sol-

id.

¹H NMR (400 MHz, CDCl₃): δ = 8.41 (s, 1 H, β-H), 8.25 (d, J = 4.8

Hz, 1 H, β-H), 8.22 (d, J = 4.8 Hz, 1 H, β-H), 8.13–8.20 (m, 2 H, β-

H, 4 H, o-H_Ph), 7.91–8.03 (m, 6 H, m-H_Ph); o-H_Ph(2 H, undetected).

¹³C NMR (100 MHz, CDCl₃): δ = 141.84, 141.66, 141.37, 140.48,

139.62, 139.35, 138.88, 136.36, 134.45, 133.23, 133.20, 131.11,

131.03, 130.78, 125.92, 125.58, 125.50, 124.51124.26, 123.93,

123.79, 123.33, 121.41, 119.90, 119.74.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 468 (17.5), 456 (2.2), 478

nm (1).

¹⁹F NMR (376 MHz, CDCl₃): δ = –53.60 (s, 3 F, β-CF₃), –62.43 (s,

3 F, CF₃), –62.44 (s, 3 F, CF₃), –62.48 (s, 3 F, CF₃), –157.76 (m, 1

F, BF).

Fluorescence (CH₂Cl₂, λ_ex= 368 nm): λ_max= 517, 486 nm, Φ_F=

0.002.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₇H₁₇BN₃F₁₂:

741.1340; found: 741.1355.

β-Hexabromo-meso-tris(4-tert-butylphenyl)subporphyrin (4c)

From subporphyrin 2c (70 mg, 106 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:8:1), to give 4c (120 mg, 100%) as a yellow

solid.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 368 (19), 456 (1.6), 476

nm (1).

¹H NMR (500 MHz, CDCl₃, –40 °C): δ = 8.02 (d, J = 7.80 Hz, 3 H,

o-H_Ph), 7.74 (d, J = 7.80 Hz, 3 H, m-H_Ph), 7.49 (d, J = 7.80 Hz, 3 H,

m-H_Ph), 7.16 (d, J = 7.80 Hz, 3 H, o-H_Ph), 1.48 (s, 27 H, t-Bu).

¹³C NMR (100 MHz, CDCl₃): δ = 152.74, 134.44, 132.38, 130.86,

128.74, 124.55, 120.32, 118.32, 34.91, 31.59.

¹⁹F NMR (376 MHz, CDCl₃): δ = –157.10 (m, 1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₅H₃₉BN₃Br₆:

Fluorescence (CH₂Cl₂, λ_ex= 368 nm): λ_max= 508 nm, Φ_F= 0.08.

β-Mono(trifluoromethyl)-meso-tris(4-methoxyphenyl)subpor-

phyrin (5d)

From subporphyrin 3d (13 mg, 19.7 μmol), chromatography (PE–

EtOAc, 4:1), to give 5d (12 mg, 95%) as an orange solid.

¹H NMR (400 MHz, CDCl₃): δ = 8.41 (s, 1 H, β-H), 8.25 (d, J = 4.8

Hz, 1 H, β-H), 8.21 (d, J = 4.8 Hz, 1 H, β-H), 8.19 (d, J = 4.8 Hz, 1

H, β-H), 8.15 (d, J = 4.8 Hz, 1 H, β-H), 7.98–8.01 (m, 4 H, o-H_Ph),

7.79 (br s, 2 H, o-H_Ph), 7.26–7.30 (m, 4 H, m-H_Ph), 7.18 (d, J = 8 Hz,

2 H, m-H_Ph), 4.02 (s, 9 H, OMe).

¹³C NMR (100 MHz, CDCl₃): δ = 160.14, 159.94, 141.60, 141.26,

140.82, 139.95, 136.16, 134.93, 134.18, 134.13, 128.81, 128.53,

128.00, 125.17, 124.80, 124.42, 124.13, 123.73, 123.44, 123.37,

122.93, 122.33, 121.74, 120.92, 120.29, 114.58, 114.51, 112.97,

55.54, 55.24.

¹⁹F NMR (376 MHz, CDCl₃): δ = –53.57 (s, 3 F, β-CF₃), –157.60

(m, 1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₇H₂₆BN₃O₃F₃:

627.2063; found: 627.2050.

1104.8368; found: 1104.8399.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 374 (26), 458 nm (3.75).

Fluorescence (in CH₂Cl₂, λ_ex= 374 nm): λ_max= 521 nm, Φ_F= 0.001.

β-Mono(trifluoromethyl)-meso-triphenylsubporphyrin (5a);

Typical Procedure

Under an N₂atmosphere, FSO₂CF₂CO₂Me (135 mg, 0.7 mmol) was

added to a mixture of 3a (20 mg, 35.2 μmol), Pd(dba)₂(5 mol%),

and CuI (130 mg, 0.7 mmol) in anhyd DMF (4 mL), the resulting

mixture was stirred at 100 °C under N₂for 2 h. The mixture was

cooled to r.t. and then it was diluted with CH₂Cl₂(10 mL) and

passed through a short column (silica gel). The filtrate was washed

with H₂O (3×), dried (anhyd Na₂SO₄), and concentrated in vacuo.

The residue was purified by column chromatography (silica gel,

CH₂Cl₂–hexane–Et₂O, 1:10:1) to give 5a (17.8 mg, 94%) as an or-

ange solid.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 379 (12.3), 466 (1), 494

nm (1.2).

