1-Aryl-3,3-diisopropyltriazenes: An easily accessible and particularly stable class of triazenes towards strong basic and lewis acid conditions

Article abstract of DOI:10.1002/ejoc.200800154

The stability of various substituted aryl-3,3-dialkyltriazenes, valuable synthetic intermediates, under several reaction conditions has been evaluated. To do so, anthranilonitrile and 2-amino-6-(trifluoromethyl)benzonitrile have been reacted in the presence of different secondary amines to the corresponding 1-(2-R-phenyl)-3,3-dialkyltriazenes. These compounds have been submitted to a series of different reaction conditions with special emphasis on strong basic and metal/acid reductive conditions in order to test the stability of the triazene moiety under these circumstances. Generally, triazenes are unstable in metal/acid reducing conditions. A lot of 1-aryl-3,3-dialkyltriazenes are known to undergo deprotonation in α-position of N-3 in the presence of strong bases, thus limiting the scope of action of this class of compounds. Among the tested substances, most triazenes were stable in the presence of titanium isopropoxide and/or strong nucleophiles. 1-(2-R-phenyl)-3,3-diisopropyltriazenes turned out to be particularly stable under strong basic conditions. 1,2-addition reactions in the presence of Grignard reagents or lithiated compounds, showed in most cases no side products resulting from a degradation of the triazene function. The same was true for the titanium-catalyzed Kulinkovich-de Meijere cyclopropanation or for reductive amination. In both cases, no triazene degradation products could be detected. 1-(2-R-phenyl)-3,3- diisopropyltriazenes were even stable in the presence of strong Lewis acids like trimethylaluminium. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejoc.200800154

FULL PAPER
DOI: 10.1002/ejoc.200800154
1-Aryl-3,3-diisopropyltriazenes: An Easily Accessible and Particularly Stable
Class of Triazenes Towards Strong Basic and Lewis Acid Conditions
Rüdiger Reingruber,[a] Sylvia Vanderheiden,[a] Alfred Wagner,[a] Martin Nieger,[b]
Thierry Muller,[a] Mazen Es-Sayed,[c] and Stefan Bräse*[a]
Keywords: Triazenes / Synthetic intermediates / Heterocycles / Cyclopropanation / Reductive amination
The stability of various substituted aryl-3,3-dialkyltriazenes,
valuable synthetic intermediates, under several reaction con-
ditions has been evaluated. To do so, anthranilonitrile and
2-amino-6-(trifluoromethyl)benzonitrile have been reacted in
the presence of different secondary amines to the corre-
Among the tested substances, most triazenes were stable in
the presence of titanium isopropoxide and/or strong nucleo-
philes. 1-(2-R-phenyl)-3,3-diisopropyltriazenes turned out to
be particularly stable under strong basic conditions. 1,2-ad-
dition reactions in the presence of Grignard reagents or lithi-
sponding 1-(2-R-phenyl)-3,3-dialkyltriazenes. These com- ated compounds, showed in most cases no side products re-
pounds have been submitted to a series of different reaction
conditions with special emphasis on strong basic and metal/
acid reductive conditions in order to test the stability of the
triazene moiety under these circumstances. Generally, triaz-
enes are unstable in metal/acid reducing conditions. A lot of
1-aryl-3,3-dialkyltriazenes are known to undergo deproton-
ation in α-position of N-3 in the presence of strong bases,
thus limiting the scope of action of this class of compounds.
sulting from a degradation of the triazene function. The same
was true for the titanium-catalyzed Kulinkovich–de Meijere
cyclopropanation or for reductive amination. In both cases,
no triazene degradation products could be detected. 1-(2-R-
phenyl)-3,3-diisopropyltriazenes were even stable in the
presence of strong Lewis acids like trimethylaluminium.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
ses of N-heterocycles. This huge class of compounds is part
of innumerable natural products.[3,5a] Thus, triazenes as pro-
tected diazonium ions are valuable synthetic intermediates.
Triazenes can also be readily converted to azides, another
widely used functional group. We have developed a one pot
synthesis of aryl azides via post-cleavage modification of
polymer-bound triazenes.[7a,7b] Recently, Knochel et al. re-
ported a method starting from triazenes and inorganic so-
dium azide in the presence of KHSO4 or BF3·OEt2/TFA.[7c]
All in all, triazenes represent a versatile and easily accessible
class of compounds.
There are however some major drawbacks which con-
siderably limit the use of 1-aryl-3,3-dialkyltriazenes as syn-
thetic intermediates. First of all, most triazenes readily de-
compose under metal/acid reducing conditions.[9] Secondly,
triazenes tend to be deprotonated at the α-position of N-3
in strongly basic conditions which normally goes along with
a fragmentation of the triazene moiety.[10] In some cases,
this base liability was used to react the formed anions with
electrophiles resulting in a triazene containing a modified
alkyl group on N-3.[11] In most cases, it is however seriously
limiting the use of 1-aryl-3,3-dialkyltriazenes as synthetic
intermediates.
Introduction
Triazenes, especially 1-aryl-3,3-dialkyltriazenes, make up
a very versatile and useful class of compounds.[1] They are
stable during palladium-mediated cross-coupling reac-
tions[2] and act as ligands in organometallic syntheses.[3]
They can easily be converted into iodoarenes and are regu-
larly used to prepare extended phenylacetylene systems.[3]
Triazenes have found application in total synthesis[4] and
are extensively used in solid phase chemistry as traceless
linker.[5] Above all, they commonly act as amine and/or dia-
zonium salt protecting groups[6] and azide precursors.[7] Tri-
azenes tend to be acid-labile and generally decompose in
the presence of Brønsted or Lewis acids to the correspond-
ing amines and diazonium salts. This acid-catalyzed degra-
dation yielding reactive diazonium ions which occurs as
well under physiological conditions, is at least partially re-
sponsible for the potent biological activities of triazenes.[8]
Aside, diazonium salts play an important role in the synthe-
[a] Institut für Organische Chemie, Universität Karlsruhe (TH),
Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
Fax: +49-721-608-8581
Here we report on the syntheses of a series of 1-(2-R-
phenyl)-3,3-dialkyltriazenes having different alkyl groups
on N-3 and two different aryl substituents on N-1. We then
investigated the stability of the triazene moiety under
E-mail: braese@ioc.uka.de
[b] Laboratory of Inorganic Chemistry, Department of Chemistry,
P. O. Box 55, 00014 University of Helsinki, Finland
[c] Bayer CropSscience AG, CS – R Dis I,
Alfred-Nobel-Str. 50, 40789 Monheim, Germany
3314
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Particularly Stable Triazenes
strongly basic, metal/acid reductive conditions. Some com- amino-3-(trifluoromethyl)benzonitrile (7b) with respectively
pounds were even reacted in the presence of strong Lewis pyrrolidine (8a), piperidine (8b), diethyl- (8c) or diisopro-
acids. It turned out that the most stable triazenes bear iso- pylamine (8d) (Scheme 1, Table 1).
propyl groups as substituents on N-3. In most cases, no
triazene fractioning or alkylation of an isopropyl group
could be detected in the presence of strong bases or electro-
philes and the prepared diisopropyltriazenes were even
stable in the presence of strong Lewis acids. Some of these
findings might have been predictable and one may find an
explanation in the pKb values of the different substituents.
