Arynes and Their Precursors from Arylboronic Acids via Catalytic C-H Silylation

Article abstract of DOI:10.1021/acs.joc.9b00221

A new, operationally simple approach is presented to access arynes and their fluoride-activated precursors based on Ru-catalyzed C-H silylation of arylboronates. Chromatographic purification may be deferred until after aryne capture, rendering the arylboronates de facto precursors. Access to various new arynes and their derivatives is demonstrated, including, for the first time, those based on a 2,3-carbazolyne and 2,3-fluorenyne core, which pave the way for novel derivatizations of motifs relevant to materials chemistry.

Full text of DOI:10.1021/acs.joc.9b00221

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Note
Arynes and Their Precursors from
Arylboronic Acids via Catalytic C–H Silylation
Karthik Devaraj, Fredric Jan Leif Ingner, Carina Sollert, Paul
J. Gates, Andreas Orthaber, and Lukasz Tadeusz Pilarski
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.9b00221 • Publication Date (Web): 05 Mar 2019
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The Journal of Organic Chemistry
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Arynes and Their Precursors from Arylboronic Acids via Catalytic C–H
Silylation
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Karthik Devaraj,a Fredric J. L. Ingner,a Carina Sollert,a Paul J. Gates,b Andreas Orthaber,c Lukasz T.
Pilarski*a
a Department of Chemistry – BMC, Uppsala University, BOX 576, 75-123, Uppsala, Sweden
email: lukasz.pilarski@kemi.uu.se, website: https://www.pilarskigroup.org/
b School of Chemistry, University of Bristol, Cantock’s Close, Clifton, Bristol, BS8 1TS, United Kingdom
c Department of Chemistry – Ångström, Uppsala University, BOX 523, 75-120, Uppsala, Sweden
Arynes, Boronates, C-H Functionalization, Ruthenium, Silanes
ABSTRACT: A new, operationally simple approach is presented to access arynes and their fluoride-activated precursors
based on Ru-catalyzed C-H silylation of arylboronates. Chromatographic purification may be deferred until after aryne cap-
ture, rendering the arylboronates de facto precursors. Access to various new arynes and their derivatives is demonstrated,
including – for the first time – those based on a 2,3-carbazolyne and 2,3-fluorenyne core, which pave the way for novel deri-
vatizations of motifs relevant to materials chemistry.
The trapping of aryne intermediates has evolved into an
extraordinarily powerful arylation strategy.1 It allows the
regioselective introduction of C-, B-, pnictogen, chalcogen
and halogen-based functionality to electrophilic2 (het-
ero)arene units via various multi-component,1e cycloaddi-
tion,3 insertion,4 and rearrangement sequences5 as well as
transition metal-mediated/catalyzed processes.6 Such ver-
satility has led to the use of aryne trapping in the synthesis
of natural products,7 polycyclic aromatic hydrocarbons
(PAHs),3b, 8 polymers9 and organometallic complexes.6, 10 Ar-
guably, aryne-based methodology has benefitted most pro-
foundly from the development of fluoride-activated precur-
sors that work mild conditions.11 These incorporate a silane
(or other fluorophile12 ortho with respect to a nucleofuge.12b,
13 Thus, the highly reactive aryne triple bond may be gener-
ated and trapped under mild, tolerant conditions. With this
advantage in hand, most of the focus has fallen on diversify-
ing the transformations aryne triple bonds undergo. Typi-
cally, however, most new reactions are demonstrated on
only a handful of simple, commercially available or easy-to-
make precursors. Many even modestly more complex pre-
cursors require de novo synthesis, sometimes via laborious
and/or low yielding routes or involve separate installation
and removal of directing groups to facilitate intermediate
ortho-lithiation.14 Few ortho-bromophenols, the most com-
mon starting materials for precursor synthesis, are com-
mercially available and their selective preparation is often
inefficient.
In recent years, catalytic C-H functionalization has
emerged as a powerful alternative to ‘classical’ reactivity,15
allowing new transformations and the circumvention of te-
dious stoichiometric routes and harsh conditions.15a
Despite this, only a small handful of C-H functionalization
routes to arynes or their precursors has been described
(Figure 1). These include the Rh-catalyzed ortho-silylation
of phenols,16 Pd-catalyzed ortho-oxygenation using a silane-
tethered directing group,17 and the direct generation of ar-
ynes via C-H palladation-decarboxylation of benzoic acids.18
Only the former benefits from an extended scope, although
it also requires stoichiometric MeLi. Otherwise, the use of
strong stoichiometric bases to remove a proton ortho to a
good leaving group continues to underpin a substantial por-
tion of modern aryne methodology.19 Our interest in C-H
functionalization and aryne chemistry20 led us to envisage
an alternative, operationally simple route to aryne precur-
sors – and even arynes themselves – predicated on Ru-
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catalyzed21 catalytic C-H silylation22 of arylboronates as the
key step.
amido- (4i), ester (4j), silyl (4k), chloro- (4l, 4m and 4p),
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fluoro- (4n, 4o and 4p) and amino- (4q) functionality were
amenable to our general conditions. The average yield for
our general conditions across these products was 65%, cor-
responding to 87% average yield per step for Scheme 1. The
route was also compatible with carbazole- and fluorene-
based substrates – obtained from commercially available
boronic acids (products 4r and 4s, respectively); both of
these units, as well as the aryl carbazole core of 4q, play
prominent roles in various organic electronic devices28 and
photocatalysts29 for whose synthesis the huge potential of
aryne chemistry has barely been explored. In Step 3 of the
synthesis of 4r and 4s, H2O2 was replaced with the milder
oxidant, H2N-OH·H2O.30
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Figure 1: Past and present approaches to aryne precursors us-
ing C-H activation strategies.
Our route starts with arylboronic acids (1), many variants
of which are commercially available or easily synthesized.
The convenience of arylboronic acids is underscored by
their near ubiquity in organic chemistry laboratories – a
consequence of the C-B bond’s considerable synthetic util-
ity.23 The key steps in our route (Scheme 1, top) are: 1) the
protection of 1 as anthranilamido boronates, ArB(aam),24 2;
2) their direct catalytic C-H silylation based on Suginome’s
approach to give intermediates 3, and 3) selective in situ ox-
idation25 of the boronate to give ortho-silylphenols 4. These
may be stored indefinitely and used directly as aryne pre-
cursors via activation using 1,1,2,2,3,3,4,4,4-nonafluorobu-
tane-1-sulfonyl fluoride (NfF) to provide the leaving
group.13b This obviates the need for much more expensive
but less stable triflate derivatives.26 As described below, we
found that phenols 4 may, alternatively, be purified via a sin-
gle aqueous wash to a degree sufficient for direct, efficient
aryne generation and capture in a sequence that requires no
chromatography until the aryne capture product is ob-
tained (Scheme 2). Thus, boronic acids 1 can act as de facto
aryne precursors.
