Pd-Catalyzed Conversion of Aryl Iodides to Sulfonyl Fluorides Using SO2 Surrogate DABSO and Selectfluor

Article abstract of DOI:10.1021/acs.joc.7b00051

A one-pot Pd-catalyzed conversion of aryl iodide to aryl sulfonyl fluorides using DABSO and Selectfluor has been developed generating aryl sulfonyl fluorides in good to excellent yields. The reaction results in the generation of electronically and sterically diverse sulfonyl fluorides. Additionally, sulfonyl fluorides can be converted to aryl sulfonamides and sulfonic esters using Cs₂CO₃ under mild conditions.

Full text of DOI:10.1021/acs.joc.7b00051

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Note
Pd-Catalyzed Conversion of Aryl Iodides to Sulfonyl
Fluorides Using SO2 Surrogate DABSO and Selectfluor
Arianna Linnae Tribby, Ismerai Rodriguez, Shamira Shariffudin, and Nicholas Dewayne Ball
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.7b00051 • Publication Date (Web): 30 Jan 2017
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The Journal of Organic Chemistry
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Pd-Catalyzed Conversion of Aryl Iodides to Sulfonyl Fluorides Using
SO2 Surrogate DABSO and Selectfluor
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Ariana L. Tribby§, Ismeraí Rodríguez§, Shamira Shariffudin#, and Nicholas D. Ball*, §
§Department of Chemistry, Pomona College, 645 North College Avenue, Claremont, California, 91711
#Department of Chemistry, Amherst College, AC #2243, Amherst, Massachusetts, 01002-5000
Supporting Information Placeholder
ABSTRACT: A one-pot Pd-catalyzed conversion of aryl iodide to aryl sulfonyl fluorides using DABSO and Selectfluor
has been developed generating aryl sulfonyl fluorides in good to excellent yields. The reaction results in the generation
of electronically- and sterically-diverse sulfonyl fluorides. Additionally, sulfonyl fluorides can be converted to aryl sulfon-
amides
and
sulfonic
esters
using
Cs2CO3
under
mild
conditions.
Compounds that contain a S–F bond have garnered in-
tense interest in the chemical and biological literature as
of late. In particular, sulfonyl fluorides, (RSO2F), are
commonly used as covalent protein inhibitors and biolog-
ical probes (Figure 1).1 Considerable efforts have recent-
ly focused on new applications in organic chemistry for
aromatic sulfonyl fluorides, ranging from fluorinating rea-
gents2 and, 19F radiolabeling,3 to synthons toward sul-
fonylated compounds using sulfur(VI) exchange (SuFEx)
“click chemistry”.4 Key to the allure of sulfonyl fluorides
are their unique properties compared to other sulfonylat-
ed functional groups. Due to their sulfur-fluorine bond,
sulfonyl fluorides are hydrolytically stable,5 resistant to
The most common approach to synthesize aromatic sul-
fonyl fluorides requires the corresponding sulfonyl chlo-
ride and an F– source (e.g., KFHF, HF, etc.).4a However,
several challenges exist with this approach, particularly
with how it pertains to the synthesis and reactivity of the
sulfonyl chloride precursor. First, the synthesis of sul-
fonyl chlorides requires the use of strong acids, oxidants,
or explosive aryl diazonium salts.8 These reagents are
often incompatible with many functional groups, thus
complicating the late-stage functionalization of mole-
cules. Second, the rapid reactivity of some sulfonyl chlo-
rides with water presents operational challenges, creat-
ing undesired side products. Thus, there is significant
impetus for alternative methods to synthesize aromatic
sulfonyl fluorides that circumvent the requirement of sul-
fonyl chloride intermediates. One strategy involves the
development of one-pot methods that begin with more
simple, organic starting materials, and permit the incor-
poration of both SO2 and fluorine.
reduction,6 and unlike other sulfonylated groups, re-
sistant to bond cleavage in metal catalysis.7
N
SO2F
H2N
SO2F
PyFluor
(fluorinating reagent)
AEBSF
(serine protease inhibitor)
Recent efforts have focused on metal-catalyzed genera-
tion of sulfones and sulfonamides using bench-stable
SO2 sources [e.g., 1,4-diazabicyclo[2.2.2]octanebis (sul-
SO2F
fur dioxide) or DABSO, and potassium metabisulfite].9-11
In particular, the generation of organic sulfinate salt in-
termediates using metal-mediated strategies are of high
interest for drug discovery, facilitating rapid derivatization
of sulfonylated analogues in structure-activity relation-
ship studies.9a Our approach was to leverage the nucle-
ophilic nature of a sulfinate intermediate and utilize elec-
trophilic fluorinating reagents to generate sulfonyl fluo-
rides (Scheme 1).12,13 Herein, we report a one-pot, Pd-
O
NH2
N
NMe2
SO2F
N
H2N
SF-p1-yne
Dansyl Fluoride
Figure 1. Representative sulfonyl fluorides and their
function.
Despite the burgeoning interest in aromatic sulfonyl fluo-
rides, significant challenges remain in their synthesis.
