N-Heterocyclic carbenes from ylides of indolyl-imidazolium, azaindolyl-imidazolium, and indolyl-triazolium salts, and their borane adducts

Article abstract of DOI:10.1016/j.tet.2014.09.035

Indol-2-yl-imidazolium salts were deprotonated at N1 of the indole ring to give ylides. Their tautomeric N-heterocyclic carbenes (NHCs) were trapped by sulfur to give imidazole-2-thiones. Treatment of the ylides with triethylborane resulted in the formation of zwitterionic borane adducts. An analogous sequence of reactions was performed with 8-azaindol-2-yl-imidazolium salts, which served as precursor to prepare first representatives of a new heterocyclic ring system on reaction of their NHC-tautomers with triethylborane. Similarly, an indol-2-yl-1,2,4-triazolium salt was examined with respect to ylide-NHC tautomerism and trapping reactions. A nucleophilic ring transformation of indol-3-amine with a 1,3,4-oxadiazolium salt gave an indol-3-yl-triazolium salt, which was converted into a triazolethione by trapping of the tautomeric N-heterocyclic carbene of its ylide.

Full text of DOI:10.1016/j.tet.2014.09.035

Tetrahedron 70 (2014) 8672e8680
Contents lists available at ScienceDirect
Tetrahedron
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N-Heterocyclic carbenes from ylides of indolyl-imidazolium,
azaindolyl-imidazolium, and indolyl-triazolium salts, and their
borane adducts
Nazar Pidlypnyi a, Sebastian Wolf a, Ming Liu a, Kari Rissanen b, Martin Nieger c,
,
Andreas Schmidt a
*
a Clausthal University of Technology, Institute of Organic Chemistry, Leibnizstrasse 6, D-38678 Clausthal-Zellerfeld, Germany
b
€
€
€
€
University of Jyvaskyla, Department of Chemistry, Nanoscience Center, PO Box 35, FIN-40014 University of Jyvaskyla, Finland
c University of Helsinki, Laboratory of Inorganic Chemistry, Department of Chemistry, PO Box 55 (A.I. Virtasen aukio 1),
FIN-00014 University of Helsinki, Finland
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 14 August 2014
Received in revised form 9 September 2014
Accepted 12 September 2014
Available online 17 September 2014
Indol-2-yl-imidazolium salts were deprotonated at N1 of the indole ring to give ylides. Their tautomeric
N-heterocyclic carbenes (NHCs) were trapped by sulfur to give imidazole-2-thiones. Treatment of the
ylides with triethylborane resulted in the formation of zwitterionic borane adducts. An analogous se-
quence of reactions was performed with 8-azaindol-2-yl-imidazolium salts, which served as precursor to
prepare first representatives of a new heterocyclic ring system on reaction of their NHC-tautomers with
triethylborane. Similarly, an indol-2-yl-1,2,4-triazolium salt was examined with respect to ylideeNHC
tautomerism and trapping reactions. A nucleophilic ring transformation of indol-3-amine with a 1,3,4-
oxadiazolium salt gave an indol-3-yl-triazolium salt, which was converted into a triazolethione by
trapping of the tautomeric N-heterocyclic carbene of its ylide.
Keywords:
Mesomeric betaine
Mesoionic compound
Borane adducts
Carbenes
Ó 2014 Elsevier Ltd. All rights reserved.
Indole
1. Introduction
When cycloimmonium-ylides V are composed of (hetero)aro-
matic partial structures, which delocalize the positive and the
The term ylide is used for compounds in which a carbanion is
directly attached to a heteroatom bearing a positive charge, as ex-
emplified by the general formula I. Subclasses of N-ylides are
ammonium-ylides (II), cycloammonium-ylides (III), immonium-
ylides (IV), cycloimmonium-ylides (V), nitrile-ylides (VI), and
diazonium-ylides (VII) (Fig. 1).1
negative charge, they can be regarded as members of one of four
distinct classes of heterocyclic mesomeric betaines.2e4 They are
usually represented by 1,2-dipolar resonance structures and play
important roles in heterocyclic synthesis, as they usually are ver-
satile 1,3-dipoles in [2þ3]-cycloadditions.1e4
Ylides also allow for the generation of radicals as well as N-
heterocyclic carbenes (Fig. 2). Calculations showed that the bir-
adical form of the azomethine ylide of 1,1-dichloro-N-methyl-
enemethanamine is more stable than the zwitterionic form.5
Indeed, Merrifield resins, which are functionalized with 4,40-
bipyridiniums are photochromic materials as they form ylides,
which undergo reversible electron transfers to a- and p-radicals by
disproportionations.6 Under these conditions, biradicals were not
detected. We found recently that imidazolium-ylides are able to
tautomerize to N-heterocyclic carbenes and that deprotonation of
these ylides result in unstable anionic N-heterocyclic carbenes.7,8
Some relationships between the classes of mesomeric betaines
(MB) and N-heterocyclic carbenes (NHC) are as follows. Hetero-
aromatic cycloimmonium ylides are related to conjugated hetero-
cyclic mesomeric betaines (CMB), which can be set apart from
Fig. 1. Types of N-ylides.
* Corresponding author. E-mail address: schmidt@ioc.tu-clausthal.de (A.
cross-conjugated
(CCMB)
and
pseudo-cross-conjugated
Schmidt).
http://dx.doi.org/10.1016/j.tet.2014.09.035
0040-4020/Ó 2014 Elsevier Ltd. All rights reserved.

N. Pidlypnyi et al. / Tetrahedron 70 (2014) 8672e8680
8673
report here on recent examples of ylideecarbene interconversions.
We prepared indol- as well as azaindol-2-yl-imidazolium salts and
new triazolium-substituted indoles and converted them into ylides,
which are tautomers of N-heterocyclic carbenes. We also report on
trapping reactions of these carbenes. We continued this project
with the non-alternant anionic partial structure shown in Fig. 4.
The indolid anion allows for the construction of conjugated systems
by joining the iminium moiety to the 2- as well as to the 3-position,
which are both active positions in the HOMOindolid (Fig. 4). There-
fore, both isomers belong to the class of conjugated mesomeric
betaines, when hetarenium rings are attached.
Fig. 2. Interconversion of N-ylides into radicals and N-heterocyclic carbenes.
mesomeric betaines (PCCMB).2 Interconversions of suited repre-
sentatives of these four classes of mesomeric betaines into N-het-
erocyclic carbenes have been reviewed.9 As example, the reagent
nitron 1 exists as mesoionic compound 1A and as tautomeric N-
heterocyclic carbene 1B10 (Fig. 3). Pseudo-cross-conjugated imi-
dazolium-2-, pyrazolium-3-, and indazolium-3-carboxylates are
versatile starting materials for the generation of imidazol-2-
Fig. 4. Attachment of hetarenium rings or N-heterocyclic carbenes (NHCs) derived
thereof to the 2- as well as 3-position of indolid results in conjugated mesomeric
betaines and conjugated anionic NHCs, respectively.
ylidenes,11e16
pyrazol-3-ylidenes,17e19
and
indazol-3-
ylidenes,20e22 respectively (e.g., 2/3). The mesoionic compound
imidazolium-4-olate 4, a conjugated mesomeric betaine (CMB),
was deprotonated to the anionic N-heterocyclic carbene 5.23,24 The
diaminocarbene moiety of 5 is bridged by an enolate, and an active
position of the highest occupied molecular orbital (HOMOenolate) is
involved. The cross-conjugated mesomeric betaine (CCMB) 6-oxo-
1,3-pyrimidinium-4-olate 6 was deprotonated to the anionic car-
bene 7.25 In anion 7 the diaminocarbene moiety is bridged through
inactive positions of the HOMOacrylaldehyd-3-olate of the anionic
fragment in accordance to the definition of cross-conjugation in
mesomeric betaines.2,26,27 These inactive positions, however, result
2. Results and discussion
3-Methylindole 8 was treated with the imidazoles 9aed in ac-
etone (9a,d) or dioxane (9b,c) according to a modified literature
procedure32 (Scheme 1). After cooling to 12e15 ꢀC, N-bromo-
succinimide was added portionwise within 5 min. The colorless to
yellowish salts 10aed precipitated within 30 min. Characteristic
chemical shifts are as follows: The NH signal appears between
1
12.06 and 12.19 ppm in DMSO-d6; the JNH coupling is approxi-
mately ꢁ95 Hz, and proved to be independent on the substitution
pattern. The resonance frequency of C-3 of indole can be detected at
approximately 105 ppm in all derivatives. We performed a model
reaction with respect to electrophilic heteroaromatic substitutions
and found that 10b reacts smoothly with bromine in excess acetic
acid to the dibromo derivative 11 in quantitative yield.
in two p-electronically relatively independent partial structures.
In continuation of our interest in mesomeric betaines,3,4,28
zwitterionic molecules,29 organic polycations,30 as well as N-het-
erocyclic carbenes in heterocycle synthesis17 and catalysis,31 we
Scheme 1. Synthesis of indol-2-yl imidazolium salts.
1H NMR investigations of the salt 10a at different temperatures
in the presence of DABCO show a spontaneous H/D exchange of the
NH proton to 10a-d1 at room temperature (Scheme 2). The signal of
2-H of the imidazolium ring broadens at approximately 60 ꢀC and
disappears at 120 ꢀC due to deuterium exchange to 10a-d2. The
deprotonated species of 10a, i.e., the ylide 12a or its tautomeric N-
heterocyclic carbene 120a is detectable by electrospray ionization
mass spectrometry (ESIMS) as prominent peak between 0 and
Fig. 3. Some relationships between mesomeric betaines and N-heterocyclic carbenes.