Scheme 1 shows the results of our study on the scope of
this approach to generate ortho-silyl phenols, 4. At the out-
set, we confirmed the greater efficiency of Ru- over Ir-catal-
Scheme 1: Scope with respect to arylboronic acids. General
conditions in detail: Boronic acid (0.5-1.0 mmol). Step 1: an-
thranilamide (1 equiv.), toluene, Dean-Stark, reflux, overnight;
Step 2: Direct addition of RuH2(CO)(PPh3)3 (6 mol%), silane (5
equiv.), norbornene (5 equiv.) toluene, 135 °C, 20 h; Step 3:
24e
ysis27 and that of HSiMe2Ph compared to HSiEt3 (4a vs
4b). Substrates bearing phenyl (4g), trifluoromethyl (4h),
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Na2CO3, H2O2, EtOH, rt. a[Ir(µ-OMe)COD]2 (5 mol%) as catalyst,
PPh3 ligand (15 mol%). b[Ru3(CO)12] (6 mol%) as catalyst, PPh3
ligand (36 mol%). cComplex mixture. d3:1 mixture of regioiso-
mers (major isomer shown). eConditions: NfF (1.1 equiv), NaH
(1.1 equiv), THF or MeCN, 0°C to rt., 16h. f Column chromatog-
raphy after steps 2 and 3. Conditions for Step 3: NH2-OH·HCl,
NaOH, EtOH, rt.
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Figure 2: Steric influence over regioselectivity of C-H silylation.
We found that the steric profile of most substituents ortho
to -B(aam) was sufficient to prevent C-H silylation (e.g. 4d
was not obtained). The crystal structure of 3b (Figure 2) is
illustrative: the -B(aam) group rests out of the plane with
respect to its neighboring C-H bond due to steric repulsion
between B(aam) and the silane residue, thereby hindering
a second ruthenation event (e.g. in proposed intermediates
of type 3b-Ru24c). Meanwhile, ortho-bromo (4e) and -
chloro (f) silyl phenols did not form; instead, only complex
mixtures were obtained, presumably arising from cleavage
of the C-halogen bond by Ru. Fluoride, however, proved
small enough to give 4c in 42% yield across all three steps
(75% average yield per step). Installing the silane between
the -B(aam) directing group and a meta-fluoro group met
with further success: an overall yield of 61% (85% average
per step) was obtained via the silylation en route to 4n and
4p. This is a pleasing outcome; the regioselectivity of aryne
trapping reactions is most profoundly influenced by
strongly electropositive31 or electronegative groups32 at the
carbon adjacent to the aryne triple bond. Fluoride is able to
induce the greatest levels of regioselectivity amongst all
known substituents.32b Asymmetrically substituted boro-
nates with two available C-H units ortho to -B(aam) under-
went silylation exclusively at the least hindered site (4m
and 4p), except for 4o, in which the less hindered position
was favored in a 3:1 ratio.
Scheme 2: Generation and capture of arynes from (a) ortho-
silyl aryl nonaflate or (b) an arylboronic acid as the de facto
precursor. a 71 h reaction time.
To the best of our knowledge, fluoride-induced genera-
tion of 2,3-carbazolynes or any fluorenynes has not been
previously reported. Arynes 6b and 6c were generated effi-
ciently and converted to the corresponding products 7a-c
in good to excellent yields via [4+2] cycloaddition to furan,
N-Boc-pyrrole and an insertion into I2,33 respectively
(Scheme 2a). The identity of 2,3-diiodo-9,9-dimethyl-fluo-
rene (7c) was confirmed crystallographically. These exam-
ples demonstrate a new route to functionalized carbazole
and fluorene motifs that leverages the synthetic versatility
of the aryne triple bond. Studies on extending this to the
synthesis of more complex compounds of import to organic
electronics applications are ongoing in our laboratory.
Finally, we carried out preliminary studies on the viabil-
ity of generating aryne capture products from phenyl-
boronic acid, 1a, without any chromatographic purification
of intermediates. Following steps 1-3 (as described above),
the crude reaction mixture was subjected to a single aque-
ous wash and then directly to the conditions shown in
Scheme 2b with furan, N-Boc-pyrrole or nitrone 8 as the
trapping reagent. We were also pleased to find that the ad-
dition of exogeneous fluoride salts were not required to
produce the aryne en route to the final products; fluoride
released from attack on NfF by the phenolic residue ap-
peared to suffice.11d Compounds 7d-f were obtained in 80%,
82% and 87%, respectively. This corresponds to a mean
We were also pleased to discover that the C-H silylation
en route to 4r proceeded with complete regioselectivity. We
attribute this to the steric influence of the C5-H unit imped-
ing C4-H silylation by Ru (e.g. in intermediates of type 2r-
Ru, Figure 2). This finding paves a new route to exclusively
C2-silyl derivatives of the carbazole and various isosteri-
cally related motifs. By contrast, the synthesis of related
compounds can require lithiation strategies that lead to
mixtures of regioisomers. Compounds 4p, 4r and 4s were
converted in good yields to their corresponding nonaflates,
5a, 5b and 5c. The structure of 5b was confirmed using X-
ray crystallography (Scheme 1, bottom).
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average yield of 95% per step across all reactions in Scheme
2b.
In summary, we have developed a new, expedient route
(multi-scan) were carried out using SADABS. CCDC
1882782-1882784 contain the supplementary crystallo-
graphic data for compounds 3b, 5b and 7c.
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to a variety of arynes, their fluoride-activated precursors
and aryne derivatives. Whilst the procedure is relatively
material-intensive compared to non-catalytic approaches
(e.g. stoichiometric anthranilamide and high silane loadings
are required) it brings several key benefits: operational
simplicity, low requirements for chromatographic purifica-
tion, high average yields per step, and the dual use of the
B(aam) group as a masked phenol able to direct C-H silyla-
tion. Moreover, it enables the use of arylboronic acids as de
facto aryne precursors; arylboronic acids are diverse and
very common reagents in organic synthesis. Complete regi-
oselectivity is obtained for both carbazole- and fluorene-
based substrates, leading to previously un-reported aryne
intermediates of high potential in the synthesis of motifs
relevant to materials chemistry. We envisage that this ap-
proach may be utilized to exploit the unique nature of the
aryne triple bond in more complex chemical environments.
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Synthesis of ortho-silyl phenols
Procedure A (direct preparation):
A 25 mL round-bottomed flask equipped with magnetic stir
bar was charged with a mixture of the appropriate aryl-
boronic acid (0.50-1.00 mmol, 1.0 eq.), anthranilamide (1.0
eq.) and toluene (10 mL/mmol). The mixture was heated at
reflux in a Dean-Stark apparatus overnight. The toluene was
then removed under reduced pressure or by draining the
Dean-Stark trap. The resulting crude Ar-B(aam) was trans-
ferred to a pre-dried 5 mL Young’s tube equipped with a
magnetic stir bar, to which were added RuH2(CO)(PPh3)3 (6
mol%) and norbornene (5.0 eq.). The flask was then evacu-
ated and backfilled three times with Ar. The indicated silane
(5.0 eq.) and toluene (0.5 mL/mmol) were added via a sep-
tum. The mixture was heated at 135 °C for 20 h, cooled to rt,
transferred to a 100 mL round-bottomed flask and the tolu-
ene was removed under reduced pressure. To this mixture,
at rt and under air, were added Na2CO3 (1.0 eq.) and ethanol
(40 mL/mmol), followed the dropwise addition of H2O2
(30% w/w, 10 mL/mmol). Reaction progress was moni-
tored by TLC. After consumption of the ortho-silyl aryl-
boronate, the mixture was extracted with CH2Cl2 (3 × 25
mL). The combined organic layers were dried (MgSO4), fil-
tered, and concentrated under reduced pressure. Unless
otherwise indicated, the product was purified by column
chromatography using pentane/EtOAc as the eluent.