It is nevertheless remarkable that to the best of our knowl-
Scheme 1. Syntheses of the different triazenes via Method A: 1.
HClaq., NaNO2; 2. amine, KOHaq., 0 °C or Method B: 1. BF3·Et2O,
tert-BuONO, THF; 2. amine, pyridine, CH3CN, –20 °C.
edge there are no examples in the literature about the use
of 1-(2-R-phenyl)-3,3-diisopropyltriazenes as synthetic in-
termediates.
Results and Discussion
Table 1. Yields of the different triazene syntheses.
1-(2-R-phenyl)-3,3-dialkyltriazenes are useful intermedi-
ates which can easily be prepared in multigram quantities
from the corresponding aniline derivatives and secondary
amines. A lot of trisubstituted triazenes are however known
to be unstable in the presence of strong bases. Figure 1
shows commonly used compounds 1–6 whose triazene
function is deprotonated in α-position of N-3 under strong
basic conditions.
Entry Method
R1
Amine
Product
Yield (%)
1
2
3
4
5
6
7
A
A
A
A
B
B
B
H
H
H
H
H
pyrrolidine
piperidine
diethylamine
diisopropylamine
diisopropylamine
9a
9b
9c
9d
9d
9e
9f
40
55
59
26
75
77
48
CF3 diisopropylamine
CF3 diethylamine
Triazenes 9a–c have been obtained using method A, that
is, preparation of the diazonium salt starting from 7a in
the presence of HCl, NaNO2 followed by its addition to
an aqueous solution of amines 8a–d respectively and KOH
(entries 1–3).[13] If diisopropylamine (8d) was treated with
7a, the classic conditions delivered the desired triazene 9d
in only poor yield along with a lot of unreacted starting
material (entry 4). The same was true when aniline deriva-
tive 7b and amine 8d were reacted following method A
(data not shown).
This problem could however be overcome using method
B (Scheme 1, Table 1). Starting from 7a,b, the respective di-
azonium ion was obtained in the presence of boron trifluo-
ride–diethyl ether and tert-butyl nitrite in THF. It was then
added to a solution of pyridine and amines 8c,d respectively
in acetonitrile which provided triazenes 9d–f in moderate to
excellent yields (entries 5–7).[14] With all the different triaz-
enes 9a–f in hand, we started investigating their stability
towards different reaction conditions.
Figure 1. Triazenes known to undergo deprotonation in α-position
of N-3 under strong basic conditions.[10,11]
Most importantly, to avoid this deprotonation is of
course the choice of suitable alkyl substituents on N-3. The
aryl substituent on N-1 on the other hand, should also have
its significance as it is also known to influence the acid-
catalyzed cleavage of triazenes.[12]
In order to evaluate the stability of differently trisubsti-
tuted triazenes, we prepared a sequence of compounds
which were subsequently submitted to reactions employing
strong basic as well as acid/metal reducing conditions. Syn-
thesized 3,3-diisopropyltriazenes were even reacted in the
presence of a strong Lewis acid without altering the triaz-
ene function.
Figure 2 shows the molecular structures of compounds
9a,d,e. One can see that at least in the solid state, the triaz-
ene moiety and the nitrile function of compounds 9a,d are
oriented in order to minimize joint steric hindrance
(Figure 2 top and middle). This changes when another sub-
stituent is added.
Comparing compounds 9d and 9e which differ by an ad-
ditional CF3 substituent Figure 2 (middle and bottom), re-
veals that the triazene in 9e is shielding the nitrile function.
Design and Synthesis of the Triazenes
Bearing the above mentioned considerations in mind, we This could result in a reduced reactivity of the latter. On
prepared triazenes 9a–f reacting either anthranilonitrile (7a) the other hand, one could state that this engenders a more
or its more electron-withdrawing fluorinated analog 2- stable triazene moiety.
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S. Bräse et al.
FULL PAPER
ide, boron trifluoride–diethyl ether and ethylmagnesium
bromide in ether in poor to modest yields (Scheme 2,
Table 2).[15,16]
Scheme 2. Kulinkovich–de Meijere cyclopropanation.
Table 2. Yields of the different cyclopropanation reactions.
Entry
Reactant
Product
Yield (%)
1
2
3
4
5
6
9a
9b
9c
9d
9e
9f
10a
10b
10c
10d
10e
10f
26
5
37
30
39
35
Cyclic substituents on N-3 (entries 1,2) lead to even
lower yields than the ones obtained with acyclic groups (en-
tries 3–6). No notable differences between the two aryl sub-
stituents were observed (entries 1–4 and 5–6). The moderate
yields observed can in part be explained because reactions
did not go to completion; no substantial triazene decompo-
sition products could however be detected. One can further
add that to the best of our knowledge this is the first time
that a Kulinkovich–de Meijere cyclopropanation reaction
has been reported on triazene containing compounds and
that if applied to other substrates, comparable yields have
already been reported.
1,2-Addition
Arylnitriles 9a,c–e were submitted to either methylmag-
nesium bromide or a number of lithiated compounds
(MeLi, BuLi, PhLi) under various reaction conditions
(Scheme 3, Table 3). Even with a large excess of nucleophile,
reactions did not always go to completion. In general term,
no double addition to the nitrile function of compounds
9a,c–e could be detected. In nearly all cases, the formation
of the corresponding imines was observed on TLC. Latter
was stable during the work up procedure as determined by
Figure 2. Top: Molecular structure of 9a. Displacement parameters
are drawn at 50% probability level. Middle: Molecular structure of
9d. Displacement parameters are drawn at 50% probability level.
Bottom: Molecular structure of 9e. Displacement parameters are TLC, hydrolyzed however most of the time at some stage
drawn at 50% probability level.
during the silica column chromatography (entries 3–6). It
is only by using nitrile derivative 9e bearing an additional
electron-withdrawing trifluoromethyl group on the aro-
matic nucleus, that some corresponding imines were stable
enough to be isolated in high yields after simple aqueous
workup (entries 7–9). If they were however to be purified
1-(2-R-phenyl)cyclopropylamines 10a–f were prepared on a silica column, they still did, at least partially, hydrolyze
from arylnitriles 9a–f in the presence of titanium isopropox- to give the corresponding ketones.