Fluorescence (CH₂Cl₂, λ_ex= 378 nm): λ_max= 557 nm, Φ_F= 0.12.

¹H NMR (400 MHz, CDCl₃): δ = 8.43 (s, 1 H, β-H), 8.26 (d, J = 4.4

Hz, 1 H, β-H), 8.22 (d, J = 4.8 Hz, 1 H, β-H), 8.20 (d, J = 4.8 Hz, 1

H, β-H), 8.16 (d, J = 4.8 Hz, 1 H, β-H), 8.05–8.08 (m, 4 H, o-H_Ph),

7.66–7.77 (m, 11 H, o,m,p-H_Ph).

¹³C NMR (100 MHz, CDCl₃): δ = 141.74, 141.51, 141.15, 140.25,

136.34, 136.28, 136.08, 135.55, 134.62, 133.14, 133.12, 128.95,

128.89, 128.49, 128.47, 128.25, 127.70, 127.44, 125.36, 124.99,

124.52, 124.02, 123.71, 123.62, 123.54, 123.49, 123.14, 122.70,

121.62, 121.21, 120.86.

¹⁹F NMR (376 MHz, CDCl₃): δ = –53.67 (s, 3 F, β-CF₃), –157.77

(m, 1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₄H₂₀BN₃F₃:

537.1715; found: 537.1733.

β-Hexakis(trifluoromethyl)-meso-triphenylsubporphyrin (6a);

Typical Procedure

Under an N₂atmosphere, FSO₂CF₂CO₂Me (237 mg, 1.23 mmol)

was added to a mixture of 4a (40 mg, 41 μmol), Pd(dba)₂(5 mol%)

and CuI (234 mg, 1.23 mmol) in anhyd DMF (8 mL), the resulting

mixture was stirred at 100 °C under N₂for 2 h. The mixture was

cooled to r.t., and then it was diluted with CH₂Cl₂(30 mL) and

passed through a short column (silica gel). The filtrate was washed

with H₂O (3 ×), dried (anhyd Na₂SO₄), and concentrated in vacuo.

The residue was purified by column chromatography (silica gel,

CH₂Cl₂–hexane–Et₂O, 1:15:1) to give 6a (33 mg, 90%) as an orange

solid.

¹H NMR (400 MHz, CDCl₃): δ = 7.79 (d, J = 6.8 Hz, 6 H, o-H_Ph),

7.72 (t, J = 7.6 Hz, 3 H, p-H_Ph), 7.62 (t, J = 8.0 Hz, 6 H, m-H_Ph).

¹³C NMR (100 MHz, CDCl₃): δ = 134.10, 133.32, 129.98, 127.28,

125.75, 122.25, 119.52.

¹⁹F NMR (376 MHz, CDCl₃): δ = –50.25 (s, 18 F, β-CF₃), –158.3

UV/Vis (CH₂Cl₂): λ (relative intensity) = 370 (17.5), 458 (1.3), 476

nm (1).

Fluorescence (CH₂Cl₂, λ_ex= 370 nm): λ_max= 515 nm, Φ_F= 0.09.

(m, 1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₉H₁₅BN₃F₁₈:

877.1088; found: 877.1102.

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Peripheral Perfluoroalkylation of Subporphyrins

1685

UV/Vis (CH₂Cl₂): λ (relative intensity) = 396 (17.5), 488 (1), 518

nm (1.1).

¹⁹F NMR (376 MHz, CDCl₃): δ = –67.13 (d, 2 F, CF₂Cl), –96.09 (t,

2 F, SubPor-CF₂), –158.01 (m, 1 F, BF).

Fluorescence (CH₂Cl₂, λ_ex= 396 nm): λ_max= 540 nm, Φ_F= 0.02.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₅H₂₀BN₃F₄Cl:

603.1406; found: 603.1415.

β-Hexakis(trifluoromethyl)-meso-tris[4-(trifluoromethyl)phe-

nyl]subporphyrin (6b)

From subporphyrin 4b (35 mg, 30 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:20:1), to give 6b (28 mg, 85%) as a yellow

solid.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 370 (16), 458 (1.1), 480

nm (1).

Fluorescence (CH₂Cl₂, λ_ex= 370 nm): λ_max= 517 nm, Φ_F= 0.11.

Subporphyrin 8b

¹H NMR (400 MHz, CDCl₃): δ = 7.92 (s, 12 H, o,m-H_Ph).

From subporphyrin 2a (15 mg, 30 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:15:1), to give 8b (8.8 mg, 41%) as an orange

solid.

¹H NMR (400 MHz, CDCl₃): δ = 8.44 (s, 1 H, β-H), 8.25 (d, J = 4.8

Hz, 1 H, β-H), 8.23 (d, J = 4.8 Hz, 1 H, β-H), 8.17 (d, J = 4.8 Hz, 1

H, β-H), 8.05–8.07 (m, 5 H, β-H, o-H_Ph), 7.63–7.78 (m, 9 H, m,p-

H_Ph), 7.54 (br s, 1 H, o-H_Ph), 7.40 (br s, 1 H, o-H_Ph).

¹³C NMR (100 MHz, CDCl₃): δ = 138.96, 135.81, 135.24, 134.41,

134.08, 133.76, 133.55, 126.97, 126.13, 126.09, 126.06, 124.25,

123.70, 120.97.