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EXPERIMENTAL SECTION
General information.
Unless otherwise stated, all reactions were performed un-
der an atmosphere of Argon with magnetic stirring. Thin
layer chromatography (TLC) was carried out using alumi-
num-backed plates coated with Kieselgel 60 (0.20 mm, UV
254) and visualized under ultraviolet light (λ = 254 nm) or
with KMnO4 staining solution. Purification by column chro-
matography was performed using Kiesel gel 60 H silica gel
(particle size 0.063-0.100 mm). THF was freshly distilled
from Na0/benzophenone and stored over 4 Å molecular
sieves under Argon. Toluene and 1,4-dioxane were pre-
dried over 4 Å molecular sieves and stored under Argon
prior to use. All arylboronic acid starting materials were ob-
tained commercially and used ‘as is’ without further purifi-
cation. Unless otherwise stated, all the other reagents, tran-
sition metal salts, anthranilamide, silanes and norbornene
were obtained commercially and used without further puri-
fication. 1H, 13C and 19F NMR spectra were recorded on Var-
ian Unity 400 MHz (1H 399.5MHz, 13C 100.6, 19F 376 MHz)
or Varian Mercury Plus 300 MHz (1H 300.0 MHz, 13C 75.5
MHz) spectrometers at ambient temperature. NMR data are
reported as follows: Chemical shift in ppm, multiplicity (s =
singlet, d = doublet, t = triplet, q = quartet, m = multiplet).
Chemical shifts are reported in ppm and referenced indi-
rectly to tetramethylsilane via the residual solvent signals.
1H: CDCl3 at 7.26, DMSO-d6 at 2.50, C6D6 at 7.16 ppm; 13C:
CDCl3 at 77.0, DMSO-d6 at 39.5, C6D6 at 128.1 ppm. 19F
(CFCl3) chemical shifts were calibrated to an external stand-
ard at 0.00 ppm. High resolution accurate-mass mass spec-
tra were run on either a VG Autospec (EI at 70eV), Bruker
micrOTOF Focus II (ESI) or Bruker ultrafleXtreme II (MALDI
with colloidal graphite matrix).
Procedure B (sequential preparation):
Step 1: Protection of arylboronic acids
A 25 mL round-bottomed flask equipped with magnetic stir-
rer bar was charged with a mixture of arylboronic acid (1.0
eq.), anthranilamide (1.0 eq.) and toluene (10 mL/mmol)
and heated at reflux in a Dean-Stark apparatus overnight.
The Ar-B(aam) intermediate was obtained by removal of
toluene, either under reduced pressure or by draining the
Dean-Stark trap.
Step 2: Silylation
To a pre-dried 5 mL Young’s tube equipped with a magnetic
stir bar were added Ar-B(aam) (1.0 eq.), RuH2(CO)(PPh3)3
(6 mol%) and norbornene (5.0 eq.). The tube was evacuated
and backfilled with argon three times and then silane (5.0
eq.) and toluene (0.5 mL/mmol of substrate) were added.
The reaction mixture was heated at 135 °C for 20 h. After
cooling to rt, the ortho-silyl arylboronate was purified by
flash column chromatography.
Step 3: Oxidation of aromatic boronates
A 100 mL round-bottomed flask equipped with a magnetic
stir bar was charged with ortho-silyl arylboronate, NaOH
(2.0 eq.), NH2OH·HCl (1.5 eq.) and ethanol (20 mL/mmol
boronate). The mixture was stirred at rt and monitored by
TLC until completion. The crude reaction mixture was ex-
tracted with EtOAc (3 × 25 mL). The combined organic lay-
ers were dried (MgSO4), filtered, and concentrated under
Crystallography: Single crystal X-ray diffraction was per-
formed on a Bruker APEX-II single-crystal X-ray diffractom-
eter at 150 K using Mo-Kα radiation, and the structures
were solved using direct methods (ShlexS-2014)34 refined
by full-matrix least-squares procedures using OLEX2.35
Semi-empirical absorption corrections from equivalents
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reduced pressure. The product was purified by column (0.25 mmol, 1.0 eq.), [Ir(OMe)(COD)] (5 mol%), PPh3 (15
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chromatography using pentane/EtOAc as the eluent.
mol%) and norbornene (5.0 eq.). The tube was evacuated
and backfilled with argon three times and then H-SiEt3 (5.0
eq.) and toluene (2 mL) were added. The reaction mixture
was heated at 135 °C for 20 h. After cooling to rt, the ortho-
silyl arylboronate was subjected to oxidation conditions
listed in procedure A and the resulting ortho-silyl phenol
was purified by flash column chromatography to afford
product 4a in 48% yield. Alternative procedure using
[Ru3(CO)12]: To a pre-dried 5 mL Young’s tube equipped
with a magnetic stir bar were added Ar-B(aam) (0.25 mmol,
1.0 eq.), [Ru3(CO)12] (6 mol%), PPh3 (36 mol%) and nor-
bornene (5.0 eq.). The tube was evacuated and backfilled
with argon three times and then H-SiEt3 (5.0 eq.) and tolu-
ene (2 mL) were added. The reaction mixture was heated at
135 °C for 20 h. After cooling to rt, the ortho-silyl aryl-
boronate was subjected to oxidation conditions listed in
procedure A and the resulting ortho-silyl phenol was puri-
fied by flash column chromatography to afford product 4a
in 40% yield.
Analytical data for aryl anthranilamido boronate
2-(4-(9H-carbazol-9-yl)phenyl)-2,3-dihydro-
benzo[d][1,3,2]diazaborinin-4(1H)-one (2a). Prepared using
General Procedure B (step 1). Yield = 0.387 g (98%, based
on 1.00 mmol of 4-(9H-carbazol-9-yl)phenyl)boronic acid),
1
beige solid. H NMR (400 MHz, DMSO-d6): δ 9.84 (s, 1H),
9.47 (s, 1H), 8.34 (d, J = 7.9 Hz, 2H), 8.25 (d, J = 8.1 Hz, 2H),
8.04 (d, J = 8.0 Hz, 1H), 7.71 (d, J = 8.1 Hz, 2H), 7.59 (dd, J =
7.6 Hz, 1H), 7.49 – 7.42 (m, 5H), 7.34 – 7.25 (m, 2H), 7.12
(dd, J = 7.6 Hz, 1H). 13C{1H} NMR (100 MHz, DMSO-d6):
166.8, 145.9, 140.4, 139.3, 135.7, 133.9, 128.4, 126.8, 126.2,
123.3, 121.4, 121.0, 120.7, 119.3, 118.7, 110.2. HRMS-ESI
calcd for C25H18BN3O [M+H]+: 388.1616, found 388.1612.