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catalyzed conversion of aryl iodides to sulfonyl fluorides
using DABSO and Selectfluor.13 This approach incorpo-
rates SO2 and fluorine into aryl iodides in a one-pot reac-
tion and requires only column chromatography for purifi-
cation. Additionally, new, mild conditions to form sulfonic
esters and sulfonamide from sulfonyl fluorides is also
described.
ever, these systems proved largely unsuccessful due to
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3
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7
8
the requirement of isolating the crude sulfinate salt and
poor yield of the sulfonyl fluoride. As an alternative, we
employed a Pd-catalyzed system reported by Willis et al.
that has previously been shown to generate an aryl am-
monium sulfinate.14 We surmised that this approach
would lead to the in-situ generation of a more soluble
sulfinate intermediate and allow a more facile fluorination
step, obviating the need to isolate the sulfinate salt. This
Scheme 1. Strategies toward sulfonylation products
using aryl sulfinates
approach
revealed
that
treatment
with
1-
9
iodonaphthalene (1a), Pd(OAc)2, DABSO, CataCXium A
Mascitti/Shavnya, Willis
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(PAd2Bu), Et3N, and iPrOH (stirred at 75 °C for 16 h)
followed by addition of Selectfluor and MeCN after 2
hours generated sulfonyl fluoride 2a with a 72% yield
(Scheme 2, entry 1). Next, we performed optimization
studies to identify the best electrophilic fluorinating rea-
gent. To this end, several common fluorinated reagents
were tested, generating comparable yields of 2a to Se-
lectfluor (Scheme 2, entries 1 and 6). Ultimately, Select-
fluor was chosen due to its ease of handling, broader
commercial availability, and affordability compared to the
O
S
SO2 source
Pd-catalyst
O O
S
X
R
O
R
R
(1)
R
M
R
X = Cl, Br, I, or OTf
Sulfones
Aryl sulfinate
M = K, Na or NHEt3
Electrophilic fluorination
O
S
O O
S
F
DABSO
Pd-catalyst
I
F
(2)
O
R
R
NHEt3
R
Sulfonyl fluoride
other reagents.15
O2S·N N·SO2
Aryl ammonium
sulfinate
DABSO
Scheme 3. Pd-catalyzed conversion of aryl iodides to
sulfonyl fluorides using Selectfluor.a,b
Scheme 2. Optimization studiesa,b
aReaction conditions: aryl iodide (1 equiv.), DABSO (1.2
equiv), Pd(OAc)2 (0.05 equiv), PAd2Bu (0.08 equiv), Et3N (3
equiv) in iPrOH (0.3 M), 75 °C, 16 h, then Selectfluor and
aReaction conditions: aryl iodide (1 equiv.), DABSO (1.2
equiv), Pd(OAc)2 (0.05 equiv), PAd2Bu (0.08 equiv), Et3N (3
equiv) in iPrOH (0.3 M), 75 °C, 16 h, then Selectfluor and
b
MeCN (0.3 M) at room temperature for 2 h. Isolated yields
b
MeCN (0.3 M) at room temperature for 2 h. Isolated yields
are an average of two trials.
are an average of two trials.
We initially endeavored to generate sulfonyl fluorides
using existing Pd-catalyzed systems that generate aryl
sulfinate intermediates using an aryl halide, an SO2
In an effort to demonstrate the broad applicability of this
system, we subjected a variety of aryl iodides to the
aforementioned reaction conditions. Our studies re-
source (i.e., DABSO, or K2S2O4), and Selectfluor.8 How-
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vealed that both electron-donating and -withdrawing aryl
scale as demonstrated in the synthesis of 1i using p-
toluenesulfonyl fluoride and 4-iodophenol (Scheme 5).
1
2
3
4
iodides are converted to their corresponding sulfonyl
fluoride in good to excellent yield (Scheme 3). Additional-
ly, this method generated sulfonyl fluorides despite in-
creasing steric congestion of the aryl unit (Scheme 3, 2j-
2l). Notably, our experiments revealed the installation of
Scheme 4: Synthesis of sulfonic esters and sulfon-
amides with 2a.a,b
5
the SO2F group can be performed even in the presence
of a tosylate (2i), a functional group that can undergo
oxidative addition and functionalization via Pd-
6
7
8
9
catalysts 16
Since sulfonyl fluorides have been demon-
.
strated to resist C–S bond cleavage in Pd-catalysis,7 we
next hypothesized that multiple C-I bonds in an organic
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molecule could be converted to C–SO2F bonds. This
would allow the installation of multiple sulfonyl-based
groups in one molecule. Such molecules could have
potential as crosslinkers using SuFEx click chemistry.17
To interrogate this hypothesis, we subjected 1,4-
diiodobenzene to our reaction conditions and increased
by two-fold: the catalyst, DABSO, base, Selectfluor and
solvent. Gratifyingly, 2h was obtained in good (57%)
yield (Scheme 3, 2h), demonstrating the feasibility of
aReaction conditions: 1-naphthylsulfonyl fluoride, 2a (1.0
equiv.), Nuc–H (1.1 equiv), Cs2CO3 (2.0 equiv), MeCN (0.3
installing multiple SO2F moieties into an organic mole-
cule.
b
M), at room temperature for 1 h. Isolated yields are an av-
erage of two trials.