¹⁹F NMR (376 MHz, CDCl₃): δ = –49.99 (s, 18 F, β-CF₃), –62.67 (s,

9 F, CF₃), –157.95 (m, 1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₂H₁₂BN₃F₂₇:

¹³C NMR (100 MHz, CDCl₃): δ = 142.33, 141.53, 141.08, 140.07,

136.29, 136.15, 136.05, 135.37, 133.87, 133.16, 133.09, 131.67,

128.96, 128.88, 128.49, 128.22, 128.17, 126.98, 125.47, 124.54,

123.88, 123.7, 123.52, 123.23, 122.99, 122.61, 122.41, 122.06,

121.08, 120.96, 116.34, 116.01, 115.67, 109.67.

1081.0690; found: 1081.0724.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 390 (24), 482 (1.5), 508

nm (1).

Fluorescence (CH₂Cl₂, λ_ex= 390 nm): λ_max= 525 nm, Φ_F= 0.01.

¹⁹F NMR (376 MHz, CDCl₃): δ = –68.01 (t, J = 15 Hz, 2 F, CF₂Cl),

–98.35 (m, 2 F, SubPor-CF₂), –117.41 (m, 2 F, CF₂CF₂Cl), –119.68

(t, J = 15 Hz, 2 F, SubPor-CF₂CF₂), –158.12 (m, 1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₇H₂₀BN₃F₈Cl:

703.1356; found: 703.1342.

β-Hexakis(trifluoromethyl)-meso-tris(4-tert-butylphenyl)sub-

porphyrin (6c)

From subporphyrin 4c (30 mg, 27 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:50:1), to give 6c (25 mg, 87%) as an orange-

reddish solid.

¹H NMR (400 MHz, CDCl₃): δ = 7.69 (d, J = 8 Hz, 6 H, o-H_Ph), 7.61

(d, J = 8 Hz, 6 H, m-H_Ph), 1.49 (s, 27 H, t-Bu).

¹³C NMR (100 MHz, CDCl₃): δ = 148.33, 137.06, 134.07, 131.44,

130.26, 130.07, 129.90, 129.84, 129.69, 128.31, 128.22, 128.13,

126.67, 123.33, 121.16, 120.68, 118.51, 118.02, 115.85, 66.47,

66.40, 54.54, 45.32, 28.38, 25.98, 18.07, 18.02.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 370 (16), 458 (1.2), 480

nm (1).

Fluorescence (CH₂Cl₂, λ_ex= 370 nm): λ_max= 517 nm, Φ_F= 0.10.

Subporphyrin 8c

From subporphyrin 2a (40 mg, 82 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:15:1), to give 8c (24 mg, 34%) as an orange

solid.

¹⁹F NMR (376 MHz, CDCl₃): δ = –50.37 (s, 18 F, β-CF₃), –158.3

(m, 1 F, BF).

¹H NMR (400 MHz, CDCl₃): δ = 8.44 (s, 1 H, β-H), 8.25 (d, J = 4.8

Hz, 1 H, β-H), 8.23 (d, J = 4.8 Hz, 1 H, β-H), 8.17 (d, J = 4.8 Hz, 1

H, β-H), 8.05–8.07 (m, 5 H, β-H, o-H_Ph), 7.63–7.78 (m, 9 H, m,p-

H_Ph), 7.54 (br s, 1 H, o-H_Ph), 7.40 (br s, 1 H, o-H_Ph).

¹³C NMR (100 MHz, CDCl₃): δ = 142.33, 141.54, 141.09, 140.08,

136.29, 136.24, 136.05, 135.35, 133.84, 133.15, 133.09, 131.64,

129.14, 128.96, 128.88, 128.50, 128.22, 128.19, 126.97, 125.49,

124.79, 124.54, 123.89, 123.73, 123.47, 123.18, 122.99, 122.62,

121.79, 121.08, 120.95, 116.09, 113.22.

¹⁹F NMR (376 MHz, CDCl₃): δ = –67.95 (m, 2 F, CF₂Cl), –98.37

(m, 2 F, SubPor-CF₂), –117.41 to –121.82 (m, 8 F), –158.12 (m, 1

F, BF).

HR-MALDI TOF-MS: m/z [M – F]⁺calcd for C₃₉H₂₀BN₃F₁₂Cl:

803.1276; found: 803.1278.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₅₁H₃₉BN₃F₁₈:

1045.3024; found: 1045.2980.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 402 (13), 494 (1), 525 nm

(1.5).

Fluorescence (CH₂Cl₂, λ_ex= 402 nm): λ_max= 537 nm, Φ_F= 0.02.

β-Mono(perfluoroalkyl)-meso-triarylsubporphyrins; General

Procedure

Using 2a as model substrate, 2a (20 mg, 40.9 μmol) was dissolved

in a mixture of CH₂Cl₂–DMSO (1:1, 6 mL), then R^FI (0.41 mmol),

Na₂S₂O₄(0.62 mmol), and NaHCO₃(0.62 mmol) were added, the

resulting solution was heated to reflux and stirred for 2–3 h under

an N₂atmosphere (monitored by TLC). The mixture was cooled to

r.t., then it was diluted with CH₂Cl₂(10 mL) and passed through a

short column (silica gel). The filtrate was washed H₂O (3 ×), dried

(anhyd Na₂SO₄), and concentrated in vacuo. The residue was puri-

fied by column chromatography (silica gel, CH₂Cl₂–hexane–Et₂O,

1:15:1) to give the product.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 370 (16), 458 (1.2), 480

nm (1).