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2-(9,9-Dimethyl-9H-fluoren-2-yl)-2,3-dihydro-
benzo[d][1,3,2]diazaborinin-4(1H)-one (2b). Prepared using
general procedure B (step 1). Yield = 0.661 g (93%, based
on 2.10 mmol of (9,9-dimethyl-9H-fluoren-2-yl)boronic
acid), colorless solid. Rf = 0.5 (petroleum ether/EtOAc =
2:1). 1H NMR (400 MHz, DMSO-d6): δ 9.75 (s, 1H), 9.35 (s,
1H), 8.33 (s, 1H), 8.09 – 8.04 (m, 2H), 7.91 (d, J = 7.7 Hz, 1H),
7.89 – 7.87 (m, 1H), 7.61 – 7.54 (m, 2H), 7.47 (d, J = 7.7 Hz,
1H), 7.38 – 7.32 (m, 2H), 7.14 – 7.10 (m, 1H), 1.50 (s, 6H).
13C{1H} NMR (100 MHz, DMSO-d6): δ 166.4, 153.8, 152.7,
145.6, 140.8, 138.4, 133.4, 132.3, 131.0, 128.0, 127.8, 127.1,
122.8, 120.7, 120.6, 119.5, 118.8, 118.1, 46.5, 26.9. HRMS-
ESI calcd for C22H20BN2O [M+H]+: 339.1667, found
339.1668.
2-(Dimethyl(phenyl)silyl)phenol (4b). Prepared according to
general procedure A. Yield = 0.092 g (81%, based on 0.50
mmol of the corresponding boronic acid). Colorless oil. Rf =
1
0.4 (Pentane/EtOAc = 20:1). H NMR (400 MHz, CDCl3): δ
7.61 – 7.59 (m, 2H), 7.41 – 7.32 (m, 4H), 7.28 – 7.22 (m, 1H),
6.93 (ddd, J = 7.3, 0.6 Hz, 1H), 6.67 (d, J = 8.0 Hz, 1H), 4.77
(s, 1H), 0.59 (s, 6H). 13C{1H} NMR (100 MHz, CDCl3): δ 160.4,
138.0, 136.0, 134.2, 131.2, 129.3, 128.0, 123.1, 120.6, 115.0,
-2.3. HRMS-MALDI calcd for C14H15OSi [M-H]-: 227.0898,
found 227.0894.
Analytical data for ortho-silyl aryl anthranilamido
boronate intermediates
2-(Dimethyl(phenyl)silyl)-6-fluorophenol (4c). Prepared ac-
cording to general procedure A. Yield = 0.052 g (42%, based
on 0.50 mmol of the corresponding boronic acid). Colorless
oil. Rf = 0.6 (pentane/EtOAc = 20:1). 1H NMR (400 MHz,
CDCl3) δ 7.62 – 7.59 (m, 2H), 7.42 – 7.35 (m, 3H), 7.12 – 7.09
(m, 1H), 7.07 – 7.03 (m, 1H), 6.83 (ddd, J = 7.7, 7.7 4.6 Hz,
1H), 5.26 (s, 1H), 0.63 (s, 6H). 13C{1H} NMR (100 MHz,
CDCl3): δ 150.7 (d, JCF = 239.6 Hz), 147.9 (d, JCF = 12.5 Hz),
137.9, 134.2, 130.9 (d, JCF = 4.0 Hz), 129.2, 127.8, 126.5,
120.1 (d, JCF = 5.6 Hz), 116.6 (d, JCF = 18.3 Hz), -2.4. 19F NMR
(376 MHz, CDCl3): δ -142.58 - -142.61 (m). HRMS- MALDI
calcd for C14H14FOSi [M-H]-: 245.0803, found 245.0799.
2-(3-(Dimethyl(phenyl)silyl)-9,9-dimethyl-9H-fluoren-2-yl)-
2,3dihydrobenzo[d][1,3,2]diazabo rinin-4(1H)-one (3a). Pre-
pared using general procedure B (step 2). Yield = 0.069 g,
(77%, based on 0.25 mmol of 2b), colorless solid. Rf = 0.5
(pentane/EtOAc = 5:1). 1H NMR (400 MHz, CDCl3): δ 8.20 –
8.18 (m, 2H), 7.87 – 7.84 (m, 1H), 7.64 (s, 1H), 7.52 – 7.48
(m, 3H), 7.44 – 7.36 (m, 6H), 7.27 (s, 1H), 7.11 (t, J = 7.6 Hz,
1H), 6.19 (d, J = 7.9 Hz, 1H), 6.03 (s, 1H), 1.53 (s, 6H), 0.56
(s, 6H). 13C{1H} NMR (100 MHz, CDCl3): δ 166.5, 154.1,
153.8, 143.5, 140.4, 139.9, 139.7, 138.7, 134.0, 133.7, 129.5,
128.9, 128.5, 127.9, 127.4, 127.1, 126.9, 122.7, 121.8, 120.3,
118.6, 117.6, 47.1, 27.0, -1.1. HRMS-ESI calcd for
C30H30BN2OSi [M+H]+: 473.2221, found 473.2212.
3-(Dimethyl(phenyl)silyl)-[1,1'-biphenyl]-4-ol (4g). Prepared
according to general procedure A. Yield = 0.108 g (71%,
based on 1.00 mmol of the corresponding boronic acid). Col-
1
orless solid. Rf = 0.5 (pentane/EtOAc = 20:1). H NMR (400
Analytical data for new ortho-silyl phenols
MHz, CDCl3): δ 7.65 – 7.63 (m, 2H), 7.57 (d, J = 2.3 Hz, 1H),
7.52 – 7.50 (m, 3H), 7.43 – 7.37 (m, 5H), 7.30 (t, J = 7.3 Hz,
1H), 6.78 (d, J = 8.3 Hz, 1H), 4.82 (s, 1H), 0.64 (s, 6H). 13C{1H}
NMR (100 MHz, CDCl3): δ 160.1, 141.1, 137.8, 134.6, 134.2,
133.7, 130.0, 129.5, 128.7, 128.1, 126.8, 126.6, 123.6, 115.4,
-2.20. HRMS-MALDI calcd for C20H19OSi [M-H]-: 303.1211,
found 303.1209.
2-(Triethylsilyl)phenol (4a). Prepared according to general
procedure A. Yield = 0.095 g (47%, based on 0.50 mmol of
the corresponding boronic acid). Yellow oil. Rf = 0.4 (pen-
tane/EtOAc = 4:1). 1H NMR (400 MHz, CDCl3) δ 7.36 (dd, J =
7.3, 1.7 Hz, 1H), 7.24 (dd, J = 7.7, 1.7 Hz, 1H), 6.93 (ddd, J =
7.3, 7.3, 0.9 Hz, 1H), 6.68 (dd, J = 7.7, 0.9 Hz, 1H), 4.77 (br s,
1H), 0.98 (d, J = 7.7 Hz, 9H), 0.91 – 0.82 (m, 6H). 13C{1H} NMR
(101 MHz, CDCl3) δ 160.7, 136.4, 130.6, 122.5, 120.5, 114.6,
7.8, 3.7. HRMS-MALDI calcd for C12H19OSi [M-H]-: 207.1211,
2-(Dimethyl(phenyl)silyl)-4-(trifluoromethyl)phenol (4h).
Prepared according to general procedure A. Yield = 0.101 g
(68%, based on 1.00 mmol of the corresponding boronic
acid). Colorless oil. Rf = 0.3 (pentane/EtOAc = 20:1). 1H NMR
(400 MHz, CDCl3): δ 7.62 – 7.60 (m, 3H), 7.52 (dd, J = 8.4, 2.0
found
207.1215.