Titanium-Catalyzed Kulinkovich–de Meijere
Cyclopropanation
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Particularly Stable Triazenes
1,3-dimethyl-1H-indazole (11), could be isolated as major
compound in poor yield (entry 1). There are ongoing stud-
ies to improve the yield and to elucidate the mechanism of
this reaction. Ethyl or isopropyl groups on N-3 delivered
the corresponding ketones 13c and 13d in satisfactory yields
(entries 4–6) which were slightly higher for the bulkier sub-
stituents (entries 5, 6). Figure 3 shows the molecular struc-
ture of 13d. The carbonyl function seems, at least in the
solid state, to be shielded from a 1,2-addition by the triaz-
ene group (Bürgi–Dunitz).
Considering the above mentioned results, only triazene
9e bearing two isopropyl groups, was tested in the series of
the fluorinated aryl substituent (entries 7–9). 9e was treated
with different lithiated compounds, e.g. methyl-, butyl- or
phenyllithium and delivered the corresponding crude imines
12e, 14e and 16e respectively in good to excellent yields af-
ter aqueous workup.
Scheme 3. Reaction of triazenes 9a,c–e with MeMgBr or different
lithiated compounds.
Table 3. Results of the different 1,2-addition reactions.
Entry Reactant
R3X
Temperature[a]
Products Yield (%)
1
2
3
4
5
6
7
8
9
9a
9a
9a
9c
9d
9d
9e
9e
9e
MeMgBr
MeLi
MeLi
MeMgBr
MeMgBr
MeLi
MeLi
BuLi
PhLi
0 °C, reflux
–65 °C to r.t.
–65 °C to r.t., CeCl3
reflux
11
13a
12
traces
23
62
68
67
78
80
95
Reductions Using LiAlH4
13a[b]
13c[b]
13d[b]
13d[b]
13e[b]
14e
Because some triazenes are known to be sensitive
towards metal-acid reducing conditions,[9] attempts were
made to investigate the reduction of the nitrile function of
9a,c–f, as well as the reduction of imines 12e, 14e and 16e
(Scheme 4, Table 4, entries 1–8). The reduction of nitriles
9a,c,d to the corresponding primary amines 18a,c,d was
achieved in the presence of lithium aluminium hydride in
THF with excellent yields (entries 1–3). On the other hand,
in the case of arylnitriles 9e and 9f containing an additional
electron-withdrawing trifluoromethyl substituent, the ex-
pected amines 18e,f could only be obtained in poor to mod-
est yields after heating for several hours at 50 °C (entries
4,5).
reflux
0 °C to r.t.
0 °C to r.t.
–20 °C to r.t.
–20 °C to r.t.
16e
[a] All reactions were carried out in THF. [b] The corresponding
imine could be observed on TLC even after an aqueous work up
but hydrolyzed during silica column chromatography.
The substituents on N-3 of the triazene function were
crucial for the outcome of the 1,2-addition reactions. If
compound 9a, containing a pyrrolidine group, was used,
no 1,2-addition product or derivative could be isolated, no
matter what nucleophile (entries 1, 2) or which conditions
were used (entries 2, 3). TLC analysis showed multiple
spots, the corresponding compounds of which were not
characterized. If methylmagnesium bromide was employed
under reflux for several hours, an unexpected side product,
Figure 3. Molecular structure of 13d, one of the two crystallo-
graphic independent molecules is shown. Displacement parameters
are drawn at 50% probability level.
Scheme 4. Reductions of nitriles 9a,c–f, imines 12e, 14e and 16e as
well as reductive aminations of ketones 13d,e.
Eur. J. Org. Chem. 2008, 3314–3327
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S. Bräse et al.
FULL PAPER
Table 4. Conditions and yields of the different reductions and re-
ductive aminations.
Entry Reactant
Conditions
Products
Yield (%)
1
2
3
4
5
6
7
8
9
9a
9c
9d
9e
9f
12e
14e
16e
13d
LiAlH4, THF, r.t.
LiAlH4, THF, r.t.
LiAlH4, THF, r.t.
18a
18c
18d
18e/19e
18f/19f
20e
21e
22e
23d
76–90[b]
86–93[b]
quant.
57/traces[c]
25/21[c]
48[d]
LiAlH4, THF, 50 °C
LiAlH4, THF, 50 °C
LiAlH4, THF, 50 °C
LiAlH4, THF, 50 °C
LiAlH4, THF, 50 °C
51[d]
30[d]
39
[a]
1) NH3, Ti(OiPr)4
2) NaBH4, 0 °C
1) NH3, Ti(OiPr)4
[a]
Scheme 5. 1,2-Addition in the presence of a strong Lewis acid.
10
13e
20e
65
2) LiBH4, 0 °C
[a] Heated at 50 °C. [b] Depending on the reaction scale. [c] Ac-
companied by recovery of about 40% starting material. [d] Yield
over two steps (1,2-addition plus reduction).
9e, the corresponding N-tert-butylsulfinylamine 24e ob-
tained in 68% yield (Scheme 5), did not react during the
1,2-addition conditions (data not shown). It was only when
the temperature was risen, that triazene 24e started decom-
posing. The fact that the 3,3-diisopropyl-substituted com-
pounds are by far the most stable triazenes in strong basic
conditions might in part be explained by the pKb value of
the isopropyl group. Another part of the explanation may
lie in the bulkiness of this group. This system is probably
so hindered that the α-position of N-3 cannot be easily de-
protonated. This steric hindrance would also account for
the unprecedented resistance towards strong Lewis acids as
it would shield the lone pair for N-3. Finally, there is the
influence of the 1-aryl substituent on the stability of the
different triazenes. This is however not to be confused with
the expectable and observed changes of reactivity of the
other functionalities of the molecule. It is known that modi-
fications in the electron-withdrawing properties of a 1-aryl
group affect the rotational barrier around the N-2–N-3
linkage.[18] Different aryl substituents may though lead to
more or less stable triazenes. In our study, we could how-
ever conclude that a change of the electron density on the
aryl substituent did not significantly modify the stability of
the triazene functions.
Even after longer reaction times (several days) at this
temperature, we were still able to isolate about 40% of start-
ing material. Besides, amine 18f was accompanied by a side
product, 1-(diethylamino)-7-(trifluoromethyl)-1H-indazol-
3(2H)-one (19f), resulting from reaction of the triazene moi-
ety (entry 5). In the case of amine 18e, the corresponding
side product 19e could only be isolated as traces (entry 4).
Reduction of imines 12e, 14e and 16e delivered amines 20e,
21e and 22e respectively in poor to moderate yields deter-
mined over two steps (1,2-addition and reduction) (entries
6–8). Considering that the 1,2-addition reactions are high
yielding (Table 3, entries 7–9), the low overall yields are
probably due to the subsequent reduction and seem to be
correlated to the R3 substituent.