Fluorescence (in CH₂Cl₂, λ _ex= 370 nm): λ_max= 517 nm, Φ_F= 0.09.

Subporphyrin 8a

Subporphyrin 9b

From subporphyrin 2a (30 mg, 61 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:15:1), to give 8a (12 mg, 31%) as an orange

solid.

From subporphyrin 2b (25 mg, 34.5 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:15:1), to give 9b (12 mg, 46%) as an orange

solid.

¹H NMR (400 MHz, CDCl₃): δ = 8.45 (s, 1 H, β-H), 8.24 (d, J = 4.8

Hz, 1 H, β-H), 8.22 (d, J = 4.8 Hz, 1 H, β-H), 8.17 (d, J = 4.8 Hz, 1

H, β-H), 8.04–8.07 (m, 5 H, β-H, o-H_Ph), 7.63–7.77 (m, 9 H, m,p-

H_Ph), 7.57 (br s, 1 H, o-H_Ph), 7.41 (br s, 1 H, o-H_Ph).

¹³C NMR (100 MHz, CDCl₃): δ = 142.57, 141.74, 141.29, 140.41,

136.52, 136.31, 135.66, 134.13, 133.33, 132.04, 129.14, 129.11,

128.70, 128.46, 127.19, 125.44, 124.73, 124.06, 123.91, 123.51,

123.19, 122.78, 121.32, 121.20.

¹H NMR (400 MHz, CDCl₃): δ = 8.60 (s, 1 H, β-H), 8.43 (s, 1 H, β-

H), 8.30 (s, 1 H, β-H), 8.26 (d, J = 4.8 Hz, 1 H, β-H), 8.24 (d, J =

4.8 Hz, 1 H, β-H), 8.16–8.19 (m, 4 H, o-H_Ph), 8.01–8.08 (m, 6 H, m-

H_Ph), 7.84 (br s, 2 H, o-H_Ph).

¹⁹F NMR (376 MHz, CDCl₃): δ = –62.48 (s, 3 F, CF₃), –62.51 (s, 3

F, CF₃), –62.62 (s, 3 F, CF₃), –68.18 (m, 2 F, CF₂Cl), –98.33 (m, 2

Synthesis 2014, 46, 1674–1688

1686

S. Zhao et al.

PAPER

F, SubPor-CF₂), –117.55 (m, 2 F, CF₂CF₂Cl), –119.88 (t, J = 15 Hz,

2 F, SubPor-CF₂CF₂), –158.07 (m, 1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₀H₁₇BN₃F₁₇Cl:

907.0963; found: 907.0963.

¹³C NMR (100 MHz, CDCl₃): δ = 160.12, 159.91, 159.71, 142.26,

141.28, 140.72, 139.78, 136.10, 135.71, 134.91, 134.21, 134.11,

132.82, 128.75, 128.58, 128.48, 125.39, 124.25, 123.63, 123.49,

123.25, 122.97, 122.81, 122.42, 122.29, 120.80, 120.31, 116.07,

114.60, 114.50, 112.42, 55.52.

¹⁹F NMR (376 MHz, CDCl₃): δ = –67.99 (t, J = 15 Hz, 2 F, CF₂Cl),

–98.10 (m, 2 F, SubPor-CF₂), –117.45 (m, 2 F, CF₂CF₂Cl), –119.63

(t, J = 15 Hz, 2 F, SubPor-CF₂CF₂), –157.98 (m, 1 F, BF).

UV/Vis (CH₂Cl₂): λ (relative intensity) = 370 (15), 458 (1.4), 476

nm (1).

Fluorescence (CH₂Cl₂, λ_ex= 370 nm): λ_max= 508 nm, Φ_F= 0.12.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₀H₂₆BN₃O₃F₈Cl:

793.1659; found: 793.1669.

Subporphyrin 10a

From subporphyrin 2c (40 mg, 60.8 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:20:1), to give 10a (16.8 mg, 35%) as an or-

ange solid.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 378 (11), 468 (1), 496 nm

(1.3).

¹H NMR (400 MHz, CDCl₃): δ = 8.47 (s, 1 H, β-H), 8.24 (d, J = 4.8

Hz, 1 H, β-H), 8.23 (d, J = 4.8 Hz, 1 H, β-H), 8.19 (d, J = 4.8 Hz, 1

H, β-H), 8.10 (d, J = 4.8 Hz, 1 H, β-H), 7.99 (m, 4 H, o-H_Ph), 7.76

(t, J = 7.6 Hz, 4 H, m-H_Ph), 7.60 (br s, 1 H, o-H_Ph, 2 H, m-H_Ph), 7.36

(br s, 1 H, o-H_Ph), 1.52 (s, 9 H, t-Bu), 1.51 (s, 9 H, t-Bu), 1.50 (s, 9

H, t-Bu).