8674
N. Pidlypnyi et al. / Tetrahedron 70 (2014) 8672e8680
Scheme 2. Results of 1H NMR spectroscopic and ESIMS spectrometric investigations.
100 V fragmentor voltage, when the sample is sprayed in the
presence of bases such as NaOH or Na2CO3 in MeOH. The anionic N-
heterocyclic carbene 13a is detectable by ESIMS in the anion de-
tection mode. This species can be seen in the NMR spectra of 10a on
treatment with n-BuLi in anhydrous CD3CN. Presumably 13a forms
a lithium adduct under these conditions with the Li atom located
between the carbene center and the indolid nitrogen atom. As
shown in Fig. 5, all signals are shifted upfield in comparison to the
starting material. In the 13C NMR spectra, a resonance frequency at
d
¼180.8 ppm is detected, which can be assigned to the carbene C
atom.33e35 The Li atom appears at
d
¼0.40 ppm in the 7Li NMR
Scheme 3. Interception reactions of the N-heterocyclic carbene tautomers of the
ylides 12.
spectra, and this value is in well agreement to literature-known
resonance frequencies for related compounds.36
with methyl iodide at room temperature and obtained the salt 15 in
quantitative yield. Interception of the N-heterocyclic carbene tau-
tomer of 12b was also accomplished by selenium in boiling p-xy-
lene, which results in the formation of 16 in excellent yield.
On treatment of the ylides 12b,c with triethylborane in dioxane
in an autoclave we were able to produce a formal trapping product
of the aforementioned anionic carbene, as the zwitterionic borane
adducts 17b,c are formed in 40e78% yield (Scheme 4). Under
analogous reaction conditions, ylide 12a decomposed. The ethyl
substituents give two separate signals in the 1H NMR spectra,
which appear with centers of gravity at
d
¼0.56 and 0.84 ppm, re-
Fig. 5. Comparison of the 1H NMR spectra of the salt 10a (1) and the NHCeLi adduct
13a (2), measured in CD3CN at ꢁ40 ꢀC, respectively.
spectively. The boron atom of 17c can be detected at
d
¼ꢁ0.35 ppm
in the 11B NMR spectra. NMR investigations show7 that the carbene
carbon atom attacks the borane before ring closure to the tetracy-
clic ring system occurs.
On a preparative scale, deprotonations of the salts 10aed to the
ylides 12aed were best accomplished by 1.5 equiv of 3 M NaOH,
which were given to an ethanolic solution of the salts (Scheme 3).
The ylides 12 precipitated in very high yields as gray to yellow
compounds, which proved to be stable on storage without any
precautions. In the 1H NMR spectra the disappearance of the NH
resonance frequencies in the salts 10aed is diagnostic for the ylide
formation. All other resonance frequencies are shifted upfield, and
Dd values between 0.15 and 0.38 ppm (DMSO-d6) can be measured.
The ylides are not soluble in nonpolar solvents. In DMSO-d6, how-
ever, no traces of the tautomeric N-heterocyclic carbenes 120aed
can be detected. Nevertheless the tautomeric carbenes can be
trapped by reaction with sulfur, which resulted in the formation of
imidazolethiones in high to excellent yields. In DMSO-d6 solution as
well as in the solid state the thiones form the tautomers 14aed
rather than 140aed. Thus, no SH absorptions (typically between
2550 and 2600 cmꢁ1) but strong NH frequencies at 3200 cmꢁ1 were
detected. However, we tested the interception of 140a by reaction
Scheme 4. Formal trapping of the N-heterocyclic carbene as zwitterionic borane
adduct.
The aza-indole 3-methyl-1H-pyrrolo[2,3-b]pyridine 18 un-
derwent a similar sequence of reactions and was converted
smoothly into the salts 19aed on treatment with the imidazoles
9aed in the presence of NBS. The spectra are in agreement with the
pure tautomer as shown in Scheme 5. Thus, the indole NH

N. Pidlypnyi et al. / Tetrahedron 70 (2014) 8672e8680
8675
the imidazo[20,10:3,4][1,4,2]diazaborolo[1,5-c]pyrimidinium-10-ide
mentioned above,37 the indoyl-imidazoliumborate moiety is pla-
ꢀ
nar (mean deviation from the l.s. plane B1/C14 0.019 A). The
phenyl ring is twisted by N13eC15eC16eC17¼ꢁ65.97(13)ꢀ from
the plane of the imidazole ring and perpendicular to the indolyl-
imidazoliumborate moiety (angle between the l.s. planes B1/C14
and C16/C21 88ꢀ).
3-Methylindole 8 was also reacted with 1-phenyl-1H-1,2,4-
triazole (22) in the presence of NBS to give the 4-(indol-2-yl)-1H-
1,2,4-triazolium salt 23 in good yield (Scheme 6). All attempts to
isolate the corresponding ylides 24 and their tautomers 240, how-
ever, failed, as the salt 23 decomposed on treatment with a variety
of bases. The carbene tautomer was trapped by reaction with sulfur
as thione 25, which was formed in good yield starting from the salt.
After a base screening, potassium 2-methylbutan-2-olate (AmOK)
proved to give the best yields, when low temperatures were ad-
justed. We then tried to intercept the carbene tautomer with trie-
thylborane as zwitterionic adduct. Indeed, we were able to isolate
the new heterocyclic ring system [1,2,4]triazolo[30,40:3,4][1,4,2]
diazaborolo[1,5-a]indol-4-ium-11-ide 26, but the purification of
the crude reaction mixture, which also contained yet unidentified
decomposition products rendered with difficulties, which is at least
in part due to the very low yield of this reaction.
Scheme 5. Interception of the NHC tautomer of azaindol-imidazolium ylides with
triethylborane as first representatives of a new heterocyclic ring system.
resonance frequencies were detected between 12.19 ppm and
12.62 ppm (DMSO-d6), respectively, and the integration corre-
sponds exactly to one proton. The ylide of the methyl derivative
20a, formed by deprotonation with sodium hydroxide in aqueous
ethanol, decomposed on attempts of isolation, but the intensely
yellow colored derivates 20bed are stable and were extracted with
EtOAc from the reaction mixture. Again, we were able to react the
stable ylides 20bed with triethylborane to synthesize the first
representatives of
a new heterocyclic ring system, imidazo
[200,100:30,40][1,4,2]diaza-borolo[10,50:1,5]pyrrolo[2,3-b]pyridinium-
11-ides 21bed, which were obtained in moderate to good yields.
Similar to the borane adducts mentioned above, the CH2-groups of
the ethyl substituents attached to boron split into two set of signals,
which appear between 0.49e0.73 ppm, and 1.08e1.12 ppm, re-
spectively. The 13C NMR resonance frequency of the former carbene
carbon atom of 21c,d was detected at 176.1 ppm and 177.7 ppm
(CDCl3), respectively.
Single crystals of 21b, which crystallized orthorhombic, were
subjected to an X-ray analysis (Fig. 6). The bond length between the
indole N and the boron atom (N1eB1; crystallographic numbering)
ꢀ
was determined to be 1.5981(13) A, while the carbeneeboron bond
ꢀ
(C14eB1) was found to be 1.6468(15) A. These bonds are slightly
longer and shorter, respectively, than in the corresponding indole
derivative, which we measured before.7 The BeCcarbene and BeN
bond lengths in another ring system, imidazo[20,10:3,4][1,4,2]dia-
zaborolo[1,5-c]pyrimidinium-10-ide were slightly different
Scheme 6. Indol-2-yl-triazolium salt, ylide, and N-heterocyclic carbene.
(1.618(4)e160.7(5) A, and 1.623(3)e1.628(4) A, respectively).37 The
BeCcarbene bond lengths have similar magnitudes as in borane ad-
ducts of sterically hindered N-heterocyclic carbenes.38e40 Similar to
ꢀ
ꢀ
The isomeric 4-(indol-3-yl) 1,2,4-triazolium salt 29 was pre-
pared by nucleophilic ring transformation of indol-3-amine hy-
drochloride 27 with 1,3,4-oxadiazolium perchlorate 28 (Scheme 7).
No stable ylide 30 could be isolated after attempts to deprotonate
the salt with sodium hydride in a variety of solvents or after
treatment with anion exchange resins in their hydroxide forms
(e.g., Amberlite IRA-96), as the reaction mixture decomposed to yet
unidentified products. N-Heterocyclic carbene 300 formation re-
quired very dry samples of the hygroscopic salt 29. Under an inert
atmosphere deprotonation of a freshly dried sample of 29 (130 ꢀC,
vacuum) with potassium 2-methylbutan-2-olate in anhydrous THF
resulted in the formation of an intermediary N-heterocyclic car-
bene, which was trapped by sulfur to give the thione 31 in good
yield.
Fig. 6. Molecular structure of 21b (displacement parameters are drawn at 50% prob-
ability level, the crystallographic numbering is different than the IUPAC numbering).

