Ortho-perfluoroalkylation and ethoxycarbonyldifluoromethylation of aromatic triazenes

Article abstract of DOI:10.1021/jo401145g

A robust protocol for perfluoroalkylation and ethoxycarbonyldifluoromethylation of functionalized aromatic triazenes is described. Using silver(I)-fluoride and different fluorinated (trimethyl)silyl substituted species, it was possible to synthesize various ortho-fluorinated triazenes in good yields via simple CH-substitution. Initial reactions under solvent-free (neat) conditions indicate a stabilizing interaction between "AgR_f" and the triazene moiety, which may be responsible for the good yields and regioselectivity. The transformation possibilities of the triazene moiety make these reactions interesting for the synthesis of fluorinated building blocks. In addition, quantum chemical calculations suggest that the stabilization of the radical intermediate in the ortho-position is distinctly more favored for aromatic triazenes than for other aromatic substrates.

Full text of DOI:10.1021/jo401145g

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Article
Ortho-Perfluoroalkylation and
Ethoxycarbonyldifluoromethylation of Aromatic Triazenes
Andreas Hafner, Angela Bihlmeier, Martin Nieger, Wim Klopper, and Stefan Bräse
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/jo401145g • Publication Date (Web): 12 Jul 2013
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Ortho-Perfluoroalkylation and Ethoxycarbonyldifluoromethylation of Aromatic
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Triazenes
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Andreas Hafner†, Angela Bihlmeier‡, Martin Nieger§, Wim Klopper‡ and Stefan Bräse†X*
†
Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Campus South,
FritzꢀHaberꢀWeg 6, 76131 Karlsruhe, Germany.
Fax: + 49 721 608 48581
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Tel: + 49 721 608 42903
http://www.ioc.kit.edu/braese/
‡
§
Institute of Physical Chemistry, FritzꢀHaberꢀWeg 2, 76131 Karlsruhe, Germany.
Laboratory of Inorganic Chemistry, Department of Chemistry, PO Box 55, FINꢀ00014
University of Helsinki, Finland.
X
Institute of Toxicology and Genetics, KIT, HermannꢀvonꢀHelmholtz Platz 1, 76344
EggensteinꢀLeopoldshafen, Germany.
Eꢀmail: braese@kit.edu
Table of Content/Abstract Graphic
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Abstract
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A robust protocol for perfluoroalkylation and ethoxycarbonyldifluoromethylation of functionalized
aromatic triazenes is described. Using silver(I)ꢀfluoride and different fluorinated (trimethyl)silyl
substituted species it was possible to synthesize various orthoꢀfluorinated triazenes in good yields
via simple CHꢀsubstitution. Initial reactions under solvent free (neat) conditions indicate a
stabilizing interaction between “AgRf” and the triazene moiety, which may be responsible for the
good yields and regioselectivity. The transformation possibilities of the triazene moiety make these
reactions interesting for the synthesis of fluorinated building blocks. In addition, quantum chemical
calculations suggest that the stabilization of the radical intermediate in orthoꢀposition is distinctly
more favored for aromatic triazenes than for other aromatic substrates.
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Introduction
Aromatic compounds bearing fluorinated groups are important structures in pharmaceutical and
agrochemical research, due to their unique chemical and physical properties. For example,
perfluoroalkylated groups are completely unknown to living organisms, which results in a high
stability for fluorinated molecules against metabolization. This is one reason for their importance in
terms of bioisosteric replacement of e.g. electron withdrawing groups.1
Therefore, perfluoroalkyl groups – first of all the trifluoromethyl group – are a common structural
motif in pharmaceutical and agrochemical compounds. Thus, many methods were reported dealing
with the direct introduction of this moiety into aromatic and heteroaromatic compounds. Most
methods are based on in situ generated “CuCF3”2 or on Pdꢀcatalyzed3 cross coupling reactions.
While many metal mediated trifluoromethylation reactions require halogenated arenes as reactant,
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methods based on radical CF3ꢀsources do not need prior functionalization and react under simple
CHꢀsubstitution.4 However, radical pathways often lead to a mixture of products. Recently, our
group5 as well as Sanford and coꢀworkers6 reported a silverꢀmediated trifluoromethylation reaction.
Noteworthy, in the meantime several other groups also reported silverꢀmediated
trifluoromethylation protocols.7 Although these reactions are based on an in situ generated metallic
“AgCF3”ꢀspecies, they also tolerate halogenated groups – most interestingly iodides. We could
show that especially aromatic triazenes are suitable substrates for this kind of trifluoromethylation
(Scheme 1, a) as they give good yields and a high ortho regioselectivity – in particular when paraꢀ
functionalized triazenes were used.5
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SCHEME 1. Perfluoroalkylation of aromatic triazenes.
Experiments with radical inhibitors and initiators conducted by the Sanford group indicated that
radical intermediates are involved6 which could be confirmed by our own experiments. Because of
the easy setꢀup of this reaction – the “AgCF3” species was generated simply by using commercially
available silver(I)ꢀfluoride and (trifluoromethyl)trimethylsilane (TMSꢀCF3) – and of the straightꢀ
forward reaction pathway, we investigated whether it were possible to expand this transformation to
other fluorinated substrates.
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Herein, we present novel and facile protocols for the pentafluoroethylation, heptafluoropropylation
and ethoxycarbonyldifluoromethylation of functionalised aromatic triazenes as well as new insights
into the mechanism of these reactions.
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Results and Discussion
While looking for a new transformation protocol to convert triazenes into the corresponding CF3ꢀ
arenes, we found that addition of an Ag(I)ꢀsalt leads to formation of the orthoꢀtrifluoromethylated
aromatic triazene. After optimization of the reaction conditions we investigate that this reaction
worked best when “AgCF3” was generated in perfluorohexane. This was surprising because
perfluorohexane has no stabilizing effects on metallic species. When the reaction was performed in
more chelating solvents like dimethylformamide (DMF) or acetonitrile at 100 °C,
perfluoroethylated byproducts were observed.8 Encouraged by these findings, we imagined that this
protocol, which is generally based on a “AgRf” species, is not only suitable for the
trifluoromethylation reaction but also for the introduction of other perfluoroalkylated chains.
Therefore, it was reasonable to test whether a simple change of the perfluoroalkyl source would
allow access to other “AgRf” species, leading to further perfluoroalkylated aromatic triazenes. The
required aromatic triazenes for this conversion can be easily synthesised by a oneꢀstep procedure
starting from commercially available aniline derivatives.9 Triazenes, as stable protected diazonium
salts, can be isolated, stored and are known to undergo a number of further transformations on the
aromatic core.10 Furthermore, the triazene moiety itself offers access to various functional groups
(e. g. halides, amines, alcohols), which makes them versatile intermediates in organic synthesis.11
Hence, we synthesized several functionalised aromatic triazenes and started to explore the
pentafluoroethylation using (pentafluoroethyl)trimethylsilane (TMSꢀC2F5) instead of TMSꢀCF3. In
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analogy to the generation of “AgCF3”, the preparation of “AgC2F5” is known in solvents like DMF
and triethylamine.12 Thus “AgC2F5” was generated in situ in the presence of the triazene using
TMSꢀC2F5/AgF in perfluorohexane as solvent. As shown in Table 1, the desired conversion
occurred in good yields under precipitation of elemental silver. In analogy to the
trifluoromethylation reaction, the pentafluoroethylation also showed a high orthoꢀselectivity,
especially when paraꢀsubstituted triazenes were used (1a–e).
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TABLE 1. Pentafluoroethylation of different aromatic triazenes.
Entry
R
monoꢀortho 2 (%)a
diꢀortho 3 (%)a
Yield (%)c
ab
bb
cb
d
4ꢀI
62
53
43
64
45
69
17
79
63
55
64
56
69
4ꢀBr
10
4ꢀCl
12
49
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4ꢀF
traces
11
e
4ꢀCOOEt
2ꢀMe, 4ꢀCN
f
ꢀ
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g
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ꢀ
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Reaction conditions: 1 (0.40 mmol), TMSꢀC2F5 (0.80 mmol), AgF (1.60 mmol), C6F14 (1 mL), 100
°C, 4 h. a)Isolated yields. b)Monoꢀ and diꢀorthoꢀpentafluoroethylated products could not be
separated by column chromatography. c)Combined yields of isolated monoꢀ and diꢀortho fluorinated
products.
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When the paraꢀposition was not blocked by a prior introduced functional group, the para, orthoꢀ
disubstituted triazene was found as major side product (~14%) along with the orthoꢀ
pentafluoroethylated as main product. Functional groups like iodides, bromides, fluorides, chlorides
as well as ethoxy or nitrile groups are tolerated, which make these compounds interesting for further
functionalization such as crossꢀcoupling reactions. Surprisingly, the ratio between monoꢀ and diꢀ
ortho pentafluoroethylated products differed significantly between the paraꢀhalogenated triazenes
1a–c and the paraꢀfluoroꢀsubstituted triazene 1d. While triazenes 1a–c showed between 10% and
17% of diꢀorthoꢀpentafluoroethylated byproduct, only trace amounts of diꢀortho substituted
byproduct could be isolated in the case of the paraꢀfluorotriazene 1d. Recently, the Sanford group
showed that in general the transfer of a C3F7ꢀgroup to benzene is possible using Ag(I).6 Starting
from commercially available TMSꢀC3F7 and AgF this reaction could be also accomplished in
presence of different functionalized aromatic triazenes under our conditions. In analogy to the prior
reaction, the corresponding perfluoroꢀalkylated triazenes were obtained in good yields (41–77%, for
the orthoꢀposition) and good orthoꢀselectivity (Table 2). In case of triazene 1g the para, orthoꢀ
disubstituted triazene was also found as major side product (~16%).