¹³C NMR (126 MHz, CDCl₃): δ = 151.69, 151.40, 151.34, 142.36,

141.57, 141.06, 140.23, 136.28, 135.77, 133.71, 133.47, 133.07,

132.99, 126.21, 126.10, 125.53, 124.60, 124.01, 123.84, 123.10,

122.67, 121.21, 35.06, 35.02, 34.99, 31.69, 31.68.

Fluorescence (CH₂Cl₂, λ_ex= 378 nm): λ_max= 549 nm, Φ_F= 0.12.

Subporphyrin 11c

From subporphyrin 2d (30 mg, 51.8 μmol), chromatography (PE–

EtOAc, 4:1), to give 11c (16.5 mg, 35%) as an orange-reddish solid.

¹H NMR (400 MHz, CDCl₃): δ = 8.39 (s, 1 H, β-H), 8.21 (d, J = 4.8

Hz, 1 H, β-H), 8.18 (d, J = 4.8 Hz, 1 H, β-H), 8.13 (d, J = 4.8 Hz, 1

H, β-H), 8.04 (d, J = 4.8 Hz, 1 H, β-H), 7.97 (m, 4 H, o-H_Ph), 7.27

(m, 6 H, m-H_Ph), 7.11 (br s, 2 H, o-H_Ph), 4.01 (s, 3 H, OMe), 4.00 (s,

3 H, OMe), 3.97 (s, 3 H, OMe).

¹⁹F NMR (376 MHz, CDCl₃): δ = –66.78 (m, 2 F, CF₂Cl), –95.96

(m, 2 F, SubPor-CF₂), –157.96 (m, 1 F, BF).

HRMS (MALDI TOF): m/z [M –F]⁺calcd for C₄₇H₄₄BN₃F₄Cl:

771.3284; found: 771.3299.

¹³C NMR (100 MHz, CDCl₃): δ = 160.14, 159.92, 159.75, 142.27,

141.30, 140.74, 139.79, 136.08, 135.70, 134.20, 134.10, 128.75,

128.48, 125.39, 124.25, 123.63, 123.49, 122.81, 122.30, 120.80,

120.30, 114.60, 114.49, 112.40, 55.52, 55.45.

¹⁹F NMR (376 MHz, CDCl₃): δ = –67.96 (t, J = 15 Hz, 2 F, CF₂Cl),

–98.10 (m, 2 F, SubPor-CF₂), –117.97 to –121.83 (m, 8 F), –157.98

(m, 1 F, BF).

UV/Vis (CH₂Cl₂): λ (relative intensity) = 374 (13.5), 462 (1), 488

nm (1).

Fluorescence (CH₂Cl₂, λ_ex= 374 nm): λ_max= 527 nm, Φ_F= 0.09.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₂H₂₆BN₃O₃F₁₂Cl:

893.1595; found: 893.1605.

Subporphyrin 10b

From subporphyrin 2c (40 mg, 60.8 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:20:1), to give 10b (21.6 mg, 40%) as an or-

ange solid.

¹H NMR (400 MHz, CDCl₃): δ = 8.45 (s, 1 H, β-H), 8.27 (d, J = 4.8

Hz, 1 H, β-H), 8.24 (d, J = 4.8 Hz, 1 H, β-H), 8.20 (d, J = 4.8 Hz, 1

H, β-H), 8.11 (d, J = 4.8 Hz, 1 H, β-H), 8.00 (m, 4 H, o-H_Ph), 7.76

(t, J = 7.6 Hz, 4 H, m-H_Ph), 7.60 (br s, 1 H, o-H_Ph, 2 H, m-H_Ph), 7.35

(br s, 1 H, o-H_Ph), 1.53 (s, 9 H, t-Bu), 1.52 (s, 9 H, t-Bu), 1.50 (s, 9

H, t-Bu).

¹³C NMR (100 MHz, CDCl₃): δ = 151.49, 151.19, 151.05, 142.18,

141.38, 140.89, 139.91, 136.09, 135.55, 133.48, 133.23, 133.14,

132.87, 132.79, 126.00, 125.90, 125.58, 124.42, 123.86, 123.65,

123.36, 123.07, 122.90, 122.54, 122.09, 120.99, 116.12, 34.85,

34.81, 34.74, 31.92, 31.46, 31.42, 29.36, 22.69, 14.12.

¹⁹F NMR (376 MHz, CDCl₃): δ = –67.99 (t, J = 12 Hz, 2 F, CF₂Cl),

–98.15 (m, 2 F, SubPor-CF₂), –117.21 (m, 2 F, CF₂), –119.82 (t,

J = 15 Hz, 2 F, CF₂), –158.00 (m, 1 F, BF).

UV/Vis (CH₂Cl₂): λ (relative intensity) = 380 (13), 466 (1), 496 nm

(1.3).

Fluorescence (CH₂Cl₂, λ_ex= 380 nm): λ_max= 549 nm, Φ_F= 0.11.

Subporphyrin 11d

From subporphyrin 2d (25 mg, 43 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:5:1), to give 11d (17.6 mg, 42%) as an

orange-reddish solid.

¹H NMR (400 MHz, CDCl₃): δ = 8.40 (s, 1 H, β-H), 8.23 (d, J = 4.8

Hz, 1 H, β-H), 8.20 (d, J = 4.8 Hz, 1 H, β-H), 8.14 (d, J = 4.8 Hz, 1

H, β-H), 8.05 (d, J = 4.8 Hz, 1 H, β-H), 7.98 (m, 4 H, o-H_Ph), 7.28

(t, J = 8.8 Hz, 6 H, m-H_Ph), 7.12 (br s, 2 H, o-H_Ph), 4.02 (s, 3 H,

OMe), 4.01 (s, 3 H, OMe), 3.99 (s, 3 H, OMe).