Reductive Aminations
The previously synthesized triazenyl ketones 13d and 13e
were treated with ammonia and titanium isopropoxide in
THF at 50 °C followed by addition of sodium or lithium
borohydride after cooling to 0 °C (Scheme 4, Table 4, en-
tries 9,10). The yield of the reaction is dependent on the
aryl substituent on N-1. A more electron-withdrawing aryl
group resulted in a clearly enhanced yield (entry 10).
Conclusions
1,2-Addition Reactions in the Presence of
Trimethylaluminium
1-(2-Substituted phenyl)-3,3-diisopropyltriazenes have
proven to be valuable synthetic intermediates because they
1-(2-R-Phenyl)-3,3-diisopropyltriazenes had proven to be are stable towards strong bases, tolerate metal/acid re-
stable in strong basic conditions and to tolerate acid/metal ductive conditions and most unexpected, stand strong
reductive conditions. In order to test their stability towards Lewis acids at low temperatures. Thus, 3,3-diisopropyltriaz-
strong Lewis acids, triazenes 9d,e were first converted to N- enes have the potential to substantially extend the already
tert-sulfinylamides 24d,e in the presence of butyllithium and broad application spectra of triazenes. The remarkable sta-
tert-butylsulfinyl chloride in THF at low temperature bility towards strong Lewis acids needs further studies and
(Scheme 5).[17]
is currently being investigated in our group. In the same
Subsequent 1,2-addition of phenyllithium on activated context, 3,3-diisopropyltriazenes containing differently sub-
imine 24d in the presence of trimethylaluminium provided stituted aryl moieties are at this time being prepared in or-
N-tert-butylsulfinylamine 25 in good yield. When the same der to study the stability of 1-aryl-3,3-diisopropyltriazenes
reaction sequence was performed on the fluorinated analog in general.
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Particularly Stable Triazenes
nilonitrile or 2-amino-3-(trifluoromethyl)benzonitrile (50.8 mmol)
in dry THF (70 mL) cooled to –20 °C. Then, tert-BuONO
(178 mmol) was added over 35 min, a precipitate formed during
addition. After the addition was completed, stirring was continued
at –20 °C for 30 min, then dry Et2O (20 mL) was added and the
mixture was stirred at 0 °C. After 1 h, the precipitated diazonium
salt was filtered off, washed with Et2O (3ϫ100 mL) and dried
under vacuum.
Experimental Section
General: 1H NMR spectra were recorded on a Bruker AM 400
(400 MHz) spectrometer as solutions in CDCl3. Chemical shifts are
expressed in parts per million (ppm, δ) downfield from tetramethyl-
silane (TMS) and are referenced to CHCl3 (δ = 7.26 ppm) as in-
ternal standard. All couplings constants J are absolute values (Hz).
Description of signals: s singlet, br.s broad singlet, d doublet, t
triplet, q quartet, m multiplet, dd doublet of doublets, ddd doublet
of dd, dt doublet of triplets, ddt doublet of dt, tt triplet of triplets,
quin quintet, qdd quartet of dd and sept septet. The spectra were
analyzed according to first order. The signal abbreviations include:
Ar-H for aromatic proton. 13C NMR spectra were recorded on a
Bruker AM 400 (100 MHz) spectrometer as solutions in CDCl3.
Chemical shifts are expressed in parts per million (ppm, δ) down-
field from tetramethylsilane (TMS) and are referenced to CHCl3 (δ
= 77.4 ppm) as internal standard. The signal structure was ana-
lyzed by DEPT and is described as follows: + denotes a primary
or tertiary C-atom (positive signal), – denotes a secondary C-atom
(negative signal), and q stands for a quaternary C-atom (no signal).
MS (EI) (electron-impact mass spectrometry): Finnigan MAT 90
(70 eV). The molecular fragments are quoted as the relation be-
tween mass and charge (m/z), the intensities as a percentaged value
relative to the intensity of the base signal (100%). The abbreviation
[M+] refers to the molecular ion. IR (infrared spectroscopy): FT-
IR Bruker IFS 88. IR spectra of solids were recorded in KBr, and
as thin films on KBr for oils and liquids. The deposit of the absorp-
Pyridine (7 mL) was added to a solution of amine (50.8 mmol) in
CH3CN (50 mL) cooled to 0 °C. The diazonium salt was added
portionwise to this solution which was then warmed to room temp.
overnight. H2O (150 mL) was added and the aqueous phase was
extracted with CH2Cl2 (3ϫ150 mL). The combined organic layers
were dried with MgSO4, filtered, and concentrated in vacuo. The
residue was purified by column chromatography to afford a white
solid.
General Procedure C. Kulinkovich–de Meijere Cyclopropanation of
2-Triazenylbenzonitriles 9d–f: A solution of EtMgBr (3  in Et2O,
4.00 mmol) was slowly added to a solution of triazene (2.00 mmol)
and titanium(IV) isopropoxide (2.40 mmol) in dry Et2O at –78 °C.
After stirring for 10 min at this temperature, the mixture was
warmed to room temp. within 2 h. Then BF3·OEt2 (4.00 mmol)
was added and after additional stirring for 2 h at room temp. a
10% aqueous solution of NaOH (20 mL) was added and the aque-
ous phase was extracted with EtOAc (3ϫ30 mL). The combined
organic layers were washed with brine, dried with Na2SO4 and
purified by flash column chromatography to afford a slightly yellow
oil.
tion band was given in wave numbers ν in cm–1. The forms and
˜
intensities of the bands were characterized as follows: vs very
strong 0–10% T, s strong 10–40% T, m medium 40–70% T, w weak
70–90% T, vw very weak 90–100% T, br. broad. Elemental analysis:
Elementar Vario Microcube. Descriptions without nominated tem-
perature were done at room temperature (r.t.), and the following
abbreviations were used: calcd. (theoretical value), found (mea-
sured value). Information is given in masspercent. Triazenes have
proven to easily lose molecular nitrogen during elemental analysis
which often gives diminished nitrogen content.[19] Routine moni-
toring of reactions were performed using Silica gel coated alumin-
ium plates (Merck, silica gel 60, F254), which were analyzed under
UV light (λ = 254 nm) and/or dipped into a solution of molybdato-
phosphate (5% phosphor molybdic acid in ethanol, dipping solu-
tion) and ninhydrine solution (3 g of ninhydrine in 100 mL of etha-
nol) and heated with a heat gun. Solvent mixtures are understood
as volume/volume. Solid materials were powdered. Solvents, rea-
gents and chemicals were purchased from Aldrich, Fluka and
Acros. Tetrahydrofuran was distilled from sodium/benzophenone
under argon prior use. Dichloromethane, ethyl acetate and diethyl
ether were distilled from calcium hydride. All reactions involving
moisture sensitive reactants were executed under an argon atmo-
sphere using oven dried and/or flame dried glassware. All other
solvents, reagents and chemicals were used as purchased unless
stated otherwise.
