Expeditious and Convenient Synthesis of Polycyclic Difluoroboron Complexes of 2-Oxoindoline-3-carboxamides by Tandem Reaction

Article abstract of DOI:10.1002/adsc.201600118

N-Aryl-2-cyanodiazoacetamides produce polycyclic difluoroboron 2-oxoindoline-3-carboxamide complexes (up to pentacyclic conjugative and fused systems) directly and expeditiously in the presence of boron trifluoride etherate. The boron trifluoride serves as both a catalyst and reactant in the tandem reaction. The tandem reaction includes the carbene aromatic C-H insertion, hydrolysis of the cyano group into an amide group, and boronation of the two amide carbonyl groups. The synthetic method features the advantages of wide substrate scope and excellent chemoselectivity.

Full text of DOI:10.1002/adsc.201600118

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DOI: 10.1002/adsc.201600118
Expeditious and Convenient Synthesis of Polycyclic
Difluoroboron Complexes of 2-Oxoindoline-3-carboxamides by
Tandem Reaction
a
a
a,
Shanyan Mo, Chuangchuang Xu, and Jiaxi Xu *
a
State Key Laboratory of Chemical Resource Engineering, Department of Organic Chemistry, Faculty of Science, Beijing
University of Chemical Technology, Beijing 100029, Peopleꢀs Republic of China
Fax: (+86)-10-6443-5565; phone: (+86)-10-6443-5565; e-mail: jxxu@mail.buct.edu.cn
Received: January 26, 2016; Revised: February 23, 2016; Published online: April 19, 2016
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201600118.
Abstract: N-Aryl-2-cyanodiazoacetamides produce cyano group into an amide group, and boronation of
polycyclic difluoroboron 2-oxoindoline-3-carboxa- the two amide carbonyl groups. The synthetic
mide complexes (up to pentacyclic conjugative and method features the advantages of wide substrate
fused systems) directly and expeditiously in the pres- scope and excellent chemoselectivity.
ence of boron trifluoride etherate. The boron tri-
fluoride serves as both a catalyst and reactant in the Keywords: boron trifluoride; cyanoacetates; diflu-
tandem reaction. The tandem reaction includes the oroboron complexes; malonamides; 2-oxoindolines;
carbene aromatic CÀH insertion, hydrolysis of the tandem reaction
Introduction
the cyano group into an amide in the presence of
water. Moreover, Lewis acids are also effective cata-
[12]
Difluoroboron (BF ) complexes of N,N- and N,O- lysts for carbene generation from diazo compounds.
2
based ligands are generally highly fluorescent sub- Thus, we envisioned that Lewis acid BF ·OEt could
3
2
[
1]
stances in the solution, film, and solid state. Recent- be applied as a catalyst first for the generation of 3-
ly, difluoroboron complexes of b-dicarbonyl com- cyanooxindoles from 2-cyano-2-diazoacetanilides, sec-
[
2–5]
pounds have been widely investigated.
b-Diketo- ondly for hydrolysis of the cyano group into an
nates, possessing two carbonyls, can easily react with amide, converting 3-cyanooxindoles into malonamide-
boron trifluoride etherate (BF ·OEt ) to form six- type products 2-oxoindoline-3-carboxamides, and fi-
3
2
membered heterocyclic difluoroboron complexes. By nally react with 2-oxoindoline-3-carboxamides to
installing different substituted conjugative groups, afford the corresponding BF complexes of 2-oxoin-
2
large molar emission ratios and high quantum yields doline-3-carboxamides.
could be realized for the BF complexes of b-diketo-
Herein, we describe a tandem reaction to synthe-
2
nates, which could serve as photochemical reagents, size BF complexes of 2-oxoindoline-3-carboxamides.
2
[
2–5]
two-photon materials, and near-IR probes.
Recent- In our approach, 2-cyano-2-diazoacetanilides 1 under-
b-keto go a carbene aromatic CÀH insertion, subsequent hy-
[
2–5]
ly, various BF complexes of b-diketonates,
2
[
6]
[7]
esters, and b-keto amides have been synthesized drolysis of the cyano group into an amide group, and
and extensively studied. However, an investigation of finally, boronation of the two carbonyl groups, leading
[
8]
malonamide-type BF complexes is very rare.
to the generation of the BF complexes. The boron
2
2
The carbene aromatic CÀH insertion of diazoaceta- trifluoride etherate serves as a catalyst as well as a re-
nilides, which generates a cyclic amide (lactam) func- actant. In the current method, a series of polyhetero-
tional group, is a powerful protocol for the oxindole cyclic BF complexes 2 of 2-oxoindoline-3-carboxa-
2
[
9]
skeleton construction. It was reported that 2-cyano- mides 3 was synthesized.
2
-diazoacetanilides produced 3-cyanooxindoles under
[
10]
the catalysis of Rh(II) compounds.
In addition, it
was also described that the electrophilicity of the
cyano group was improved by coordination with
[
11]
a Lewis acid,
resulting in favorable hydrolysis of
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Results and Discussion
Table 1. Optimization of the reaction conditions.
2
2
-Cyano-2-diazoacetamides (1) were synthesized from
-cyanoacetamides 4, which were in turn prepared
from cyanoacetic acid or cyanoacetic chloride and the
corresponding secondary amines, by diazo transfor-
mation with the use of triflic azide under basic condi-
tions. 2-Cyano-2-diazo-N-phenylacetanilide (1a) was
selected as a model substrate and treated with En- Solvent BF
·OEt
(equiv.)
Additive
(mol%)
Yield
[a]
3
2
try
[%]
BF ·OEt , affording the desired BF complex of 1-
3
2
2
phenyl-2-oxoindoline-3-carboxamide (3a), 4-amino-
1
2
3
4
5
6
7
8
9
1
1
1
1
1
DCE
toluene 2.0
DCM
MeCN
ether
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
2.0
none
none
none
none
none
none
none
none
48
37
37
57
trace
49
54
63
61
71
2
,2-difluoro-9-phenyl-2,9-dihydro-[1,3,2]dioxaborini-
no[4,5-b]indol-3-ium-2-uide (2a), successfully in 48%
yield after work-up in our first trial in 1,2-dichloro-
ethane (DCE) (Scheme 1). The yield was improved to
2.0
2.0
2.0
1.0
1.5
2.5
3.0
2.5
2.5
2.5
2.5
2.5
2.5
2.5
77% in acetonitrile with 4-nitrophenol as an additive
after optimization (Table 1, entry 15). The structure of
1
13
19
11
2
a was confirmed by H, C, F, and B NMR, IR,
[13]
none
TsOH (10)
HR-MS, and X-ray diffraction analyses (Figure 1).
For reaction optimization, several commonly used
solvents were tested, revealing that acetonitrile was
the best solvent for the reaction, while diethyl ether
was almost completely not applicable (Table 1, en-
0
1
2
3
4
p-O NC H CO H (10) 56
2
6
4
2
(CF ) CHOH (10)
66
72
75
77
72
3
2
p-O NC H OH (10)
2
6
4
p-O NC H OH (20)
2
6
4
tries 1–5). The loading amounts of BF ·OEt were fur- 15
p-O NC H OH (15)
3
2
2 6 4
ther screened, and the results indicated that better 16
yields were obtained when 2.5 equivalents of
p-O NC H OH (5)
2 6 4
[
a]
Isolated yield after flash chromatography. All reactions
were performed on 0.38 mmol (100 mg) scale in 5 mL of
solvent.
BF ·OEt were employed (Table 1, entries 6–9). To
3
2
adjust the pH value for the hydrolysis of the cyano
group, different protonic acids were added. Satisfacto-
rily, except for p-nitrobenzoic acid, the addition of
other protonic acids [TsOH, (CF ) CHOH, p-
3
2
O NC H OH] led to better yields, and p-nitrophenol
2
6
4
Scheme 1. Tandem reaction of 2-cyano-2-diazo-N,N-diphe- was found to be the best additive for the reaction
nylacetamide (1a). (Table 1, entries 11–13). After evaluating the loading
Figure 1. X-ray diffraction analytical structure of the BF complex (2a) of 1-phenyl-2-oxoindoline-3-carboxamide (3a).
2
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[a]
Table 2. Substrate scope.
desired products 2. The substrate 1i with 3,5-dimethyl
groups on the aromatic ring furnished product 2i in
only 20% yield due to steric bulkiness (Table 2, 2i).
The reactions of 2-cyano-2-diazoacetanilides 1k–1n
derived from cyclic secondary amines were all suc-
cessful, producing polycyclic BF complexes 2k–2n in
2
4
2–67% yields (Table 2, 2k–2n). The N-naphthyl sub-
stituted substrate 1o afforded the polycyclic BF com-
2
plex as well (Table 2, 2o).