¹³C NMR (100 MHz, CDCl₃): δ = 160.15, 159.93, 159.76, 142.28,

141.33, 140.77, 139.81, 136.02, 135.64, 134.80, 134.20, 134.10,

132.89, 128.72, 128.46, 125.34, 124.28, 123.67, 123.52, 123.16,

122.85, 122.59, 122.34, 120.82, 120.27, 114.60, 114.50, 113.25,

112.46, 112.09, 55.52, 55.44.

¹⁹F NMR (376 MHz, CDCl₃): δ = 45.89 (s, 1 F, SO₂F), –81.88 (s, 2

F, CF₂O), –82.97 (s, 2 F, CF₂O), –98.15 (m, 2 F, SubPor-CF₂),

–118.53 (m, 4 F, CF₂), –125.00 (t, J = 15 Hz, 2 F, SubPor-CF₂CF₂),

–157.80 (m, 1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₉H₄₄BN₃F₈Cl:

871.3220; found: 871.3223.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 374 (13.5), 462 (1), 488

nm (1).

Fluorescence (CH₂Cl₂, λ_ex= 374 nm): λ_max= 527 nm, Φ_F= 0.10.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₂H₂₆BN₃O₆F₁₃S:

957.1459; found: 957.1448.

Subporphyrin 11b

From subporphyrin 2d (40 mg, 69 μmol), chromatography (PE–

UV/Vis (CH₂Cl₂): λ (relative intensity) = 380 (13), 466 (1), 496 nm

(1.3).

EtOAc (4:1), to give 11b (29.7 mg, 53%) as an orange-reddish sol-

id.

Fluorescence (CH₂Cl₂, λ_ex= 380 nm): λ_max= 549 nm, Φ_F= 0.13.

¹H NMR (400 MHz, CDCl₃): δ = 8.41 (s, 1 H, β-H), 8.22 (d, J = 4.8

Hz, 1 H, β-H), 8.20 (d, J = 4.8 Hz, 1 H, β-H), 8.14 (d, J = 4.8 Hz, 1

H, β-H), 8.05 (d, J = 4.8 Hz, 1 H, β-H), 7.97–8.00 (m, 4 H, o-H_Ph),

7.26–7.30 (m, 6 H, m-H_Ph), 7.13 (br s, 2 H, o-H_Ph), 4.02 (s, 3 H,

OMe), 4.01 (s, 3 H, OMe), 3.99 (s, 3 H, OMe).

Subporphyrin 11e

From subporphyrin 2d (25 mg, 43 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:5:1), to give 11e (16 mg, 39%) as an orange-

reddish solid.

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Peripheral Perfluoroalkylation of Subporphyrins

1687

¹H NMR (400 MHz, CDCl₃): δ = 8.40 (s, 1 H, β-H), 8.23 (d, J = 4.8

Hz, 1 H, β-H), 8.20 (d, J = 4.8 Hz, 1 H, β-H), 8.15 (d, J = 4.8 Hz, 1

H, β-H), 8.05 (d, J = 4.8 Hz, 1 H, β-H), 7.98 (m, 4 H, o-H_Ph), 7.28

(t, J = 8.8 Hz, 6 H, m-H_Ph), 7.12 (br s, 2 H, o-H_Ph), 4.02 (s, 3 H,

OMe), 4.01 (s, 3 H, OMe), 3.98 (s, 3 H, OMe).

¹³C NMR (100 MHz, CDCl₃): δ = 160.14, 159.93, 159.76, 142.28,

141.31, 140.75, 139.79, 136.07, 135.68, 134.88, 134.20, 134.10,

132.71, 128.74, 128.47, 125.40, 124.26, 123.64, 123.50, 123.13,

122.82, 122.32, 120.81, 120.29, 118.53, 116.58, 116.15, 114.93,

114.60, 114.50, 113.58, 112.51, 111.03, 110.77, 108.16, 55.52,

55.41.

¹⁹F NMR (376 MHz, CDCl₃): δ = –80.75 (d, J = 9.8 Hz, 3 F, CF₃),

–98.16 (m, 2 F, SubPor-CF₂), –118.15 (m, 2 F), –121.51 (s, 2 F),

–121.95 (s, 4 F), –122.74 (s, 2 F), –126.15 (s, 2 F), –157.79 (m, 1 F,

BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₄H₂₆BN₃O₃F₁₇:

977.1827; found: 977.1830.

¹H NMR (400 MHz, CDCl₃): δ = 8.49 (br s, 2 H, β-H), 8.20 (d, 2 H,

β-H), 8.17 (m, 2 H, o-H_Ph), 8.02 (m, 4 H, m-H_Ph), 7.84 (m, 2 H, m-

H_Ph), 7.79 (m, 2 H, o-H_Ph), 7.44 (m, 2 H, o-H_Ph), 7.26 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 142.92, 142.37, 141.05, 141.01,

140.82, 139.94, 138.86, 138.76, 133.49, 133.26, 131.89, 131.07,

130.95, 130.77, 130.63, 125.97, 125.94, 124.56, 124.52, 124.48,

123.40, 123.20, 122.69, 122.37, 118.18, 117.44, 105.91, 105.68,

105.40.