8676
N. Pidlypnyi et al. / Tetrahedron 70 (2014) 8672e8680
4.2.1. Compound 21b. Colorless crystals, C22H25BN4, M¼356.27,
crystal size 0.21ꢂ0.18ꢂ0.15 mm, orthorhombic, space group Pbca
ꢀ
ꢀ
ꢀ
(No. 61): a¼8.3558(1) A, b¼18.2204(2) A, c¼25.8687(2) A,
3
ꢀ
V¼3938.41(7) A , Z¼8,
r
(calcd)¼1.202 Mg mꢁ3, F(000)¼1520,
m
¼0.554 mmꢁ1, 20,664 reflections (2qmax¼153.8ꢀ), 4135 unique
[Rint¼0.020], 245 parameters, R1 (for 3919 I>2 (I))¼0.039, wR2 (all
s
data)¼0.101, GooF¼1.05, largest diff. peak and hole 0.288 and
ꢀꢁ3
ꢁ0.264 e A
.
Crystallographic data (excluding structure factors) for the
structure reported in this work have been deposited with the
Cambridge Crystallographic Data Centre as supplementary publi-
cation no. CCDC-1018185 (21b). Copies of the data can be obtained
free of charge on application to The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (fax: þ44 1223 336 033; e-mail:
deposit@ccdc.cam.ac.uk).
4.3. General procedure for the synthesis of the imidazolium
salts 10c,d, 19aed, and 23
Solutions of 3.0 mmol of 3-methylindole (for the synthesis of
10aed) and 4.0 mmol of 3-methylpyrrolo[2,3-b]pyridine (for the
synthesis of 19aed), respectively, in 10 mL of dioxane or acetone
were treated under an inert atmosphere with 5.3 mmol (10aed) or
4.0 mmol (19aed) of the imidazoles 9aed, or 5.3 mmol of 1-
phenyl-1,2,4-triazole (23). Then the solutions were cooled to
12e15 ꢀC and 4.4 mmol of N-bromosuccinimide (NBS) was added
portionwise within 5 min. After stirring over a period of 30 min the
imidazolium salts were filtered off (10aed) or precipitated by ad-
dition of a mixture of ethanol and diethyl ether (19aed). The
products were obtained as colorless to slightly yellow solids.
Scheme 7. Isomeric indol-3-yl-triazolium salt, ylide, and N-heterocyclic carbene.
3. Conclusion
Ylides derived from imidazolium- and triazolium-substituted
indole anions (which are not stable in all cases) belong to the
class of conjugated mesomeric betaines (CMB). Their tautomers are
N-heterocyclic carbenes (NHC), which undergo trapping reactions
with sulfur, selenium, and triethylborane, respectively. The latter
reagent results in the formation of zwitterionic tetracyclic ring
systems, among those first representatives of new heterocyclic ring
systems.
4.3.1. 3-(3-Methylindol-2-yl)-1-phenylimidazolium bromide 10c. 3-
Methylindole 8 (525 mg), 769 mg of 1-phenylimidazole 9c, and
741 mg of NBS were used in acetone as solvent. Yield 1403 mg (99%)
of a colorless solid, mp 235 ꢀC. 1H NMR (DMSO-d6, 400 MHz):
4. Experimental section
d
¼2.39 (s, 3H, Me-indole), 7.18 (dd, 1H, J¼7.8, 7.5 Hz, 5-H-indole),
4.1. General considerations
7.30 (dd, 1H, J¼8.0, 7.5 Hz, 6-H-indole), 7.50 (d, 1H, J¼8.0 Hz, 7-H-
indole), 7.64e7.75 (m, 4H), 7.96 (d, 2H, J¼8.1 Hz, 2,6-H-Ph), 8.47 (dd,
1H, JzJ4¼1.8 Hz, H-imidazole), 8.68 (dd, 1H, JzJ4¼1.8 Hz, H-imid-
azole), 10.37 (dd, 1H, J1zJ2¼1.8 Hz, 2-H-imidazole), 12.10 ppm (s,
Dioxane was dried over sodium according to standard pro-
cedures before usage. Flash-chromatography was performed with
silica gel 60 (0.040e0.063 mm). Nuclear magnetic resonance
(NMR) spectra were obtained with a Bruker Avance 400 MHz and
Bruker Avance III 600 MHz. 1H NMR spectra were recorded at
400 MHz or 600 MHz. 13C NMR spectra were recorded at 100 MHz
or 150 MHz, with the solvent peak or tetramethylsilane used as the
internal reference. Multiplicities are described by using the fol-
lowing abbreviations: s¼singlet, d¼doublet, t¼triplet, q¼quartet,
and m¼multiplet. FTIR spectra were obtained on a Bruker Alpha T
equipped with a Platinum ATR unit. The mass spectra were mea-
sured with a Varian 320 MS Triple Quad GC/MS/MS with a Varian
450-GC. The electrospray ionization mass spectra (ESIMS) were
measured with an Agilent LCMSD series HP 1100 with APIES.
Melting points are uncorrected and were determined in an appa-
1H, NH); 13C NMR (DMSO-d6, 100 MHz):
d¼7.7, 104.6, 111.8, 119.5,
120.0, 121.9, 122.3, 123.7, 124.3, 124.9, 126.9, 130.2, 133.5, 134.5,
136.0 ppm; ESIMS: m/z (%)¼274.1 (100) [MꢁBr]þ; IR (KBr):
~
n
¼ 3049; 1560, 1460, 1366, 1340, 1282, 1256, 1116, 1079, 873, 753,
680, 631, 611, 597, 533, 517, 441 cmꢁ1. HR-ESI-MS for C18H16N3 re-
quired 274.1342. Found 274.1338.
4.3.2. 1-(2,6-Diisopropylphenyl)-3-(3-methylindol-2-yl)-imidazo-
lium bromide 10d. 3-Methylindole 8 (525 mg), 1217 mg of 1-(2,6-
diisopropylphenyl)imidazole 9d, and 741 mg of NBS were used.
Yield 1543 mg (88%) of a colorless solid, mp 306 ꢀC. 1H NMR
(DMSO-d6, 400 MHz):
d¼1.22 (d, 12H, J¼6.8 Hz, Me), 2.31 (s, 3H,
Me-indole), 2.43 (sept, 2H, J¼6.8 Hz, CH), 7.19 (dd,1H, J1zJ2¼7.6 Hz,
5-H-indole), 7.32 (dd, 1H, J¼7.8, 7.6 Hz, 6-H-indole), 7.52 (d, 1H,
J¼7.8 Hz, 7-H-indole), 7.53 (d, 2H, J¼7.7 Hz, 3,5-H-Ph), 7.67e7.71
(m, 2H), 8.48 (s, 1H, H-imidazole), 8.56 (s, 1H, H-imidazole), 10.20
(br s, 1H, 2-H-imidazole), 12.19 ppm (br s, 1H, NH); 13C NMR
€
ratus according to Dr. Tottoli (Buchi). Yields are not optimized. We
described the compounds 10a,8 10b,7 12a,8 12b,7 14a,8 14b,7 and
17b7 in our earlier publications.
4.2. Crystal structure studies of 21b
(DMSO-d6, 100 MHz):
d
¼7.5, 23.8, 28.2, 104.8, 111.8, 119.6, 120.1,
123.8, 124.6, 124.7, 125.7, 126.7, 130.2,þ131.7, 133.5, 138.5, 145.1 ppm;
~
n
The single-crystal X-ray diffraction studies of 21b were carried
out on an Agilent SuperNova Dual Source diffractometer with Atlas
ESIMS: m/z (%)¼358.1 (100) [MꢁBr] ; IR (KBr):
¼ 3034; 2933,
1532,1456,1336,1242,1183,1067, 909, 808, 751, 682, 648 cmꢁ1. HR-
ꢀ
detector at 120(2) K using Cu K
a
radiation (
l
¼1.54178 A). Direct
ESI-MS for C24H28N3 required 358.2283. Found 358.2287.
methods (SHELXS-97)41 were used for structure solution, and full-
matrix least-squares refinement on F2 (SHELXL-97).41 H atoms
were localized by difference Fourier synthesis and refined using
a riding model. An analytical absorption correction was applied.
4.3.3. 1-Methyl-3-(3-methyl-1H-pyrrolo[2,3-b]pyridin-2-yl)-1H-imi-
dazolium
bromide
19a. 3-Methylpyrrolo[2,3-b]pyridine
18
(529 mg), 438 mg of (425
m
L) 1-methylimidazol 9a, and 741 mg of

N. Pidlypnyi et al. / Tetrahedron 70 (2014) 8672e8680
8677
NBS were used. Yield 826 mg (70%) of a yellow solid, mp 239 ꢀC. 1H
NMR (DMSO-d6, 400 MHz):
(m, 2H, H-Ph), 8.07e8.09 (m, 2H, H-Ph), 9.97 (s, 1H, H-1,2,4-triazole),
d¼2.31 (s, 3H, Me-azaindole), 4.03 (s,
11.51 (s, 1H, H-1,2,4-triazole), 12.05 ppm (br s, 1H, NH); 13C NMR
3H, Me-imidazole), 7.22 (dd, 1H, J¼7.9, 4.7 Hz, 5-H-azaindole), 8.07
(s, 1H, H-imidazole), 8.13 (dd, 1H, J¼7.9, 1.6 Hz, 4-H-azaindole), 8.18
(dd, 1H, J1zJ2¼1.8 Hz, H-imidazole), 8.37 (dd, 1H, J¼4.7, 1.5 Hz, 6-H-
azaindole), 9.77 (s, 1H, 2-H-imidazole), 12.61 ppm (br s, 1H, NH);
(DMSO-d6, 100 MHz):
124.1, 126.7, 130.2, 130.9, 133.7, 134.8, 141.6, 144.8 ppm; ESIMS: m/z
d
¼7.5, 105.9, 111.9, 119.7, 120.2, 121.0, 121.7,
þ
~
(%)¼275.1 (100) [MꢁBr] ; IR (KBr):
n
¼ 3054; 2958,1557,1456,1341,
1233, 1122, 1115, 1093, 962, 759, 743, 683, 673, 664, 632, 574 cmꢁ1
.