Alternative
procedure
using
[Ir(OMe)(COD)]2: To a pre-dried 5 mL Young’s tube
equipped with a magnetic stir bar were added Ar-B(aam)
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 6 of 12
Hz, 1H), 7.46 – 7.38 (m, 3H), 6.74 (d, J = 8.4 Hz, 1H), 5.14 (s,
129.9, 128.3, 124.7, 124.3, 117.2, -2.5. HRMS-MALDI calcd
1H), 0.63 (s, 6H). 13C{1H} NMR (100 MHz, CDCl3): δ 162.9,
136.8, 134.2, 133.0 (q, JCF = 3.7 Hz), 129.8, 128.6 (q, JCF = 3.7
for C14H13Cl2OSi [M-H]-: 295.0118, found 295.0114.
1
2
Hz), 128.2, 124.5 (d, JCF = 285.4 Hz), 124.2, 123.0 (d, JCF
=
2-(Dimethyl(phenyl)silyl)-3,5-difluorophenol (4n). Prepared
according to general procedure A. Yield = 0.081 g (61%,
based on 0.55 mmol of the corresponding boronic acid). Yel-
low oil. Rf = 0.3 (pentane/EtOAc = 20:1). 1H NMR (400 MHz,
CDCl3): δ 7.71 – 7.67 (m, 2H), 7.50 – 7.43 (m, 3H), 6.37 (ddd,
J = 9.3, 9.3 2.2 Hz, 1H), 6.23 (ddd, J = 10.2, 2.2, 1.3 Hz, 1H),
5.29 (s, 1H), 0.66 (s, 3H), 0.65 (s, 3H). 13C{1H} NMR (100
MHz, CDCl3): δ 168.2 (dd, JCF = 241.2, 15.1 Hz), 163.9 (dd, JCF
= 247.8, 17.0 Hz), 162.3 (dd, JCF = 17.2, 13.9 Hz), 136.7,
134.4, 130.5, 128.8, 105.1 (dd, JCF = 33.2, 3.5 Hz), 99.6 (dd,
JCF = 23.4, 3.8 Hz), 96.2 (dd, JCF = 31.6, 24.7 Hz), -1.2 (two silyl
methyl peaks appears). 19F NMR (376 MHz, CDCl3): δ -94.41-
(-94.47) (m),-107.81-(-107.89) (m). HRMS-MALDI calcd for
C14H13F2OSi [M-H]-: 263.0709, found 263.0702.
3
4
5
6
7
8
9
44.3 Hz), 115.1, -2.5. 19F NMR (376 MHz, CDCl3): δ -61.40.
HRMS- MALDI calcd for C15H14F3OSi [M-H]-: 295.0772,
found 295.0771.
N-(tert-Butyl)-3-(dimethyl(phenyl)silyl)-4-hydroxyben-
zamide (4i). Prepared according to general procedure A.
Yield = 0.103 g (63%, based on 1.00 mmol of the corre-
sponding boronic acid). Colorless solid. Rf = 0.2 (pen-
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
1
tane/EtOAc = 15:1). H NMR (400 MHz, CDCl3): δ 7.63 (s,
1H), 7.58 – 7.52 (m, 4H), 7.37 – 7.30 (m, 3H), 6.71 (d, J = 8.4
Hz, 1H), 5.82 (s, 1H), 1.43 (s, 9H), 0.58 (s, 6H). 13C{1H} NMR
(100 MHz, CDCl3): δ 167.7, 164.5, 137.9, 134.8, 134.2, 130.2,
129.2, 127.8, 126.5, 123.6, 114.8, 51.6, 28.9, -2.5. HRMS-
MALDI calcd for C19H24NO2Si [M-H]-: 326.1582, found
326.1589.
2-(Dimethyl(phenyl)silyl)-4,5-difluorophenol (4o). Prepared
according to general procedure A. Yield = 0.075 g (57%,
based on 0.50 mmol of the corresponding boronic acid). Col-
Methyl 3-(dimethyl(phenyl)silyl)-4-hydroxybenzoate (4j).
Prepared according to general procedure A. Yield = 0.120 g
(84%, based on 0.500 mmol of the corresponding boronic
1
orless oil. Rf = 0.4 (pentane/EtOAc = 20:1). H NMR (400
MHz, CDCl3): δ 7.60 – 7.57 (m, 2H), 7.45 – 7.38 (m, 3H), 7.06
(dd, J = 10.2, 9.8 Hz, 1H), 6.54 (dd, J = 11.4, 6.0 Hz, 1H), 4.79
(s, 1H), 0.58 (s, 6H). 13C{1H} NMR (100 MHz, CDCl3): δ 156.5
(dd, JCF = 8.5, 2.2 Hz), 151.4 (dd, JCF = 250.2, 14.2 Hz), 145.9
(dd, JCF = 241.9, 11.7 Hz), 136.8, 134.1, 129.8, 128.3, 123.1
(dd, JCF = 16.5, 1.8 Hz), 119.7 (dd, JCF = 3.8, 2.0 Hz), 104.8 (d,
JCF = 18.9 Hz), -2.5. 19F NMR (376 MHz, CDCl3): δ -134.01 – -
134.12 (m), -149.17 – -149.27 (m). HRMS-MALDI calcd for
C14H14F2NaOSi [M+Na]+ : 287.0674, found 287.0670.
1
acid). Grey solid. Rf = 0.2 (pentane/EtOAc = 15:1). H NMR
(400 MHz, CDCl3): δ 8.09 (d, J = 2.2 Hz, 1H), 7.95 (dd, J = 8.5,
2.2 Hz, 1H), 7.61 – 7.58 (m, 2H), 7.42 – 7.35 (m, 3H), 6.72 (d,
J = 8.5 Hz, 1H), 5.71 (s, 1H), 3.87 (s, 3H), 0.62 (s, 6H). 13C{1H}
NMR (100 MHz, CDCl3): δ 167.3, 164.7, 138.1, 137.3, 134.1,
133.3, 129.6, 128.1, 123.4, 122.3, 114.9, 51.9, -2.4. HRMS-
MALDI calcd for C16H17O3Si [M-H]-: 285.0952, found
285.0949.
2-(Dimethyl(phenyl)silyl)-4-(trimethylsilyl)phenol (4k). Pre-
pared according to general procedure A. Yield = 0.092 g
(61%, based on 0.50 mmol of the corresponding boronic
2-(Dimethyl(phenyl)silyl)-3,4-difluorophenol (4o´). Prepared
according to general procedure A. Yield = 0.017 g (13%,
based on 0.50 mmol of the corresponding boronic acid). Yel-
low oil. Rf = 0.3 (pentane/EtOAc = 20:1). 10% of regioiso-
mer 4o present. 1H NMR (400 MHz, CDCl3): δ 7.68 – 7.66 (m,
2H), 7.46 – 7.41 (m, 3H), 7.06 – 6.99 (m, 1H), 6.39 (ddd, J =
8.9, 3.3, 1.7 Hz, 1H), 4.86 (s, 1H), 0.68 (s, 6H). 13C{1H} NMR
(100 MHz, CDCl3): δ 155.9 (dd, JCF = 12.0, 2.5 Hz), 154.2 (dd,
JCF = 241.5, 12.5 Hz), 144.9 (dd, JCF = 241.6, 16.9 Hz), 136.6,
134.2, 130.3, 128.6, 119.0 (dd, JCF = 18.7, 2.3 Hz), 112.0 (dd,
JCF = 28.1, 2.6 Hz), 111.2 (d, JCF = 5.0, 3.4 Hz), -1.2 (two silyl
methyl peaks appears). 19F NMR (376 MHz, CDCl3): δ -
122.73 – -122.84 (m) -148.47 - -149.29 (m). HRMS-MALDI
calcd for C14H14F2NaOSi [M+Na]+: 287.0674, found
287.0670.