Sulfonic esters and sulfonamides are classes of sul-
fonylated compounds with a myriad of applications in
synthetic chemistry and as drug targets18-19 However,
compared to sulfonyl chlorides, there are few examples
Scheme 5: Gram-scale synthesis of sulfonic ester 1i.
of facile generation of sulfonic esters and sulfonamides
4a
from sulfonyl fluorides
.
Additionally, studies investigat-
ing the protease activity of sulfonyl fluorides have sug-
gested aromatic sulfonyl fluorides can chemoselectively
react with tyrosine residues (phenols) over other nucleo-
philic amino acid residues.1d-1f Therefore, we next inves-
tigated the reactivity of sulfonyl fluorides with a variety of
nitrogen- and oxygen-based nucleophiles. In contrast to
sulfonyl chlorides, we hypothesized that sulfonyl fluoride
stability could be leveraged to exhibit chemoselectivity
In conclusion, we have developed a new Pd-catalyzed
method to convert electronically and sterically diverse
aryl iodides to sulfonyl fluorides using DABSO and Se-
lectfluor in good to excellent yields, allowing for a versa-
tile generation of sulfonyl fluorides. Additionally, this re-
action permits multiple installations of the SO2F moiety.
This reaction utilizes Selectfluor, the most economical
and readily available source of electrophilic fluorine. Fi-
nally, conditions were developed to generate sulfonate
esters and sulfonamides from sulfonyl fluorides at room
temperature. Ongoing investigations are underway to
better understanding of sulfonyl fluoride reactivity. Fur-
ther studies will focus on alternative catalytic approaches
toward sulfonyl fluorides using cheaper metal-catalysts
and fluorinating reagents.
for nucleophiles.20 To test this hypothesis, several nitro-
gen- and oxygen-based nucleophiles were allowed to
react with sulfonyl fluoride 2a to generate sulfonamides
and sulfonate esters.
Our initial studies focused on screening base and phenol
combinations to generate a sulfonate ester (Table S1,
Supporting Information); Cs2CO3 and DBU emerged as
the best candidates, providing a high yield of sulfonate
ester after just one hour at room temperature. Notably, in
the absence of base, no sulfonate ester formation was
detected by TLC or GC/MS, nor was any decomposition
of the sulfonyl fluoride detected after 24 hours. Ultimate-
Experimental Section
General Considerations. NMR spectra were obtained
1
on a Bruker 400 (400.00 MHz for H: 376.50 MHz for
ly, Cs2CO3 was chosen as the base of choice due to
ease of purification. Subsequently, a series of electroni-
cally diverse phenols were allowed to react with 2a, gen-
1
19F; 100.61 MHz for 13C) spectrometer. H, 19F and 13C
chemical shifts are reported in parts per million (ppm)
relative to TMS, with the residual peak used as an inter-
nal reference.19F NMR are referenced on a unified scale,
where the single primary reference is that of the fre-
quency of the residual solvent peak in the 1H NMR spec-
erating sulfonate esters in good to excellent yields
21
(Scheme 4, entries 3c-3f).
Moreover, 2a in the pres-
ence of Cs2CO3 and EtOH
,
did not result in any detecta-
ble product by GC/MS after 24 h, whereas electron-
deficient trifluoroethanol afforded 3h in excellent yield. In
addition to alcohols, aromatic amines (e.g., imidazole
and pyrazole) resulted in sulfonamides 3a and 3b in
great yield. This reaction can be performed on a gram
trum.22 19F NMR is proton coupled. Multiplicities are re-
ported as follows: singlet (s), doublet (d), doublet of dou-
blet (dd), triplet (t) and multiplet (m). The 1H, 19F and 13
C
were taken at room temperature. Elemental analysis
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3,5-dimethylbenzenesulfonyl fluoride 2d. Isolated as
a brown solid (99 mg, 59%). 1H NMR (CDC 3
): δ 7.63 (s,
2H), 7.39 (s, 1H), 2.44 (s, 6H); 19F NMR (CDC 3
): δ
65.71 (s, 1F); 13C NMR (CDC 3
): δ 139.9, 137.2, 132.7
(d, J = 23 Hz, 1C), 125.9, 21.2. IR ν (neat, ATR)/cm–
1
2
3
4
5
6
7
8
using WO3 as a combustion catalyst. High-resolution
Mass Spectroscopy was conducted at the California In-
stitute of Technology Mass Spectroscopy Center using a
JMS-60H (JEOL) double-focusing magnetic sector mass
spectrometer with resolution set to 3000. IR spectra
were obtained on a Perkin-Elmer Spectrum RXI FT-IR
spectrometer using a MIRacle ATR attachment. Melting
points were obtained on a Mettler Toledo MP50 Melting
Point System. Column chromatography was performed
on an ISCO Combiflash Rf+ system using a 25 g pre-
packed standard column.
l
l
l
1
2908, 1610, 1449, 1273, 1201, 1094, 1040, 865, 756,
668, 609, 537. Anal. Calc. for C8H9FO2S: C, 51.05, H,
4.82; Found: C, 51.41, H, 4.76. mp (EtOAc/hexanes): 33
– 36 °C.