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TABLE 2. Heptafluoropropylation of different aromatic triazenes.
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Entry
R
monoꢀortho 4 (%)a
diꢀortho 5 (%)a
Yield (%)c
ab
bb
cb
db
e
4ꢀI
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64
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49
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19
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4ꢀBr
4ꢀCl
4ꢀF
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4ꢀCOOEt
18
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f
2ꢀMe, 4ꢀCN 70
g
2ꢀI
41
ꢀ
Reaction conditions: 1 (0.40 mmol), TMSꢀC3F7 (0.80 mmol), AgF (1.60 mmol), C6F14 (1 mL), 100
°C, 4 h. a)Isolated yields. b)Monoꢀ and diꢀorthoꢀheptafluoropropylated products could not be
separated by column chromatography. c)Combined yields of isolated monoꢀ and diꢀortho fluorinated
products.
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With these results in hand we tried to expand this kind of reaction to other fluorinated TMSꢀsources
like difluoromethyl precursors. Lately, TMSꢀCF2H, which is easily prepared from TMSꢀCF3 and
NaBH4,13 was introduced as difluoromethylation agent for aromatic halides.14 However, when we
tested the difluoromethylation of aromatic triazenes under our conditions, only traces of the desired
product could be observed via GCMS analysis. Neither an increase of the TMSꢀCF2H or the AgF
equivalents nor an elongation of the reaction time did lead to higher conversion.
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Amii and coꢀworkers reported the use of TMSꢀCF2COOEt as a precursor for the generation of
difluoromethyl groups.15 Following their oneꢀstep procedure, this agent could be obtained starting
from commercially available ClCF2COOEt. However, using the latter fluorinating agent under the
previously optimized reaction conditions resulted in only poor yield (32% mono orthoꢀ
ethoxycarbonyldifluoromethylated product in case of triazene 1b). We therefore doubled the TMSꢀ
CF2COOEt equivalents and elongated the reaction time. After these modifications the desired
ethoxycarbonylated products could be obtained in good yields (Table 3).
TABLE 3. Ethoxycarbonyldifluoromethylation of different aromatic triazenes.
Entry
R
monoꢀortho
6 diꢀortho 7 (%)a
Yield (%)b
(%)a
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a
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4ꢀCl
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4ꢀF
4ꢀCOOEt
4ꢀCN
Reaction conditions: 1 (0.40 mmol), TMSꢀCF2COOEt (1.60 mmol), AgF (1.60 mmol), C6F14 (1
a)
b)
mL), 100 °C, 4 h. Isolated yields. Combined yields of isolated monoꢀ and diꢀortho fluorinated
products.
It is interesting to note that triazenes 1c, 1d and 1e yielded more diꢀortho substituted triazene (7c,
7d, 7e) than monoꢀsubstituted triazene (6c, 6d, 6e), which might be a result of the higher
equivalents of the fluorinating source. Nonetheless, this observation along with the different ratios
between the ortho and diꢀortho products in the perfluoroalkylation reactions could be also explained
by the nonꢀhomogeneous reaction media. In fact, fluorinated solvents like perfluorohexane show in
general nearly no solubility for nonꢀfluorinated substrates and act most probably just as an inert heat
carrier. Aromatic triazenes are also not soluble in perfluorohexane but after the reactions were
completed, the formerly colourless perfluorohexane phases were coloured slightly yellow which
might be explained by the partial solubility of the perfluoroalkylated triazenes (most probable the
diperfluoroalkylated triazenes).
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It is known that perfluoroalkyl silver compounds decompose to radical intermediates.16
Nevertheless, until recently, it was not possible to use these perfluoroalkyl radicals for synthetic
purposes like aromatic substitution reactions. Due to the fact that aromatic triazenes show such
promising results in aromatic perfluoroalkylation reactions under these conditions, we imagined that
somehow the “AgCF3” species is stabilised by coordination to the triazene moiety, since
stabilization of “AgCF3” through Nꢀdonor solvents like triethylamine or acetonitrile is known.
Furthermore, such a coordination could also explain the high ortho selectivity because of the
proximity to the orthoꢀposition. Naumann et al. showed that in solution an equilibrium between
AgCF3 and [Ag(CF3)2]– exists, and its ratio depends on the donor ability of the solvent.12 For
example, this equilibrium is completely shifted towards the neutral species in triethylamine.
Therefore, we investigated whether there is an influence on this equilibrium in the presence of
aromatic triazenes. In acetonitrile, both species can be observed by 19F NMR spectroscopy and the
ratio between the neutral and ionic species was found to be 1:3.9. When one equivalent of triazene
1c was added, this equilibrium slightly changed to 1:3.3 (see SI). Compared to the influence of
triethylamine, these observations do not clearly indicate an interaction. Therefore, we further
examined the trifluoromethylation reaction under solvent free (neat) conditions and in triethylamine
as solvent. We thought that if there is an interaction between AgCF3 and the triazene moiety which
is responsible for the good yields and good selectivity compared to other substrates, the reaction
should be suppressed on one hand when a strong stabilizing donor solvent like triethylamine is
present whereas on the other hand the reaction should work under neat conditions comparable to
our standard protocol. These assumptions could be confirmed: while the reaction proceeds smoothly
under neat conditions, the reaction was completely suppressed in triethylamine (Scheme 2).
Recently, we could also show that the ortho selectivity is lost when steric more demanding silver
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organyls are used, which can be explained by the fact that the steric hindrance of these substrates
does not allow coordination to the triazene moiety.17
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SCHEME 2. Trifluoromethylation of the triazene 1a under solvent free conditions. Reaction
conditions: 1a (0.40 mmol), TMSꢀCF3 (0.80 mmol), AgF (1.60 mmol), 100 °C, 4 h. Isolated yields
are shown. For the molecular structure of 9a see SI.
Nevertheless, when we wanted to expand the substrate spectrum to other aromatic substrates like
electron rich anilines (primary and tertiary), electron poor aromatic nitriles or azides, no conversion
was observed via 19F NMR spectroscopy. Only anisoles and thioanisoles led to a conversion of
around 40%. However, compared to paraꢀsubstituted aromatic triazenes 4ꢀiodoanisole and 4ꢀ
bromothioanisole showed only a slight preference for the orthoꢀposition (in both cases ~30%) over
the metaꢀposition (~10% for both cases) (results not shown). These observations were surprising
because we expected some sort of interaction between AgCF3 and these compounds under our
conditions as well. Therefore, we performed quantum chemical calculations of the reaction energies
for the addition of a trifluoromethyl radical towards these arenes. As it is shown in Table 4 the
reaction energies for the paraꢀsubstituted aromatic nitrile and azide are lower than for anisole and
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significantly lower than for aromatic triazenes. These values directly reflect the ability of the radical
intermediate to stabilize the unpaired electron, for example via delocalization. Especially for
triazenes much higher reaction energies for the orthoꢀsubstitution have been calculated. Therefore,
stabilizing effects of the triazene moiety via e. g. delocalization could be also responsible for the
higher orthoꢀselectivity compared to the anisole substrate where the energy difference for orthoꢀ
and metaꢀsubstitution is much smaller. However, for a more thorough understanding of the
reactivity and selectivity, it might be necessary to identify the structures and relative energies of the
corresponding transition states. Other mechanism like an oxidative aromatic substitution
mechanism can also not be ruled out but seem to be rather unlikely under our reaction conditions.18
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TABLE 4. Reaction energies (TPSS; B3LYP in brackets; reaction energy = –[Eproduct–Ereactant])
for the addition of a trifluoromethyl radical to various 4-iodosubstituted aromatic com-
pounds. All values are given in kJ/mol.
Entry
R
ortho 10
meta 11
ꢀE(ortho–meta)
12 (12)
a
CN
N3
50 (51)
54 (55)
38 (39)
42 (44)
b
12 (11)
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OMe
57 (59)
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9 (10)
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N3(iPr)2
28 (26)
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Based on these results, we propose that the high yields (compared to other arenes) as well as the
good regioselectivity of these reactions in the presence of triazenes can be explained by i) a
coordination of a neutral AgCF3 species towards the triazene moiety, which enables the generation
of a CF3ꢀradical next to the orthoꢀposition of the aromatic core and ii) a good stabilisation of the
radical intermediate by the triazene moiety.
SCHEME 3. Transformation of the triazene moiety into the azide 12 and the iodide 13.
As previously mentioned, aromatic triazenes offer various functionalization possibilities, which
makes this reaction interesting for the synthesis of fluorinated building blocks. Exemplarily, the
conversion of the pentafluoroethylated triazene 2e to the corresponding azide19 (12) and iodide20
(13) is shown in scheme 3.
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Conclusion
In conclusion,
we
report
pentafluoroethylation,
heptafluoropropylation
and
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ethoxycarbonyldifluoromethylation of functionalized aromatic triazenes by simple CHꢀsubstitution.