To get a mechanistic insight of the reaction, some
designed experiments were conducted. At first, we
used Rh (Oct) (dirhodium tetraoctanoate) instead of
2
4
[10]
BF ·OEt as the catalyst for the model reaction. 3-
3
2
Cyano-1-phenyl-2-oxindole (3a) was obtained in 40%
yield and it was further converted into the BF com-
2
plex 2a under the optimized reaction conditions in
the presence of BF ·OEt , indicating that the tandem
3
2
reaction intermediate is 3-cyano-1-phenyl-2-oxindole
3a). To verify hydrolysis of the cyano group under
the catalysis of BF ·OEt , acetonitrile, benzonitrile, 2-
(
3
2
cyanoacetophenone, and 2-cyano-N,N-diphenylaceta-
mide (4a) were examined under the optimal reaction
conditions. The results reveal that no reaction oc-
curred for acetonitrile, benzonitrile, and 2-cyanoace-
tophenone. However, 2-cyano-N,N-diphenylacetamide
(
4a) was partially converted into the corresponding
BF2 complex (2p) of N,N-diphenylmalonamide in
9% yield after work-up (Scheme 2). The results indi-
2
cate that the rigid vicinal cis-hydroxy (or carbonyl,
which can enolize into hydroxy) group is required for
[a]
Isolated yield. All reactions were performed under the
optimized conditions on a 100 mg scale of 1.
amount of the additive, the optimal yield of 77% was
achieved when 15% of the additive was utilized
(
Table 1, entries 13–16).
After establishing the optimal reaction conditions,
the substrate scope was examined with a diverse array
of 2-cyano-2-diazoacetanilides 1, and the results are
summarized in Table 2. The effect of the N-substitu-
ent group was investigated. The results indicate that
the substrates with N-alkyl and N-benzyl groups pro-
duced the corresponding desired products exclusively,
showing excellent chemospecificity, only aromatic CÀ
H insertion occurred (Table 2, 2a–2d). The electronic
effect of the substituents on the aromatic ring does
not affect the yields obviously in the reactions
(
Table 2, 2d–2f, 2g, 2h, 2j). The steric effect of the
substituents on the aromatic ring was also studied. Scheme 2. Designed reactions for investigations on the
Not surprisingly, all of them were converted into the mechanism of the tandem reaction.
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hydrolysis of the cyano group. Even freely rotable vi-
cinal oxo nitriles cannot be hydrolyzed in the pres-
ence of boron trifluoride.
Simple nitriles, such as acetonitrile and benzonitrile,
which lack the chelating coordination sites, cannot be
hydrolyzed under the catalysis of boron trifluoride. A
freely rotatable vicinal oxo nitrile, 2-cyanoacetophe-
none, is also inert for the BF -catalyzed hydrolysis.
3
However, 2-cyano-N,N-diphenylacetamide (4a) can
be partially hydrolyzed under the same conditions,
further generating difluoroboron complex (2p) in
2
9% yield after work-up (Scheme 2).
After carefully analyzing their structural features,
we can rationalize that the s-cis conformation of the
oxo and cyano groups in the substrates is required for
the hydrolysis. 2-Cyanoacetophenone favorably exists
in the s-trans conformation due to the lower molecu-
lar dipole moment (electronic repulsion). However, 2-
cyano-N,N-diphenylacetamide (4a) exists in both s-cis
and s-trans conformations due to the balance between
molecular dipole moment and steric hindrance. This
Scheme 3. Rationale for the BF -catalyzed hydrolysis of 2-
cyano-N,N-diphenylacetamide (4a).
3
is the reason why cyanoacetamide 4a can be partially in cyanoacetamide 4a, which is favorably hydrolyzed
hydrolyzed and 2-cyanoacetophenone cannot under by water. The fact that 3-cyano-1-phenyl-2-oxindole
BF -catalysis (Scheme 3). In the s-cis conformation, (3a) can be efficiently hydrolyzed can thus be under-
3
the boron atom of difluoroborate, generated from stood, since its oxo and cyano groups are locked in an
boron trifluoride and enol of 4a, can coordinate with s-cis conformation.
one of the p bonds in the cyano group. The coordina-
We thus propose the tandem reaction mechanism
tion increases the electrophilicity of the cyano group as shown in Scheme 4. An aromatic carbene CÀH in-
Scheme 4. Proposed mechanism for the tandem reaction.
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sertion of 2-diazo-2-cyanoacetanilides 1 catalyzed by Table 3. Fluorescence properties of representative difluoro-
[
a]
boron complexes 2.
the Lewis acid BF ·OEt provides 3-cyanooxindoles 3,
3
2
which tautomerize into 2-hydroxyindoles 3’. Subse-
quently, the hydroxy group of 3’ reacts with BF and
3
another molecule of BF coordinates with the cyano
3
group of 3’, leading to the formation of difluorobo-
rates A, in which the boron atom in the difluorobo-
rate group also coordinates with one of the p bonds
of the cyano group. The difluoroborates A can reso-
nate into unsaturated azaboririne forms A’, activating
in the original CꢀN bond. During work-up, water at-
tacks the carbon atom of the azaboririne ring in reso-
nance forms A’ nucleophilically through a nucleophilic
[
14]
three-membered ring opening reaction. Meanwhile,
because the coordination between the cyano group
and BF is just Lewis acid-base bonding, which is re-
3
versible, water destroys the CꢀNÀBF complexes, re-
3
sulting in the formation of intermediates B, which can
lose a proton to give intermediates C. The intermedi-
ates C favorably convert into intermediates D
through transition states TS1 because the boron atom
is a hard acid and the oxygen atom is a harder base
than the nitrogen atom, based on Pearsonꢀs hard and
soft acid-base concept. The intermediates D undergo
a water-participating proton transfer to give rise to
the final products 2 through six-membered ring transi-
tion states TS2 because the direct proton 1,3-shift is
orbital-symmetry forbidden. The protonic solvent-par-
ticipating proton transfer has been observed and ra-
tionalized previously in our studies on Claisen and
[
a]
À5
À3
Measured at a concentration of 1.0”10 dm at 258C
with DMSO as solvent.
[
15]
benzidine rearrangements. The difluoroboron com-
plexes 2 show better stability to water during work-
up. The above mechanistic analysis reveals that the
boron atom shows more stable coordination with the Conclusions
oxygen atom than with the nitrogen atom. Thus, the
function of the additive 4-nitrophenol in the reaction We have developed an expeditious and convenient
can be rationalized as follows: it first reacts with BF3 synthesis of difluoroboron complexes of oxindole-3-
to generate 4-nitrophenyl difluoroborate, which is carboxamides from 2-cyanodiazoacetanilides and
a softer acid comparing with BF and coordinates boron trifluoride etherate. This tandem reaction in-
3
better with the soft nitrogen atom in the cyano group, cludes carbene aromatic CÀH insertion, hydrolysis of
promoting more efficient hydrolysis of the cyano nitriles, and boronation of two carbonyl groups. The
group (the step from A’ to B in Scheme 4).
boron trifluoride serves as a catalyst as well as a reac-
The fluorescence properties of representative BF2 tant. The reaction mechanism is proposed on the
complexes 2 were measured (Table 3). The results basis of some designed experiments. The current
showed that the measured products exhibit low emis- method provides an efficient way to prepare the di-
sion wavelengths (l =307–436 nm) and excitation fluoroboron complexes of malonamide-type com-
em
1
wavelengths (l =281–300 nm). With different R and pounds from 2-cyanodiazoacetanilides.
ex
2
R substituents, the l and lex values of BF com-
em
2
plexes 2a, 2b, 2j, and 2k are almost the same. The BF2
complexes 2m and 2o show higher lem and l than 2a,
ex
Experimental Section
2
b, 2j, and 2k, but lower than 2l. BF complex 2l
2
shows the highest l , presumably due to the good
em
General Information
conjugative property of its structure. Thus, the fluo-
rescence properties indicate that installation of more
conjugative and fused rings are required to get higher
Melting points were measured on a Yanaco MP-500 melting
1
13
point apparatus and are uncorrected. H and C NMR spec-
tra were recorded on a Bruker 400 MHz spectrometer.
Chemical shifts are reported in ppm with TMS as an inter-
[
16]
l .
em
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3
1
11
1
nal standard. F and B NMR spectra were recorded at
75 MHz and 193 MHz on Bruker 400 MHz and 600 MHz
91–948C; H NMR (400 MHz, CDCl ): d=7.38–7.37 (m,
3
3
3H), 7.32–7.22 (m, 3H), 7.22–7.11 (m, 2H), 7.07–6.91 (m,
2H), 4.89 (s, 2H), 3.21 (s, 2H); C NMR (100 MHz,
CDCl ): d=161.7, 140.6, 136.1, 130.2, 129.2, 129.1, 128.5,
1
3
spectrometers, respectively, with BF ·OEt2 as an external
standard. The IR spectra (KBr pellets, v [cm ]) were taken
3
À1
3
on a Nicolet 370 MCT FT-IR spectrometer. The high resolu-
tion mass spectra were obtained with ESI ionization using
an Agilent LC/MSD TOF mass spectrometer. Column chro-
matography was carried out on silica gel (200–300 mesh)
with petroleum ether (PE, 608C-908C) and ethyl acetate
128.2, 127.9, 114.1, 53.7, 25.7; IR (KBr): n=2259 (CN),
1664 cm (C=O).