9
4-cyanobenzenesulfonyl fluoride 2e. Isolated as an
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1
off-white solid (106 mg, 64%). H NMR (CDC 3
l
): δ 8.17
):
): δ 136.9 (d, J = 27 Hz,
General Procedure for Aryl Sulfonyl Fluoride Syn-
thesis 2a-2l: In air, a 50 mL Cajon Schlenk tube was
loaded with aryl iodide (0.90 mmol, 1.0 equiv), Cata-
CXium® A (24 mg, 0.069 mmol, 0.08 equiv), and
DABSO (0.130 g, 0.54 mmol, 0.6 equiv; 1.2 equiv of
SO2), and Pd(OAc)2 (10 mg, 0.45 mmol, 0.05 equiv) and
a magnetic stir bar.* The Schlenk tube was sealed with a
rubber septum and placed under vacuum for 10 minutes.
The tube was backfilled with argon and evacuated; this
was repeated two additional times. Under argon, anhy-
drous isopropanol (3 mL, 0.3 M) and anhydrous triethyl-
amine (380 ꢀL, 2.7 mmol, 3 equiv) were added via sy-
ringe. The tube was sealed with a Teflon screw cap plug
and placed in a preheated sand bath at 75° C (bath tem-
perature) to stir for 14 h. *Liquid aryl iodides (1a, 1d, 1e,
and 1g) were added after the addition of isopropanol and
before addition of triethylamine.
(d, J = 8 Hz, 2H), 7.96 (J = 8 Hz, 2H); 19F NMR (CDC 3
l
δ 66.01 (s, 1F); 13C NMR (CDC 3
l
1C), 133.4, 129.2, 119.4, 116.5. IR ν (neat, ATR)/cm–1
1410, 1212, 1095, 847, 807, 760, 642, 557. Anal. Calc.
for C7H4FNO2S: C, 45.40, H, 2.18, N, 7.56; Found: C,
45.74, H, 2.21, N, 7.48. mp (EtOAc/hexanes): 89 - 92
°C.
4-chlorobenzenesulfonyl fluoride 2f. Isolated as a
brown solid (97 mg, 55 %). 1H NMR (CDC 3
l
): δ 7.97 (d, J
= 8.4 Hz, 2H), 7.63 (d, J = 8.4 Hz, 2H); 19F NMR
(CDC 3
l
): δ 66.49 (s, 1F); 13C NMR (CDC 3
l ): δ 142.7,
131.3, 130.1, 129.9. IR ν (neat, ATR)/cm–1 3099, 2905,
1569, 1461, 1406, 1284, 1209, 1089, 1014, 969, 829,
781, 743, 701, 623, 526. HRMS (FAB-magnetic sector)
m/z: [M-F]+ Calcd for C6H4ClO2S 174.9620; found
174.9616. mp (EtOAc/hexanes): 49 – 53 °C.
1-Naphtylenesulfonyl fluoride 2a. Isolated as a brown
[1,1’-biphenyl]-4-sulfonyl fluoride 2g. Isolated as a
brown solid (147 mg, 69 %) H NMR (CDC 3
1
1
solid (136 mg, 72%). H NMR (CDC 3
l
): δ 8.56 (d, J = 8
l
): δ 8.09 (d,
Hz, 1H), 8.39 (J = 7 Hz, 1H), 8.25 (d, J = 8Hz, 1H), 8.02
J = 8Hz, 2H), 7.83 (d, J = 8 Hz, 2H), 7.64 (d, J = 8 Hz,
2H), 7.51 (m, 3H); 19F NMR (CDC 3): δ 66.50 (s, 1F); 13
NMR (CDC 3): δ 148.7, 138.5, 131.4 (d, J = 24 Hz, 1C),
(d, J = 8 Hz, 1H), 7.79 (t, J = 8 Hz, 1H), 7.70 (t, J = 8Hz,
l
C
1H), 7.65 (t, J = 8 Hz, 1H); 19F NMR (CDC 3
l
): δ 62.54 (s,
l
1F); 13C NMR (C CDC 3
l ): δ 137.0, 134.0, 131.1, 129.5,
129.3, 129.2, 129.0, 128.2, 127.5. IR ν (neat, ATR)/cm–1
2922, 1588, 1480, 1406, 1209, 1099, 1008, 951, 842,
783, 743, 674, 587, 548, 518. HRMS (FAB-magnetic
sector) m/z: [M]+ Calcd for C12H9FO2S calculated
236.0308; Found 236.0307. mp (EtOAc/hexanes): 78–
79 °C.