In all cases, the desired fluorinated products could be obtained in a high orthoꢀselectivity and
mostly good yields. The transformation possibilities of the triazene moiety make these reactions
interesting for the synthesis of fluorinated building blocks. Furthermore, we could show that the
similar trifluoromethylation reaction is also possible under neat conditions whereas this reaction is
completely suppressed in triethylamine as a solvent. These observations combined with the fact that
nonꢀfluorinated triazenes showed nearly no solubility in perfluorohexane indicate a stabilizing
interaction between AgRf and the triazene moiety. This kind of coordination might be responsible
for the good regioselectivity of these transformations. Nevertheless, first quantum chemical
calculations suggest that the stabilization of the radical intermediate plays also an important role in
terms of reactivity and selectivity but further investigations are necessary to get a more thorough
understanding.
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Experimental Section
Computational details: All calculations presented in this work were performed using density
functional theory methods as implemented in the TURBOMOLE program package.21 The structures
of reactants and radical intermediates were optimized with the TPSS22 and B3LYP23 functionals in
combination with the dhfꢀTZVP24basis set employing tight convergence criteria (SCF energy: 10−8
Eh, energy gradient: 10−5 Eh/a0), fine quadrature grids (m5)25 and including the derivatives of
quadrature weights. In case of TPSS, the efficient resolutionꢀofꢀtheꢀidentity (RI) approximation for
twoꢀelectron Coulomb integrals was used. Vibrational frequencies for all species were computed in
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the harmonic approximation and the reported reaction energies are zero point vibrational energy
corrected.
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General procedure for the perfluoroethylation of triazenes: A vial equipped with a septum and a
stirring bar was charged with 202 mg (1.60 mmol) of AgF and the triazene (0.40 mmol). The
reaction vessel was closed and perfluorohexane (1 mL) was added via syringe under argon
atmosphere. Then 154 mg (0.80 mmol) of TMSꢀC2F5 was added and the suspension was heated to
100 °C. The reaction mixture was stirred for 4 hours. Then, the solution was cooled to room
temperature and ethyl acetate was added and was stirred for 5 min. The solution was poured into a
flask and silica gel was added. Finally, the solvent was removed in vacuum and the crude product
was purified by flash column chromatography (silica gel, solvent).
(E)ꢀ1ꢀ(4ꢀiodoꢀ2ꢀ(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (2a) and (E)ꢀ1ꢀ(4ꢀiodoꢀ2,6ꢀ
bis(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (3a)
19
The product was obtained as an inseparable mixture (3.6:1, determined by F NMR) of (E)ꢀ1ꢀ(4ꢀ
iodoꢀ2ꢀ(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene
and
(E)ꢀ1ꢀ(4ꢀiodoꢀ2,6ꢀ
bis(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene after flash column chromatography
(cyclohexane) as a yellow oil. 151 mg of a mixture (62% monoꢀortho, 17% diꢀortho). Rf = 0.43 (2a)
(cyclohexane) and Rf = 0.48 (3a) (cyclohexane). Data for 2a: 1H NMR (400 MHz, CDCl3): δ = 1.24
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(d, J = 6.8 Hz, 6 H), 1.39 (d, J = 6.6 Hz, 6 H), 4.04 (sept, J = 6.6 Hz, 1 H), 5.17 (sept, J = 6.8
Hz, 1 H), 7.30 (d, 3J = 8.7 Hz, 1 H), 7.74 (dd, 3J = 8.7 Hz, 4J = 2.0 Hz, 1 H), 7.84 (d, 4J = 2.0 Hz, 1
1
H) ppm. – 13C NMR (100 MHz, CDCl3): δ = 19.1, 23.8, 47.4, 49.7, 87.1, 112.7 (tq, J = 256.6 Hz,
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2J = 39.7 Hz), 118.4 (qt, J = 287.4 Hz, 2J = 39.0 Hz), 119.6, 123.1 (t, J = 21.9 Hz), 136.5 (t, J =
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9.5 Hz), 141.1, 150.2 ppm. – 19F NMR (367 MHz, CDCl3): δ = –82.8 (m, 3 F), –108.9 (m, 2 F)
ppm. – MS (70 eV, EI), m/z (%): 449 (54) [M+], 348 (20) [M+–C6H14N], 320 (46) [M+–C6H14N3],
271 (100) [M+–C7H14N3F2]. – HRMS (C14H17IN3F5 [M+]): calcd. 449.0387; found 449.0388. Data
for 3a: 1H NMR (400 MHz, CDCl3): δ = 1.21 (d, 3J = 6.8 Hz, 6 H), 1.28 (d, 3J = 6.6 Hz, 6 H), 3.96
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(sept, J = 6.6 Hz, 1 H), 5.17 (sept, J = 6.8 Hz, 1 H), 8.02 (s, 2 H) ppm. – C NMR (100 MHz,
CDCl3): δ = 19.0, 23.0, 45.7, 49.1, 86.3, 124.6 (t, 2J = 22.1 Hz), 140.8 (t, 3J = 8.8 Hz), 153.3 ppm. –
19F NMR (367 MHz, CDCl3): δ = –82.8 (m, 6 F), –106.8 (m, 4 F) ppm. – MS (70 eV, EI), m/z (%):
527 (21) [M+], 466 (5) [M+–C6H14N], 438 (9) [M+–C6H14N3], 388 (38) [M+–C7H14N3F2]. – HRMS
(C16H16IN3F10 [M+]): calcd. 527.0229; found 527.0226. – IR (KBr, mixture of 2a and 3a): ν˜ = 2977
(w), 2935 (w), 1562 (vw), 1470 (w), 1414 (m), 1393 (w), 1367 (w), 1327 (w), 1292 (w), 1274 (w),
1199 (m), 1159 (w), 1129 (w), 1097 (w), 1071 (w), 1030 (w), 976 (w), 888 (vw), 828 (vw), 750
(vw), 691 (vw), 652 (vw), 549 (vw) cm–1.
(E)ꢀ1ꢀ(4ꢀbromoꢀ2ꢀ(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (2b) and (E)ꢀ1ꢀ(4ꢀbromoꢀ
2,6ꢀbis(pentafluoroꢀethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (3b)
19
The product was obtained as an inseparable mixture (5.7:1, determined by F NMR) of (E)ꢀ1ꢀ(4ꢀ
bromoꢀ2ꢀ(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene
and
(E)ꢀ1ꢀ(4ꢀbromoꢀ2,6ꢀ
bis(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene after flash column chromatography
(cyclohexane) as a yellow oil. 104 mg of a mixture (53% monoꢀortho, 10% diꢀortho). Rf = 0.28
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(2b/3b) (cyclohexane). Data for 2b: H NMR (400 MHz, CDCl3): δ = 1.23 (d, J = 6.8 Hz, 6 H),
1.40 (d, 3J = 6.6 Hz, 6 H), 4.04 (sept, J = 6.6 Hz, 1 H), 5.17 (sept, J = 6.8 Hz, 1 H), 7.46 (d, J =
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8.8 Hz, 1 H), 7.54 (dd, J = 8.8 Hz, 4J = 2.2 Hz, 1 H), 7.68 (d, J = 2.2 Hz, 1 H) ppm. – 13C NMR
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4
(100 MHz, CDCl3): δ = 19.1, 23.8, 47.4, 49.7, 113.9 (tq, 1J = 256.7 Hz, 2J = 39.6 Hz), 116.9, 119.4,
119.5 (qt, 1J = 287.2 Hz, 2J = 39.0 Hz), 122.8 (t, J = 22.1 Hz), 130.7 (t, 3J = 9.6 Hz), 135.2, 149.6
2
ppm – 19F NMR (367 MHz, CDCl3): δ = –82.8 (m, 3 F, CF3), –109.0 (m, 2 F, CF2) ppm. – MS
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(70 eV, EI), m/z (%): 401 (8) [M+], 301 (8) [M+–C6H14N], 273 (13) [M+–C6H14N3], 222 (44) [M+–
C6H14N1Br], 100 (100) [C6H14N]. – HRMS (C14H17BrN3F5 [M+]): calcd. 401.0526; found 401.0524.
Data for 3b: 1H NMR (400 MHz, CDCl3): δ = 1.22 (d, 3J = 6.8 Hz, 6 H), 1.28 (d, 3J = 6.6 Hz, 6 H),
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3.97 (sept, J = 6.6 Hz, 1 H), 5.18 (sept, J = 6.8 Hz, 1 H), 7.87 (s, 2 H) ppm. – 13C NMR
(100 MHz, CDCl3): δ = 19.1, 23.1, 45.7, 49.1, 116.8, 124.5 (t, 2J = 22.3 Hz), 135.1 (t, 3J = 8.8 Hz),
152.7 ppm. – 19F NMR (367 MHz, CDCl3): δ = –82.8 (m, 6 F), –106.8 (m, 4 F) ppm. – MS (70 eV,
EI), m/z (%): 519 (2) [M+], 340 (7) [M+–C6H14NBr]. – HRMS (C16H16IN3F10 [M+]): calcd.
519.0368; found 519.0369. – IR (KBr, mixture of 2b and 3b): ν˜ = 2978 (w), 2936 (w), 2874 (vw),
1569 (vw), 1473 (m), 1396 (m), 1368 (m), 1327 (w), 1296 (w), 1271 (m), 1200 (s), 1158 (m), 1128
(m), 1095 (m), 1068 (m), 1031 (m), 980 (m), 887 (w), 829 (w), 750 (vw), 697 (w), 655 (vw), 551
(w) cm–1.