13C NMR (DMSO-d6, 100 MHz):
d
¼7.5, 36.3,103.0,116.5, 119.6,123.2,
HR-ESI-MS for C17H15N4 required 275.1297. Found 275.1296.
124.3, 125.7, 128.3, 137.6, 144.8, 145.8 ppm. ESI-MS: m/z (%)¼213.1
(65) [MꢁBr]þ; IR (KBr):
n
¼ 3045; 1568, 1417, 1379, 1246, 1126,
4.3.8. 1-Benzyl-3-(5,7-dibromo-3-methylindol-2-yl)-imidazolium
bromide 11. A solution of the salt 10b (3 mmol) in concd acetic acid
was treated with 3 equiv of bromine at 0 ꢀC. After 30 min the
resulting precipitate was filtered off, washed with cold AcOH, and
dried. Yield: 100% of a colorless solid, mp 281 ꢀC. 1H NMR (DMSO-d6,
~
1076, 859, 798, 774, 749, 679, 636, 614, 599, 539, 413 cmꢁ1. HR-ESI-
MS for C12H13N4 required 213.1140. Found: 213.1141.
4.3.4. 1-Benzyl-3-(3-methyl-1H-pyrrolo[2,3-b]pyridin-2-yl)imidazo-
lium bromide 19b. 3-Methylpyrrolo[2,3-b]pyridine 18 (529 mg),
843 mg of 1-benzyl-imidazole 9b, and 741 mg of NBS were used in
acetone. Yield 1063 mg (72%) of a yellow solid, mp 300 ꢀC. 1H NMR
400 MHz):
d
¼2.29 (s, 3H, Me-indole), 5.62 (s, 2H, CH2), 7.39e7.51
(m, 3H), 7.57 (d, 2H, J¼7.2 Hz, 2,6-H-Ph), 7.89 (s, 1H), 8.11 (s, 1H), 8.17
(s, 1H), 8.22 (s, 1H), 10.04 (s, 1H, 2-H-imidazole), 12.41 ppm (br s, 1H,
(DMSO-d6, 400 MHz):
d
¼2.33 (s, 3H, Me-azaindole), 5.64 (s, 2H,
NH); 13C NMR (DMSO-d6, 100 MHz):
d¼7.5, 52.4, 104.3, 114.4, 116.5,
CH2), 7.22 (dd, 1H, J¼7.9, 4.7 Hz, 5-H azaindole), 7.37e7.51 (m, 3H),
7.58 (d, 2H, J¼7.2 Hz, 2,6-H-Ph), 8.13 (dd, 1H, J¼7.9, 1.4 Hz, 4-H-
azaindole), 8.19 (s, 1H, H-imidazole), 8.23 (dd, 1H, J1zJ2¼1.8 Hz, H-
imidazole), 8.37 (dd, 1H, J¼4.7, 1.4 Hz, 6-H-azaindole), 10.08 (s, 1H,
2-H-imidazole), 12.62 ppm (s, 1H, NH); 13C NMR (DMSO-d6,
117.7, 123.1, 123.8, 124.2, 126.9, 127.9, 128.5, 128.9, 129.0, 133.0, 134.4,
137.3 ppm; ESI-MS: m/z (%)¼446.1 (100) [MꢁBr]þ. IR (KBr):
~
n
¼ 3006; 1631, 1565, 1539, 1439, 1273, 11,070, 915, 866, 855, 780,
754, 708, 660, 638, 626, 468, 412 cmꢁ1. HR-ESI-MS: C19H16Br2N3:
calcd 443.9711. Found: 443.9718.
100 MHz):
d
¼7.6, 52.4, 103.1, 116.5, 119.7, 123.0, 123.8, 125.7, 128.3,
128.5, 128.9, 129.0, 134.4, 137.2, 144.8, 145.8 ppm; ESIMS: m/z (%)¼
4.4. General procedure for the preparation of the ylides 12c,d
and 20bed
þ
~
n
289.1 (100) [MꢁBr] ; IR (KBr):
¼ 2981; 1629, 1565, 1419, 1123,
1052, 900, 791, 770, 699, 651, 629, 462 cmꢁ1. HR-ESI-MS for
C
18H17N4 required 289.1453. Found 289.1443.
Salts 10c,d and 19bed of 1 mmol, respectively, were dissolved in
10 mL of aqueous ethanol (50%) and then 0.5 mL of NaOH (3 M,
1.5 equiv) was added dropwise under cooling. The mixture was
stirred for 30 min. The precipitated solids of 12c,d were filtered off
and dried in vacuo. For the isolation of 20aed, the aqueous solution
was concentrated in vacuo and then extracted with EtOAc, dried
over MgSO4, and finally evaporated to dryness.
4.3.5. 3-(3-Methylpyrrolo[2,3-b]pyridin-2-yl)-1-phenylimidazolium
bromide 19c. 3-Methylpyrrolo[2,3-b]pyridine 18 (529 mg), 438 mg
(425
Yield 1062 mg (75%) of a yellow solid, mp 150 ꢀC.1H NMR (DMSO-d6,
400 MHz):
mL) of 1-phenyl-imidazole 9c, and 741 mg of NBS were used.
d
¼2.41 (s, 3H, Me-azaindole), 7.25 (dd, 1H, J¼7.9, 4.7 Hz,
H-azaindole), 7.64e7.68 (m, 1H, H-Ph), 7.71e7.76 (m, 2H, H-Ph),
7.94e7.97 (m, 2H, H-Ph), 8.17 (dd, 1H, J¼7.9, 1.6 Hz, H-azaindole),
8.40 (dd, 1H, J¼4.7, 1.5 Hz, H-azaindole), 8.48 (dd, 1H, J¼1.7, 2.0 Hz,
H-imidazole), 8.69 (dd, 1H, J1zJ2¼1.6 Hz, H-imidazole), 10.39 (dd,
1H, J1zJ2¼1.6 Hz, 2-H-imidazole),12.62 ppm (br s,1H, NH); 13C NMR
4.4.1. 3-Methyl-2-(1-phenylimidazolium-3-yl)indol-1-ide 12c. A sam-
ple of 354 mg of the salt 10c was used. Yield 235 mg (86%) of a col-
orless solid, mp 92 ꢀC. 1H NMR (DMSO-d6, 400 MHz):
d¼2.42 (s, 3H,
Me-indole), 6.67e6.75 (m, 1H, 5-H-indole), 6.78 (ddd, 1H, J¼8.0, 6.9,
1.3 Hz, 6-H-indole), 7.27 (d, 1H, J¼8.0 Hz, 7-H-indole), 7.33 (d, 1H,
J¼7.5 Hz, 4-H-indole), 7.55e7.64 (m, 1H, 4-H-Ph), 7.66e7.70 (m, 2H,
3,5-H-Ph), 7.94 (d, 2H, J¼8.0 Hz, 2,6-H-Ph), 8.32 (d, 1H, J¼2.0 Hz, H-
imidazole), 8.44 (d,1H, J¼2.0 Hz, H-imidazole), 9.99 ppm (s,1H, 2-H-
(DMSO-d6, 100 MHz):
d¼7.6, 103.6, 116.6, 120.0, 121.9, 122.3, 124.2,
125.5, 128.5, 130.2, 130.2,þ134.5, 136.1, 145.0, 145.7 ppm; ESIMS: m/z
~
n
(%)¼275.1 (100) [MꢁBr] ; IR (KBr):
¼ 3052; 2948, 2846, 1562,
1420, 1283, 1257, 1115, 872, 753, 745, 681, 637, 612, 597, 519 cmꢁ1
.
HR-ESI-MS for C17H15N4 required 275.1297. Found 275.1295.
imidazole); 13C NMR (DMSO-d6, 100 MHz):
d
¼9.3, 93.7, 114.8, 116.6,
117.1, 117.2, 120.8, 122.0, 122.5, 129.5, 130.0, 130.8, 131.9, 135.0, 136.7,
4.3.6. 1-(2,6-Diisopropylphenyl)-3-(3-methylindol-2-yl)imidazolium
bromide 19d. 3-Methylpyrrolo[2,3-b]pyridine 18 (529 mg),
1215 mg of 1-(2,6-diisopropylphenyl)imidazole 9d, and 741 mg of
NBS were used. Yield 1314 mg (75%) of a yellow solid, mp 142 ꢀC. 1H
142.8 ppm; ESIMS: m/z (%)¼274.1 (100) [MþH]þ; IR (KBr):
¼ 1541; 1491, 1334, 1296, 1068, 767, 731, 693, 646, 527 cmꢁ1. HR-
~
n
ESI-MS for C18H15N3 required 274.1344. Found 274.1342.