General Procedure D. Reaction of 2-Triazenylbenzonitriles with
Methylmagnesium Bromide or Different Lithiated Compounds: A
solution of Grignard or lithiated compound (1.60 mmol) was
slowly added to a solution of triazene (1.00 mmol) in dry THF
cooled to 0 °C. The resulting mixture was warmed to room temp.
After 3 h, a saturated solution of NH4Cl was added and the aque-
ous phase was extracted with EtOAc. The combined organic layers
were dried with MgSO4, filtered, and concentrated in vacuo. The
residue was purified by flash column chromatography to afford a
white solid.
General Procedure E. Reduction of Nitriles 9a,c–d: LiAlH4
(2.00 mmol) was added portionwise to a solution of triazene
(1.00 mmol) in dry THF (7 mL) cooled to 0 °C. The resulting mix-
ture was warmed to room temp. After 3 h, a saturated solution of
sodium/potassium tartrate (100 mL) was added and the aqueous
phase was extracted with EtOAc (4ϫ100 mL). The combined or-
ganic layers were dried with MgSO4, filtered and concentrated in
vacuo to give a slightly yellow oil that was used without further
purification.
General Procedure F. Reduction of Nitriles 9e,f and Imines 12e, 14e
and 16e with Lithium Aluminium Hydride: A solution of LiAlH4
(1  in THF, 2.00 mmol) was added portionwise to a solution of
triazene (1.00 mmol) in dry THF (7 mL) cooled to 0 °C. The re-
sulting mixture was heated at 50 °C. After 16 h, the reaction mix-
ture was cooled to room temp. and a saturated solution of sodium/
potassium tartrate (100 mL) was added and the aqueous phase was
extracted with EtOAc (4ϫ100 mL). The combined organic layers
were dried with MgSO4, filtered, concentrated in vacuo. The resi-
due was purified by flash column chromatography to give a slightly
yellow oil.
General Procedure A. Synthesis of 2-Triazenylbenzonitriles 9a–c: A
solution of sodium nitrite (50.8 mmol) in cold H2O (5 mL) was
added over 30 to 40 min to a suspension of anthranilonitrile
(50.8 mmol) in concd. HCl (10 mL) at 0 °C. After complete ad-
dition, the resulting mixture was stirred for additional 10 min at
0 °C and then added all at once to a solution of KOH (50.8 mmol)
and amine (50.8 mmol) in H2O (50 mL) cooled to –20 °C. After
10 min, the resulting solid was filtered off, dried and purified by
flash column chromatography to afford a slightly yellow solid.
General Procedure G. Reductive Amination of Triazenyl Ketones
13d,e: A mixture of triazenyl ketone (1.00 mmol), a solution of am-
monia (2  in MeOH, 5.00 mmol) and titanium(IV) isopropoxide
General Procedure B. Synthesis of 2-Triazenylbenzonitriles 9d–f:
BF3·OEt2 (203 mmol) was slowly added to a solution of anthra-
Eur. J. Org. Chem. 2008, 3314–3327
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3319

S. Bräse et al.
FULL PAPER
(2.00 mmol) was stirred for 6 h at 50 °C under a dry argon atmo-
sphere. After cooling to 0 °C, a solution of LiBH4 (2  in THF,
1.50 mmol) was added and stirring at this temperature was contin-
ued for 3 h. The solution was put into an aqueous solution of
NH4OH (2 ) and after additional stirring of 1 h, the aqueous
phase was extracted with CH2Cl2 (3ϫ30 mL). The combined or-
ganic layers were dried with MgSO4, filtered, concentrated in
vacuo. The residue was purified by flash column chromatography
to give a slightly yellow oil.
= 1.2 Hz, 1 H, Ar-H5), 3.82 [quin, J = 7.3 Hz, 4 H, N(CH2)2], 1.35
(t, J = 7.2 Hz, 3 H, CH3), 1.28 (t, J = 7.1 Hz, 3 H, CH3) ppm. 13
C
NMR (100 MHz, CDCl3): δ = 153.76 (Cq, C2-Ar), 133.03 (+, C6-
Ar), 132.80 (+, C4-Ar), 124.58 (+, C5-Ar), 118.20 (Cq, CN), 117.40
(+, C3-Ar), 107.28 (Cq, C1-Ar), 49.50 (–, CH2), 42.24 (–, CH2),
14.41 (+, CH ), 10.85 (+, CH ) ppm. IR (KBr): ν = 3470 (vw),
˜
3
3
3070 (vw) [=C–H valence], 2977 (m), 2936 (m) [–C–H valence],
2875 (w), 2224 (m) [CN], 1592 (m), 1573 (w), 1468 (m), 1445 (m),
1400 (m), 1330 (m), 1276 (m) [–C– N valence], 1241 (m), 1094 (m),
761 (m) 520 (w) cm–1. MS (70 eV, EI): m/z (%) = 202 (77) [M+],
130 (46) [C7H4N3+], 103 (51), 102 (100) [C7H4N+], 76 (18) [C6H4+],
72 (10) [C4H10N+], 51 (6) [C4H3+]. HR-EIMS (C11H14N4): calcd.
202.1218; found 202.1220; elemental analysis (C11H14N4): calcd.
C 65.32, H 6.98, N 27.70; found C 65.63, H 7.03, N 25.95.