129.2, 128.9, 128.3, 127.8, 124.2, 124.1. IR ν (neat,
ATR)/cm–1 1508, 1395, 1354, 1195, 1150, 1073, 980,
823, 802, 768, 735, 667, 591. Anal. Calc. for
C10H7FO2S: C, 57.13, H, 3.36; Found: C, 57.14, H, 3.72.
mp (EtOAc/hexanes): 50 - 53 °C
4-Acetylbenzenesulfonyl fluoride 2b. Isolated as a
Benzene-1,3-disulfonyl fluoride 2h. Isolated as a
brown solid (125 mg, 57 %). The general procedure to
make aryl sulfonyl fluorides was followed, but with twice
the equivalents/volume of Pd(OAc)2, CataXCium A,
Et3N, DABSO, Selectfluor®, iPrOH, and acetonitrile.
1
brown solid (122 mg, 67%). H NMR (CDC 3
l
): δ 8.18 (d,
J = 8 Hz, 2H), 8.13 (d, J = 9 Hz, 2H), 2.70 (s, 3H); 19F
NMR (CDC 3 ): δ 196.1,
): δ 65.9 (s, 1F); 13C NMR (CDC 3
l
l
142.2, 136.6 (d, J = 27 Hz, 1C), 129.3, 128.9, 26.96. IR ν
(neat, ATR)/cm–1 1692, 1403, 1359, 1255, 1209, 1097,
836, 789, 750, 636, 578. Anal. Calc. for C8H7FO3S: C,
47.52, H, 3.49; Found: C, 47.64, H, 3.62. mp
(EtOAc/hexanes): 78 – 79 °C.
(125 mg, 58 %, brown solid) 1H NMR (CDC 3
4H); 19F NMR (CDC 3
(CDC 3
l
): δ 8.30 (s,
l
): δ 66.08 check (s, 2F); 13C NMR
l
): δ 139.5 (d, J = 27 Hz, 1C), 129.8. IR ν (neat,
ATR, ATR)/cm–1 2905, 1407, 1286, 1205, 1093, 1015,
772, 743, 623. HRMS (FAB-magnetic sector) m/z:
[M+H]+ Calcd for HRMS Calc. for C6H5F2O4S2 242.9609;
Found 242.9597. mp (EtOAc/hexanes): 155 – 156 °C.
Methyl 4-(fluorosulfonyl)benzoate 2c. Isolated as an
1
off-white solid (183 mg, 93%). H NMR (CDC 3
l
): δ 8.29
(d, J = 8Hz, 2H), 8.10 (d, J = 8Hz, 2H), 4.00 (s, 3H); 19F
NMR (CDC 3 ): δ
): δ 65.78 (s, 1F); 13C NMR (CDC 3
4-(fluorosulfonyl)phenyl 4-methylbenzenesulfonate
2i. Isolated as a brown solid (229 mg, 77 %). H NMR
l
l
1
164.9, 136.6 (d, J = 25 Hz, 1C), 136.5, 130.7, 128.5,
53.0. IR ν (neat, ATR)/cm–1 3104, 2965, 1724, 1578,
1408, 1277, 1209, 1092, 959, 835, 767, 758, 728, 684,
607. HRMS (FAB-magnetic sector) m/z: [M+H]+ Calc. for
(CDC 3
7.37 (d, J = 8 Hz, 2H), 7.29 (d, J = 8 Hz, 2H), 2.48 (s, 3
H); 19F NMR (CDC 3): δ 66.5 (s, 1F); 13C NMR (CDC 3
):
l ): δ 7.98 (d, J = 8 Hz, 2H), 7.75 (d, J = 8 Hz, 2H),
l
l
δ 154.7, 146.4, 131.6 (d, J = 26 Hz, 1C), 131.2, 130.5,
C8H8FO4S
(EtOAc/hexanes): 84 – 86 °C.
219.0125;
found
219.0127.
mp
130.2, 128.5, 123.7, 21.8. IR ν (neat, ATR)/cm–1 1583,
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The Journal of Organic Chemistry
1485, 1411, 1380, 1297, 1212, 1177, 1156, 1091, 1015,
1-(naphthalen-1-ylsulfonyl)-1H-pyrazole 3b. Isolated
1
as a white solid (33 mg, 68 %). H NMR (d6-DMSO): δ
1
2
3
4
5
6
7
8
852, 785, 746, 708, 675, 695, 583, 541. HRMS (FAB-
magnetic sector) m/z: [M+H]+ Calcd for C13H12FO5S2
331.0110; Found 331.0124. mp (EtOAc/hexanes): 76–
78 °C.