NMR (DMSO-d6, 400 MHz):
d
¼1.21 (dd, 12H, Me),
d
¼2.34 (s, 3H,
4.4.2. 2-(1-(2,6-Diisopropylphenyl)imidazolium-3-yl)-3-methylindol-
1-ide12d. A sample of 438 mg of the salt 10d was used. Yield 311 mg
(87%) of a yellow solid, mp 300 ꢀC. 1H NMR (DMSO-d6, 400 MHz):
Me-azaindole), 2.40e2.47 (m, 2H, CH), 7.24 (dd,1H, J¼7.9, 4.7 Hz, H-
azaindole), 7.52 (d, 2H, H-Ph), 7.69 (t, 1H, H-Ph), 8.17 (dd, 1H, J¼7.9 ,
1.3 Hz, H-azaindole), 8.41 (dd, 1H, J¼4.6, 1.3 Hz, H-azaindole), 8.48
(dd, 1H, J¼1.7, 1.6 Hz, H-imidazole), 8.58 (dd, 1H, J1zJ2¼1.6 Hz, H-
d
¼1.22 (d, 12H, J¼6.8 Hz, Me), 2.36 (s, 3H, Me-indole), 2.42 (sept, 1H,
J¼6.8 Hz, CH), 6.69 (ddd, 1H, J¼7.8, 6.6 Hz, J3¼0.8 Hz, 5-H-indole),
6.76 (ddd, 1H, J¼7.9, 6.6 Hz, J5¼1.3 Hz, 6-H-indole), 7.25 (d, 1H,
J¼7.9 Hz, 7-H-indole), 7.31 (d, 1H, J¼7.8 Hz, 4-H-indole), 7.49 (d, 2H,
J¼7.8 Hz, 3,5-H-Ph), 7.65 (t, 1H, J¼7.8 Hz, 4-H-Ph), 8.20 (s, 1H, H-
imidazole), 8.38 (s, 1H, H-imidazole), 9.89 ppm (br s, 1H, 2-H-im-
imidazole), 10.23 (s, 1H, H-imidazole), 12.19 ppm (br s, 1H, NH); 13
C
NMR (DMSO-d6, 100 MHz):
d
¼7.4, 23.8, 28.2, 103.7, 108.0, 116.6,
119.6, 124.4, 124.6, 124.6, 125.7, 128.6, 130.2, 131.8, 138.5, 145.1,
145.8 ppm; ESIMS: m/z (%)¼359.2 (100) [MꢁBr]þ; IR (KBr):
n
¼ 2693; 2928, 2869, 1649, 1533, 1508, 1460, 1362, 1256, 1103,
idazole); 13C NMR (DMSO-d6, 100 MHz):
d¼9.1, 23.7, 23.8, 28.3,93.7,
~
1084, 1056, 803, 750, 735 cmꢁ1
.
114.8, 116.7, 117.1, 122.6, 124.3, 124.7, 130.6, 130.9, 131.2, 135.0, 136.7,
142.9, 145.2 ppm; ESIMS: m/z (%)¼358.1 (100) [MþH]þ; IR (KBr):
¼ 2965; 1545, 1459, 1355, 1290, 1180, 1061, 804, 739 cmꢁ1. HR-
~
n
4.3.7. 4-(3-Methylindol-2-yl)-1-phenyl-1,2,4-triazolium bromide 23. A
sample of 525 mg of 3-methyl-indole 8, 773 mg of 1-phenyl-1,2,4-
triazole 22, and 741 mg of NBS were used. Yield 849 mg (80%) of
ESI-MS for C24H27N3 required 358.2283. Found 358.2278.
a yellow solid, mp 220 ꢀC. 1H NMR (DMSO-d6, 400 MHz):
d¼2.42 (s,
4.4.3. 2-(1-Benzylimidazolium-3-yl)-3-methylpyrrolo[2,3-b]pyridin-
1-ide 20b. A sample of 369 mg of the salt 19b was used. Yield:
236 mg (82%) of a yellow solid, mp 120 ꢀC. 1H NMR (DMSO-d6,
3H, Me-indole), 7.18e7.22 (m, 1H, H-indole), 7.31e7.35 (m, 1H, H-
indole), 7.54 (d,1H, J¼8.3 Hz, H-indole), 7.68e7.72 (m, 2H), 7.75e7.79

8678
N. Pidlypnyi et al. / Tetrahedron 70 (2014) 8672e8680
400 MHz):
d
¼2.36 (s, 3H, Me-indole), 5.54 (s, 2H, CH2), 6.66 (dd,1H,
936, 760, 750, 718, 690, 583, 530 cmꢁ1. HR-ESI-MS for C18H15N3S
required 306.1065. Found 306.1066.
J¼7.6, 4.4 Hz, 5-H-azaindole), 7.35e7.48 (m, 3H), 7.51 (d, 2H,
J¼6.8 Hz, 2,6-H-Ph), 7.64 (dd, 1H, J¼7.6, 1.4 Hz, 4-H-azaindole), 7.91
(s, 1H, H-imidazole), 7.97 (dd, 1H, J¼4.4, 1.4 Hz, 6-H-azaindole), 8.12
(s, 1H, H-imidazole), 9.91 ppm (s, 1H, 2-H-imidazole); 13C NMR
(DMSO-d6, 100 MHz):
124.0, 128.3, 128.7, 129.0, 133.9, 135.2, 138.1, 139.5, 154.3 ppm; ESI-
4.5.2. 1-(2,6-Diisopropylphenyl)-3-(3-methylindol-2-yl)imidazol-2-
thione 14d. Method A was applied. A sample of 179 mg of the ylide
12d and 32 mg of sulfur were used. Yield 207 mg (100%) of yellow
d¼9.0, 51.9, 91.8, 111.0, 121.6, 122.1, 123.1,
solid, mp 300 ꢀC. 1H NMR (DMSO-d6, 400 MHz):
d¼1.17 (d, 6H,
þ
~
n
MS: m/z (%)¼289.1 (100) [MþH] . IR (KBr):
¼ 3139; 1601, 1550,
J¼6.9 Hz, Me), 1.31 (d, 6H, J¼6.9 Hz, Me), 2.41 (s, 3H, Me-indole),
2.66 (sept, 2H, CH, J¼6.9 Hz, CH), 6.81 (d, 1H, J¼2.4 Hz, H-imidaz-
ole), 7.14e7.18 (m, 2H), 7.22e7.26 (m, 1H), 7.31 (d, 2H, J¼7.8 Hz, 3,5-
H-Ph), 7.38 (d, 1H, J¼8.1 Hz), 7.48 (d, 1H, J¼7.8 Hz), 7.58 (d, 1H,
J¼7.8 Hz), 9.96 ppm (br s, 1H, NH); 13C NMR (DMSO-d6, 100 MHz):
1453, 1390, 1301, 1279, 1158, 1122, 1072, 1030, 721, 658, 457 cmꢁ1
.
HR-ESI-MS for C18H16N4 required 289.1453. Found: 289.1450.
4.4.4. 3-Methyl-2-(1-phenylimidazolium-3-yl)pyrrolo[2,3-b]pyridin-
1-ide 20c. A sample of 354 mg of the salt 19c was used. Yield 219 mg
(80%) of a yellow solid, mp 133 ꢀC. 1H NMR (DMSO-d6, 400 MHz):
d
¼9.1, 23.5 24.6, 28.8, 104.2, 111.5, 118.4, 119.0, 119.5, 120.0, 123.2,
124.4, 127.9, 128.7, 130.4, 133.0, 133.7, 146.5, 165.1 ppm; ESI-MS: m/
~
d
¼2.41 (s, 3H, Me-azaindole), 6.68 (dd, 1H, J¼7.7, 4.5 Hz, H-azain-
z¼390 (100%) [MþHþ]; IR (KBr):
n
¼ 3436; 3158, 3079, 2959,1613,
dole), 7.58e7.62 (m,1H, H-Ph), 7.66e7.70 (m, 3H, H-Ph, H-azaindole),
7.94e7.97 (m, 2H, H-Ph), 8.00 (dd, 1H, J¼4.6, 1.8 Hz, H-azaindole),
8.36 (dd, 1H, J¼1.7, 1.3 Hz, H-imidazole), 8.47 (dd, 1H, J1zJ2¼1.6 Hz,
H-imidazole), 10.07 (dd, 1H, J1zJ2¼1.6 Hz, 2-H-imidazole); 13C NMR
1466, 1359, 1240, 1123, 1097, 937, 805, 747, 683, 608 cmꢁ1. HR-ESI-
MS for C24H27N3S required 390.2004. Found 390.2004.
4.5.3. 4-(3-Methylindol-2-yl)-2-phenyl-1,2,4-triazole-3-thione
25. Method B was applied: A sample of 177 mg of salt 23, 32 mg of
S8, and 0.3 mL of AmOK were used in 5 mL of THF. Yield 107 mg
(70%) of a yellowish solid, mp 185 ꢀC. 1H NMR (DMSO-d6, 400 MHz):
(DMSO-d6, 100 MHz):
d¼8.9, 92.6, 111.1, 121.1, 122.1, 122.5, 123.1,
124.2, 129.6, 130.0, 132.3, 134.9, 137.9, 139.7, 154.4 ppm; ESI-MS: m/z
þ
~
n
(%)¼275.1 (100) [MþH] ; IR (KBr): ¼ 3072; 3026,1601,1546,1413,
1362, 1306, 1113, 1067, 767, 743, 679, 623, 511 cmꢁ1. HR-ESI-MS for
d
¼2.19 (s, 3H, Me-indole), 7.10e7.14 (m, 1H, H-indole), 7.22e7.26
C
17H15N4 required 275.1297. Found 275.1298.
(m, 1H, H-indole), 7.42 (d, 1H, J¼8.1 Hz, H-indole), 7.47e7.51 (m, 1H,
H-Ph), 7.58e7.64 (m, 3H), 8.03e8.06 (m, 2H, H-Ph), 9.07 (s, 1H, H-
1,2,4-triazole), 11.60 ppm (br s, 1H, NH); 13C NMR (DMSO-d6,
4.4.5. 2-(1-(2,6-Diisopropylphenyl)imidazolium-3-yl)-3-
methylpyrrolo[2,3-b]pyridin-1-ide 20d. A sample of 438 mg of the
salt 19d was used. Yield 286 mg (80%) of a yellow solid, mp 219 ꢀC.