(E)ꢀ1ꢀ(4ꢀchloroꢀ2ꢀ(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (2c) and (E)ꢀ1ꢀ(4ꢀchloroꢀ
2,6ꢀbis(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (3c)
19
The product was obtained as an inseparable mixture (3.6:1, determined by F NMR) of (E)ꢀ1ꢀ(4ꢀ
chloroꢀ2ꢀ(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene
and
(E)ꢀ1ꢀ(4ꢀchloroꢀ2,6ꢀ
bis(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene after flash column chromatography
(cyclohexane) as a yellow oil. 84 mg of a mixture (43% monoꢀortho, 12% diꢀortho). Rf = 0.52
(2c/3c) (cyclohexane/ethyl acetate = 90:1). Data for 2c: 1H NMR (400 MHz, CDCl3): δ = 1.24 (d, 3J
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= 6.8 Hz, 6 H), 1.40 (d, J = 6.6 Hz, 6 H), 4.04 (sept, J = 6.6 Hz, 1 H), 5.18 (sept, J = 6.8 Hz, 1
H), 7.40 (dd, J = 8.8 Hz, J = 2.3 Hz, 1 H), 7.51–7.54 (m, 2 H) ppm. – 13C NMR (100 MHz,
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2
1
CDCl3): δ = 19.1, 23.8, 47.3, 49.6, 114.0 (tq, J = 256.3 Hz, J = 39.7 Hz), 119.1, 119.3 (qt, J =
287.2 Hz, 2J = 39.0 Hz), 122.4 (t, J = 22.2 Hz), 127.8 (t, J = 9.6 Hz), 129.4, 132.3, 149.2 ppm. –
19F NMR (367 MHz, CDCl3): δ = –82.9 (m, 3 F), –109.1 (m, 2 F) ppm. – MS (70 eV, EI), m/z (%):
357 (10) [M+], 257 (27) [M+–C6H14N], 229 (22) [M+–C6H14N3], 179 (63) [M+– C7H14F2N3], 100
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(100) [C6H14N]. – HRMS (C14H17ClN3F5 [M+]): calcd. 357.1031; found 357.1032. – Data for 3c: 1H
NMR (400 MHz, CDCl3): δ = 1.22 (d, 3J = 6.8 Hz, 6 H), 1.28 (d, 3J = 6.6 Hz, 6 H), 3.97 (sept, 3J =
13
6.6 Hz, 1 H), 5.19 (sept, 3J = 6.8 Hz, 1 H), 7.73 (s, 2 H) ppm. – C NMR (100 MHz, CDCl3): δ =
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19.0, 23.1, 45.7, 49.0, 113.2 (tq, J = 257.8 Hz, J = 39.4 Hz), 119.1 (qt, J = 287.5 Hz, J = 38.3
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Hz), 124.3 (t, J = 22.2 Hz), 129.8, 132.3 (t, J = 9.1 Hz), 152.2 ppm. – F NMR (367 MHz,
CDCl3): δ = –82.86 (m, 6 F), –106.96 (m, 4 F) ppm. – MS (70 eV, EI), m/z (%): 475 (20) [M+], 375
(10) [M+–C6H14N], 347 (11) [M+–C6H14N3], 297 (49) [M+– C7H14F2N3], 100 (100) [C6H14N]. –
HRMS (C16H16ClN3F10 [M+]): calcd. 475.0873; found 475.0870. – IR (KBr, mixture of 2c and 3c):
ν˜ = 2979 (m), 2937 (w), 1573 (w), 1476 (m), 1425 (m), 1399 (m), 1368 (m), 1328 (m), 1298 (m),
1270 (m), 1202 (s), 1159 (m), 1129 (m), 1100 (m), 1069 (m), 1031 (m), 985 (m), 912 (w), 888 (w),
857 (w), 832 (w), 795 (vw), 765 (w), 750 (w), 709 (w), 662 (w), 613 (w), 593 (w), 555 (w), 441
(vw) cm–1.
(E)ꢀ1ꢀ(4ꢀfluoroꢀ2ꢀ(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (2d)
The product was obtained after flash column chromatography (cyclohexane) as a slightly yellow oil.
87 mg (64%). Rf = 0.39 (cyclohexane). 1H NMR (400 MHz, CDCl3): δ = 1.24 (d, 3J = 6.8 Hz, 6 H),
1.39 (d, 3J = 6.5 Hz, 6 H), 4.02 (sept, 3J = 6.5 Hz, 1 H), 5.16 (sept, 3J = 6.8 Hz, 1 H), 7.17–7.20 (m,
13
1 H), 7.25–7.28 (m, 1 H), 7.51–7.55 (m, 1 H) ppm. – C NMR (100 MHz, CDCl3): δ = 19.2, 23.8,
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47.1, 49.4, 114.6 (dt, J = 25.4 Hz, J = 9.5 Hz), 119.3 (d, J = 21.8 Hz), 119.34 (d, J = 7.7 Hz),
147.0, 159.4 (d, 1J = 243.8 Hz) ppm. – 19F NMR (367 MHz, CDCl3): δ = –82.9 (m, 3 F), –109.0 (m,
2 F), –118.5 (s, 1 F) ppm. – IR (KBr): ν˜ = 2978 (vw), 1612 (vw), 1488 (w), 1405 (m), 1368 (w),
1312 (w), 1266 (w), 1253 (w), 1207 (m), 1157 (w), 1119 (w), 1097 (w), 1063 (w), 1032 (w), 1002
(w), 913 (vw), 866 (w), 825 (w), 742 (w), 674 (vw), 621 (vw), 603 (vw), 567 (w), 533 (vw), 489
(vw), 449 (vw), 421 (vw) cm–1. – MS (70 eV, EI), m/z (%): 341 (57) [M+], 241 (37) [M+–C6H14N],
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213 (35) [M+–C6H14N3], 163 (100) [M+–C7H14N3F2]. – HRMS (C14H17N3F6 [M+]): calcd. 341.1326;
found 341.1324.
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The product was obtained after flash column chromatography (cyclohexane/ethyl acetate = 70:1) as
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a yellow oil. 71 mg (45%). Rf = 0.21 (cyclohexane/ethyl acetate = 90:1). H NMR (400 MHz,
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CDCl3): δ = 1.25 (d, J = 6.8 Hz, 6 H), 1.40 (t, J = 7.1 Hz, 3 H), 1.41 (d, J = 6.6 Hz, 6 H), 4.08
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(sept, J = 6.6 Hz, 1 H), 4.38 (q, J = 7.1 Hz, 2 H), 5.23 (sept, J = 6.8 Hz, 1 H), 7.62 (d, J = 8.6
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Hz, 1 H), 8.10 (dd, J = 8.6 Hz, J = 1.9 Hz, 1 H), 8.26 (d, J = 1.9 Hz, 1 H) ppm. – C NMR
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(100 MHz, CDCl3): δ = 14.3, 19.1, 23.7, 47.8, 50.0, 61.0, 114.3 (tq, J = 256.2 Hz, J = 39.6 Hz),
117.5, 119.6 (qt, 1J = 287.3 Hz, 2J = 39.2 Hz), 121.1 (t, 2J = 22.2 Hz), 125.9, 130.0 (t, 3J = 9.3 Hz),
133.4, 153.8, 165.8 ppm. – 19F NMR (367 MHz, CDCl3): δ = ꢀ82.8 (m, 3 F), –109.0 (m, 2 F) ppm. –
IR (KBr): ν˜ = 2980 (m), 2937 (w), 1719 (s), 1609 (m), 1468 (m), 1400 (s), 1366 (s), 1301 (m),
1251 (s), 1198 (s), 1158 (m), 1128 (s), 1068 (m), 1029 (m), 994 (m), 925 (w), 891 (m), 853 (m),
772 (w), 741 (w), 696 (w), 657 (w), 553 (vw) cm–1. – MS (70 eV, EI), m/z (%): 395 (32) [M+], 350
(11) [M+–C2H5O], 295 (6) [M+–C6H14N], 267 (48) [M+–C6H14N3], 217 (100) [M+–C7H14N3F2]. –
HRMS (C17H22O2N3F5 [M+]): calcd. 395.1632; found 395.1633.
(E)ꢀ1ꢀ(4ꢀethoxycarbonylꢀ2,6ꢀbis(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (3e)
The product was obtained after flash column chromatography (cyclohexane/ethyl acetate = 70:1) as
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a yellow oil. 22 mg (11%). Rf = 0.29 (cyclohexane/ethyl acetate = 90:1). H NMR (400 MHz,
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CDCl3): δ = 1.22 (d, J = 6.8 Hz, 6 H), 1.30 (d, J = 6.6 Hz, 6 H), 1.42 (t, J = 7.1 Hz, 3 H), 3.99
(sept, 3J = 6.6 Hz, 1 H), 4.43 (q, 3J = 7.1 Hz, 2 H), 5.20 (sept, 3J = 6.8 Hz, 1 H), 8.42 (s, 2 H) ppm.