N-Benzyl-2-cyano-N-(p-tolyl)acetamide (4e): yield: 2.53 g
À1
(96%, 10 mmol scale); colorless crystals; mp 104–1068C;
1
H NMR (400 MHz, CDCl ): d=7.29–7.25 (m, 3H), 7.19–
3
(EA) as the eluent. All reactions were followed by thin-
7.15 (m, 4H), 6.87–6.84 (m, 2H), 4.86 (s, 2H), 3.21 (s, 2H),
1
3
layer chromatography (TLC) where practical, using silica
gel 60 F254 fluorescent treated silica gel plates, which were
visualized under UV light (254 nm). For the reactions con-
ducted under anhydrous conditions, solvents were refluxed
with drying reagents and freshly distilled prior to use. Di-
chloromethane (DCM) and acetonitrile were dried over cal-
cium hydride. 1,2-Dichloroethane (DCE) and chloroform
were dried by phosphorus pentoxide. Toluene and benzene
were dried over sodium wire with benzophenone as an indi-
cator. Reagents used were obtained from commercial sup-
pliers and used without purification except triethylamine
2.35 (s, 3H); C NMR (100 MHz, CDCl ): d=161.8, 139.3,
3
137.9, 136.2, 130.8, 129.0, 128.5, 127.9, 127.8, 114.1, 53.7,
À1
25.7, 21.1; IR (KBr): n=2259 (CN), 1670 cm (C=O); HR-
+
MS (ESI): m/z=265.1335, calcd. for C H N O ([M+H] ):
1
7
17
2
2
65.1335.
N-Benzyl-N-(4-chlorophenyl)-2-cyanoacetamide
yield: 4.6 g (84%, 19 mmol scale); colorless crystals; mp
(4f):
1
1
8
00–1028C; H NMR (400 MHz, CDCl ): d=7.35 (d, J=
.5 Hz, 2H), 7.31–7.24 (m, 3H), 7.19–7.13 (m, 2H), 6.94 (d,
3
1
3
J=8.5 Hz, 2H), 4.86 (s, 2H), 3.22 (s, 2H); C NMR
100 MHz, CDCl ): d=161.5, 138.9, 135.7, 135.2, 130.4,
(
3
(TEA) which was dried over calcium hydride and freshly
1
2
3
29.6, 129.0, 128.6, 128.0, 113.9, 53.7, 25.7; IR (DCM): n=
distilled prior to use.
À1
261 (CN), 1673 cm
07.0620, calcd. for C H ClN NaO ([M+Na] ): 307.0609.
(C=O); HR-MS (ESI): m/z=
+
1
6
13
2
2
-Cyano-N,N-di(p-tolyl)acetamide (4g): yield: 1.02 g
General Procedure for the Preparation of 2-Cyano-
acetamides 4a–i and 4m–o using DCC/DMAP as
Condensation Reagent
(
46%, 8.3 mmol scale); colorless crystals; mp 78–808C;
H NMR (400 MHz, CDCl ): d=7.29–7.09 (m, 8H), 3.40 (s,
H), 2.38 (s, 3H), 2.31 (s, 3H). C NMR (100 MHz,
1
3
[
17]
1
3
2
CDCl ): d=161.7, 139.2, 139.1, 138.9, 136.7, 131.0, 129.7,
3
To a solution of a secondary amine (10 mmol) and 2-cyano-
1
1
28.0, 125.6, 114.1, 26.6, 21.0, 20.9; IR (KBr): n=2260 (CN),
acetic acid (93.5 mg, 11 mmol) in CH Cl2 (10 mL) was
2
À1
674 cm (C=O); HR-MS (ESI): m/z=287.1167, calcd. for
added a solution of DCC (N,N’-dicyclohexylcarbodiimide,
+
C H N NaO ([M+Na] ): 287.1155.
1
7
16
2
226.6 mg, 11 mmol) and DMAP [4-(N,N-dimethylamino)pyr-
N,N-Di(4-chlorophenyl)-2-cyanoacetamide (4h): yield:
idine, 6 mg, 0.05 mmol] in CH Cl (20 mL) at 08C. The re-
2
2
1
1
3
1
1
.23 g (66%, 6.1 mmol scale); colorless crystals; mp 138–
sulting solution was stirred for 1 h. During this period
a white solid (1,3-dicyclohexylurea, DCU) was precipitated
which was subsequently filtered. After removal of the sol-
vent under reduced pressure, the resulting crude product
was recrystallized from EtOH to afford the pure amide 4.
1
408C; H NMR (400 MHz, CDCl ): d=7.47–7.18 (m, 8H),
3
1
3
.42 (s, 2H). C NMR (100 MHz, CDCl ): d=161.6, 131.0,
3
29.7, 129.4, 127.1, 113.6, 26.8; IR (KBr): n=2260 (CN),
À1
681 cm (C=O); HR-MS (ESI): m/z=305.0247, calcd. for
+
C H Cl N O ([M+H] ): 305.0243.
2
-Cyano-N,N-diphenylacetamide (4a): yield: 2.00 g (88%,
15 10
2
2
[
18]
2-Cyano-N,N-di(3,5-dimethylphenyl)acetamide (4i): yield:
1
1
1
1
0 mmol scale); colorless crystals; mp 161–1628C, Lit.
54–1568C; H NMR (300 MHz, CDCl ): d=7.47–7.23 (m,
0H), 3.41 (s, 2H); C NMR (100 MHz, CDCl ): d=161.6,
41.4, 130.5, 129.1, 128.4, 126.9, 125.8, 113.9, 26.7; IR (KBr):
1
1.09 g (67%, 5.5 mmol scale); colorless crystals; mp 205–
3
1
13
2078C; H NMR (400 MHz, CDCl ): d=7.03–6.85 (m, 6H),
3
3
3
1
3
.40 (s, 2H), 2.34 (s, 6H), 2.28 (s, 6H). C NMR (100 MHz,
À1
CDCl ): d=161.7, 141.3, 140.3, 138.8, 130.6, 128.8, 125.7,
n=2260 (CN), 1676 cm (C=O).
3
À1
1
23.7, 114.1, 26.5, 21.2; IR (KBr): n=2258 (CN), 1686 cm
2
-Cyano-N-methyl-N-phenylacetamide (4b): yield: 1.43 g
[19]
(
(
C=O); HR-MS (ESI): m/z=293.1660, calcd. for C H N O
19 21 2
+
(
82%, 10 mmol scale); colorless crystals; mp 87–898C, Lit.
6–798C; H NMR (300 MHz, CDCl ): d=7.51–7.47 (m,
H), 7.45–7.41 (m, 1H), 7.26–7.23 (m, 2H), 3.32 (s, 3H),
.25 (s, 2H); C NMR (100 MHz, CDCl ): d=161.6, 142.3,
30.4, 128.9, 127.0, 114.1, 37.8, 25.3; IR (KBr): n=2259
CN), 1668 cm (C=O).
1
[M+H] ): 293.1648.
-(2-Chlorodibenzo[b,f][1,4]oxazepin-10(11H)-yl)-3-oxo-
7
2
3
1
3
3
13
propanenitrile (4m): yield: 0.30 g (75%, 1.34 mmol scale);
3
1
colorless crystals; mp 166–1688C; H NMR (400 MHz,
À1
(
CDCl
): d=7.47–7.43 (m, 1H), 7.37–7.34 (m, 2H), 7.31–7.27
3
2
-Cyano-N-phenyl-N-propylacetamide (4c): yield: 1.84 g
(m, 1H), 7.22–7.19 (m, 1H), 7.14 (d, J=8.8 Hz, 2H), 5.69 (s,
1
3
(
91%, 10 mmol scale); colorless crystals; mp 60–648C;
H NMR (400 MHz, CDCl ): d=7.51–7.42 (m, 3H), 7.23–
1H), 4.26 (s, 1H), 3.39 (s, 2H); C NMR (100 MHz,
CDCl ): d=161.7, 153.3, 152.1, 132.6, 130.9, 128.8, 128.7,
1
3
3
7
.21 (m, 2H), 3.69 (t, J=7.6 Hz, 2H), 3.19 (s, 2H), 1.56
128.7, 127.7, 125.9, 125.7, 122.5, 122.4, 113.5, 48.6, 25.3; IR
13
À1
(
(
sixtet, J=7.6 Hz, 2H), 0.91 (t, J=7.6 Hz, 3H); C NMR
100 MHz, CDCl ): d=161.4, 140.9, 130.3, 129.0, 127.9,
(KBr): n=2261 (CN), 1685 cm
(ESI):299.0598, m/z= calcd. for C16
299.0582.
(C=O); HR-MS
+
H12ClN O ([M+H] ):
2 2
3
1
1
14.2, 51.5, 25.7, 20.6, 11.0; IR (KBr): n=2254 (CN),
À1
670 cm (C=O); HR-MS (ESI): m/z=203.1179, calcd. for
3-(3,4-Dihydroquinolin-1(2H)-yl)-3-oxopropanenitrile
+
C H N O ([M+H] ): 203.1179.
(4n): yield: 0.88 g (88%, 5 mmol scale); colorless oil;
1
2
15
2
1
N-Benzyl-2-cyano-N-phenylacetamide (4d): yield: 1.25 g
50%, 10 mmol scale); colorless crystals; mp 94–978C, Lit.
H NMR (400 MHz, CDCl ): d=7.26–7.04 (m, 4H), 3.82 (s,
3
[
18]
13
(
2H), 3.65 (s, 2H), 2.74 (s, 2H), 2.04–1.96 (m, 2H); C NMR
Adv. Synth. Catal. 2016, 358, 1767 – 1777
1772
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FULL PAPERS
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(
1
1
100 MHz, CDCl ): d=161.3, 137.6, 134.6, 128.8, 126.7,
(C=O); HR-MS (ESI): m/z=267.0583, calcd. for
3
+
23.6, 114.2, 43.4, 26.4, 25.8, 23.6; IR (KBr): n=2258 (CN),
C H N OS ([M+H] ): 267.0587.