100 MHz):
d
¼7.9, 107.0, 111.5, 119.2, 119.2, 122.9, 123.8, 123.9, 126.8,
128.2, 128.9, 133.8, 137.8, 142.5, 166.6 ppm; ESIMS: m/z (%)¼307.1
1H NMR (DMSO-d6, 400 MHz):
d¼1.19 (d, 6H, J¼2.2 Hz, Me), 1.29 (d,
(100) [MþH] ; IR (KBr):
¼ 3211; 1593, 1451, 1370, 1338, 1331,
þ
~
n
6H, J¼2.2 Hz, Me), 2.36 (s, 3H, Me-azaindole), 2.39e2.46 (m, 2H,
eCH), 6.94 (dd,1H, J¼7.8, 4.6 Hz, H-azaindole), 7.49 (d, 2H, J¼7.8 Hz,
H-Ph), 7.66 (dd, 1H, J1zJ2¼7.8 Hz, H-Ph), 7.90 (dd, 1H, J1zJ2¼1.7 Hz,
H-azaindole), 8.16 (dd, 1H, J¼1.7, 1.6 Hz, H-azaindole), 8.34 (dd, 1H,
J¼1.8, 1.7 Hz, H-imidazole), 8.52 (dd, 1H, J¼1.8, 1.6 Hz, H-imidazole),
10.17 (dd, 1H, J¼1.5, 1.4 Hz, H-imidazole); 13C NMR could not be
measured due to slow decomposition of the ylide; ESIMS: m/z (%)¼
1305, 1290, 951, 757, 745, 686, 669, 643, 664, 442 cmꢁ1. HR-ESI-MS
for C17H15SN4 required 307.1017. Found 307.1015.
4.5.4. 4-(Indol-3-yl)-1-phenyl-1,2,4-triazol-5(4H)-thione 31. Method
B was applied. A sample of 150 mg (0.42 mmol) of 29, 118 mg
(0.46 mmol) of sulfur, and 0.32 mL (0.52 mmol) of t-AmOK (25% in
toluene) were used in 3 mL of THF. Yield: 78 mg (64%), mp 205 ꢀC.1H
þ
~
n
359.2 (100) [MþH] ; IR (KBr):
¼ 2692; 1674, 1538, 1460, 1398,
NMR: (400 MHz, DMSO-d6)
d
¼11.65 (s, 1H, NH), 8.97 (s, 1H, NCHN),
1386, 1364, 1260, 1058, 803, 770, 758, 677, 645, 596 cmꢁ1
.
8.11e8.01 (m, 2H, AreH), 7.85 (d, J¼2.8 Hz,1H, NHCH), 7.62e7.43 (m,
5H, AreH), 7.23 (ddd, J¼8.2, 7.1, 1.1 Hz, 1H, AreH), 7.12 (ddd, J¼8.0,
4.5. General procedure for the synthesis of the thiones 14c,d,
25, and 31
7.1, 0.9 Hz,1H, AreH); 13C NMR (100 MHz, DMSO-d6):
d¼166.5,143.1,
138.3, 134.5, 128.8 (2C), 128.0, 124.1 (2C), 123.4, 122.5, 122.1, 119.9,
~
117.9, 112.2, 110.2; ATR-IR:
n
¼ 3239; 1595, 1536, 1497, 1399, 1325,
Method A: A flask was charged with the ylides (0.5 mmol), sulfur
(32 mg, 1.0 mmol), and p-xylene (5 mL), and the mixture was
stirred and heated at reflux temperature for 3 h. After evaporation,
the resulting precipitate was purified by column chromatography.
Method B: Under a nitrogen atmosphere a Schlenk tube was
charged with the corresponding salt. Then, the tube was evapo-
rated and heated at 150 ꢀC for 1 h. After cooling to ꢁ5 ꢀC, sulfur and
THF were added. The reaction mixture was cooled with ice and
a solution of AmOK was added via a syringe. After stirring for 2 h
the solvent was distilled off and the residue was separated by
column chromatography.
1303, 1243, 1054, 973, 943, 763, 732, 687, 618, 580, 429 cmꢁ1. ESI-
MS: m/z¼291 (100%) [MþHþ]. HR-ESI-MS for C16H11N4Sꢁ required
291.0704. Found 291.0706.
4.5.5. 1-Methyl-3-(3-methylindol-2-yl)-2-(methylthio)imidazolium
iodide 15. The thione 14a (487 mg, 2 mmol) was dissolved in 15 mL
of acetone and then treated with 1419 mg (0.62 mL, 10 mmol) of
iodomethane. After stirring overnight the solution was concen-
trated in vacuo. The resulting precipitate was collected by filtration
and dried in vacuo. Yield: 740 mg (96%) of a yellow solid, mp 156 ꢀC.
1H NMR (DMSO-d6, 400 MHz):
d¼2.19 (s, 3H, Me-indole), 2.38 (s,
3H, SMe-imidazole), 4.06 (s, 3H, NMe-imidazole), 7.17 (dd, 1H,
J1zJ2¼7.5 Hz, 5-H-indole), 7.30 (dd, 1H, J1zJ2¼7.6 Hz, 6-H-indole),
7.48 (d, 1H, J¼8.2 Hz, 7-H-indole), 7.67 (d, 1H, J¼7.9 Hz, 4-H-indole),
8.21 (d, 1H, J¼2.1 Hz, H-imidazole), 8.25 (d, 1H, J¼2.1 Hz, H-imid-
4.5.1. 1-(3-Methylindol-2-yl)-3-phenylimidazole-2-thione
14c.
Method A was applied. A sample of 137 mg of ylide 12c and 32 mg
of sulfur were used. Yield 100 mg (67%) of a brown solid,
mp 253 ꢀC. 1H NMR (DMSO-d6, 400 MHz):
d
¼2.16 (s, 3H, Me-
azole), 11.72 ppm (s, 1H, NH); 13C NMR (DMSO-d6, 100 MHz):
d
¼7.6,
indole), 7.09 (ddd, 1H, J¼7.8, 7.0 Hz, J5¼0.8 Hz, 5-H-indole), 7.19
(ddd, 1H, J¼8.2, 7.0 Hz, J5¼1.0 Hz, 6-H-indole), 7.36 (d, 1H,
J¼8.2 Hz, 7-H-indole), 7.47 (tt, 1H, J¼7.5, 1.2 Hz), 7.53 (d, 1H,
J¼2.6 Hz), 7.55e7.60 (m, 4H), 7.73 (dt, 2H, J¼7.3, 1.0 Hz),
17.1, 36.9, 107.5, 111.9, 119.6, 119.9, 123.7, 124.3, 125.7, 126.2, 126.3,
þ
~
133.7, 144.1 ppm; ESIMS: m/z (%)¼258.0 (100) [MꢁI] ; IR (KBr):
n
¼
1629; 1559, 1484, 1450, 1387, 1329, 1225, 1156, 1128, 986, 768, 757,
746, 703, 688, 663, 582, 522, 427 cmꢁ1. HR-ESI-MS for C14H16N3S
required 258.1065. Found: 258.1062.
11.49 ppm (s, 1H, NH); 13C NMR (DMSO-d6, 100 MHz):
d
¼8.2,
105.5, 111.3, 118.8, 118.9, 119.3, 120.2, 122.2, 125.9, 127.0, 128.0(2),
128.9, 133.6, 138.0, 164.4 ppm; GCeMS: m/z (%)¼305.1 [M]þ; IR
4.5.6. 1-Benzyl-3-(3-methylindol-2-yl)imidazole-2-selenone 16. A
flask was charged with the ylide 12b (0.5 mmol, 124 mg), selenium
~
n
(KBr):
¼ 3291; 1596, 1496, 1464, 1456, 1353, 1326, 1309, 1098,

N. Pidlypnyi et al. / Tetrahedron 70 (2014) 8672e8680
8679
(40 mg, 1.0 mmol), and p-xylene (5 mL), and the mixture was
stirred and heated at reflux temperature for 3 h. After evaporation,
the resulting precipitate was purified by column chromatography.
Yield: 172 mg (94%) of a yellow solid, mp 178 ꢀC. 1H NMR (CDCl3,
3H, Me-azaindole), 7.00 (dd, 1H, J¼7.8, 4.8 Hz, H-azaindole), 7.42 (d,
1H, J¼1.8 Hz, H-imidazole), 7.57e7.65 (m, 5H, H-Ph), 7.76 (d, 1H,
J¼1.9 Hz, H-imidazole), 7.87 (dd, 1H, J¼7.8, 1.6 Hz, H-azaindole),
8.36 (dd, 1H, J¼4.7, 1.6 Hz, H-azaindole), 13C NMR (CDCl3, 100 MHz):
400 MHz):
d
¼2.31 (s, 3H, Me-indole), 5.42 (s, 2H, CH2), 6.84 (d, 1H,
d
¼8.1, 10.9, 14.4, 88.4, 113.6, 114.1, 123.5, 123.7, 124.4, 126.0, 129.6,
J¼2.4 Hz, H-imidazole), 7.07 (d, 1H, J¼2.4 Hz, H-imidazole), 7.17
(ddd, 1H, J¼8.1, 7.2, 1.0 Hz, 5-H-indole), 7.27 (ddd, 1H, J¼8.2, 7.1,
1.2 Hz, 6-H-indole), 7.32e7.46 (m, 6H), 7.58 (dd, 1H, J¼7.9, 0.5 Hz, 4-
129.9, 136.2, 136.8, 142.3, 148.0, 176.1 ppm; 11B NMR (CDCl3,
193 MHz, BF3$Et2O):
d
¼ꢁ0.93 ppm. ESIMS: m/z (%)¼343.2 (100)
þ
~
[MþH] ; IR (KBr):
n
¼ 2931; 2896, 2856, 1646, 1599, 1503, 1427,
H-indole), 9.50 ppm (s, 1H, NH); 13C NMR (CDCl3, 100 MHz):
d
¼8.8,
1414, 1330, 1133, 1036, 768, 745, 732, 692, 685 cmꢁ1. HR-ESI-MS for
53.4, 105.6, 111.6, 119.1, 119.2, 120.1, 121.0, 123.5, 127.8, 128.6, 128.7,
C21H24BN4 required 343.2094. Found 343.2095.