8.73 (d, J = 3Hz, 1H), 8.62 (d, J = 8Hz, 1H), 8.46 (d, J =
8 Hz, 1H), 8.41 (d, J = 8Hz, 1H), 8.14 (d, J = 8Hz, 1H),
7.83 (m, 1H), 7.76 (multiple peaks, 3H), 6.59 (dd, J =
3Hz, 2Hz, 1H);13C NMR (d6-DMSO): δ 145.4, 136.9,
133.7, 132.5, 131.5, 131.2, 129.5, 129.2, 127.5, 127.2,
124.8, 123.3, 109.3; IR ν(neat, ATR)/cm–1 3128, 1507,
1400, 1367, 1343, 1281, 1157, 1059, 1025, 930, 834,
804, 763, 682, 628, 616, 603, 588, 586, 579, 576, 567,
563, 542. HRMS (FAB-magnetic sector) m/z: [M+H]+
4-methoxybenzenesulfonyl fluoride 2j. Isolated as a
brown liquid (77 mg, 45%). 1H NMR (CDC 3
l
): δ 7.95 (d, J
= 14 Hz, 2H), 7.07 (d, J = 9Hz, 2H), 3.93 (s, 3H); 19F
NMR (CDC 3 ): δ
): δ 67.29 (s, 1F); 13C NMR (CDC 3
l
l
9
165.2, 130.8, 124.9 (d, J = 25 Hz, 1C), 114.9, 55.9. IR ν
(neat, ATR)/cm–1 1594, 1578, 1501, 1398, 1319, 1267,
1206, 1172, 1099, 1020, 834, 807, 752, 670, 562, 538.
HRMS (FAB-magnetic sector) m/z: [M+H]+ Calcd for
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Calcd for C13H11N2O2S 259.0546; Found 259.0541. mp
(EtOAc/hexanes): decomposed at 160 °C.
Phenyl naphthalene-1-sulfonate 3c. Isolated as a
C7H8FSO3 191.0178; measured, 191.0178.
1
white solid (44 mg, 81 %) H NMR (CDC 3
l
): δ 8.85 (d, J
3-methoxybenzenesulfonyl fluoride 2k. Isolated as a
= 8Hz, 1H), 8.11 (d, J = 8Hz, 1H), 8.08 (d, J = 7 Hz, 1H),
1
brown liquid (106 mg, 62%). H NMR (CDC 3
l
): δ 7.60 (d,
7.98 (d, J = 8Hz, 1H), 7.77 (m, 1H), 7.67 (m, 1H), 7.44
(m, 1H), 7.17 (m, 3 H), 6.87 (m, 2 H); 13C NMR (CDC 3
l ):
8Hz, 1 H), 7.53 (dd, 8Hz, 1Hz, 1H), 7.48 (m, 1H), 7.29
(dd, 8Hz, 2 Hz, 1H), 3.90 (s, 3H); 19F NMR (CDC 3
): δ
65.57 (s, 1F); 13C NMR (CDC 3
): δ 160.2, 133.9 (d, 24
l
δ 149.5, 135.6, 133.9, 131.2, 130.7, 129.5 129.0, 128.9,
128.4, 127.3, 127.0, 125.0, 123.9, 121.9; IR ν (neat,
ATR)/cm–1 1590, 1508, 1484, 1369, 1202, 1189, 1167,
1158, 1144, 1137, 1022, 981, 917, 854, 823, 784, 768,
728, 692, 673, 585, 581. HRMS (FAB-magnetic sector)
m/z: [M+H]+ Calcd for C16H13O3S 285.0585; Found
285.0591. mp (EtOAc/hexanes): 71 – 73 °C.
l
Hz, 2C), 130.7, 122.1, 120.5, 122.7, 55.8. IR ν (neat,
ATR)/cm–1 1601, 1408, 1326, 1247, 1208, 1032, 761,
691, 677, 584. HRMS (FAB-magnetic sector) m/z: [M]+
Calcd for C7H7FO3S 190.0100; Found 190.0126.
2-methoxybenzenesulfonyl fluoride 2l. 23 Isolated as
a brown liquid (76 mg, 45%, brown liquid). 1H NMR
4-methoxyphenyl naphthalene-1-sulfonate 3d. Iso-
lated as a white solid (57 mg, 95 %). m.p. = 108 – 110
(CDC 3
7.11 (multiple peaks, 2H); 19F NMR (CDC 3
1F); 13C NMR (CDC 3
): δ 158.0 (d, J = 2 Hz, 1C), 137.4,
l
): δ 7.93 (dd, 8Hz, 2 Hz, 1H), 7.69 (t, 8Hz, 1H),
1
°C) H NMR (CDC 3
l
): δ 8.83 (d, J = 9Hz, 1H), 8.11 (d, J
l
): δ 58.56 (s,
= 8Hz, 1H), 8.06 (d, J = 7 Hz, 1H), 7.98 (d, J = 8Hz, 1H),
7.78 (m, 1H), 7.67 (m, 1H), 7.47 (m, 1H), 6.75 (d, J =
9Hz, 2 H), 6.63 (d, J = 9Hz, 2 H), 3.68 (s, 3H); 13C NMR
l
131.1 (d, J = 1Hz, 1C), 121.2 (d, J = 23 Hz, 1C), 120.4,
112.7, 56.47. IR ν (neat, ATR)/cm–1 1579, 1483, 1437,
1396, 1285, 1258, 1204, 1166, 1139, 1073, 1014, 807,
751, 698, 590, 569. HRMS (FAB-magnetic sector) m/z:
[M+H]+ Calcd for C7H8FSO3, 191.0178; Found 191.0187.