– 13C NMR (100 MHz, CDCl3): δ = 14.3, 19.1, 23.1, 45.9, 49.2, 61.8, 113.6 (tq, J = 257.3 Hz, 2J =
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39.3 Hz), 119.0 (qt, J = 287.0 Hz, J = 38.7 Hz), 123.0 (t, J = 22.3 Hz), 126.4, 133.4 (t, J = 8.7
Hz), 157.1, 164.4 ppm. – 19F NMR (367 MHz, CDCl3): δ = –82.8 (s, 6 F), –106.8 (s, 4 F) ppm. – IR
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(KBr): ν˜ = 2980 (m), 2932 (m), 1730 (s), 1612 (m), 1433 (s), 1369 (s), 1327 (m), 1206 (s), 1162
(s), 1132 (s), 1088 (m), 1031 (s), 991 (w), 930 (w), 912 (w), 897 (w), 882 (w), 768 (w), 755 (w),
738 (w), 717 (w), 700 (m), 638 (vw), 572 (vw), 540 (vw) cm–1. – MS (70 eV, EI), m/z (%): 513 (28)
[M+], 468 (10) [M+–C2H5O], 413 (9) [M+–C6H14N], 385 (29) [M+–C6H14N3], 335 (100) [M+–
C7H14N3F2]. – HRMS (C19H21O2N3F10 [M+]): calcd. 513.1474; found 513.1475.
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(E)ꢀ1ꢀ(2ꢀpentafluoroethylꢀ4ꢀcyanoꢀ6ꢀ(methyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (2f)
The product was obtained after flash column chromatography (cyclohexane/ethyl acetate = 90:1) as
1
a yellow oil. 100 mg (69%). Rf = 0.21 (cyclohexane/ethyl acetate = 90:1). H NMR (400 MHz,
CDCl3): δ = 1.26 (d, 3J = 6.8 Hz, 6 H), 1.31 (d, 3J = 6.6 Hz, 6 H), 2.21 (s, 3 H), 4.02 (sept, 3J = 6.6
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Hz, 1 H), 5.24 (sept, J = 6.8 Hz, 1 H), 7.62 (s, 1 H), 7.71 (s, 1 H) ppm. – C NMR (100 MHz,
CDCl3): δ = 19.1, 19.7, 23.7, 46.2, 49.2, 107.4, 113.7 (tq, 1J = 256.8 Hz, 2J = 39.7 Hz), 118.3, 119,0
(qt, 1J = 287.0 Hz, 2J = 38.8 Hz), 122.7 (t, 2J = 22.1 Hz), 129.9 (t, 3J = 9.3 Hz), 133.0, 137.7, 154.7
ppm. – 19F NMR (367 MHz, CDCl3): δ = –82.9 (m, 3 F), –108.8 (m, 2 F) ppm. – IR (KBr): ν˜ =
2979 (w), 2936 (w), 2876 (vw), 2229 (w), 1604 (w), 1469 (w), 1407 (m), 1368 (m), 1309 (w), 1257
(w), 1228 (m), 1169 (m), 1119 (m), 1036 (m), 1000 (w), 894 (m), 828 (w), 763 (vw), 726 (vw), 608
(vw) cm–1. – MS (70 eV, EI), m/z (%): 362 (20) [M+], 262 (6) [M+–C6H14N], 234 (36) [M+–
C6H14N3] 184 (100) [M+–C7H14N3F2]. – HRMS (C16H19N4F5 [M+]): calcd. 362.1529; found
362.1529.
(E)ꢀ1ꢀ(2ꢀiodoꢀ6ꢀ(pentafluoroethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (2g)
The product was obtained after flash column chromatography (cyclohexane) as a yellow oil. 78 mg
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(43%). Rf = 0.18 (cyclohexane). 1H NMR (400 MHz, CDCl3): δ = 1.28 (d, J = 6.8 Hz, 6 H, CH3),
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1.37 (d, J = 6.6 Hz, 6 H), 4.03 (sept, J = 6.6 Hz, 1 H), 5.18 (sept, J = 6.8 Hz, 1 H), 6.95 (t, J =
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7.9 Hz, 1 H), 7.54 (d, J = 7.9 Hz, 1 H), 8.04 (d, J = 7.9 Hz, 1 H) ppm. –13C NMR (100 MHz,
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CDCl3): δ = 19.1, 23.7, 46.2, 49.3, 93.7, 113.6 (tq, J = 256.5 Hz, J = 39.3 Hz), 119.1 (qt, J =
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287.1 Hz, 2J = 38.9 Hz), 121.9 (t, J = 22.0 Hz), 125.7, 128.3 (t, J = 8.3 Hz), 143.3, 153.1 ppm. –
19F NMR (367 MHz, CDCl3): δ = –83.2 (s, 3 F), –108.5 (s, 2 F) ppm. – IR (KBr): ν˜ = 2976 (m),
2934 (w), 1586 (w), 1468 (m), 1421 (m), 1405 (m), 1382 (m), 1368 (m), 1329 (m), 1279 (m), 1195
(s), 1148 (m), 1132 (m), 1097 (m), 1079 (m), 1032 (m), 978 (m), 916 (w), 776 (w), 759 (w), 727
(w), 698 (m), 658 (vw), 549 (vw) cm–1. – MS (70 eV, EI), m/z (%): 449 (61) [M+], 321 (12) [M+–
C6H14N3] 271 (15) [M+–C7H14N3F2], 100 (100) [C6H14N]. – HRMS (C14H17IN3F5 [M+]): calcd.
449.0387; found 449.0389.
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General procedure for the perfluoropropylation of triazenes: A vial equipped with a septum
and a stirring bar was charged with 202 mg (1.60 mmol) of AgF and the triazene (0.40 mmol). The
reaction vessel was closed and perfluorohexane (1 mL) was added via syringe under argon
atmosphere. Then 0.16 mL (195 mg, 0.80 mmol) of TMSꢀC3F7 was added and the suspension was
heated to 100 °C. The reaction mixture was stirred for 4 hours. Then, the solution was cooled to
room temperature and ethyl acetate was added and was stirred for 5 min. The solution was poured
into a flask and silica gel was added. Finally, the solvent was removed in vacuum and the crude
product was purified by flash column chromatography (silica gel, solvent). Note: 13C NMR analysis
of the perfluoropropyl group was not possible due to the complexity of the signals.
(E)ꢀ1ꢀ(4ꢀiodoꢀ2ꢀ(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (4a) and (E)ꢀ1ꢀ(4ꢀiodoꢀ2,6ꢀ
bis(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (5a)
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The product was obtained as an inseparable mixture (2.7:1, determined by F NMR) of (E)ꢀ1ꢀ(4ꢀ
iodoꢀ2ꢀ(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene
and
(E)ꢀ1ꢀ(4ꢀiodoꢀ2,6ꢀ
bis(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene after flash column chromatography
(cyclohexane) as a yellow oil. 148 mg of a mixture (50% monoꢀortho, 19% diꢀortho). Rf = 0.45
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(4a/5a) (cyclohexane). Data for 4a: H NMR (400 MHz, CDCl3): δ = 1.21 (d, J = 6.8 Hz, 6 H),
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1.37 (d, 3J = 6.6 Hz, 6 H), 4.03 (sept, J = 6.6 Hz, 1 H), 5.16 (sept, J = 6.8 Hz, 1 H), 7.29 (d, J =
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8.7 Hz, 1 H), 7.73 (dd, J = 8.7 Hz, 4J = 2.0 Hz, 1 H), 7.82 (d, J = 2.0 Hz, 1 H) ppm. – 13C NMR
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(100 MHz, CDCl3): δ = 19.1, 23.8, 47.3, 49.6, 87.0, 119.6, 123.1 (t, 2J = 22.2 Hz), 136.7 (t, 3J = 9.7
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Hz), 141.1, 150.5 ppm. – 19F NMR (367 MHz, CDCl3): δ = –80.33 (t, 3J = 10.0 Hz, 3 F), –105.6 (m,
2 F), –124.1 (s, 2 F) ppm. – MS (70 eV, EI), m/z (%): 499 (35) [M+], 398 (8) [M+–C6H14N], 370
(15) [M+–C6H14N3], 100 (100) [C6H14N]. – HRMS (C15H17IN3F7 [M+]): calcd. 499.0355; found
499.0357. Data for 5a: 1H NMR (400 MHz, CDCl3): δ = 1.18 (d, 3J = 6.8 Hz, 6 H), 1.28 (d, 3J = 6.6
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Hz, 6 H), 3.94 (sept, J = 6.6 Hz, 1 H), 5.21 (sept, J = 6.8 Hz, 1 H, CH), 8.02 (s, 2 H) ppm. – C
NMR (100 MHz, CDCl3): δ = 19.0, 23.1, 45.2, 48.8, 86.3, 124.6 (t, 2J = 22.2 Hz), 141.1 (t, 3J = 8.6
Hz), 154.0 ppm. – 19F NMR (367 MHz, CDCl3): δ = –80.3 (t, 3J = 10.2 Hz, 6 F), –103.5 (m, 4 F), –
124.4 (s, 4 F) ppm. – MS (70 eV, EI), m/z (%): 667 (43) [M+], 566 (2) [M+–C6H14N], 538 (12) [M+–
C6H14N3]. – HRMS (C18H16IN3F14 [M+]): calcd. 667.0165; found 667.0163. – IR (KBr, mixture of
4a and 5a): ν˜ = 2979 (m), 2937 (w), 1563 (vw), 1470 (m), 1416 (s), 1393 (m), 1382 (m), 1368 (m),
1345 (s), 1273 (m), 1229 (vs), 1199 (s), 1158 (m), 1127 (m), 1110 (s), 1073 (w), 1053 (m), 1031
(m), 959 (w), 940 (w), 909 (m), 877 (m), 853 (vw), 828 (w), 750 (w), 725 (w), 690 (w), 550 (w)
cm–1.