1
5
11
2
À1
667 cm (C=O); HR-MS (ESI): m/z=223.0853, calcd. for
+
C H N NaO ([M+H] ): 223.0842.
1
2
12
2
2
-Cyano-N-ethyl-N-(naphthalen-1-yl)acetamide
(4o): General Procedure for the Synthesis of 2-Cyano-2-
[20]
yield: 0.76 g (64%, 5 mmol scale); colorless crystals; mp 95– diazoacetamides 1 via Diazo Transformation
1
9
7
1
3
1
78C; H NMR (400 MHz, CDCl ): d=7.98–7.95 (m, 2H),
3
Sodium azide (2.34 g, 36 mmol) was dissolved in a mixture
of H O (10 mL) and CH Cl (5 mL) and the resulting solu-
.78 (d, J=8.0 Hz, 1H), 7.66–7.59 (m, 2H), 7.57–7.52 (m,
H), 7.40 (d, J=7.2 Hz, 1H), 4.27 (dq, J=14.1, 7.2 Hz, 1H),
.51 (dq, J=14.1, 7.2 Hz, 1H), 3.17 (dd, J=18.2, 0.8 Hz,
H), 3.00 (d, J=18.2 Hz, 1H), 1.21 (t, J=7.2 Hz, 3H);
C NMR (100 MHz, CDCl ): d=162.2, 136.5, 134.9, 130.0,
29.9, 129.0, 128.2, 127.2, 126.7, 125.7, 121.6, 114.1, 44.8,
2
2
2
tion was cooled to 08C in an ice-water bath. To this vigo-
rously stirred solution was added triflic anhydride (1 mL,
6 mmol) dropwise through a syringe during 10 min. After
being stirred at 08C for 2 h, the organic phase was separated
and the aqueous phase was extracted with 5 mL of CH Cl .
1
3
3
1
2
À1
2
2
5.5, 13.1; IR (KBr): n=2259 (CN), 1671 cm (C=O); HR-
+
The combined organic phase was washed with 10 mL of sa-
turated aqueous NaHCO , then dried over Na SO and used
MS (ESI): m/z=239.1198, calcd. for C H N O ([M+H] ):
15
15
2
3
2
4
2
39.1198.
in the next step immediately.
An amide 4 (5 mmol) was dissolved in 10 mL of CH CN,
3
then the freshly prepared solution of triflic azide in CH Cl2
2
was added under N at 08C with cooling in an ice-water
General Procedure for the Preparation of 2-Cyano-
acetamides 4j–l using 2-Cyanoacetic Chloride as
Acylating Reagent
2
bath. After addition of triethylamine (758 mg, 7.5 mmol) the
resulting mixture was stirred at room temperature for 18 h.
The solution was concentrated under reduced pressure. The
resulting residue was purified by silica gel column chroma-
tography to give the pure product 1.
[
19]
To a stirred suspension of 2-cyanoacetic acid (553 mg,
.5 mmol) in CH Cl2 (25 mL) was added oxalyl chloride
6
2
(
762 mg, 6 mmol) followed by seven drops of DMF at 08C.
The reaction mixture was stirred at room temperature for
h.
To the above clear pale yellow solution was added a solu-
tion of a secondary amine (5 mmol) in dichloromethane
20 mL) followed by triethylamine (1.26 g, 12.5 mmol) at
8C. The reaction mixture was stirred for 24 hrs and then
2-Cyano-2-diazo-N,N-diphenylacetamide
1.20 g (92%, 5 mmol scale); yellow crystals; mp 96–998C;
(1a):
yield:
1
3
H NMR (400 MHz, CDCl ): d=7.43–7.38 (m, 4H), 7.36–
3
1
3
7.33 (m, 2H), 7.28–7.25 (m, 4H); C NMR (100 MHz,
CDCl ): d=159.8, 141.3, 129.7, 128.1, 127.4, 106.9; IR
3
À1
(
0
(DCM): n=2218 (CN), 2129 (CN ), 1735 cm (C=O); HR-
2
+
MS (ESI): m/z=263.0925, calcd. for C H N O ([M+H] ):
1
5
11
4
washed with water (25 mL) and 1 mol/L HCl (25 mL). The
263.0927.
2-Cyano-2-diazo-N-methyl-N-phenylacetamide
yield: 0.90 g (90%, 5 mmol scale); yellow oil; H NMR
[17]
organic layer was dried over MgSO and then evaporated.
(1b):
4
1
The resulting residue was purified by silica gel chromatogra-
phy (petroleum ether/EtOAc, v/v, 6:1–2:1) to give the amide
(400 MHz, CDCl ): d=7.48–7.44 (m, 3H), 7.29–7.24 (m,
3
1
3
4.
2H), 3.37 (s, 3H); C NMR (100 MHz, CDCl ): d=159.2,
3
2
-Cyano-N,N-di(o-tolyl)acetamide (4j): yield: 0.26 g
141.2, 130.1, 129.5, 127.7, 107.2, 39.1; IR (DCM): n=2180
À1
(
26%, 3.8 mmol scale); colorless crystals; mp 179–1808C;
H NMR (400 MHz, CDCl ): d=7.33–7.24 (m, 5H), 7.17 (td,
J=7.5, 1.2 Hz, 1H), 7.10 (td, J=7.7, 1.1 Hz, 1H), 6.91–6.88
m, 1H), 3.39 (s, 2H), 2.38 (s, 3H), 2.28 (s, 3H); C NMR
100 MHz, CDCl ): d=161.1, 140.5, 139.4, 135.5, 134.9,
32.5, 131.4, 129.2, 129.0, 127.8, 127.4, 126.6, 125.9, 113.8,
6.1, 19.0, 18.1; IR (KBr): n=2258 (CN), 1681 cm (C=O);
(CN), 2135 (CN ), 1729 cm (C=O).
2
1
2-Cyano-2-diazo-N-phenyl-N-propylacetamide (1c): yield:
3
1
1.02 g (90%, 5 mmol scale); yellow oil; H NMR (400 MHz,
13
(
(
1
2
CDCl ): d=7.48–7.43 (m, 3H), 7.26–7.21 (m, 2H), 3.72 (t,
3
J=7.6 Hz, 2H), 1.59 (sixtet, J=7.6 Hz, 2H), 0.92 (t, J=
3
1
3
7.6 Hz, 3H); C NMR (100 MHz, CDCl ): d=158.9, 139.7,
3
À1
130.0, 129.6, 128.7, 107.2, 52.8, 20.8, 11.0; IR (DCM): n=
À1
HR-MS (ESI): m/z=265.1345, calcd. for C H N O ([M+
2216 (CN), 2125 (CN ), 1729 cm (C=O); HR-MS (ESI):
17
17
2
2
+
+
H] ): 265.1335.
-(10,11-Dihydro-5H-dibenzo[b,f]azepin-5-yl)-3-oxopropa-
m/z=229.1083, calcd. for C H N O ([M+H] ): 229.1084.
1
2
13
4
3
N-Benzyl-2-cyano-2-diazo-N-phenylacetamide (1d): yield:
nenitrile (4k): yield: 0.86 g (66%, 5 mmol scale); colorless
1.24 g (90% yield, 5 mmol scale); yellow crystals; mp 46–
1
1
crystals; mp 192–1948C; H NMR (400 MHz, CDCl ): d=
478C; H NMR (400 MHz, CDCl ): d=7.45–7.40 (m, 1H),
3
3
7
.39–7.14 (m, 8H), 3.54–3.27 (m, 4H), 2.91–2.82 (m, 2H);
7.38–7.34 (m, 2H), 7.30–7.26 (m, 3H), 7.21–7.19 (m, 2H),
7.07–7.05 (m, 2H), 4.93 (s, 2H); C NMR (100 MHz,
1
3
13
C NMR (100 MHz, CDCl ): d=161.7, 140.7, 138.9, 137.9,
3
1
1
34.2, 130.8, 130.5, 129.6, 128.1, 128.0, 127.9, 127.0, 126.8,
13.7, 30.7, 30.1, 25.7; IR (KBr): n=2259 (CN), 1679 cm
CDCl ): d=159.3, 139.5, 136.1, 129.9, 129.7, 128.9, 128.5,
3
À1
127.9, 107.0, 54.9; IR (DCM): n=2215 (CN), 2121 (CN ),
2
À1
(
(
C=O); HR-MS (ESI): m/z=263.1190, calcd. for C H N O
[M+H] ): 263.1179.
-Oxo-3-(10H-phenothiazin-10-yl)propanenitrile
1638 cm (C=O); HR-MS (ESI): m/z=277.1092, calcd. for
1
7
17
2
+
+
C H N O ([M+H] ): 277.1084.