(CDCl3): δ 158.1, 143.0, 135.6, 133.9, 131.2, 130.6,
128.9, 128.9, 128.5, 127.3, 125.02, 123.9, 122.9, 114.3,
55.4; IR ν (neat, ATR)/cm–1 1591, 1501, 1358, 1299,
1256, 1160 (SO2), 1132, 1028. Anal. Calc. for
C17H14O4S: C, 64.95, H, 4.49; Found: C, 64.85, H, 4.44.
mp (EtOAc/hexanes): 71 – 73 °C.
General Procesure for Sulfonic esters and Sulfon-
amides Synthesis: 2a (0.19 mmol, 1.0 equiv) and the
appropriate alcohol or amine (0.21 mmol, 1.1 equiv)
were combined in a 20 ml scintillation vial. Acetonitrile
was added (0.8 mL, 0.2 M) followed by Cs2CO3 (0.00 g,
0.38 mmol, 2 equiv), sealed with PTFE-lined cap, and
stirred vigorously for one hour. After one hour, the sol-
vent was removed by rotary evaporation. The crude
product was isolated using automated flash chromatog-
raphy (SiO2) on a 100% hexane to 50%:50% hex-
ane:ethyl acetate gradient over 19 mins. Reactions were
ran in duplicate and yields are an average of the trials.
4-aminophenyl naphthalene-1-sulfonate 3e. Isolated
as a light brown solid (45 mg, 79 %). 1H NMR (CDC 3
l ): δ
8.82 (d, J = 9Hz, 1H), 8.11 (d, J = 8Hz, 1H), 8.06 (d, J =
7Hz, 1H), 7.98 (d, J = 8Hz, 1H), 7.78 (m, 1H), 7.67 (m,
1H), 7.45 (m, 1H), 6.60 (d, J = 6Hz, 2H), 6.40 (d, J =
6Hz, 2H), 3.60 (broad s, 2H); 13C NMR (CDC 3
l ): δ 145.4,
141.6, 135.5, 134.0, 131.4, 130.8, 129.0, 128.90, 128.6,
127.3, 125.2, 124.00, 122.8, 115.3; IR ν (neat, ATR)/cm–
1
2924, 1629, 1505, 1356, 1174, 981, 840, 803, 799,
770, 581. Anal. Calc. for C16H13NO3S: C, 64.20, H, 4.38;
N, 4.68 Found: C, 64.25, H, 4.52, N, 4.47. mp
(EtOAc/hexanes): 110 – 115 °C.
1-(naphthalen-1-ylsulfonyl)-1H-imidazole 3a. Isolated
1
as a white solid (34 mg, 69 %). H NMR (CDC 3
l
): δ 8.64
(d, J = 8Hz, 2H), 8.11 (d, J = 9Hz, 1H), 8.35 (dd, 7 Hz, 1
Hz, 1H), 8.14 (multiple peaks, 2H), 7.92 (dd, 8Hz, 1 Hz,
1H), 7.68 (m, 1H), 7.58 (multiple peaks, 2H), 7.31 (s,
2,2,2-trifluoroethyl naphthalene-1-sulfonate 3f. Iso-
lated as a light brown solid (46 mg, 84 %). 1H NMR
1H), 7.02 (s, 1H); 13C NMR (CDC 3
l ): δ 136.9, 136.8,
(CDCl3): δ 8.59 (d, J = 9Hz, 1H), 8.31 (d, J = 8Hz, 1H),
8.20 (d, J = 8Hz, 1H), 7.99 (d, J = 8Hz, 1H), 7.76 (m,
1H), 7.67 (m, 1H), 7.60 (m, 1H), 4.34 (q, J = 8 Hz, 2H);
134.2, 132.7, 131.0, 130.5, 129.5, 127.8, 127.6, 124.3,
123.1, 117.8 (one of the signal represents 2Cs; however
we were not able to determine which one). IR ν (neat,
ATR)/cm–1 3122, 3101, 2921, 2851, 1513, 1460, 1156,
1055, 801, 762, 680, 592. HRMS (FAB-magnetic sector)
m/z: [M+H]+ Calcd for C13H11N2O2S 259.0541; Found
259.0560. mp (EtOAc/hexanes): decomposed at 160 °C.
19F NMR (CDC 3): δ –73.71(s, 3F); 13C NMR (CDC 3
l l ): δ
136.3, 134.2, 130.9, 130.0, 129.2, 129.0, 128.3, 127.6,
124.6, 124.0, 121.8 (q, J = 278 Hz), 64.8 (q, J = 38 Hz);
IR ν (neat, ATR)/cm–1 1372, 1289, 1175, 1035, 982, 864,
800, 788, 681, 594, 565. HRMS (FAB-magnetic sector)
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m/z: [M]+ Calcd for C12H9F3O3S 290.0225; Found
290.0222. mp (EtOAc/hexanes): m.p. = 60 – 61 °C
The authors declare no competing financial interest.