Synthesis and Characterization of Compounds
(E)-2-(Pyrrolidin-1-yldiazenyl)benzonitrile 9a: Following general
procedure A, anthranilonitrile (7a) (6.00 g, 50.8 mmol) was treated
with sodium nitrite (3.50 g, 50.7 mmol) and pyrrolidine (8a)
(3.97 g, 55.8 mmol) to yield 4.06 g (20.3 mmol, 40%) as a light yel-
low solid after column chromatography on silica (n-pentane/diethyl
ether, 2:1). Rf (n-pentane/diethyl ether, 2:1) = 0.31. 1H NMR
(400 MHz, CDCl3): δ = 7.58 (ddd, J = 7.7, J = 1.4, J = 0.5 Hz, 1
H, Ar-H6), 7.53 (ddd, J = 8.3, J = 0.7 Hz, 1 H, Ar-H3), 7.46 (ddd,
J = 7.2, J = 1.5 Hz, 1 H, Ar-H4), 7.11 (ddd, J = 7.3, J = 1.2 Hz, 1
H, Ar-H5), 3.96 (t, J = 6.4 Hz, 2 H, NCH2), 3.76 (t, J = 6.4 Hz, 2
(E)-2-(3,3-Diisopropyltriaz-1-enyl)benzonitrile (9d): Following gene-
ral procedure B, anthranilonitrile (7a) (6.00 g, 50.8 mmol) was
treated with BF3·OEt2 (28.8 g, 203 mmol), tert-BuONO (20.4 g,
177 mmol) and diisopropylamine (8d) (5.13 g, 50.7 mmol) to yield
8.81 g (43.6 mmol, 75%) as a slightly yellow solid after column
chromatography on silica (n-pentane/diethyl ether, 55:15). Rf (n-
1
pentane/diethyl ether, 3:1) = 0.29. H NMR (400 MHz, CDCl3): δ
H, NCH2), 2.11–1.99 (m,
4
H, 2ϫCH2) ppm. 13C NMR
= 7.58 (ddd, J = 7.7, J = 1.1 Hz, 1 H, Ar-H6), 7.53 (ddd, J = 8.4,
J = 0.7 Hz, 1 H, Ar-H3), 7.46 (ddd, J = 7.2, J = 1.5 Hz, 1 H, Ar-
H4), 7.10 (ddd, J = 7.7, J = 1.2, J = 0.8 Hz, 1 H, Ar-H5), 5.29
(sept, J = 6.8 Hz, 1 H, CH), 4.07 (sept, J = 6.6 Hz, 1 H, CH), 1.40
(d, J = 6.6 Hz, 6 H, 2ϫCH3), 1.30 (d, J = 6.8 Hz, 6 H, 2ϫCH3)
ppm. 13C NMR (100 MHz, CDCl3): δ = 154.30 (Cq, C2-Ar), 133.09
(+, C6-Ar), 132.97 (+, C4-Ar), 124.24 (+, C5-Ar), 118.48 (Cq, CN),
117.31 (+, C3-Ar), 106.96 (Cq, C1-Ar), 50.27 (+, CH), 47.75 (+,
(100 MHz, CDCl3): δ = 153.90 (Cq, C2-Ar), 133.33 (+, C6-Ar),
133.06 (+, C4-Ar), 124.59 (+, C5-Ar), 118.15 (Cq, CN), 117.33 (+,
C3-Ar), 107.20 (Cq, C1-Ar), 51.34 (–, NCH2), 47.11 (–, NCH2),
23.98 (–, CH ), 23.44 (–, CH ) ppm. IR (KBr): ν = 3813 (w), 3402
˜
2
2
(w), 3072 (m) [=C–H valence], 2976 (s), 2889 (s) [–C–H valence],
2759 (m), 2498 (w), 2222 (s) [CN], 1976 (w), 1724 (w), 1591 (m),
1571 (m), 1393 (s), 1277 (s) [–C–N valence], 1227 (s), 1159 (s), 762
(s), 679 (m), 515 (m) cm–1. MS (70 eV, EI): m/z (%) = 200 (24)
[M+], 130 (35) [C7H4N3+], 102 (100) [C7H4N+], 76 (7) [C6H4+], 70
(5) [C4H8N+], 51 (5) [C4H3+], 41 (8). HR-EIMS (C11H12N4): calcd.
200.1062; found 200.1059 (C11H12N4): calcd. C 65.98, H 6.04, N
27.98; found C 66.06, H 6.03, N 26.97.
CH), 23.69 (+, 2ϫCH ), 19.10 (+, 2ϫCH ) ppm. IR (KBr): ν =
˜
3
3
3404 (vw), 3099 (w), 3058 [=C–H valence] (w), 2973 (m), 2932 (m)
[-C–H valence], 2872 (w), 2627 (w), 2424 (vw), 2222 (m) [CN], 1983
(w), 1950 (w), 1837 (w), 1591 (m), 1468 (m), 1396 (m), 1270 (m)
[–C–N valence], 1229 (m), 1156 (m), 1030 (m), 798 (m), 772 (m),
638 (w), 544 (m) cm–1. MS (70 eV, EI): m/z (%) = 230 (100) [M+],
130 (27) [C7H4N3+], 102 (59) [C7H4N+], 100 (31) [C6H14N+], 58
(24) [C3H8N+], 43 (8) [C3H7+]. HR-EIMS (C11H12N4): calcd.
200.1062; found 200.1059; elemental analysis (C13H18N4): calcd. C
67.80, H 7.88, N 24.33; found C 67.72, H 7.79, N 22.67.
(E)-2-(Piperidin-1-yldiazenyl)benzonitrile (9b): Following general
procedure A, anthranilonitrile (7a) (6.00 g, 50.8 mmol) was treated
with sodium nitrite (3.50 g, 50.7 mmol) and piperidine (8b) (4.33 g,
50.8 mmol) to yield 6.02 g (28.1 mmol, 55%) as a yellow solid after
column chromatography on silica (n-pentane/diethyl ether, 3:1).
Rf (n-pentane/diethyl ether, 3:1) = 0.76. 1H NMR (400 MHz,
CDCl3): δ = 7.60–7.56 (m, 2 H, Ar-H6, Ar-H3), 7.47 (ddd, J = 7.3,
J = 1.5 Hz, 1 H, Ar-H4), 7.13 (ddd, J = 7.5, J = 1.2 Hz, 1 H, Ar-
(E)-2-(3,3-Diisopropyltriaz-1-enyl)-3-(trifluoromethyl)benzonitrile
(9e): Following general procedure B, 2-amino-3-(trifluoromethyl)-
benzonitrile (7b) (1.84 g, 9.90 mmol) was treated with BF3·OEt2
(5.68 g, 40.0 mmol), tert-BuONO (3.60 g, 35.0 mmol) and of diiso-
propylamine (8d) (1.01 g, 10.0 mmol) to yield 2.30 g (7.70 mmol,
77%) as a slightly yellow solid after column chromatography on
silica (n-pentane/diethyl ether, 5:1). Rf (n-pentane/diethyl ether, 3:1)
= 0.60. 1H NMR (400 MHz, CDCl3): δ = 7.81 (dd, J = 7.8, J =
0.8 Hz, 1 H, Ar-H4), 7.76 (dd, J = 7.8, J = 1.0 Hz, 1 H, Ar-H6),
7.19 (dt, J = 7.8, J = 0.6 Hz, 1 H, Ar-H5), 5.17 (sept, J = 6.8 Hz,
1 H, CH), 4.13 (sept, J = 6.7 Hz, 1 H, CH), 1.47 (d, J = 6.7 Hz, 6
H, 2ϫCH3), 1.32 (d, J = 6.8 Hz, 6 H, 2ϫCH3) ppm. 13C NMR
(100 MHz, CDCl3): δ = 152.45 (Cq, C2-Ar), 138.12 (+, C6-Ar),
130.45 (+, J = 5.5 Hz, q, C4-Ar), 124.76 (+, q, C5-Ar, J = 30.4 Hz),
123.28 (Cq, CN), 123.43 (+, q, CF3, J = 273.6 Hz), 118.97 (+, C3-
Ar), 103.13 (Cq, C1-Ar), 51.30 (+, CH), 48.41 (+, CH), 23.17 (+,
H5), 3.90 [bd, 4 H, N(CH2)2], 1.77–1.71 [m, 6 H, (CH2)3] ppm. 13
C
NMR (100 MHz, CDCl3): δ = 153.36 (Cq, C2-Ar), 133.09 (+, C6-
Ar), 132.79 (+, C4-Ar), 124.93 (+, C5-Ar), 118.14 (Cq, CN), 117.31
(+, C3-Ar), 107.40 (Cq, C1-Ar), 53.22 (–, o-CH2), 26.43 (–, p-CH2),
24.18 (–, m-CH ). IR (KBr): ν = 3067 (w) [=C–H valence], 2953
˜
2
(m), 2859 (m) [–CH2 valence], 2224 (m) [CN], 1973 (w), 1832 (w),
1589 (m), 1406 (s), 1298 (m) [–C–N valence], 765 (m) cm–1. MS
(70 eV, EI): m/z (%) = 214 (24) [M+], 130 (49) [C7H4N3+], 102 (100)
[C7H4N+], 84 (16) [C5H10N+], 76 (6) [C6H4+], 56 (5) [C3H6N+],
42 (8) [C2H4N+]. HR-EIMS (C11H12N4): calcd. 200.1062; found
200.1059. (C12H14N4): calcd. C 67.27, H 6.59, N 26.15; found
C 67.35, H 6.42, N 24.87.