1
6
13
4
3
(4l):
N-Benzyl-2-cyano-2-diazo-N-(p-tolyl)acetamide
(1e):
yield: 0.80 g (60%, 5 mmol scale); colorless crystals; mp
yield: 1.00 g (69%, 5 mmol scale); yellow crystals; mp 95–
1
1
2
7
7
02–2048C; H NMR (400 MHz, DMSO-d ): d=7.68 (d, J=
968C; H NMR (400 MHz, CDCl ): d=7.29–7.25 (m, 3H),
6
3
.0 Hz, 2H), 7.61 (dd, J=7.7, 1.2 Hz, 2H), 7.44 (ddd, J=7.7,
.0, 1.2 Hz, 2H), 7.36 (dd, J=7.0, 7.0 Hz, 2H), 4.17 (s, 2H);
7.21–7.19 (m, 2H), 7.15 (d, J=8.0 Hz, 2H), 6.92 (d, J=
1
3
8.0 Hz, 2H), 4.89 (s, 2H), 2.37 (s, 3H); C NMR (100 MHz,
1
3
C NMR (100 MHz, DMSO-d ): d=162.3, 137.3, 128.1,
CDCl ): d=159.4, 140.0, 136.8, 136.2, 130.4, 128.9, 128.6,
6
3
À1
127.6, 127.0, 115.2, 26.4; IR (KBr): n=2259 (CN), 1670 cm
128.5, 127.8, 107.2, 54.9, 21.2; IR (DCM): n=2213 (CN),
Adv. Synth. Catal. 2016, 358, 1767 – 1777
1773
ꢁ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

FULL PAPERS
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À1
2
2
124 (CN ), 1724 cm
(C=O); HR-MS (ESI): m/z=
3-(2-Chlorodibenzo[b,f][1,4]oxazepin-10(11H)-yl)-2-
diazo-3-oxopropanenitrile (1m): yield: 132 mg1 (61%,
0.67 mmol scale); yellow crystals; mp 149–1518C; H NMR
2
+
91.1244, calcd. for C H N O ([M+H] ): 291.1240.
17
15
4
N-Benzyl-N-(4-chlorophenyl)-2-cyano-2-diazoacetamide
1f): yield: 1.42 g (91%, 5 mmol scale); yellow crystals; mp
03–1058C; H NMR (400 MHz, CDCl ): d=7.33 (d, J=
.6 Hz, 2H), 7.31–7.26 (m, 3H), 7.21–7.14 (m, 2H), 6.97 (d,
J=8.6 Hz, 2H), 4.89 (s, 2H); C NMR (100 MHz, CDCl ):
(
1
8
(400 MHz, CDCl
): d=7.46 (td, J=8.2, 1.7 Hz, 1H), 7.32
3
1
(ddd, J=9.4, 8.1, 1.4 Hz, 2H), 7.25 (dd, J=7.4, 1.4 Hz, 1H),
3
1
3
7.23–7.11 (m, 3H), 5.56 (s, 1H), 4.30 (s, 1H); C NMR
100 MHz, CDCl ): d=159.4, 153.9, 152.3, 131.8, 131.5,
13
(
3
3
1
28.8, 128.6, 128.6, 125.6, 125.6, 122.6, 122.2, 106.7, 49.5; IR
d=159.2, 137.9, 135.7, 135.7, 130.2, 130.1, 128.9, 128.6, 128.1,
07.0, 54.8; IR (DCM): n=2216 (CN), 2124 (CN ),
À1
(KBr): n=2218 (CN), 2124 (CN ), 1648 cm (C=O); HR-
1
1
2
2
À1
MS (ESI): m/z=325.0503, calcd. for C H ClN O ([M+
16 10 4 2
+
638 cm (C=O); HR-MS (ESI): m/z=311.0704, calcd. for
+
H] ): 325.0487.
-Diazo-3-(3,4-dihydroquinolin-1(2H)-yl)-3-oxopropaneni-
C H ClN O ([M+H] ): 311.0694.
1
6
12
4
2
2
-Cyano-2-diazo-N,N-di(p-tolyl)acetamide (1g): yield:
55 mg (95%, 2 mmol scale); yellow crystals; mp 100–
038C; H NMR (400 MHz, CDCl ): d=7.19 (d, J=8.4 Hz,
H), 7.13 (d, J=8.4 Hz, 4H), 2.36 (s, 6H); C NMR
100 MHz, CDCl ): d=159.7, 138.9, 130.2, 127.0, 126.1,
07.1, 21.1; IR (DCM): n=2216 (CN), 2124 (CN ),
650 cm (C=O); HR-MS (ESI): m/z=291.1249, calcd. for
C H N O ([M+H] ): 291.1240.
N,N-Di(4-chlorophenyl)-2-cyano-2-diazoacetamide (1h):
yield: 331 mg (50%, 2 mmol scale); yellow crystals; mp 125–
288C; H NMR (400 MHz, CDCl ): d=7.38 (d, J=8.7 Hz,
H), 7.17 (d, J=8.7 Hz, 4H); C NMR (100 MHz, CDCl ):
trile (1n): yield: 286 mg (63%, 2 mmol scale); yellow crys-
5
1
4
(
1
1
1
1
tals; mp 125–1278C; H NMR (400 MHz, CDCl ): d=7.30–
3
3
13
7.19 (m, 4H), 3.82 (t, J=6.7 Hz, 2H), 2.73 (t, J=6.7 Hz,
1
3
2
H), 2.00 (p, J=6.7 Hz, 2H); C NMR (100 MHz, CDCl ):
3
3
d=159.2, 137.0, 133.0, 128.8, 126.8, 126.5, 123.7, 108.0, 45.1,
2
À1
À1
26.4, 23.9; IR (KBr): n=2218 (CN), 2125 (CN ), 1640 cm
2
(
(
C=O); HR-MS (ESI): m/z=227.0932. calcd. for C H N O
12 11 4
+
+
1
7
15
4
[M+H] ): 227.0927.
-Cyano-2-diazo-N-ethyl-N-(naphthalen-1-yl)acetamide
1o): yield: 202 mg (77%, 1 mmol scale); yellow oil;
2
(
1
1
4
1
3
H NMR (400 MHz, CDCl ): d=8.03 (d, J=8.3 Hz, 1H),
13
3
3
7.98–7.94 (m, 1H), 7.81 (d, J=7.9 Hz, 1H), 7.65–7.57 (m,
d=159.9, 139.4, 134.2, 130.0, 128.4, 106.7; IR (DCM): n=
2
4
H), 7.55–7.50 (m, 1H), 7.42 (dd, J=7.2, 1.0 Hz, 1H), 4.39–
À1
2
218 (CN), 2133 (CN ), 1648 cm (C=O): HR-MS (ESI):
2
.27 (m, 1H), 3.59 (dq, J=14.2, 7.1 Hz, 1H), 1.25 (t, J=
+
m/z=331.0156, calcd. for C H Cl N O ([M+H] ): 331.0148.
-Cyano-2-diazo-N,N-di(3,5-dimethylphenyl)acetamide
1i): yield: 492 mg (77%, 2 mmol scale); yellow crystals; mp
49–1518C; H NMR (400 MHz, CDCl ): d=6.97 (s, 2H),
.87 (s, 4H), 2.30 (s, 12H); C NMR (100 MHz, CDCl ):
d=159.6, 141.1, 139.4, 129.8, 125.0, 107.1, 21.2; IR (DCM):
n=2215 (CN), 2120 (CN ), 1647 cm (C=O); HR-MS
13
15
9
2
4
7.1 Hz, 3H); C NMR (100 MHz, CDCl ): d=159.6, 135.2,
3
2
1
1
34.6, 131.2, 130.8, 128.9, 127.9, 127.9, 127.0, 125.4, 121.7,
(
1
6
07.0, 46.1, 13.2; IR (KBr): n=2218 (CN), 2125 (CN ),
2
1
À1
3
1640 cm (C=O); HR-MS (ESI): m/z=227.0932, calcd. for
C H N O ([M+H] ): 227.0927.
13
+
3
1
2
11
4
À1
2
+
(
3
ESI): m/z=319.1571, calcd. for C H N O ([M+H] ): General Procedure for the Preparation of the
19
19
4
19.1553.
-Cyano-2-diazo-N,N-di(o-tolyl)acetamide (1j): yield:
64 mg (91%, 1 mmol scale); yellow crystals; mp 61–638C;
H NMR (400 MHz, CDCl ): d=7.39–7.26 (m, 5H), 7.21–
.07 (m, 2H), 6.88–6.82 (m, 1H), 2.37 (s, 3H), 2.18 (s, 3H);
C NMR (100 MHz, CDCl ): d=159.3, 139.8, 134.6, 132.3,
31.2, 129.5, 127.2, 126.8, 125.9, 106.8, 18.7, 18.0; IR (DCM):
n=2216 (CN), 2130 (CN ), 1654 (cm
ESI): m/z=291.1248, calcd. for C H N O ([M+H] ):
Difluoroboron Complexes 2 of Oxindole-3-
carboxamides
2
2
1
A solution of 1 (100 mg), BF ·OEt (2.5 equiv.) and the addi-
3
2
3
tive (0.15 equiv.) in 5 mL of CH CN was refluxed for 20 h.
3
7
13
Then water (5 mL) was added followed by the addition of
3
5
mL of EtOAc. The organic phase was separated and the
1
À1
aqueous phase was extracted with 5 mL of CH Cl . The
2
2
(C=O); HR-MS
2
+
combined organic phase was concentrated under reduced
pressure. The resulting residue was purified by silica gel
column chromatography to give the pure product 2.