129.1, 133.9, 135.0, 157.6 ppm; GCeMS: m/z (%)¼367.1 [M]þ; IR
~
n
(KBr):
¼ 3307; 1566, 1495, 1467, 1392, 1323, 1120, 745, 724, 708,
4.6.4. 1-(2,6-Diisopropylphenyl)-11,11-diethyl-5-methyl-1,11-
dihydroimidazo[200,100:30,40][1,4,2]diazaborolo[10,50:1,5]pyrrolo[2,3-b]
pyridin-4-ium-11-ide 21d. A sample of 358 mg of the ylide 20d
was used. Yield 170 mg (40%) of a yellow solid, mp 219 ꢀC. 1H NMR
663, 470, 437, 413 cmꢁ1. HR-ESI-MS for C19H17N3Se required
368.0666. Found: 368.0661.
4.6. General procedure for the preparation of the boranes 17c,
21bed, and 26
(CDCl3, 400 MHz):
d
¼0.39 (t, 6H, J¼7.7 Hz, Me), 0.49 (dq, 2H,
J2¼15.3 Hz, J¼7.7 Hz, BCH2), 1.12 (dq, 2H, J2¼15.3 Hz, J¼7.7 Hz,
BCH2), 1.10 (d, 6H, J¼7.7 Hz, Me), 1.29 (d, 6H, J¼6.8 Hz, Me), 2.52 (s,
3H, Me-azaindole), 2.54e2.59 (m, 2H, -CH), 7.00 (dd, 1H, J¼7.8,
4.7 Hz, H-azaindole), 7.05 (d, 1H, J¼2.1 Hz, H-imidazole), 7.32 (d,
2H, J¼7.7 Hz, H-Ph), 7.51 (dd, 1H, J¼8.0, 7.7 Hz, H-Ph), 7.74 (d, 1H,
J¼5.1 Hz, H-imidazole), 7.82 (dd, 1H, J¼10.2, 5.1 Hz, H-azaindole),
7.82 (dd, 1H, J¼4.8, 1.7 Hz, H-azaindole); 13C NMR (CDCl3,
The starting materials (1 mmol) 12c, 20bed, and 23, re-
spectively, were placed in a glovebox in a bomb tube with trie-
thylborane in dioxane (1.5 mL, 50%, 5 equiv). Then, the tube was
closed tightly and placed in a preheated oil bath at 150 ꢀC over-
night. Then the bomb was cooled and the mixture was diluted with
5
mL of dioxane. The products were isolated by column
100 MHz):
d
¼8.1, 10.7, 12.8, 21.7, 26.5, 28.3, 88.5, 113.3, 113.6, 124.0,
chromatography.
124.3, 126.0, 126.4, 130.9, 132.2, 136.0, 142.2, 146.1, 148.1,
177.7 ppm; 11B NMR(CDCl3, 193 MHz, BF3$Et2O):
d¼ꢁ1.90 ppm.
4.6.1. 11,11-Diethyl-5-methyl-1-phenyl-1,11-dihydroimidazo
[20,10:3,4][1,4,2]diazaborolo[1,5-a]indol-4-ium-11-ide 17c. A sample
of 273 mg of the ylide 12c was used. Yield 100 mg (29%) of a col-
ESIMS: m/z (%)¼427.3 (100) [MþH]þ; IR (KBr): 2966, 2936, 2496,
2859, 1639, 1475, 1433, 1309, 1135, 1046, 1101, 883, 791, 775, 759,
747, 548 cmꢁ1
.
orless solid, mp 146 ꢀC. 1H NMR (DMSO-d6, 400 MHz):
d¼0.36 (t,
6H, J¼7.6 Hz, Me), 0.56 (dq, 2H, J2¼15.3, 7.7 Hz, BCH2), 0.84 (dq, 2H,
J2¼15.3, 7.7 Hz, BCH2), 2.54 (s, 3H, Me-indole), 7.02 (ddd, 1H, J¼8.0,
7.1, 1.1 Hz, 5-H-indole), 7.10 (ddd, 1H, J¼8.2, 7.0, 1.3 Hz, 6-H-indole),
7.31 (d, 1H, J¼1.9 Hz, H-imidazole), 7.41 (dd, 1H, J¼8.0, 0.9 Hz, 7-H-
indole), 7.53e7.64 (m, 6H), 7.68 ppm (d, 1H, J¼1.9 Hz, H-imidazole);
4.6.5. 11,11-Diethyl-5-methyl-1-phenyl-1,11-dihydro[1,2,4]triazolo
[30,40:3,4] [1,4,2]diazaborolo[1,5-a]indol-4-ium-11-ide 26. Under an
inert atmosphere 354 mg (1 mmol) of the salt 23 was dissolved in
5 mL of anhydrous THF in a bomb tube and then 0.6 mL of AmOK in
toluene (0.6 mL, 25%, 1 equiv) was added dropwise at 0 ꢀC. The
mixture was stirred at room temperature for 1 h. Then trie-
thylborane in dioxane (1.5 mL, 50%, 5 equiv) was added in one
portion. Then, the tube was closed tightly and placed into a pre-
heated oil bath at 100 ꢀC overnight. Then the bomb was cooled and
the mixture was diluted with 5 mL of THF. The product was isolated
by column chromatography. Yield 17 mg (5%) of a yellow solid;
13C NMR (DMSO-d6, 100 MHz):
d
¼8.3, 10.9, 14.8, 89.8, 112.3, 112.4,
114.0, 117.4, 118.5, 120.1, 123.1, 123.7, 129.4, 129.9, 131.6, 135.8, 137.0,
171.2 ppm; 11B NMR (CDCl3, 128þMHz, BF3$Et2O):
d
¼ꢁ0.35 ppm;
~
n
ESIMS: m/z (%)¼342.1 (15) [MþH] ; IR (KBr):
¼ 2856; 1636,1597,
1501, 1474, 1452, 1341, 1246, 1137, 1036, 1006, 969, 877, 805, 793,
772, 735, 722, 690, 622, 501, 439 cmꢁ1. HR-ESI-MS for C22H24BN3
required 342.2142. Found 342.2139.
purification failed. 1H NMR (CDCl3, 400 MHz):
d
¼0.40 (t, 6H,
J¼9.4 Hz, Me), 0.84 (dq, 2H, J2¼18.8 Hz, J¼9.4 Hz, BCH2), 1.01 (dq,
2H, J2¼18.8 Hz, J¼9.4 Hz, BCH2), 2.56 (s, 3H, Me-indole), 7.06e7.10
(m, 1H), 7.14e7.18 (m, 1H), 7.46 (d, 1H, J¼8.1 Hz), 7.51e7.55 (m, 1H),
7.59e7.62 (m, 3H), 7.91e7.94 (m, 2H, H-indole), 8.69 (s, 1H, H-tri-
4.6.2. 1-Benzyl-11,11-diethyl-5-methyl-1,11-dihydroimidazo
[200,100:30,40][1,4,2]diazaborolo[10,50:1,5]pyrrolo[2,3-b]pyridin-4-ium-
11-ide 21b. A sample of 288 mg of the ylide 20b was used. Yield
278 mg (78%) of a yellow solid, mp 126 ꢀC. 1H NMR (DMSO-d6,
þ
~
n
azolo); ESIMS: m/z (%)¼366.2 (100) [MþNa] ; IR (KBr):
¼ 2937;
400 MHz):
d
¼0.42 (t, 6H, J¼7.7 Hz, Me), 0.73 (dq, 2H, J2¼15.2 Hz,
2861,1957,1506,1450,1345,1315,1260,1243,1194,1098,1047,1021,
741, 689, 649 cmꢁ1
J¼7.6 Hz, BCH2), 1.08 (dq, 2H, J2¼15.2 Hz, J¼7.6 Hz, BCH2), 2.38 (s,
3H, Me-azaindole), 5.20 (s, 2H, CH2), 6.83e6.90 (m, 2H), 7.20e7.28
(m, 2H), 7.31e7.38 (m, 3H), 7.44 (d, 1H, J¼1.9 Hz, H-imidazole), 7.73
(dd, 1H, J¼7.8, 1.6 Hz, 4-H-azaindole), 8.21 ppm (dd, 1H, J¼4.8,
.
4.6.6. 4-(1H-Indol-3-yl)-1-phenyl-1,2,4-triazolium perchlorate 29.