(E)-2-(3,3-Diethyltriaz-1-enyl)benzonitrile (9c): Following general
procedure A, anthranilonitrile (7a) (6.00 g, 50.8 mmol) was treated
with sodium nitrite (3.50 g, 50.7 mmol) and diethylamine (8c)
(3.70 g, 50.8 mmol) to yield 6.04 g (29.9 mmol, 59%) as a light yel-
low solid after column chromatography on silica (n-pentane/diethyl
ether, 3:1). Rf (n-pentane/diethyl ether, 3:1) = 0.28. 1H NMR
(400 MHz, CDCl3): δ = 7.58 (ddd, J = 7.7, J = 1.4, J = 0.4 Hz, 1
H, Ar-H6), 7.53 (ddd, J = 8.3, J = 1.1, J = 0.3 Hz, 1 H, Ar-H3),
CH ), 18.95 (+, CH ) ppm. IR (KBr): ν = 3090 (m) [=C–H val-
˜
3
3
ence], 2977 (m), 2938 (m) [–C–H valence], 2877 (m), 2469 (w), 2221
(m) [CN], 1980 (w), 1954 (w), 1913 (w), 1581 (m), 1472 (m), 1396
(s), 1380 (s) [–C–N valence], 1318 (m), 1294 (m), 1235 (s), 1141 (s)
[CF3], 1026 (m), 870 (m), 839 (m), 764 (m), 723 (m), 520 (m), 405
(w) cm–1. MS (70 eV, EI): m/z (%) = 298 (43) [M+], 198 (37)
[C8H3F3N3+], 170 (100) [C8H3F3N+], 100 (23) [C6H14N+], 84 (5)
7.46 (ddd, J = 7.2, J = 1.5 Hz, 1 H, Ar-H4), 7.11 (ddd, J = 7.6, J [C3H6N3+], 58 (22) [C3H8N+], 43 (16) [C3H7+]. HR-EIMS
3320
www.eurjoc.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2008, 3314–3327

Particularly Stable Triazenes
(C14H17F3N4): calcd. 298.1405; found 298.1400; elemental analysis
1.1 Hz, 1 H, Ar-H3), 7.28 (ddd, J = 7.5, J = 1.4 Hz, 1 H, Ar-H6),
(C14H17F3N4): calcd. C 56.37, H 5.74, N 18.78; found C 56.52, H 7.20 (ddd, J = 7.3, J = 1.6 Hz, 1 H, Ar-H5), 7.08 (ddd, J = 7.4, J
5.63, N 17.09.
= 1.3 Hz, 1 H, Ar-H4), 3.82–3.80 [m, 4 H, N(CH2)2], 2.13 (br.s,
2 H, NH2), 1.72 [br.s, 6 H, (CH2)3], 0.96–0.93 (m, 2 H, CH2, [cyclo-
propane]), 0.85–0.82 (m, 2 H, CH2, [cyclopropane]) ppm. 13C
NMR (100 MHz, CDCl3): δ = 148.35 (Cq, C2-Ar), 138.61 (+, C4-
Ar), 126.66 (+, C6-Ar), 126.45 (Cq, C1-Ar), 124.52 (+, C5-Ar),
116.02 (+, C3-Ar), 77.24 [–, N(CH2)2], 52.92 (Cq, CNH2), 24.43
(–, p-CH2), 14.43 (–, 2ϫm-CH2), 8.08 (–, CH2, [cyclopropane])
(E)-2-(3,3-Diethyltriaz-1-enyl)-3-(trifluoromethyl)benzonitrile (9f):
Following general procedure B, 2-amino-3-(trifluoromethyl)benzo-
nitrile (7b) (1.84 g, 9.90 mmol) was treated with BF3·OEt2 (5.68 g,
40.0 mmol), of tert-BuONO (3.60 g, 35.0 mmol) and diethylamine
(8c) (0.73 g, 10.0 mmol) to yield 1.30 g (4.81 mmol, 48%) as a
slightly yellow solid after column chromatography on silica (n-pen-
ppm. IR (KBr): ν = 3360 (w) [NH ], 3064 (w) [cyclopropane], 2938
˜
2
1
tane/diethyl ether, 3:1). Rf (n-pentane/diethyl ether, 3:1) = 0.23. H
(m), 2855 (m) [–C–H valence], 1480 (m), 1430 (m), 1356 (m) 1294
(m) [–C–N valence], 1259 (m), 1180 (m), 1105 (m), 1084 (m), 1016
(m), 760 (m) cm–1. MS (70 eV, EI): m/z (%) = 244 (3) [M+], 159
(12) [C9H9N3+], 147 (17), 146 (40) [C9H10N2+], 145 (100)
[C8H7N3+], 132 (16) [C9H10N+], 131 (24) [C7H5N3+], 130 (48), 117
(21) [C9H9+], 115 (10) [C9H7+], 104 (10) [C7H6N+], 103 (10)
[C7H5N+], 99 (80), 91 (10) [C6H5N+], 42 (12) [C3H6+]. HR-EIMS
(C14H20N4): calcd. 244.1688; found 244.1691.