(E)ꢀ1ꢀ(4ꢀbromoꢀ2ꢀ(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (4b) and (E)ꢀ1ꢀ(4ꢀbromoꢀ
2,6ꢀbis(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (5b)
The product was obtained as an inseparable mixture (5:1, determined by 19F NMR) of (E)ꢀ1ꢀ(4ꢀ
bromoꢀ2ꢀ(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene
and
(E)ꢀ1ꢀ(4ꢀbromoꢀ2,6ꢀ
bis(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene after flash column chromatography
(cyclohexane) as a yellow oil. 148 mg of a mixture (64% monoꢀortho, 13% diꢀortho). Rf = 0.44
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(4b/5b) (cyclohexane). Data for 4b: H NMR (400 MHz, CDCl3): δ = 1.22 (d, J = 6.8 Hz, 6 H,),
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1.40 (d, 3J = 6.6 Hz, 6 H), 4.04 (sept, J = 6.6 Hz, 1 H), 5.17 (sept, J = 6.8 Hz, 1 H), 7.46 (d, J =
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8.8 Hz, 1 H), 7.55 (dd, J = 8.8 Hz, 4J = 2.2 Hz, 1 H), 7.65 (d, J = 2.2 Hz, 1 H) ppm. – 13C NMR
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7
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(100 MHz, CDCl3): δ = 19.1, 23.8, 47.3, 49.6, 116.8, 119.4, 122.8 (t, J = 22.3 Hz), 130.8 (t, J =
9.8 Hz), 135.3, 149.8 ppm. – 19F NMR (367 MHz, CDCl3): δ = –80.4 (t, 3J = 10.0 Hz, 3 F, CF3), –
105.7 (m, 2 F), –124.2 (m, 2 F) ppm. – MS (70 eV, EI), m/z (%): 451 (8) [M+], 351 (1) [M+–
C6H14N], 325 (2) [M+–C6H14N3], 100 (100) [C6H14N]. – HRMS (C15H17BrN3F7 [M+]): calcd.
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451.0494; found 451.0497. Data for 5b: H NMR (400 MHz, CDCl3): δ = 1.17 (d, J = 6.8 Hz, 6
H), 1.27 (d, 3J = 6.6 Hz, 6 H), 3.95 (sept, 3J = 6.6 Hz, 1 H), 5.23 (sept, 3J = 6.8 Hz, 1 H), 7.87 (s, 2
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H) ppm. – C NMR (100 MHz, CDCl3): δ = 19.0, 23.1, 45.2, 48.8, 116.7, 124.6 (t, J = 22.7 Hz),
132.5 (t, 3J = 9.0 Hz), 153.4 ppm. – 19F NMR (367 MHz, CDCl3): δ = –80.3 (t, 3J = 10.1 Hz, 6 F), –
103.6 (m, 4 F), 124.4 (m, 4 F) ppm. – MS (70 eV, EI), m/z (%): 619 (4) [M+], 519 (1) [M+–
C6H14N], 100 (100) [C6H14N]. – HRMS (C18H16BrN3F14 [M+]): calcd. 619.0304; found 619.0303. –
IR (KBr, mixture of 4b and 5b): ν˜ = 2979 (m), 2937 (w), 2875 (w), 1568 (w), 1473 (m), 1421 (s),
1396 (s), 1383 (s), 1369 (s), 1345 (s), 1271 (s), 1228 (s), 1196 (s), 1158 (m), 1127 (s), 1111 (s),
1054 (m), 1031 (m), 959 (w), 941 (m), 911 (m), 878 (m), 854 (w), 829 (m), 778 (w), 749 (m), 726
(w), 694 (m), 651 (w) cm–1.
(E)ꢀ1ꢀ(4ꢀchloroꢀ2ꢀ(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (4c) and (E)ꢀ1ꢀ(4ꢀchloroꢀ
2,6ꢀbis(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (5c)
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The product was obtained as an inseparable mixture (6.8:1, determined by F NMR) of (E)ꢀ1ꢀ(4ꢀ
chloroꢀ2ꢀ(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene
and
(E)ꢀ1ꢀ(4ꢀchloroꢀ2,6ꢀ
bis(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene after flash column chromatography
(cyclohexane/ethyl acetate = 90:1) as a yellow oil. 103 mg of a mixture (52% monoꢀortho, 8% diꢀ
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ortho). Rf = 0.75 (4c/5c) (cyclohexane/ethyl acetate = 90:1). Data for 4c: H NMR (400 MHz,
CDCl3): δ = 1.22 (d, 3J = 6.8 Hz, 6 H), 1.40 (d, 3J = 6.6 Hz, 6 H), 4.04 (sept, 3J = 6.6 Hz, 1 H), 5.16
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(sept, J = 6.8 Hz, 1 H), 7.42 (dd, J = 8.8 Hz, J = 2.2 Hz, 1 H), 7.50–7.52 (m, 2 H) ppm. – C
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NMR (100 MHz, CDCl3): δ = 19.1, 23.8, 47.3, 49.6, 119.1, 122.5 (t, 2J = 22.6 Hz), 128.0 (t, 3J = 9.8
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7
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Hz), 129.4, 132.4, 149.4 ppm. – 19F NMR (367 MHz, CDCl3): δ = –80.3 (t, J = 10.0 Hz, 3 F), –
105.7 (m, 2 F), –124.2 (m, 2 F) ppm. – MS (70 eV, EI), m/z (%): 407 (31) [M+], 307 (17) [M+–
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C6H14N], 278 (40) [M+–C6H14N3], 229 (28) [M+–C7H14F2N3], 179 (62) [M+–C8H14F4N3], 100 (100)
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[C6H14N]. – HRMS (C15H17ClN3F7 [M+]): calcd. 407.0999; found 407.0997. – Data for 5c: H
NMR (400 MHz, CDCl3): δ = 1.17 (d, 3J = 6.8 Hz, 6 H), 1.27 (d, 3J = 6.6 Hz, 6 H), 3.95 (sept, 3J =
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6.6 Hz, 1 H), 5.23 (sept, 3J = 6.8 Hz, 1 H), 7.72 (s, 2 H) ppm. – C NMR (100 MHz, CDCl3): δ =
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19.0, 23.1, 45.2, 48.8, 124.3 (t, J = 22.9 Hz), 129.7, 132.5 (t, J = 9.3 Hz), 152.9 ppm. – 19F NMR
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(367 MHz, CDCl3): δ = –80.3 (t, J = 10.1 Hz, 6 F), –103.7 (m, 4 F), –124.4 (m, 4 F) ppm. – MS
(70 eV, EI), m/z (%): 575 (5) [M+], 475 (4) [M+–C6H14N], 447 (5) [M+–C6H14N3], 397 (4) [M+–
C7H14F2N3], 100 (100) [C6H14N]. – HRMS (C18H16ClN3F14 [M+]): calcd. 575.0809; found
575.0808. – IR (KBr, mixture of 4c and 5c): ν˜ = 2979 (w), 2937 (w), 1475 (w), 1423 (m), 1399
(m), 1368 (w), 1346 (m), 1295 (w), 1269 (m), 1227 (m), 1195 (m), 1158 (w), 1127 (w), 1111 (m),
1054 (w), 1031 (w), 944 (w), 917 (w), 880 (w), 854 (vw), 831 (w), 786 (vw), 749 (w), 706 (w), 682
(vw), 579 (vw), 551 (vw) cm–1.
(E)ꢀ1ꢀ(4ꢀfluoroꢀ2ꢀ(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (4d) and (E)ꢀ1ꢀ(4ꢀfluoroꢀ
2,6ꢀbis(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (5d)
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The product was obtained as an inseparable mixture (6.8:1, determined by F NMR) of (E)ꢀ1ꢀ(4ꢀ
fluoroꢀ2ꢀ(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene
and
(E)ꢀ1ꢀ(4ꢀfluoroꢀ2,6ꢀ
bis(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene after flash column chromatography
(cyclohexane) as a yellow oil. 91 mg of a mixture (49% monoꢀortho, 7% diꢀortho). Rf = 0.32
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(4d/5d) (cyclohexane). Data for 4d: H NMR (400 MHz, CDCl3): δ = 1.23 (d, J = 6.8 Hz, 6 H),
1.39 (d, 3J = 6.6 Hz, 6 H), 4.02 (sept, 3J = 6.6 Hz, 1 H), 5.16 (sept, 3J = 6.8 Hz, 1 H), 7.16–7.21 (m,
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1 H), 7.24–7.27 (m, 1 H), 7.52–7.56 (m, 1 H) ppm. – C NMR (100 MHz, CDCl3): δ = 19.2, 23.8,
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47.0, 49.4, 114.8 (dt, J = 25.5 Hz, J = 9.8 Hz), 119.37 (d, J = 7.8 Hz), 119.44 (d, J = 21.9 Hz),
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122.4 (dt, J = 22.6 Hz, J = 6.9 Hz), 147.3, 159.3 (d, J = 243.9 Hz) ppm. – 19F NMR (367 MHz,
CDCl3): δ = –80.4 (t, 3J = 9.9 Hz, 3 F), –105.7 (m, 2 F), –118.6 (s, 1 F), –124.3 (s, 2 F) ppm. – MS
(70 eV, EI), m/z (%): 391 (25) [M+], 291 (26) [M+–C6H14N], 263 (34) [M+–C6H14N3], 213 (22)
[M+–C7H14N3F2], 100 (100) [C6H14N]. – HRMS (C15H17N3F8 [M+]): calcd. 391.1294; found
391.1293. Data for 5d: 1H NMR (400 MHz, CDCl3): δ = 1.19 (d, 3J = 6.8 Hz, 6 H), 1.28 (d, 3J = 6.6
Hz, 6 H), 3.95 (sept, 3J = 6.6 Hz, 1 H), 5.24 (sept, 3J = 6.8 Hz, 1 H), 8.02 (d, 3J = 8.5 Hz, 2 H) ppm.