1
acid). Yellow oil. Rf = 0.4 (pentane/EtOAc = 20:1). H NMR
(400 MHz, CDCl3): δ 7.65 – 7.59 (m, 2H), 7.49 (d, J = 1.7 Hz,
1H), 7.44 (dd, J = 7.9, 1.7 Hz, 1H), 7.41 – 7.33 (m, 3H), 6.70
(d, J = 7.9 Hz, 1H), 4.90 (s, 1H), 0.61 (s, 6H), 0.22 (s, 9H).
13C{1H} NMR (100 MHz, CDCl3): δ 161.3, 141.3, 138.1, 136.6,
134.2, 131.0, 129.4, 128.0, 122.4, 114.5, -0.9, -2.2. HRMS-
MALDI calcd for C17H23OSi2 [M-H]-: 299.1293, found
299.1289.
4-Chloro-2-(dimethyl(phenyl)silyl)phenol (4l). Prepared ac-
cording to general procedure A. Yield = 0.092 g (70%, based
on 1.0 mmol of the corresponding boronic acid). Yellow oil.
Rf = 0.3 (pentane/EtOAc = 20:1). 1H NMR (400 MHz, CDCl3):
δ 7.60 – 7.58 (m, 2H), 7.44 – 7.37 (m, 3H), 7.26 (d, J = 2.4 Hz,
1H), 7.20 (dd, J = 8.5, 2.4 Hz, 1H), 6.63 (d, J = 8.5 Hz, 1H),
4.77 (s, 1H), 0.60 (s, 6H). 13C{1H} NMR (100 MHz, CDCl3): δ
158.9, 137.1, 135.2, 134.2, 130.9, 129.7, 128.2, 125.9, 125.8,
116.6, -2.5. HRMS-MALDI calcd for C14H14ClOSi [M-H]-:
261.0508, found 261.0502.
5-Chloro-2-(dimethyl(phenyl)silyl)-3-fluorophenol (4p). Pre-
pared according to general procedure A. Yield = 0.086 g
(61%, based on 0.50 mmol of the corresponding boronic
acid). Colorless oil. Rf = 0.5 (pentane/EtOAc = 20:1). 1H NMR
(400 MHz, CDCl3): δ 7.72 – 7.60 (m, 2H), 7.50 – 7.37 (m, 3H),
6.65 (dd, J = 8.8, 1.7 Hz, 1H), 6.51 (d, J = 1.7 Hz, 1H), 5.18 (s,
1H), 0.65 (s, 3H), 0.64 (s, 3H). 13C{1H} NMR (100 MHz,
CDCl3): δ 167.8 (d, JCF = 242.7 Hz), 161.7 (d, JCF = 15.8 Hz),
137.3 (d, JCF = 14.4 Hz), 136.6, 134.3, 130.4, 128.7, 112.3 (d,
JCF = 3.4 Hz), 108.5 (d, JCF = 32.0 Hz), 108.2 (d, JCF = 32.7 Hz),
-1.2 (two silyl methyl peaks appear). 19F NMR (376 MHz,
CDCl3): δ -95.78 – -95.80 (m). HRMS-MALDI calcd for
C14H13ClFOSi [M-H]-: 279.0414, found 279.0418.
4,5-Dichloro-2-(dimethyl(phenyl)silyl)phenol (4m). Pre-
pared according to general procedure A. Yield = 0.106 g
(71%, based on 0.500 mmol of the corresponding boronic
1
acid). Brown oil. Rf = 0.4 (pentane/EtOAc = 20:1). H NMR
(400 MHz, CDCl3): δ 7.59 – 7.56 (m, 2H), 7.44 – 7.38 (m, 3H),
7.33 (s, 1H), 6.82 (s, 1H), 4.94 (s, 1H), 0.58 (s, 6H). 13C{1H}
NMR (100 MHz, CDCl3): δ 159.2, 136.7, 136.5, 134.2, 134.1,
ACS Paragon Plus Environment

Page 7 of 12
The Journal of Organic Chemistry
4-(9H-Carbazol-9-yl)-2-(dimethyl(phenyl)silyl)phenol (4q). perfluorobutanesulfonyl fluoride (NfF) (0.33 mmol, 1.1 eq.).
1
2
3
4
5
6
7
8
Prepared according to general procedure A. Yield = 0.082 g
(39% based on 0.33 mmol of anthranilamido boronate 2a).
Brown oil, Rf = 0.2 (pentane/EtOAc = 5:1). 1H NMR (400
MHz, CDCl3) δ 8.16 (d, J = 7.8 Hz, 2H), 7.71 – 7.63 (m, 2H),
7.54 – 7.48 (m, 1H), 7.44 – 7.38 (m, 5H), 7.37 – 7.22 (m, 5H),
6.91 (d, J = 8.4 Hz, 1H), 5.15 (s, 1H), 0.64 (s, 6H). 13C{1H}
NMR (101 MHz, CDCl3) δ 159.7, 141.3, 137.3, 134.7, 134.2,
130.3, 130.1, 129.7, 128.2, 125.8, 125.3, 123.1, 120.2, 119.6,
116.4, 109.7, -2.3. HRMS-ESI calcd for C26H23NOSiNa
[M+Na]+: 416.1441, found 416.1433.
After 30 min the ice-bath was removed and the reaction was
stirred at rt for 16 h. The reaction was quenched with water
(20 mL) and extracted with CH2Cl2 (3 x 25mL). Organic
phases were combined, dried over Na2SO4 and reduced un-
der vacuum. The products were purified by column chroma-
tography using EtOAc/pentane or Et2O/pentane as the elu-
ent.
Analytical data for aryne precursors
9
5-Chloro-2-(dimethyl(phenyl)silyl)-3-fluorophenyl-
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
1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonate (5a). Synthe-
sized from ortho-silyl phenol 4p according to the general
sulfonylation procedure listed above. Yield = 0.131 g (78%,
based on 0.300 mmol of 4p). Colorless oil. Rf = 0.9 (pen-
tane/EtOAc 15:1). 1H NMR (400 MHz, CDCl3): δ 7.56 – 7.50
(m, 2H), 7.40 – 7.33 (m, 3H), 7.21 – 7.18 (m, 1H), 7.07 (dd, J
= 8.4, 1.7 Hz, 1H), 0.71 (s, 6H). 13C{1H} NMR (101 MHz,
CDCl3) δ 167.1 (d, JCF = 249.0 Hz), 154.4 (d, JCF = 16.4 Hz),
137.5 (d, JCF = 13.2 Hz), 136.3 (d, JCF = 1.3 Hz), 133.6, 133.0,
129.6, 127.9, 127.7, 125.3, 117.6 (d, JCF = 33.6 Hz), 117.1 (q,
JCF = 2.6 Hz), 116.0 (d, JCF = 30.8 Hz), -0.82, -0,86. 19F NMR
(376 MHz, CDCl3) δ -80.60 – -80.80 (m), -90.86 – -91.07 (m),
-108.82 – -109.06 (m), -120.82 – -121.03 (m), -125.73 – -
125.91 (m). HRMS-ESI calcd for C18H13ClF10O3SSiNa
[M+Na]+: 584.9776, found 584.9772.