¹⁹F NMR (376 MHz, CDCl₃): δ = –62.34 (s, 6 F, CF₃), –62.48 (s, 3

F, CF₃), –104.00 (m, 1 F), –132.14 (m, 1 F), –134.54 (m, 1 F),

–156.83 (m, 1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₀H₁₇BN₃F₁₂:

777.1355; found: 777.1361.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 376 (11), 466 (1.2), 490

nm (1).

Fluorescence (CH₂Cl₂, λ_ex= 376 nm): λ_max= 511 nm, Φ_F= 0.09.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 380 (13), 466 (1), 496 nm

(1.3).

Subporphyrin 13b

From subporphyrin 9b (16 mg, 17.2 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:20:1), to give 13b (0.8 mg, <5%) as a yellow

solid.

Fluorescence (CH₂Cl₂, λ_ex= 380 nm): λ_max= 549 nm, Φ_F= 0.09.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₀H₁₈BN₃F₁₇:

873.1353; found: 873.1342

β-Mono(tri/tetrafluorobenzo)-meso-triarylsubporphyrins;

General Procedure

Subporphyrin 8b (20 mg, 27.6 μmol) was dissolved in DMSO (8

mL) and heated to 100 °C, then Na₂S₂O₄(0.27 mmol) and K₂CO₃

(0.27 mmol) were added; the resulting solution was stirred for 15–

30 min under a N₂atmosphere (monitored by TLC). The mixture

was cooled to r.t., then it was diluted with CH₂Cl₂(30 mL) and

passed through a short column (silica gel). The filtrate was washed

with H₂O (3 ×), dried (anhyd Na₂SO₄), and concentrated in vacuo.

The residue was purified by column chromatography (silica gel,

CH₂Cl₂–hexane–Et₂O, 1:15:1) to give the product.

Subporphyrin 14

From subporphyrin 10a (20 mg, 25.2 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:20:1), to give 14 (14.1 mg, 78%) as an orange

solid.

¹H NMR (400 MHz, CDCl₃): δ = 8.27 (d, J = 8.4 Hz, 1 H, β-H), 8.47

(s, 1 H, H_Ph), 8.35 (s, 1 H, H_Ph), 8.31 (d, J = 4.8 Hz, 1 H, β-H), 8.28

(d, J = 4.4 Hz, 1 H, β-H), 8.23 (d, J = 4.4 Hz, 1 H, β-H), 8.17 (d, J =

4.4 Hz, 1 H, β-H), 8.04 (m, 5 H, H_Ph), 7.76 (m, 4 H, H_Ph), 1.58 (s, 9

H, t-Bu), 1.54 (s, 9 H, t-Bu), 1.52 (s, 9 H, t-Bu).

Subporphyrin 12a

¹³C NMR (100 MHz, CDCl₃): δ = 151.34, 151.12, 141.63, 140.79,

140.44, 139.87, 139.40, 138.52, 135.17, 133.90, 133.82, 132.77,

132.52, 129.72, 127.93, 125.90, 125.75, 123.28, 122.67, 122.26,

121.85, 120.27, 117.87, 111.59, 35.21, 34.83, 34.80, 31.48, 31.34.

¹⁹F NMR (376 MHz, CDCl₃): δ = –132.7 (d, J = 12 Hz, 1 F), –135.1

(d, J = 12 Hz, 1 F), –157.60 (m, 1 F, BF).

From subporphyrin 8b (12 mg, 16.6 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:15:1), to give 12a (9.5 mg, 85%) as an orange

solid.

¹H NMR (400 MHz, CDCl₃): δ = 8.35 (br s, 2 H, β-H), 8.16 (d, J =

4.4 Hz, 2 H, β-H), 8.08 (d, J = 7.2 Hz, 2 H, o-H_Ph), 7.84 (t, J = 4.8

Hz, 2 H, p-H_Ph), 7.65–7.75 (m, 7 H, m,p-H_Ph), 7.52 (m, 2 H, o-H_Ph),

7.33 (m, 2 H, o-H_Ph), 7.19 (m, 1 H).

¹³C NMR (100 MHz, CDCl₃): δ = 142.89, 142.34, 138.56, 138.50,

137.54, 137.48, 137.28, 137.23, 136.44, 133.10, 133.01, 131.50,

128.80, 128.38, 128.29, 128.08, 127.29, 127.19, 123.96, 123.12,

122.92, 121.99, 119.30, 118.48, 105.12, 104.88, 104.61.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₇H₄₃BN₃F₂:

697.3549; found: 697.3531.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 382 (10), 468 (1), 524 nm

(1.5).

¹⁹F NMR (376 MHz, CDCl₃): δ = –104.54 (m, 1 F), –133.64 (dq,

J₁= 22.2 Hz, J₂= 5.3 Hz, 1 F), –135.00 (m, 1 F), –156.88 (m, 1 F,

BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₇H₂₀BN₃F₃:

573.1733; found: 573.1731.

Fluorescence (CH₂Cl₂, λ_ex= 382 nm): λ_max= 549 nm, Φ_F= 0.07.