(
2
17 15 4
91.1240.
2
-Diazo-3-(10,11-dihydro-5H-dibenzo[b,f]azepin-5-yl)-3-
oxopropanenitrile (1k): yield: 403 mg (70%); yellow crys-
tals; mp 98–1008C; H NMR (400 MHz, CDCl ): d=7.41 (d,
J=7.8 Hz, 2H), 7.36–7.32 (m, 2H), 7.30–7.26 (m, 4H), 3.51–
.42 (m, 2H), 2.96–2.87 (m, 2H).; C NMR (100 MHz,
CDCl ): d=159.0, 139.4, 130.5, 129.3, 128.2, 127.2, 106.8,
0.4; IR (KBr): n=2214 (CN), 2128 (CN ), 1645 (cm (C=
O); HR-MS (ESI): m/z=289.1079, calcd. for C H N O
[M+H] ): 289.1084.
-Diazo-3-oxo-3-(10H-phenothiazin-10-yl)propanenitrile
1l): yield: 295 mg (50%, 2 mmol scale); yellow crystals; mp
55–1578C; H NMR (400 MHz, DMSO-d ): d=7.65 (dd,
J=8.0, 1.2 Hz, 2H), 7.46 (dd, J=7.8, 1.5 Hz, 2H), 7.36 (ddd,
J=8.0, 7.6, 1.5 Hz, 2H), 7.30 (ddd, J=7.8, 7.6, 1.2 Hz, 2H);
4-Amino-2,2-difluoro-9-phenyl-2,9-dihydro-[1,3,2]dioxa-
borinino[4,5-b]indol-3-ium-2-uide (2a): yield: 88 mg (77%);
1
3
1
colorless crystals; mp 220–2238C; H NMR (400 MHz,
DMSO-d ): d=9.48 (s, 1H), 8.83 (s, 1H), 8.08 (d, J=7.6 Hz,
13
6
3
1
1
7
H), 7.65 (t, J=7.2, 7.2 Hz, 2H), 7.58 (dd, J=7.2, 7.2 Hz,
H), 7.54 (d, J=7.2 Hz, 2H), 7.28 (dd, J=7.9, 7.0 Hz, 1H),
.20 (dd, J=7.6, 7.0 Hz, 1H), 7.13 (d, J=7.9 Hz, 1H);
3
À1
3
2
13
1
7
13
4
C NMR (100 MHz, DMSO-d ): d=164.4, 161.0, 133.7,
6
+
(
1
8
32.8, 129.8, 128.9, 126.9, 123.0, 122.9, 120.9, 118.6, 110.4,
2
19
1.4; F NMR (376 MHz, DMSO-d ): d=À141.9, À142.0;
6
1
1
(
1
B NMR (193 MHz, DMSO-d ): d=1.08; IR (KBr): n=656,
6
1
6
693, 736, 748, 768, 882, 1024, 1044, 1076, 1107, 1142, 1180,
1
206, 1256, 1308, 1384, 1455, 1484, 1508, 1549, 1586, 1601,
À1
1622, 1651, 2921, 3378, 3487 cm ; HR-MS (ESI) m/z=
301.0965, calcd. for C H BF N O ([M+H] ): 301.0954.
13
+
C NMR (100 MHz, DMSO-d ): d=158.8, 137.4, 133.0,
6
15 12
2
2
2
1
2
2
28.1, 127.8, 127.5, 126.4, 106.7; IR (KBr): n=2218 (CN),
4-Amino-2,2-difluoro-9-methyl-2,9-dihydro-[1,3,2]dioxa-
À1
131 (CN ), 1652 (cm
93.0494, calcd. for C H N OS ([M+H] ): 293.0492.
(C=O); HR-MS (ESI): m/z=
borinino[4,5-b]indol-3-ium-2-uide (2b): yield: 23 mg (19%);
2
+
1
colorless crystals; mp 180–1828C; H NMR (400 MHz,
15
9
4
Adv. Synth. Catal. 2016, 358, 1767 – 1777
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FULL PAPERS
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À1
DMSO-d ): d=9.23 (s, 1H), 8.59 (s, 1H), 7.99–7.96 (m, 1H),
3351 cm ; HR-MS (ESI): m/z=371.0551, calcd. for
6
+
7
.45–7.42 (m, 2H), 7.25–7.19 (m, 2H), 3.57 (s, 3H);
C H BClF N NaO ([M+Na] ): 371.0541.
4-Amino-2,2-difluoro-6-methyl-9-(p-tolyl)-2,9-dihydro-
[1,3,2]dioxaborinino[4,5-b]indol-3-ium-2-uide (2g): yield:
79 mg (70%); colorless crystals; mp 238–2408C; H NMR
(400 MHz, DMSO-d ): d=9.40 (s, 1H), 8.73 (s, 1H), 7.92 (s,
1H), 7.43 (d, J=8.0 Hz, 2H), 7.37 (d, J=8.0 Hz, 2H), 7.00
(s, 2H), 2.41 (s, 6H); C NMR (100 MHz, DMSO-d ): d=
164.3, 160.9, 138.4, 132.1, 132.0, 130.4, 130.2, 126.4, 123.6,
1
6
12
2
2
2
13
C NMR (100 MHz, DMSO-d ): d=163.9, 161.4, 133.8,
6
1
9
122.3, 122.3, 120.7, 118.3, 110.2, 80.7, 27.2; F NMR
11
1
(
(
376 MHz, DMSO-d ): d=À141.8, À141.8; B NMR
193 MHz, DMSO-d ): d=1.12; IR (KBr): n=616, 748, 773,
6
6
6
9
1
91, 1024, 1113, 1170, 1264, 1326, 1406, 1455, 1514, 1580,
À1
13
595, 1622, 2934, 3372 cm ); HR-MS (ESI): m/z=261.0811,
6
+
calcd. for C H BF N O ([M+H] ): 261.0789.
10
10
2
2
2
1
9
4-Amino-2,2-difluoro-9-propyl-2,9-dihydro-[1,3,2]dioxa-
1
20.9, 118.8, 110.1, 81.2, 21.1, 20.7; F NMR (376 MHz,
1
1
borinino[4,5-b]indol-3-ium-2-uide (2c): yield: 40 mg (35%);
DMSO-d ): d=À141.9, À142.0;
B NMR (193 MHz,
6
1
colorless crystals; mp 259–2608C; H NMR (400 MHz,
DMSO-d ): d=1.06; IR (KBr): n=881, 1025, 1048, 1076,
6
DMSO-d ): d=9.24 (s, 1H), 8.60 (s, 1H), 7.99–7.97 (m, 1H),
6
1142, 1180, 1384, 1461, 1487, 1517, 1552, 1598, 1631, 2927,
973, 3387 cm ; HR-MS (ESI): m/z=329.1278, calcd. for
7
2
.51–7.47 (m, 1H), 7.23–7.18 (m, 2H), 4.04 (t, J=7.2 Hz,
H), 1.72 (sixtet, J=7.2 Hz, 2H), 0.85 (t, J=7.2 Hz, 3H);
À1
2
+
C H BF N O ([M+H] ): 329.1267.
1
7
16
2
2
2
1
3
C NMR (100 MHz, DMSO-d ): d=164.2, 160.9, 133.1,
6
4-Amino-6-chloro-9-(4-chlorophenyl)-2,2-difluoro-2,9-di-
hydro-[1,3,2]dioxaborinino[4,5-b]indol-3-ium-2-uide
yield: 76 mg (68%); colorless crystals; mp >3008C;
H NMR (400 MHz, DMSO-d ): d=9.62 (s, 1H), 9.02 (s,
H), 8.26 (d, J=1.8 Hz, 1H), 7.72 (d, J=8.7 Hz, 2H), 7.60
d, J=8.7 Hz, 2H), 7.22 (dd, J=8.6, 1.8 Hz, 1H), 7.16 (d,
J=8.6 Hz, 1H); C NMR (100 MHz, DMSO-d ): d=164.2,
61.3, 133.7, 132.1, 131.4, 129.9, 128.7, 127.9, 122.6, 122.3,
1
22.3, 122.2, 120.8, 118.4, 110.4, 104.5, 80.6, 42.2, 21.5, 10.9;
(2h):
1
1
9
F NMR (376 MHz, DMSO-d ): d=À142.1, À142.2;
6
1
B NMR (193 MHz, DMSO-d ): d=1.13; IR (KBr): n=757,
1
6
6
1
1
045, 1298, 1383, 1459, 1491, 1509, 1561, 1611, 1638, 1648,
1
À1
655, 1676, 1686, 1701, 1719, 2853, 2925, 3369 cm ; HR-MS
(
+
(ESI): m/z=267.1127, calcd. for C H BF N O ([M+H] ):
13
12
14
2
2
2
6
267.1111.