2-(Dimethyl(phenyl)silyl)-9-phenyl-9H-carbazol-3-ol (4r).
Prepared using a modified version of procedure A. 9-phe-
nyl-9H-carbazol-3-yl)boronic acid (1.00 mmol, 0.287 g) and
anthranilamide (1.00 mmol, 0.136 g) was heated at reflux in
toluene (15 mL) in a Dean-Stark apparatus overnight. Silyla-
tion was performed according to silylation conditions listed
in method A to yield 2-(2-(dimethyl(phenyl)silyl)-9-phenyl-
9H-carbazol-3-yl)-2,3-dihydrobenzo[d][1,3,2]diazabo-
rinin-4(1H)-one. The crude mixture was transferred to a
100 mL round-bottomed flask and concentrated under re-
duced pressure. The resulting mixture was suspended in
ethanol/THF (5:2 volume ratio, 35 mL). NH2OH·HCl (4.0
mmol, 0.278 g) and NaOH (5.0 mmol, 0.200 mmol) was
added in one portion and the resulting mixture stirred at rt
for 3 h. The reaction was quenched with H2O, extracted with
EtOAc, dried (MgSO4), filtered, and concentrated under re-
duced pressure. Silica gel chromatography (pentane/EtOAc
25:1). Yield = 0.248 g (63%, based on 1.00 mmol of the cor-
responding boronic acid). Beige solid. Rf = 0.3 (pen-
tane/EtOAc = 25:1). 1H NMR (400 MHz, CDCl3): δ 8.04 (d, J =
7.8 Hz, 1H), 7.63 – 7.53 (m, 6H), 7.45 – 7.35 (m, 8H), 7.26 –
7.19 (m, 1H), 4.68 (s, 1H), 0.61 (s, 6H). 13C{1H} NMR (101
MHz, CDCl3) δ 154.4, 141.4, 138.3, 137.9, 135.9, 134.2,
129.7, 129.3, 127.9, 127.0, 126.7, 126.3, 125.7, 123.0, 122.8,
120.5, 119.5, 116.5, 109.9, 105.5, -2.1. HRMS-ESI calcd for
C26H23NOSiNa [M+Na]+: 416.1441, found 416.1444.
2-(Dimethyl(phenyl)silyl)-9-phenyl-9H-carbazol-3-yl
1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonate (5b). Synthe-
sized from ortho silyl phenol 4r according to the general sul-
fonylation procedure listed above. Yield = 0.164 g (78%,
based on 0.300 mmol of 4r). Colorless solid. Rf = 0.8 (pen-
1
tane/Et2O = 3:1). H NMR (400 MHz, CDCl3): δ 8.15 (d, J =
7.9 Hz, 1H), 8.11 – 8.05 (m, 1H), 7.60 – 7.50 (m, 4H), 7.49 –
7.42 (m, 5H), 7.42 – 7.29 (m, 5H), 0.70 (s, 6H). 13C{1H} NMR
(101 MHz, CDCl3) δ 149.3, 141.8, 138.8, 136.9, 136.9, 134.1,
129.9, 129.3, 128.2, 127.8, 127.7, 127.4, 126.7, 125.2, 122.5,
120.9, 120.5, 117.7, 111.4 (t, JCF = 2.6 Hz), 110.3, -2.0. 19F
NMR (376 MHz, CDCl3): δ -80.54 – -80.69 (m), -109.66 – -
109.84 (m), -120.84 – -121.04 (m), -125.63 – -125.88 (m).
HRMS-ESI calcd for C30H22F9NO3SSiNa [M+Na]+: 698.0838,
found 698.0846.
3-(Dimethyl(phenyl)silyl)-9,9-dimethyl-9H-fluoren-2-ol (4s).
Prepared according to general procedure B. Yield = 0.042 g
(81%, based on 0.15 mmol of the corresponding boronic
1
acid). Colorless solid. Rf = 0.2 (pentane/EtOAc = 20:1). H
NMR (400 MHz, CDCl3): δ 7.69 (s, 1H), 7.67 – 7.65 (m, 2H),
7.62 – 7.60 (m, 1H), 7.42 – 7.37 (m, 4H), 7.29 (ddd, J = 7.4,
7.4, 1.3 Hz, 1H), 7.25 – 7.21 (m, 1H), 6.77 (s, 1H), 4.84 (s,
1H), 1.45 (s, 6H), 0.65 (s, 6H). 13C{1H} NMR (100 MHz,
CDCl3): δ 160.5, 157.7, 152.9, 139.1, 138.1, 134.3, 132.1,
129.4, 128.1, 127.0, 126.9, 126.1, 122.4, 121.5, 119.0, 109.9,
46.7, 27.2, -2.1. HRMS-EI calcd for C23H24OSi [M]+: 344.1591,
found 344.1599.
3-(Dimethyl(phenyl)silyl)-9,9-dimethyl-9H-fluoren-2-
yl1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonate (5c). Syn-
thesized from ortho-silyl phenol 4s according to the general
sulfonylation procedure listed above. Yield = 0.532 g (85%,
based on 1.00 mmol of 4s). Colorless solid. Rf = 0.4 (pen-
tane). 1H NMR (400 MHz, CDCl3): δ 7.68 (s, 1H), 7.61 – 7.57
(m, 3H), 7.44 – 7.38 (m, 4H), 7.36 (s, 1H), 7.33 – 7.40 (m,
2H), 1.49 (s, 6H), 0.71 (s, 6H). 13C{1H} NMR (100 MHz,
CDCl3): δ 157.5, 155.0, 153.8, 138.3, 137.4, 136.7, 134.2,
129.5, 129.2, 128.0, 127.9, 127.9, 127.2, 122.7, 120.2, 114.3
(t, JCF = 2.5 Hz), 47.3, 26.8, -2.0. 19F NMR (376 MHz, CDCl3): δ
-80.61 – -80.67 (m), -109.65 – -109.74 (m), -120.94 – -
121.01 (m), -125.71 – -125.86 (m). HRMS-ESI calcd for
C27H23F9O3SSiNa [M+Na]+: 649.0886, found 649.0891
Sulfonylation procedure
Nonaflation of ortho-silyl ethers was performed according
to a modified literature procedure.13b Ortho-silyl phenol
(0.30 mmol, 1.0 eq.) and NaH (0.30 mmol, 1.0 eq.) was
added to a 10 mL oven-dried round bottomed flask
equipped with a stir bar. The flask was then evacuated and
backfilled three times with argon. Dry THF or MeCN (3.0
mL, 0.1 M) was added and the mixture was stirred 1h in
room temperature. The flask was cooled on ice-bath for 15
Cycloadditions of arynes (trapping procedure 1)
A pre-dried microwave vial equipped with magnetic stir bar
was charged with aryne precursor (1.0 eq.), N-Boc-pyrrole
minutes
followed
by
dropwise
addition
of
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or furan (3.0 eq.), CsF (3.0 eq.) and CH3CN was added to ob- extracted with CH2Cl2 (25 mL × 3). The combined layers
1
2
3
4
5
6
7
8
tain a 0.10 M solution with respect to the aryne precursor.