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– C NMR (100 MHz, CDCl3): δ = 19.0, 23.1, 45.1, 48.7, 119.8 (d, J = 25.1 Hz), 124.4 (dt, J =
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1
19
23.2 Hz, J = 6.1 Hz), 133.0, 158.1 (d, J = 245.2 Hz) ppm. – F NMR (367 MHz, CDCl3): δ = –
80.3 (t, 3J = 10.1 Hz, 6 F), –103.7 (m, 4 F), –116.5 (s, 1 F), –124.5 (s, 4 F) ppm. – MS (70 eV, EI),
m/z (%): 560 (100) [M++H]. – HRMS (C18H17N3F15 [M++H]): calcd. 560.1183; found 560.1185. –
IR (KBr, mixture of 4d and 5d): ν˜ = 2980 (s), 2937 (w), 1611 (s), 1489 (m), 1433 (m), 1408 (s),
1383 (m), 1369 (m), 1347 (m), 1311 (m), 1267 (m), 1253 (m), 1226 (s), 1182 (s), 1158 (m), 1109
(m), 1049 (w),1032 (m), 981 (w), 965 (w), 950 (m), 913 (w), 880 (w), 857 (w), 838 (m), 822 (w),
748 (m), 684 (w), 625 (vw) cm–1.
(E)ꢀ1ꢀ(4ꢀethoxycarbonylꢀ2ꢀ(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (4e)
The product was obtained after flash column chromatography (cyclohexane/ethyl acetate = 90:1) as
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a yellow oil. 77 mg (43%). Rf = 0.31 (cyclohexane/ethyl acetate = 70:1). H NMR (400 MHz,
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CDCl3): δ = 1.25 (d, J = 6.8 Hz, 6 H), 1.40 (t, J = 7.1 Hz, 3 H), 1.41 (d, J = 6.6 Hz, 6 H), 4.08
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3
3
3
(sept, J = 6.6 Hz, 1 H), 4.38 (q, J = 7.1 Hz, 2 H), 5.23 (sept, J = 6.8 Hz, 1 H), 7.61 (d, J = 8.6
3
4
4
13
Hz, 1 H), 8.11 (dd, J = 8.6 Hz, J = 1.8 Hz, 1 H), 8.24 (d, J = 1.8 Hz, 1 H) ppm. – C NMR
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(100 MHz, CDCl3): δ = 14.3, 19.1, 23.8, 47.7, 49.9, 61.1, 117.5, 121.1 (t, J = 22.2 Hz), 125.9,
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130.2 (t, J = 9.5 Hz), 133.4, 154.0, 165.8 ppm. – F NMR (367 MHz, CDCl3): δ = –80.3 (t, J =
10.0 Hz, 3 F), –105.7 (m, 2 F), –124.2 (m, 2 F) ppm. – IR (KBr): ν˜ = 2981 (m), 2937 (w), 1720 (s),
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1608 (m), 1573 (w), 1468 (w), 1401 (s), 1383 (m), 1366 (m), 1346 (m), 1300 (m), 1250 (s), 1225
(s), 1195 (s), 1158 (m), 1109 (s), 1054 (w), 1030 (m), 955 (w), 940 (w), 922 (w), 856 (w), 773 (w),
749 (w), 694 (w), 654 (vw), 576 (w), 554 (vw) cm–1. – MS (70 eV, EI), m/z (%): 445 (28) [M+], 400
(7) [M+–C2H5O], 345 (4) [M+–C6H14N], 317 (23) [M+–C6H14N3], 217 (10) [M+–C8H14N3F4], 100
(100) [C6H14N]. – HRMS (C18H22O2N3F7 [M+]): calcd. 445.1600; found 445.1602.
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(E)ꢀ1ꢀ(4ꢀethoxycarbonylꢀ2,6ꢀbis(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (5e)
The product was obtained after flash column chromatography (cyclohexane/ethyl acetate = 70:1) as
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a yellow oil. 42 mg (18%). Rf = 0.43 (cyclohexane/ethyl acetate = 70:1). H NMR (400 MHz,
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CDCl3): δ = 1.18 (d, J = 6.8 Hz, 6 H), 1.30 (d, J = 6.6 Hz, 6 H), 1.42 (t, J = 7.1 Hz, 3 H), 3.97
(sept, 3J = 6.6 Hz, 1 H), 4.45 (q, 3J = 7.1 Hz, 2 H), 5.24 (sept, 3J = 6.8 Hz, 1 H), 8.41 (s, 2 H) ppm.
– 13C NMR (100 MHz, CDCl3): δ = 14.3, 18.9, 23.1, 45.4, 48.9, 61.8, 123.1 (t, 2J = 22.5 Hz), 126.5,
133.7 (t, 3J = 8.6 Hz), 157.8, 164.4 ppm. – 19F NMR (367 MHz, CDCl3): δ = –80.2 (t, 3J = 10.2 Hz,
6 F), –103.6 (m, 4 F), –124.4 (s, 4 F, CF2CF2CF3) ppm. – IR (KBr): ν˜ = 3094 (vw), 2983 (s), 2940
(m), 2878 (w), 1730 (s), 1612 (m), 1577 (w), 1434 (s), 1370 (s), 1345 (s), 1320 (s), 1230 (s), 1159
(s), 1113 (s), 1075 (s), 1054 (m), 1031 (m), 965 (m), 950 (m), 926 (m), 911 (w), 869 (m), 768 (m),
751 (m), 739 (w), 726 (m), 696 (m), 582 (w), 538 (w) cm–1. – MS (70 eV, EI), m/z (%): 613 (16)
[M+], 513 (3) [M+–C6H14N], 485 (8) [M+–C6H14N3], 385 (6) [M+–C8H14N3F4], 100 (100) [C6H14N].
– HRMS (C21H21O2N3F14 [M+]): calcd. 613.1410; found 613.1407.
(E)ꢀ1ꢀ(2ꢀheptafluoropropylꢀ4ꢀcyanoꢀ6ꢀ(methyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (4f)
The product was obtained after flash column chromatography (cyclohexane/ethyl acetate = 90:1) as
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a yellow oil. 115 mg (70%). Rf = 0.11 (cyclohexane/ethyl acetate = 90:1). H NMR (400 MHz,
CDCl3): δ = 1.23 (d, 3J = 6.8 Hz, 6 H), 1.32 (d, 3J = 6.6 Hz, 6 H), 2.21 (s, 3 H), 4.02 (sept, 3J = 6.6
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Hz, 1 H), 5.27 (sept, J = 6.8 Hz, 1 H), 7.63 (s, 1 H), 7.69 (s, 1 H) ppm. – C NMR (100 MHz,
CDCl3): δ = 19.1, 19.8, 23.7, 46.0, 49.1, 107.3, 118.3, 122.8 (t, 2J = 22.2 Hz), 130.2 (t, 3J = 9.6 Hz),
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132.9, 137.8, 154.9 ppm. – 19F NMR (367 MHz, CDCl3): δ = ꢀ80.29 (t, J = 10.2 Hz, 3 F, CF3), –
105.6 (m, 2 F), –124.4 (m, 2 F) ppm. – IR (KBr): ν˜ = 2979 (m), 2937 (w), 2230 (w), 1603 (w),
1469 (m), 1408 (m), 1382 (m), 1368 (m), 1348 (m), 1308 (w), 1257 (m), 1229 (s), 1206 (s), 1160
(m), 1113 (s), 1032 (w), 1011 (w), 965 (w), 945 (m), 894 (w), 809 (w), 739 (w), 722 (w), 586 (vw),
514 (vw) cm–1. – MS (70 eV, EI), m/z (%): 412 (32) [M+], 312 (16) [M+–C6H14N], 284 (100) [M+–
C6H14N3], 234 (36) [M+–C7H14N3F2], 184 (92) [M+–C8H14N3F4]. – HRMS (C17H19N4F7 [M+]):
calcd. 412.1497; found 412.1499.
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(E)ꢀ1ꢀ(2ꢀiodoꢀ6ꢀ(heptafluoropropyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (4g)
product was obtained after flash column chromatography (cyclohexane) as a yellow oil. 83 mg
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(41%). Rf = 0.12 (cyclohexane). H NMR (400 MHz, CDCl3): δ = 1.27 (d, J = 6.8 Hz, 6 H), 1.36
(d, 3J = 6.6 Hz, 6 H), 4.02 (sept, 3J = 6.6 Hz, 1 H), 5.20 (sept, 3J = 6.8 Hz, 1 H), 6.95 (t, 3J = 7.9 Hz,
1 H), 7.52 (d, 3J = 7.9 Hz, 1 H), 8.05 (d, 3J = 7.9 Hz, 1 H) ppm. – 13C NMR (100 MHz, CDCl3): δ =
19.1, 23.8, 46.0, 49.3, 93.5, 122.1 (t, 2J = 22.1 Hz), 125.7, 128.5 (t, 3J = 8.8 Hz), 143.4, 153.3 ppm.