1
1
4-Amino-9-benzyl-2,2-difluoro-2,9-dihydro-[1,3,2]dioxa-
19
18.2, 111.9, 81.5; F NMR (376 MHz, DMSO-d ): d=
6
borinino[4,5-b]indol-3-ium-2-uide (2d): yield: 55 mg (48%);
11
À141.7, À141.8; B NMR (193 MHz, DMSO-d ): d=0.99;
1
6
colorless crystals; mp 163–1658C; H NMR (400 MHz,
IR (KBr): n=627, 657, 670, 694, 708, 717, 736, 750, 771, 805,
DMSO-d ): d=9.34 (s, 1H), 8.70 (s, 1H), 8.00 (d, J=7.1 Hz,
6
8
1
1
3
31, 859, 942, 958, 1015, 1044, 1069, 1093, 1115, 1143, 1180,
207, 1256, 1289, 1322, 1384, 1407, 1428, 1457, 1483, 1500,
553, 1578, 1603, 1621, 1647, 2930, 3107, 3204, 3277, 3373,
482, 3568 cm ; HR-MS (ESI): m/z=369.0193, calcd. for
C H BClF N O ([M+H] ): 369.0175.
4-Amino-9-(3,5-dimethylphenyl)-2,2-difluoro-5,7-dimeth-
yl-2,9-dihydro-[1,3,2]dioxaborinino[4,5-b]indol-3-ium-2-uide
2i): yield: 22 mg (20%); colorless crystals; mp 226–2288C;
H NMR (400 MHz, DMSO-d
1
H), 7.43 (d, J=7.8 Hz, 1H), 7.36–7.31 (m, 2H), 7.28–7.26
13
(
(
m, 3H), 7.22–7.14 (m, 2H), 5.32 (s, 2H); C NMR
100 MHz, DMSO-d ): d=164.1, 161.3, 136.1, 132.9, 128.7,
6
À1
1
27.7, 127.1, 122.5, 122.4, 120.9, 118.5, 110.7, 80.9, 43.9;
+
1
1
9
15 10
2
2
2
F NMR (376 MHz, DMSO-d ): d=À142.1, À142.1;
6
1
B NMR (193 MHz, DMSO-d ): d=1.18; IR (KBr): n=704,
6
7
1
3
47, 770, 1027, 1081, 1142, 1238, 1263, 1332, 1383, 1456,
479, 1510, 1555, 1598, 1625, 1642, 1701, 2927, 3375,
(
1
À1
): d=9.29 (s, 1H), 7.79 (s,
6
481 cm ; HR-MS (ESI): m/z=315.1125, calcd. for
+
1H), 7.22 (s, 1H), 7.07 (s, 2H), 6.87 (s, 1H), 6.67 (s, 1H),
.67 (s, 3H), 2.38 (s, 6H), 2.29 (s, 3H); C NMR (100 MHz,
C H BF N O ([M+H] ): 315.1111.
1
6
14
2
2
2
13
2
4-Amino-9-benzyl-2,2-difluoro-6-methyl-2,9-dihydro-
DMSO-d ): d=164.8, 161.5, 139.3, 135.0, 132.8, 130.6, 128.3,
6
[
4
1,3,2]dioxaborinino[4,5-b]indol-3-ium-2-uide (2e): yield:
0 mg (36%); colorless crystals; mp 203–2058C; H NMR
19
1
126.4, 124.8, 118.1, 108.4, 82.5, 21.3, 20.9, 20.7; F NMR
1
1
(
(
376 MHz, DMSO-d ): d=À145.5, À145.6;
B NMR
6
(
400 MHz, DMSO-d ): d=9.27 (s, 1H), 8.61 (s, 1H), 7.84 (s,
6
193 MHz, DMSO-d ): d=0.87; IR (KBr): n=741, 770, 837,
6
1
2
1
1
H), 7.34–7.23 (m, 6H), 6.97 (d, J=8.2 Hz, 1H), 5.28 (s,
13
914, 1036, 1075, 1142, 1180, 1239, 1276, 1383, 1475, 1506,
534, 1589, 1637, 2924, 3377, 3512 cm ; HR-MS (ESI):
m/z=357.1584, calcd. for C H BF N O ([M+H] ):
H), 1.99 (s, 3H); C NMR (100 MHz, DMSO-d ): d=
6
À1
1
64.0, 161.2, 136.1, 131.6, 131.0, 128.7, 127.6, 127.1, 123.3,
+
19
21.0, 118.7, 110.4, 80.7, 43.9, 21.1; F NMR (376 MHz,
19 20 2 2 2
11
357.1580.
-Amino-2,2-difluoro-8-methyl-9-(o-tolyl)-2,9-dihydro-
1,3,2]dioxaborinino[4,5-b]indol-3-ium-2-uide (2j): yield:
68 mg (60%); colorless crystals; mp 236–2398C; H NMR
400 MHz, DMSO-d ): d=9.44 (s, 1H), 8.75 (s, 1H), 7.93 (d,
J=7.6 Hz, 1H), 7.55–7.39 (m, 4H), 7.16 (dd, J=7.6, 7.6 Hz,
H), 6.94 (d, J=7.6 Hz, 1H), 1.97 (s, 3H), 1.73 (s, 3H);
C NMR (100 MHz, DMSO-d ): d=164.3, 161.5, 136.7,
DMSO-d ): d=À142.1, À142.1;
B NMR (193 MHz,
6
4
DMSO-d ): d=1.17. IR (KBr): n=560, 703, 828, 1021, 1082,
6
[
1
3
142, 1240, 1264, 1312, 1456, 1508, 1555, 1597, 1630, 2924,
1
À1
376, 3485 cm ; HR-MS (ESI): m/z=329.1286, calcd. for
+
(
C H BF N O ([M+H] ): 329.1267.
6
1
7
16
2
2
2
4
-Amino-9-benzyl-6-chloro-2,2-difluoro-2,9-dihydro-
1,3,2]dioxaborinino[4,5-b]indol-3-ium-2-uide (2f)1: yield:
3 mg (48%); colorless crystals; mp 226–2288C; H NMR
400 MHz, DMSO-d ): d=9.45 (s, 1H), 8.87 (s, 1H), 8.17 (d,
1
[
5
(
1
3
6
134.2, 131.3, 130.5, 130.0, 129.5, 126.9, 125.7, 122.6, 121.4,
6
1
9
J=1.9 Hz, 1H), 7.46 (d, J=8.6 Hz, 1H), 7.36–7.24 (m, 5H),
121.3, 116.6, 81.1, 17.4, 16.8; F NMR (376 MHz, DMSO-
): d=À141.6, À141.7, À141.8, À141.9, À142.8, À142.8,
13
7
.20 (dd, J=8.6, 1.9 Hz, 1H), 5.33 (s, 2H); C NMR
d
6
1
1
(
100 MHz, DMSO-d ): d=163.9, 161.7, 135.8, 131.5, 128.8,
À143.0, À143.0; B NMR (193 MHz, DMSO-d
): d=1.03;
6
6
1
27.8, 127.4, 127.1, 122.3, 122.1, 118.1, 112.2, 80.9, 44.1;
IR (KBr): n=618, 634, 655, 729, 742, 769, 782, 878, 1030,
1093, 1124, 1174, 1264, 1297, 1319, 1354, 1410, 1456, 1481,
1505, 1557, 1590, 1616, 1645, 1651, 2928, 3267, 3370,
1
1
9
F NMR (376 MHz, DMSO-d ): d=À142.0, À142.1;
6
1
B NMR (193 MHz, DMSO-d ): d=1.11; IR (KBr): n=700,
6
À1
7
1
22, 737, 833, 1028, 1045, 1093, 1143, 1191, 1263, 1360, 1384,
402, 1454, 1493, 1583, 1599, 1636, 1720, 2216, 2927,
3478 cm ; HR-MS (ESI): m/z=329.1280, calcd. for
+
C H BF N O ([M+H] ): 329.1267.
1
7
16
2
2
2
Adv. Synth. Catal. 2016, 358, 1767 – 1777
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FULL PAPERS
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1
4-Amino-12,12-difluoro-5,12-dihydro-4H-benzo[6,7]aze-
(400 MHz, DMSO-d ): d=9.46 (s, 1H), 8.84 (s, 1H), 8.34 (d,
J=8.6 Hz, 1H), 8.21 (d, J=8.6 Hz, 1H), 8.02 (d, J=7.9 Hz,
6
pino[3,2,1-hi][1,3,2]dioxaborinino[4,5-b]indol-13-ium-12-
uide (2k): yield: 73 mg (65%); colorless crystals; mp 235–
1H), 7.79 (d, J=8.6 Hz, 1H), 7.62 (dd, J=8.6, 7.2 Hz, 1H),
7.47 (dd, J=7.9, 7.2 Hz, 1H), 4.57 (q, J=7.0 Hz, 2H), 1.43
1
2
8
1
7
378C; H NMR (400 MHz, DMSO-d ): d=9.57 (s, 1H),
6
1
3
.81 (s, 1H), 7.89 (d, J=7.7 Hz, 1H), 7.68 (d, J=7.9 Hz,
H), 7.45–7.38 (m, 2H), 7.35–7.30 (m, 1H), 7.18 (dd, J=7.7,
.5 Hz, 1H), 7.05 (d, J=7.5 Hz, 1H), 3.14–3.00 (m, 4H);
(t, J=7.0 Hz, 3H); C NMR (400 MHz, DMSO-d
): d=
6
164.4, 159.8, 130.5, 129.3, 126.7, 125.4, 123.7, 123.3, 121.2,
1
9
120.2, 118.1, 118.0, 82.1, 38.3, 14.7; F NMR (376 MHz,
1
3
11
C NMR (100 MHz, DMSO-d ): d=164.4, 161.0, 136.8,
DMSO-d
DMSO-d
6
): d=À141.9, À142.0;
B NMR (193 MHz,
6
1
1
34.7, 131.5, 130.1, 127.4, 127.3, 126.8, 124.6, 124.3, 122.5,
6
): d=1.22; IR (KBr): n=616, 1037, 1118, 1332,
19
21.6, 116.1, 83.1, 33.5, 33.2; F NMR (376 MHz, DMSO-
1405, 1458, 1474, 1500, 1535, 1560, 1591, 1638, 1648, 1654,
11
À1
d ): d=À142.4; B NMR (193 MHz, DMSO-d ): d=2.11;
1686, 1701, 1719, 2935, 3370, 3568 cm ; HR-MS (ESI):
6
6
+
IR (KBr): n=636, 651, 760, 788, 882, 939, 1030, 1115, 1248,
m/z=303.1126, calcd. for
C
15
H14BF
N
2
2
O
2
([M+H] ):
1
3
280, 1319, 1361, 1441, 1487, 1557, 1592, 1615, 1651, 2928,
303.1111.