Under an inert atmosphere 0.987 g (4 mmol) of 3-phenyl-1,3,4-
oxadiazolium perchlorate 28, 0.675 g (4 mmol) 1-methyl-1H-
indol-3-amine hydrochloride 27, and 0.324 g (4 mmol) of anhy-
drous NaOAc were suspended in 4.8 mL of anhydrous MeCN. The
mixture was then stirred at 40 ꢀC for 24 h. Then, 50 mL of Et2O was
added whereupon a precipitate formed, which was filtered off and
recrystallized from dioxane with a few drops of EtOH. Yield 984 mg
1.6 Hz, 1H, 7-H-azaindole); 13C NMR (DMSO-d6, 100 MHz):
d
¼8.0,
11.1, 13.8, 52.3, 88.3, 113.5, 114.1, 122.4, 124.6, 126.2, 128.3,129.1,
129.4, 134.1, 136.7, 141.7, 147.7 ppm; 11B NMR (CDCl3, 193 MHz,
BF3$Et2O):
d
¼ꢁ1.90 ppm. ESIMS: m/z (%)¼357.1 (100) [MþH]þ; IR
~
(KBr):
n
¼ 2867; 1645,1543,1487,1417,1324,1296,1134,1029, 900,
868, 790, 775, 725, 709, 575, 460 cmꢁ1. HR-ESI-MS for C22H25N4B
required 357.2251. Found 357.2249.
(68%), mp 187 ꢀC. 1H NMR: (400 MHz, DMSO-d6)
d 12.09 (s, 1H, NH),
11.39 (s, 1H, NCHN), 9.91 (s, 1H, NCHN), 8.12e8.08 (m, 2H, AreH),
8.08e8.04 (m, 1H, AreH), 7.89 (d, J¼8.0 Hz, 1H, AreH), 7.78e7.72
(m, 2H, AreH), 7.71e7.64 (m, 1H, AreH), 7.62 (d, J¼8.2 Hz, 1H,
AreH), 7.37e7.30 (m, 1H, AreH), 7.29e7.23 (m, 1H, AreH); 13C NMR
4.6.3. 11,11-Diethyl-5-methyl-1-phenyl-1,11-dihydroimidazo
[200,100:30,40][1,4,2]diazaborolo[10,50:1,5]pyrrolo[2,3-b]pyridin-4-ium-
11-ide 21c. A sample of 274 mg of the ylide 20c was used. Yield
257 mg (75%) of a yellowish solid, mp 204 ꢀC. 1H NMR (CDCl3,
(100 MHz, DMSO-d6):
123.2, 122.0, 120.9 (2C), 120.8, 120.3, 117.4, 112.6, 108.5; ATR-IR:
d
¼144.8, 141.0, 135.1, 134.5, 130.6, 130.1 (2C),
~
n
600 MHz):
d
¼0.44 (t, 6H, J¼7.7 Hz, Me), 0.65 (dq, 2H, J2¼15.3 Hz,
¼
J¼7.5 Hz, BCH2), 1.12 (dq, 2H, J2¼15.3 Hz, J¼7.5 Hz, BCH2),
d
¼2.58 (s,
3138; 1459, 1254, 1066, 967, 864, 748, 685, 618, 422 cmꢁ1. ESI-MS:

8680
N. Pidlypnyi et al. / Tetrahedron 70 (2014) 8672e8680
m/z¼261.0 (100%) ½M ꢁ ClOꢁ4 ꢃ. HR-ESI-MS for C16H13N4 required
€
17. Schmidt, A.; Munster, N.; Dreger, A. Angew. Chem. 2010, 122, 2851; Angew. Chem.
, Int. Ed. 2010, 49, 2790.
261.1140. Found 261.1139.
18. Schmidt, A.; Habeck, T. Lett. Org. Chem. 2005, 2, 37.
19. Schmidt, A.; Habeck, T.; Kindermann, M. K.; Nieger, M. J. Org. Chem. 2003, 68,
5977.
20. Schmidt, A.; Merkel, L.; Eisfeld, W. Eur. J. Org. Chem. 2005, 2124.
21. Schmidt, A.; Beutler, A.; Habeck, T.; Mordhorst, T.; Snovydovych, B. Synthesis
2006, 1882.
Acknowledgements
€
Dr. Gerald Drager, University of Hannover (Germany), is grate-
22. Schmidt, A.; Habeck, T.; Snovydovych, B.; Eisfeld, W. Org. Lett. 2007, 9, 3515.
23. Benhamou, L.; Cesar, V.; Gornitzka, H.; Lugan, N.; Lavigne, G. Chem. Commun.
fully acknowledged for measuring the HR-ESI-MS spectra.
ꢂ
2009, 4720.
References and notes
ꢂ
24. Benhamou, L.; Vudjkovic, N.; Cesar, V.; Gornitzka, H.; Lugan, N.; Lavigne, G.
Organometallics 2010, 29, 2616.
25. Cesar, V.; Lugan, N.; Lavigne, G. J. Am. Chem. Soc. 2008, 130, 11286.
26. Potts, K. T.; Murphy, P. M.; Kuehnling, W. R. J. Org. Chem. 1988, 53, 2889.
27. Potts, K. T.; Murphy, P. M.; DeLuca, M. R.; Kuehnling, W. R. J. Org. Chem. 1988, 53,
2898.
ꢁ
1. Zugravescu, I.; Petrovanu, M. N-Ylide Chemistry; McGraw Hill International
ꢂ
Book: New York, NY, 1976.
2. Ollis, W. D.; Stanforth, S. P.; Ramsden, C. A. Tetrahedron 1985, 41, 2239.
3. Schmidt, A. Curr. Org. Chem. 2004, 8, 653.
4. Schmidt, A. Adv. Heterocycl. Chem. 2003, 85, 67.
5. Pliego, J. R., Jr.; De Almeida, W. B. J. Chem. Soc., Perkin Trans. 2 1997, 2365.
6. Albrecht, M.; Yulikov, M.; Kohn, T.; Jeschke, G.; Adams, J.; Schmidt, A. J. Mater.
Chem. 2010, 20, 3025.
28. Schmidt, A.; Snovydovych, B. Synthesis 2008, 2798.
29. Wamhoff, H.; Schmidt, A. Heterocycles 1993, 35, 1055.
30. Schmidt, A.; Mordhorst, T.; Habeck, T. Org. Lett. 2002, 4, 1375.
31. Schmidt, A.; Rahimi, A. Chem. Commun. 2010, 46, 2995.
32. Hino, T.; Nakagawa, M.; Wakatsuki, T.; Ogawa, K.; Yamada, S. Tetrahedron 1967,
23, 1441.
33. Arnold, P. L.; Mungur, S. A.; Blake, A. J.; Wilson, C. Angew. Chem. 2003, 115, 6163;
Angew. Chem., Int. Ed. 2003, 42, 5981.
34. Wacker, A.; Pritzkow, H.; Siebert, W. Eur. J. Inorg. Chem. 1998, 843.
35. Moser, M.; Wucher, B.; Kunz, D.; Rominger, F. Organometallics 2007, 26, 1024.
36. Lavallo, V.; Ishida, Y.; Donnadieu, B.; Bertrand, G. Angew. Chem. 2006, 118, 6804;
Angew. Chem., Int. Ed. 2006, 45, 6652.
7. Pidlypnyi, N.; Namyslo, J. C.; Drafz, M. H. H.; Nieger, M.; Schmidt, A. J. Org. Chem.
2013, 78, 1070.
€
8. Pidlypnyi, N.; Uhrner, F.; Nieger, M.; Drafz, M. H. H.; Hubner, E. G.; Namyslo, J.
C.; Schmidt, A. Eur. J. Org. Chem. 2013, 7739.
9. Schmidt, A.; Wiechmann, S.; Freese, T. ARKIVOC 2013, i, 424.
€
10. Farber, C.; Leibold, M.; Bruhn, C.; Maurer, M.; Siemeling, U. Chem. Commun.
2012, 48, 227.
11. Voutchkova, A. M.; Feliz, M.; Clot, E.; Eisenstein, O.; Crabtree, R. H. J. Am. Chem.
Soc. 2007, 129, 12834.
37. Zhang, J.; Pidlypnyi, N.; Nieger, M.; Namylo, J. C.; Schmidt, A. Org. Biomol. Chem.
12. Voutchkova, A. M.; Appelhans, L. N.; Chianese, A. R.; Crabtree, R. H. J. Am. Chem.
Soc. 2005, 127, 17624.
13. Thomazeau, C.; Olivier-Bourbigou, H.; Magna, L.; Luts, S.; Gilbert, B. J. Am. Chem.
2014, 12, 2737.
38. Chase, P. A.; Stephan, D. W. Angew. Chem. 2008, 120, 7543; Angew. Chem., Int. Ed.
2008, 47, 7433.
39. Phillips, A. D.; Power, P. P. Acta Crystallogr., Sect. C 2005, 61, o291.
40. Tsai, J.-H.; Lin, S.-T.; Yang, R. B.-G.; Yap, G. P. A.; Ong, T.-G. Organometallics 2010,
29, 4004.
Soc. 2003, 125, 5264.
14. Delaude, L.; Demonceau, A.; Noels, A. F. Curr. Org. Chem. 2006, 10, 203.
15. Schmidt, A.; Beutler, A.; Snovydovych, B. Eur. J. Org. Chem. 2008, 4073.
16. Sauvage, X.; Zaragoza, G.; Demonceau, A.; Delaude, L. Adv. Synth. Catal. 2010,
352, 1934.
41. Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112.