– 19F NMR (367 MHz, CDCl3): δ = –80.3 (s, 3 F), –105.3 (m, 2 F), –124.6 (s, 2 F) ppm. – IR (KBr):
ν˜ = 2977 (s), 1585 (w), 1468 (w), 1420 (m), 1368 (m), 1345 (m), 1269 (m), 1228 (s), 1206 (m),
1158 (m), 1130 (m), 1111 (m), 1076 (w), 1060 (w), 1031 (w), 939 (w), 922 (w), 892 (m), 772 (w),
753 (w), 732 (w), 697 (m), 589 (vw), 547 (vw) cm–1. – MS (70 eV, EI), m/z (%): 499 (24) [M+], 399
(5) [M+–C6H14N], 371 (34) [M+–C6H14N3], 244 (41) [M+–C7H14N3I], 100 (100) [C6H14N]. – HRMS
(C15H17IN3F7 [M+]): calcd. 499.0355; found 499.0354.
General procedure for the ethoxycarbonyldifluoromethylation of triazenes: A vial equipped
with a septum and a stirring bar was charged with 202 mg (1.60 mmol) of AgF and the triazene
(0.40 mmol). The reaction vessel was closed and perfluorohexane (1 mL) was added via syringe
under argon atmosphere. Then 315 mg (1.60 mmol) of TMSꢀCF2COOEt was added and the
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suspension was heated to 100 °C. The reaction mixture was stirred for 16 h. Then, the solution was
cooled to room temperature and ethyl acetate was added and was stirred for 5 min. The solution was
poured into a flask and silica gel was added. Finally, the solvent was removed in vacuum and the
crude product was purified by flash column chromatography (silica gel, solvent).
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(E)ꢀ1ꢀ(4ꢀiodoꢀ2ꢀ(ethoxycarbonyldifluoromethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (6a)
The product was obtained after flash column chromatography (cyclohexane/ethyl acetate = 50:1) as
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a slightly yellow oil. 51 mg (28%). Rf = 0.30 (cyclohexane/ethyl acetate = 50:1). H NMR (400
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MHz, CDCl3): δ = 1.19 (d, 3J = 6.8 Hz, 6 H), 1.22 (t, J = 7.1 Hz, 3 H), 1.37 (d, J = 6.6 Hz, 6 H),
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4.00 (sept, 3J = 6.6 Hz, 1 H), 4.22 (q, J = 7.1 Hz, 2 H), 5.05 (sept, J = 6.8 Hz, 1 H), 7.29 (d, J =
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8.7 Hz, 1 H), 7.70 (dd, J = 8.7 Hz, 4J = 1.9 Hz, 1 H), 7.98 (d, J = 1.9 Hz, 1 H) ppm. – 13C NMR
(100 MHz, CDCl3): δ = 13.9, 19.2, 24.0, 47.3, 49.1, 62.3, 87.4, 112.3 (t, 1J = 247.6 Hz), 128.5 (t, 2J
= 23.2 Hz), 117.8, 134.2 (t, 3J = 8.6 Hz), 140.1, 148.2 (t, 3J = 4.3 Hz), 163.7 (t, 3J = 34.4 Hz) ppm.
– 19F NMR (367 MHz, CDCl3): δ = –101.6 (s, 2 F) ppm. – IR (KBr): ν˜ = 2976 (w), 2925 (w), 1772
(w), 1469 (w), 1396 (m), 1381 (w), 1366 (w), 1289 (w), 1264 (w), 1240 (m), 1216 (w), 1156 (w),
1095 (m), 1082 (m), 1058 (w), 1029 (m), 890 (vw), 825 (w), 761 (w), 690 (vw), 595 (vw), 557
(vw), 452 (vw) cm–1. – MS (70 eV, EI), m/z (%): 453 (13) [M+], 100 (78) [C6H14N], 43 (100). –
HRMS (C16H22N3O2F2I [M+]): calcd. 453.0724; found 453.0727.
(E)ꢀ1ꢀ(4ꢀiodoꢀ2,6ꢀbis(ethoxycarbonyldifluoromethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (7a)
The product was obtained after flash column chromatography (cyclohexane/ethyl acetate = 50:1) as
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an orange solid. 65 mg (28%). Rf = 0.21 (cyclohexane/ethyl acetate = 50:1). H NMR (400 MHz,
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CDCl3): δ = 1.23 (d, J = 6.8 Hz, 6 H), 1.23 (t, J = 7.1 Hz, 6 H), 1.30 (d, J = 6.7 Hz, 6 H), 3.97
(sept, 3J = 6.7 Hz, 1 H), 4.20 (q, 3J = 7.1 Hz, 4 H), 4.99 (sept, 3J = 6.8 Hz, 1 H), 8.10 (s, 2 H) ppm.
– 13C NMR (100 MHz, CDCl3): δ = 13.8, 19.2, 22.8, 46.3, 49.9, 62.6, 86.8, 111.7 (t, 1J = 249.1 Hz),
128.6 (t, 2J = 23.7 Hz), 137.5 (t, 3J = 9.1 Hz), 149.1 (t, 3J = 3.4 Hz), 162.8 (t, 2J = 34.1 Hz) ppm. –
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19F NMR (367 MHz, CDCl3): δ = –98.1 (s, 2 F) ppm. – IR (ATR): ν˜ = 2983 (vw), 2939 (vw), 1769
(m), 1452 (w), 1416 (w), 1400 (w), 1383 (w), 1369 (w), 1296 (w), 1278 (w), 1229 (m), 1190 (w),
1152 (m), 1115 (m), 1094 (m), 1068 (m), 1031 (w), 1011 (w), 917 (vw), 888 (w), 858 (w), 839 (w),
804 (vw), 782 (w), 761 (w), 737 (w), 688 (w), 636 (vw), 618 (w) cm–1. – MS (70 eV, EI), m/z (%):
575 (27) [M+], 475 (4) [M+–C6H14N], 100 (100). – HRMS (C20H26IN3O4F4 [M+]): calcd. 575.0904;
found 575.0903.
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(E)ꢀ1ꢀ(4ꢀbromoꢀ2ꢀ(ethoxycarbonyldifluoromethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (6b)
The product was obtained after flash column chromatography (cyclohexane/ethyl acetate = 70:1) as
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a slightly yellow oil. 58 mg (36%). Rf = 0.28 (cyclohexane/ethyl acetate = 50:1). H NMR (400
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MHz, CDCl3): δ = 1.19 (d, 3J = 6.8 Hz, 6 H), 1.21 (t, J = 7.1 Hz, 3 H), 1.37 (d, J = 6.6 Hz, 6 H),
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4.00 (sept, 3J = 6.6 Hz, 1 H), 4.22 (q, J = 7.1 Hz, 2 H), 5.05 (sept, J = 6.8 Hz, 1 H), 7.42 (d, J =
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8.7 Hz, 1 H), 7.50 (dd, J = 8.7 Hz, 4J = 2.1 Hz, 1 H), 7.81 (d, J = 2.1 Hz, 1 H) ppm. – 13C NMR
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(100 MHz, CDCl3): δ = 13.9, 19.2, 24.0, 47.3, 49.0, 62.3, 112.4 (t, J = 247.7 Hz), 117.0, 117.5,
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128.2 (t, J = 23.2 Hz), 128.4 (t, J = 8.6 Hz), 134.2, 147.5 (t, J = 4.2 Hz), 163.7 (t, 3J = 34.2 Hz)
ppm. – 19F NMR (367 MHz, CDCl3): δ = –101.6 (s, 2 F) ppm. – IR (KBr): ν˜ = 2979 (m), 2935 (w),
1774 (s), 1689 (vw), 1471 (m), 1400 (s), 1382 (m), 1368 (m), 1292 (m), 1263 (m), 1242 (m), 1217
(m), 1157 (m), 1133 (m), 1112 (m), 1095 (m), 1062 (w), 1017 (w), 888 (vw), 828 (w), 763 (w), 695
(vw), 568 (vw) cm–1. – MS (70 eV, EI), m/z (%): 405 (12) [M+], 305 (4) [M+–C6H14N], 146 (100). –
HRMS (C16H22BrN3O2F2 [M+]): calcd. 405.0863; found 405.0860.
(E)ꢀ1ꢀ(4ꢀbromoꢀ2,6ꢀbis(ethoxycarbonyldifluoromethyl)phenyl)ꢀ3,3ꢀdiisopropyltriazꢀ1ꢀene (7b)
The product was obtained after flash column chromatography (cyclohexane/ethyl acetate = 70:1) as
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a nearly white solid. 68 mg (32%). Rf = 0.19 (cyclohexane/ethyl acetate = 50:1). H NMR (400
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MHz, CDCl3): δ = 1.22 (d, 3J = 6.8 Hz, 6 H), 1.23 (t, J = 7.1 Hz, 6 H), 1.31 (d, J = 6.7 Hz, 6 H),
3.97 (sept, 3J = 6.7 Hz, 1 H), 4.20 (q, 3J = 7.1 Hz, 4 H), 5.00 (sept, 3J = 6.8 Hz, 1 H), 7.93 (s, 2 H)
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