1
2
3
4
5
6
7
8
4-iodophenyl 4-methylbenzenesulfonate 1i.24 Isolat-
ed as a light brown solid (1.8 g, 84 %, light brown solid,
m.p. = 96 – 99 °C) Procedure to make sulfonate esters
was followed on a 1g scale using p-toluene sulfonyl fluo-
ride (1.0 g, 5.74 mmol, 1 equiv.), Cs2CO3 (3.7 g, 11.48
mmol, 2 equiv.), 4-iodophenol (1.4 g, 6.3 mmol, 1.1
equiv.), and 19 mL (0.3 M) of acetonitrile. 1H NMR
ACKNOWLEDGMENT
NDB would like to thank Amherst College and Pomona Col-
lege for start-up funds. Additionally, acknowledgment is
made to the Donors of the American Chemical Society Pe-
troleum Research Fund for support (or partial support) of
this research (54419-UNI). IR and AT would like to thank
the Pomona SURF program and the Pomona Department of
Chemistry for their funding. The authors would like to thank
Cynthia Nyongesa and Conner Reilly for their help with ini-
tial results and characterization of compounds. The authors
would also like to thank Mona Shahgholi and Nassem Tori-
an (Caltech) for the HRMS analysis.
9
(CDC
7.35 (d, J = 8Hz, 2H), 6.74 (d, J = 8Hz, 2H), 2.46 (s, 3H);
13C NMR (CDC 3
): δ 149.4, 145.7, 138.7, 132.0, 129.9,
l3): δ 7.69 (d, J = 8Hz, 2H), 7.60 (d, J = 8 Hz, 2H),
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
l
128.5, 124.5, 91.77, 21.78. HRMS (FAB-magnetic sec-
tor) m/z: [M+H]+ Calcd for C13H12IO3S 374.9552; Found
374.9547.
REFERENCES
General Procedure for Electrophilic Fluorinating Re-
agent Screen: The reaction was setup according to the
procedure to generate the sulfonyl fluoride 2a (1-
iodonapthalene, 229 mg, 0.90 mmol and 1.8 mmol of the
fluorinating reagent). The crude products were isolated
using automated flash chromatography (SiO2) on a
100% hexanes to 60%:40% hexanes:ethyl acetate) over
1) For representative examples see: (a) Shannon, D. A.; Gu,
C.; McLaughlin, C. J.; Kaiser, M.; van der Hoorn, R. A. L.; We-
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1
19 mins. H NMR spectroscopy was used to compare
against the spectra of the isolated and purified 2a using
Selectfluor®. Yields are an average of two trials.
General Procedure for the Base Screen Using Phe-
24
nol and p-Toluenesulfonyl Fluoride.
The reaction
was setup according to the previously described proce-
dure to generate the sulfonate esters using commercially
available p-toluenesulfonyl fluoride (100 mg, 0.57 mmol,
1 equiv.), phenol (59 mg, 0.63 mmol, 1.1 equiv.), and
base (1.15 mmol, 2 equiv.). The crude products were
isolated using automated flash chromatography (SiO2)
on a 100% hexane to 60%:40% hexanes:ethyl acetate).
1H NMR spectroscopy was used to compare against the
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spectra of the isolated and purified sulfonate ester 4.
1
Yields are an average of two trials. H NMR (CDC 3
l
): δ
7.71 (d, J = 8Hz, 2H), 7.26 (multiple peaks, 5H), 6.99 (d,
J = 8Hz, 2H), 2.46 (s, 3H); 13C NMR (CDC 3
l
3): δ 149.6,
145.3, 132.4, 129.7, 129.6, 128.5, 127.1, 122.4, 21.73.
HRMS (FAB- magnetic sector) m/z: [M+H]+ Calcd for
C13H13O3S 249.0585; found 249.0593.
6) For examples of reduction of sulfonyl halides:
ASSOCIATED CONTENT
(a) Chatgilialogu, C. Sulfonyl Radicals. In Sulphones and
Sulphoxides (1988); Patai, S, Rappoport, Z.; Stirling, C. Eds.;
Wiley, Chichester, 2006, p.1089-1113. (b) Bertrand, M. P.; Org.
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Arvidsson, P. I. J. Org. Chem. 2016, 81, 2618-2623.
8) (a) Gilbert, E. E. Synthesis 1969, 1, 3-10. (b) Zhang, L.-L.;
Guo, C.-B.; Zheng, X.-L.; Zhu, R.-F.; Yang, X.-Z.; Tang, C.-J.
Chin. J. Synth. Chem. 2009, 2, 133-139. ꢀ
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Supporting Information
Procedures, methods, characterization data including NMR
data are present in the supporting information. This material
is available free of charge via the Internet at
http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
* Nicholas.ball@pomona.edu
Author Contributions
The manuscript was written through contributions of all au-
thors. / All authors have given approval to the final version
of the manuscript. /
Notes
10) For an example using Au: Johnson, M. W.; Bagley, S. W.;
Mankad, N. P.; Bergman, R. G.; Mascitti, V.; Toste, F. D. An-
gew. Chem. Int. Ed. 2014, 53, 4404-4407.
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J. Org. Chem. Front. 2016, 3, 693-696.
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The Journal of Organic Chemistry
12) For examples of sulfonyl fluoride synthesis using sulfur
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1
2
3
4
5
6
7
8
9
13) While this manuscript was in preparation, Davies et al. pub-
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fluorobenzenesulfonimide ($2636/mol, used in ref 13).
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