Subporphyrin 15a

From subporphyrin 11b (18 mg, 21.8 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:5:1), to give 15a (13 mg, 85%) as an orange

solid.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 378 (25), 464 (1.5), 488

nm (1).

¹H NMR (400 MHz, CDCl₃): δ = 8.24 (d, J = 8.4 Hz, 2 H, β-H), 8.15

(t, J = 4 Hz, 2 H), 8.01 (d, J = 8.4 Hz, 2 H, β-H), 7.83 (t, J = 4.4 Hz,

2 H), 7.26 (m, 4 H, m-H_Ph), 7.22 (d, J = 7.2 Hz, 2 H, o-H_Ph), 7.04 (d,

J = 6 Hz, 2 H, o-H_Ph), 4.02 (s, 6 H, OMe), 4.00 (s, 3 H, OMe).

¹³C NMR (100 MHz, CDCl₃): δ = 160.11, 159.76, 142.77, 138.42,

134.09, 132.71, 132.46, 129.47, 128.78, 123.93, 123.04, 122.80,

121.92, 121.82, 118.59, 118.03, 114.47, 113.01, 112.64, 55.52,

55.43, 29.69.

¹⁹F NMR (376 MHz, CDCl₃): δ = –130.15 (d, J = 19.2 Hz, 2 F),

–154.56 (d, J = 18.8 Hz, 2 F), –156.60 (m, 1 F, BF).

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₀H₂₅BN₃O₃F₄:

Fluorescence (CH₂Cl₂, λ_ex= 378 nm): λ_max= 505, 534 nm, Φ_F=

0.09.

Subporphyrin 12b

From subporphyrin 8b (12 mg, 16.6 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:15:1), to give 12b (0.6 mg, <5%) as an orange

solid.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₃₇H₂₁BN₃F₈:

669.1732; found: 669.1741.

681.1956; 681.1947.

Subporphyrin 13a

From subporphyrin 9b (16 mg, 17.2 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:20:1), to give 13a (11 mg, 80%) as a yellow

solid.

UV/Vis (CH₂Cl₂): λ (relative intensity) = 384 (14), 466 (1.7), 488

nm (1).

Synthesis 2014, 46, 1674–1688

1688

S. Zhao et al.

PAPER

Fluorescence (CH₂Cl₂, λ_ex= 384 nm): λ_max= 537 nm, Φ_F= 0.08.

Osuka, A. Chem. Eur. J. 2009, 15, 237. (h) Tsurumaki, E.;

Osuka, A. Chem. Asian J. 2013, 8, 3042.

(4) (a) Kim, K. S.; Lim, J. M.; Myśliborski, R.; Pawlicki, M.;

Latos-Grażyński, L.; Kim, D. J. Phys. Chem. Lett. 2011, 2,

477. (b) Shimizu, S.; Matsuda, A.; Kobayashi, N. Inorg.

Chem. 2009, 48, 7885.

(5) Representative reports on peripherally fabricated

subphthalocyanine: (a) Claessens, C. G.; Torres, T. Angew.

Chem. Int. Ed. 2002, 41, 2561. (b) Fukuda, T.; Stork, J. R.;

Potucek, R. J.; Olmstead, M. M.; Noll, B. C.; Kobayashi, N.;

Durfee, W. S. Angew. Chem. Int. Ed. 2002, 41, 2565.

(c) Claessens, C. G.; Torres, T. Chem. Eur. J. 2000, 6, 2168.

(d) Kobayashi, N.; Nonomura, T. Tetrahedron Lett. 2002,

43, 4253. (e) Rodríguez-Morgade, M. S.; Esperanza, S.;

Torres, T.; Barberá, J. Chem. Eur. J. 2005, 11, 354.

(f) Martinez-Diaz, M. V.; Quintiliani, M.; Torres, T. Synlett

2008, 1. (g) Iglesias, R. S.; Claessens, C. G.; Herranz, M. Á.

G.; Torres, T. Org. Lett. 2007, 9, 5381.

Subporphyrin 15b

From the subporphyrin 11b (18 mg, 21.8 μmol), chromatography

(CH₂Cl₂–PE–Et₂O, 1:5:1), to give 15b (0.8 mg, <5%) as an orange

solid.

HRMS (MALDI TOF): m/z [M – F]⁺calcd for C₄₀H₂₇BN₃O₃F₈:

759.2049; found: 759.2071.

Acknowledgement

Thanks for the financial support from the Natural Science Founda-

tion of China (21032006, 21302207), and the 973 Program of China

(2012CB821600).We also thank Professor Wei-Shi Li of Shanghai

Institute of Organic Chemistry for obtaining UV/Vis absorption

spectra and electrochemical data.

(6) (a) Gassman, P. G.; Ghosh, A.; Almlöf, J. J. Am. Chem. Soc.

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Chem. 1994, 59, 6943.

Supporting Information for this article is available online at

http://www.thieme-connect.com/ejournals/toc/synthesis.SnuIomprifgtooatrinSugpIoi

n

nfomartit

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Synthesis 2014, 46, 1674–1688

Article Doi

β-Perfluoroalkylated meso -aryl-substituted subporphyrins: Synthesis and properties

DOI: 10.1055/s-0033-1341055

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Article abstract of DOI:10.1055/s-0033-1341055

Full text of DOI:10.1055/s-0033-1341055

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