This mixture was heated at 60 °C for 16 h. The resulting cap-
ture product was purified by column chromatography using
pentane/EtOAc as the eluent.
were dried over MgSO4 and concentrated under reduced
pressure. To this mixture Cs2CO3 (1.5 mmol, 1.5 eq.), 18-
crown-6 (0.6 mmol, 0.6 eq.), NfF (1.2 mmol, 1.2 eq.), aryno-
phile (3.0 mmol, 3.0 eq.) and CH3CN (10 mL, 0.10 M) were
added. This mixture was heated at 60 °C for 18 h. The reac-
tion mixture was extracted with CH2Cl2 (25 mL × 3). The
combined organic layers were dried (MgSO4), filtered, and
concentrated under reduced pressure. The product was pu-
rified by column chromatography using pentane/EtOAc as
the eluent. Yields are reported over 4 steps.
5-Phenyl-7,10-dihydro-5H-7,10-epoxybenzo[b]carbazole
(7a). Synthesized from aryne precursor 5b according to
trapping procedure 2 using furan as arynophile. Yield =
0.042 g (94%, based on 0.20 mmol of 5b). Colorless solid. Rf
9
1
= 0.2 (pentane/EtOAc = 25:1). H NMR (400 MHz, CDCl3) δ
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12
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14
15
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8.08 – 8.01 (m, 1H), 7.98 – 7.93 (m, 1H), 7.63 – 7.56 (m, 2H),
7.55 – 7.50 (m, 2H), 7.50 – 7.43 (m, 1H), 7.38 – 7.30 (m, 3H),
7.28 – 7.23 (m, 1H), 7.14 – 7.07 (m, 1H), 7.05 – 6.98 (m, 1H),
5.89 – 5.83 (m, 1H), 5.76 – 5.71 (m, 1H). 13C{1H} NMR (101
MHz, CDCl3) δ 147.2, 143.6, 142.4, 141.0, 140.0, 138.6,
137.6, 129.9, 127.6, 127.3, 124.9, 123.4, 119.9, 119.7, 119.5,
112.3, 109.9, 104.0, 82.6, 82.4. HRMS-ESI calcd for C22H16NO
[M+H]+: 310.1226, found 310.1231.
1,4-Dihydro-1,4-epoxynaphthalene (7d). Synthesized in a 4-
step procedure from phenylboronic acid according to trap-
ping procedure 1 using furan as arynophile. Yield = 0.100 g
(70%, based on 1.00 mmol of phenylboronic acid). Colorless
solid. Rf = 0.3 (pentane/EtOAc = 20:1). Spectral data agrees
with previously reported values.36
Tert-butyl 1,4-dihydro-1,4-epiminonaphthalene-9-carbox-
ylate (7e). Synthesized in a 4-step procedure from phenyl-
boronic acid according to trapping procedure 1 using N-
Boc-pyrrole as arynophile. Yield = 0.126 g (52%, based on
1.00 mmol of phenylboronic acid). Colorless solid. Rf = 0.2
(pentane/EtOAc = 25:1). Spectral data is in accordance with
previously reported values.37
Tert-butyl
11,11-dimethyl-9,11-dihydro-6H-6,9-epimino-
benzo[b]fluorene-12-carboxylate (7b). Synthesized from ar-
yne precursor 5c using N-Boc-pyrrole as the arynophile.
Yield = 0.055 g (94%, based on 0.10 mmol of 5c). Colorless
1
solid. Rf = 0.2 (pentane/EtOAc = 25:1). H NMR (500 MHz,
CDCl3): δ 7.64 – 7.60 (m, 2H), 7.40 – 7.37 (m, 1H), 7.33 – 7.31
(m, 1H), 7.31 – 7.24 (m, 2H), 7.02 (m, 2H), 5.55 – 5.52 (m,
2H), 1.44 (s, 3H), 1.42 (s, 3H), 1.39 (s, 9H). 13C{1H} NMR (75
MHz, CDCl3): δ 155.1, 154.0, 151.0, 147.8, 147.5, 143.0,
139.2, 136.0, 126.8, 126.6, 122.3, 119.4, 115.8, 113.1, 80.6
(2C), 66.5, 46.6, 28.2, 27.0, 26.7. HRMS-ESI calcd for
C24H25NO2Na [M+Na]+: 382.1777, found 382.1781.
2-(Tert-butyl)-3-phenyl-2,3-dihydrobenzo[d]isoxazole
(7f). Synthesized in a 4-step procedure from phenylboronic
acid according to trapping procedure 1 using N-tert-butyl-
α-phenylnitrone as arynophile. Yield = 0.176 g (69%, based
on 1.00 mmol of phenylboronic acid). Colorless solid. Rf =
0.5 (pentane/EtOAc = 20:1). Spectral data is in accordance
with previously reported values.38
Iodine insertion into aryne (trapping procedure 2)
ASSOCIATED CONTENT
2,3-Diiodo-9,9-dimethyl-9H-fluorene (7c). A pre-dried mi-
crowave vial equipped with a magnetic stir bar was charged
with aryne precursor 5c (1.0 eq.), iodine (4.0 eq.), CsF (8.0
eq.) and CH3CN was added to obtain a 0.10 M solution with
respect to the aryne precursor. This mixture was heated at
60 °C for 71 h. The resulting product 7c was purified by col-
umn chromatography using pentane as the eluent. Yield =
0.054 g, 77% (based on 0.10 mmol of 5c). Colorless solid. Rf
The Supporting Information is available free of charge on the
ACS Publications website. This includes copies of NMR spectra
for all new compounds (.pdf format) and crystallography data:
(ORTEP plots in .pdf and original data in .cif format) for com-
pounds 3b, 5b and 7c.
AUTHOR INFORMATION
Corresponding Author
1
= 0.9 (pentane). H NMR (500 MHz, CDCl3): δ 8.23 (s, 1H),
7.95 (s, 1H), 7.66 – 7.65 (m, 1H), 7.42 - 7.40 (m, 1H), 7.38 –
7.33 (m, 2H), 1.46 (s, 6H). 13C{1H} NMR (75 MHz, CDCl3): δ
155.2, 153.2, 141.3, 136.9, 133.8, 130.7, 128.5, 127.3, 122.7,
120.4, 105.6, 105.5, 46.8, 26.8. HRMS-EI calcd for C15H12I2
[M]+: 445.9023, found 445.9041
* Lukasz T. Pilarski, Department of Chemistry – BMC, Uppsala
University, BOX 576, Uppsala 75-213, Sweden. Email:
Lukasz.Pilarski@kemi.uu.se, website: https://www.pilar-
skigroup.org.
ACKNOWLEDGMENT
We thank the Swedish Research Council (Vetenskapsrådet)
and the Carl Trygger Foundation for financial support. We are
also grateful to Dr. Johanna Larsson and Dr. Christine Dyrager
for manuscript proof-reading.
Direct generation and cycloaddition of benzyne (trap-
ping procedure 3).
Ortho-silyl phenol (1.0 mmol, 1.0 eq.) was prepared accord-
ing to a modified procedure A. After completion of the oxi-
dation, without further purification of the ortho-silyl phenol
by column chromatography, the crude mixture was
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