4
4
3
4
À1
2,2-Difluoro-N ,N -diphenyl-2H-1l ,3,2l -dioxaborinine-
365, 3480 cm ; HR-MS (ESI): m/z=327.1113, calcd. for
+
4
,6-diamine (2p): yield: 69 mg (29%, 118 mg scale); colorless
C H BF N O ([M+H] ): 327.1111.
1
7
14
2
2
2
crystals; mp 169–1728C; R =0.15 (silica gel plate, ethyl ace-
tate-petroleum ether 1:3, v/v); H NMR (400 MHz, DMSO-
4-Amino-2,2-difluoro-2H-[1,3,2]dioxaborinino[5’,4’:4,5]-
f
1
pyrrolo[3,2,1-kl]phenothiazin-3-ium-2-uide (2l): yield: 76 mg
1
d ): d=8.02 (s, 1H), 7.92 (s, 1H), 7.47–7.43 (m, 4H), 7.40–
(
(
67%); colorless crystals; mp 251–2538C; H NMR
6
1
3
7
.30 (m, 6H,), 4.25 (s, 1H); C NMR (100 MHz, DMSO-
d6): d=169.5, 166.2, 141.5, 129.6, 127.8, 127.5, 66.5; F NMR
400 MHz, DMSO-d ): d=9.62 (s, 1H), 8.79 (s, 1H), 8.24 (d,
6
19
J=8.3 Hz, 1H), 7.61 (d, J=7.8 Hz, 1H), 7.28–7.23 (m, 1H),
(
376 MHz, DMSO-d ): d=À143.19 (d, J=22.9 Hz);
7
7
.20–7.17 (m, 1H), 7.14–7.12 (m, 1H), 7.08 (dd, J=7.8,
.6 Hz, 1H), 6.81 (d, J=7.6 Hz, 1H); C NMR (100 MHz,
6
1
1
13
B NMR (193 MHz, DMSO-d ): d=0.58; IR (KBr): v=
6
3
488, 3385, 2849, 1637, 1589, 1560, 1540, 1490, 1458, 1426,
DMSO-d ): d=164.1, 159.8, 131.8, 127.8, 127.2, 126.8, 126.8,
6
À1
1
9
1295, 1104, 1047, 1026, 994, 761, 700 cm ; HR-MS (ESI):
m/z=303.1119, calcd for C H BF N O
1
(
(
25.4, 120.5, 120.1, 118.2, 117.2, 115.8, 115.4, 83.4; F NMR
+
11
([M+H] ):
376 MHz, DMSO-d ): d=À141.9, À142.0;
B NMR
15 13
2
2
2
6
303.1111.
193 MHz, DMSO-d ): d=0.96; IR (KBr): n=644, 744, 774,
6
8
1
28, 1026, 1076, 1143, 1196, 1308, 1438, 1474, 1551, 1601,
À1
645, 2925, 3366 cm ; HR-MS (ESI): m/z=331.0526, calcd. Preparation of 2-Oxo-1-phenylindoline-3-carbonitrile
+
for C H BF N O S ([M+H] ): 331.0519.
(3a)
15
10
2
2
2
4
-Amino-11-chloro-6,6-difluoro-6,9-dihydrobenzo[6,7]
1,4]oxazepino[2,3,4-hi][1,3,2]dioxaborinino[4,5-b]indol-5-
ium-6-uide (2m): yield: 69 mg (62%); colorless crystals; mp
2
1
-Cyano-2-diazo-N,N-diphenylacetamide
.06 mmol) and dirhodium tetraoctanoate (82.6 mg,
(1a)
(277 mg,
[
1
0.11 mmol) were dissolved in dichloromethane (5 mL). The
reaction mixture was refluxed for 2 h. After removal of the
solvent under reduced pressure, the resulting residue was
purified by silica gel chromatography (methanol/dichloro-
methane 20:1, v/v) to give the crude product 3a. Finally, the
crude product 3a was recrystallized from a mixture of ethyl
>
3008C; H NMR (400 MHz, DMSO-d ): d=9.39 (s, 1H),
6
8
1
7
.71 (s, 1H), 7.83 (d, J=2.5 Hz, 1H), 7.74 (d, J=7.7 Hz,
H), 7.46 (dd, J=8.6, 2.5 Hz, 1H), 7.37 (d, J=8.6 Hz, 1H),
.15 (dd, J=7.8, 7.7 Hz, 1H), 7.06 (d, J=7.8 Hz, 1H), 5.40
13
(s, 2H); C NMR (100 MHz, DMSO-d ): d=164.1, 159.6,
6
1
1
56.9, 143.1, 130.3, 130.2, 129.4, 128.9, 123.4, 123.4, 123.3,
19
acetate-petroleum ether to afford the pure white solid prod-
23.1, 114.5, 112.7, 81.2, 43.0; F NMR (376 MHz, DMSO-
[21]
uct 3a; yield: 113 mg (40%); mp 152–1568C, Lit.
154–
11
d ): d=À141.6, À141.6; B NMR (193 MHz, DMSO-d ):
6
6
1
1
5
8
588C; R =0.45 (silica gel plate, methanol-dichloromethane
f
d=1.15; IR (KBr): n=965, 1073, 1141, 1180, 1455, 1471,
1
:10, v/v). H NMR (400 MHz, CDCl ): d=7.58–7.45 (m,
3
1
2
486, 1505, 1520, 1538, 1557, 1614, 1633, 1645, 1651, 1682,
H), 7.42–7.40 (m, 2H), 7.34 (t, J=8.0 Hz, 1H), 7.20 (t, J=
À1
925, 3564, 3585, 3626 cm ; HR-MS (ESI): m/z=363.0514,
13
.0 Hz, 1H), 6.83 (d, J=8.0 Hz, 1H), 4.75 (s, 1H); C NMR
+
calcd. for C H BClF N O ([M+H] ): 363.0514.
16
11
2
2
3
(
100 MHz, CDCl ): d=166.4, 144.0, 133.3, 130.4, 130.0,
3
11-Amino-9,9-difluoro-4,5,6,9-tetrahydro-[1,3,2]dioxabori-
129.0, 126.5, 125.1, 124.2, 119.9, 114.0, 110.5, 37.0.
nino[5’,4’:4,5]pyrrolo[3,2,1-ij]quinolin-10-ium-9-uide (2n):
yield: 50 mg (42%); colorless crystals; mp 242–2448C;
1
H NMR (400 MHz, DMSO-d ): d=9.14 (s, 1H), 8.54 (s,
6
1
H), 7.77 (d, J=7.6 Hz, 1H), 7.09 (t, J=7.6 Hz, 1H), 6.96
Acknowledgements
(d, J=7.6 Hz, 1H), 3.99 (t, J=5.6 Hz, 2H), 2.87 (t, J=
13
5.6 Hz, 2H), 2.08 (quintet, J=5.6 Hz, 2H); C NMR
This work was supported in part by the National Basic Re-
search Program of China (No. 2013CB328905) and the Na-
tional Natural Science Foundation of China (Nos. 21372025
and 21572017). Miss Jianxiu Fang is thanked for her gener-
ous experimental help.
(
1
100 MHz, DMSO-d ): d=164.1, 160.1, 130.1, 122.1, 122.0,
6
1
9
20.4, 119.1, 116.0, 81.0, 39.6, 23.7, 21.2;
F NMR
11
(
(
376 MHz, DMSO-d ): d=À141.7, À141.7;
B NMR
6
193 MHz, DMSO-d ): d=1.10; IR (KBr): n=746, 776, 888,
6
9
1
2
23, 1022, 1075, 1123, 1172, 1214, 1243, 1296, 1355, 1372,
446, 1461, 1485, 1514, 1566, 1584, 1608, 1627, 1654, 1689,
À1
929, 3390, 3506 cm ; HR-MS (ESI): m/z=265.0954, calcd.
+
for C H BF N O ([M+H] ): 256.0954.
References
12
12
2
2
2
7-Amino-11-ethyl-9,9-difluoro-9,11-dihydrobenzo[g]-
[
5
1,3,2]dioxaborinino[4,5-b]indol-8-ium-9-uide (2o): yield:
0 mg (43%); colorless crystals; mp 204–2078C; H NMR
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