NMR (400 MHz, CDCl3): δ = 7.81 (dd, J = 7.8, J = 0.8 Hz, 1 H,
Ar-H4), 7.75 (dd, J = 7.8, J = 1.0 Hz, 1 H, Ar-H6), 7.21 (dt, J =
7.8, J = 0.6 Hz, 1 H, Ar-H5), 3.88 (q, J = 7.3 Hz, 2 H, CH2), 3.82
(q, J = 7.1 Hz, 2 H, CH2), 1.42 (t, J = 7.3 Hz, 3 H, CH3), 1.27 (t,
J = 7.1 Hz, 3 H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ =
152.03 (Cq, C2-Ar), 137.86 (+, C6-Ar), 130.46 (+, q, C4-Ar, J =
5.5 Hz), 124.79 (+, q, C5-Ar, J = 30.7 Hz), 123.61 (Cq, CN), 123.33
(+, q, CF3, J = 273.7 Hz), 118.43 (+, C3-Ar), 103.85 (Cq, C1-Ar),
49.82 (–, CH2), 42.63 (–, CH2), 14.15 (+, CH3), 10.78 (+, CH3)
(E)-1-[2-(3,3-Diethyltriaz-1-enyl)phenyl]cyclopropanamine
(10c):
Following general procedure C, compound 9c (500 mg, 2.47 mmol)
was treated with titanium(IV) isopropoxide (0.65 mL, 5.44 mmol),
EtMgBr (3  in diethyl ether, 1.80 mL, 5.22 mmol) and BF3·OEt2
(0.63 mL, 4.94 mmol). After aqueous work up, column chromatog-
raphy (0.2% triethylamine in diethyl ether) on silica yielded 210 mg
(0.90 mmol, 37%) as an oil. Rf (0.2% triethylamine in diethyl ether)
ppm. IR (KBr): ν = 3405 (vw), 2981 (w) [=C–H valence], 2940 (w),
˜
2878 (vw), 2224 (w) [CN], 1638 (w), 1586 (w), 1397 (s), 1340 (m)
[–C–N valence], 1318 (m), 1244 (m), 1203 (m), 1139 (s) [CF3], 1077
(m), 752 (w), 726 (w) cm–1. MS (70 eV, EI): m/z (%) = 270 (28)
[M+], 198 (36) [C8H3F3N3+], 170 (100) [C8H3F3N+], 72 (16)
[C4H10N+], 44 (5) [C2H6N+], 42 (4) [CH2N2+]. HR-EIMS
(C12H13F3N4): calcd. 270.1092; found 270.1095; elemental analysis
(C12H13F3N4): calcd. C 53.33, H 4.85, N 20.73; found C 53.72,
H 5.07, N 19.67.
1
= 0.09. H NMR (400 MHz, CDCl3): δ = 7.41 (ddd, J = 8.0, J =
1.1 Hz, 1 H, Ar-H3), 7.26 (ddd, J = 7.5, J = 1.4 Hz, 1 H, Ar-H6),
7.20 (ddd, J = 7.3, J = 1.6 Hz, 1 H, Ar-H5), 7.05 (ddd, J = 7.4, J
= 1.3 Hz, 1 H, Ar-H4), 3.80 [q, J = 7.1 Hz, 4 H, N(CH2)2], 1.31–
1.27 (br.s, 2 H, NH2), 1.23 (t, 6 H, 2ϫCH3), 1.01–0.98 (m, 2 H,
CH2, [cyclopropane]), 0.86–0.83 (m, 2 H, CH2, [cyclopropane])
ppm. 13C NMR (100 MHz, CDCl3): δ = 157.59 (Cq, C2-Ar), 131.68
(+, C4-Ar), 127.63 (+, C6-Ar), 125.11 (Cq, C1-Ar), 118.28 (+, C5-
Ar), 103.98 (+, C3-Ar), 63.84 [–, N(CH2)2], 36.21 (Cq, CNH2),
118.24 (–, 2ϫCH2, [cyclopropane]), 14.07 (+, 2ϫCH3) ppm. MS
(70 eV, EI): m/z (%): 232 (5) [M+], 158 (12) [C9H8N3+], 147 (18),
146 (25) [C9H10N2+], 145 (51) [C9H9N2+], 132 (15) [C9H10N+], 131
(18) [C7H5N3+], 130 (51) [C9H8N+], 117 (33) [C9H9+], 115 (15)
[C9H7+], 106 (11), 104 (13) [C7H6N+], 103 (16) [C7H5N+], 91 (15),
87 (100) [C4H11N2+], 77 (17) [C6H5+], 57 (20) [C3H7N+], 45 (10),
43 (21) [C2H5N+]. HR-EIMS (C12H20N4): calcd.232.1688; found
232.1685.
(E)-1-[2-(Pyrrolidin-1-yldiazenyl)phenyl]cyclopropanamine
(10a):
Following general procedure C, compound 9a (300 mg, 1.50 mmol)
was treated with titanium(IV) isopropoxide (0.53 mL, 1.80 mmol),
EtMgBr (3  in diethyl ether, 1.0 mL, 3.0 mmol) and BF3·OEt2
(0.38 mL, 3.0 mmol). After aqueous work up, column chromatog-
raphy (0.2% triethylamine in diethyl ether) on silica yielded 89 mg
(0.39 mmol, 26%) as an oil. Rf (0.2% triethylamine in diethyl ether)
1
= 0.12. H NMR (400 MHz, CDCl3): δ = 7.40 (ddd, J = 8.0, J =
1.2 Hz, 1 H, Ar-H3), 7.25 (ddd, J = 7.5, J = 1.4 Hz, 1 H, Ar-H6),
7.20 (ddd, J = 7.4, J = 1.5 Hz, 1 H, Ar-H5), 7.04 (ddd, J = 7.4, J
= 1.3 Hz, 1 H, Ar-H4), 3.93–3.13 [m, 4 H, N(CH2)2], 3.15 (br.s,
2 H, NH2), 2.05 [br.s, 4 H, (CH2)2], 1.01–0.94 (m, 2 H, CH2, [cyclo-
propane]), 0.90–0.84 (m, 2 H, CH2, [cyclopropane]) ppm. 13C
NMR (100 MHz, CDCl3): δ = 149.76 (Cq, C2-Ar), 138.41 (Cq, C1-
Ar), 127.53 (+, C4-Ar), 126.48 (+, C6-Ar), 124.93 (+, C5-Ar),
116.72 (+, C3-Ar), 53.98 [–, N(CH2)2], 36.23 (Cq, CNH2), 23.77
(–, 2ϫm-CH2), 14.06 (–, 2ϫCH2, [cyclopropane]) ppm. IR (KBr):
(E)-1-[2-(3,3-Diisopropyltriaz-1-enyl)phenyl]cyclopropanamine
10d): Following general procedure C, compound 9d (500 mg,
2.17 mmol) was treated with titanium(IV) isopropoxide (0.77 mL,
2.61 mmol), EtMgBr (3  in diethyl ether, 1.74 mL, 5.21 mmol) and
BF3·OEt2 (0.55 mL, 4.34 mmol). After aqueous work up, column
chromatography (0.2% triethylamine in diethyl ether) on silica
yielded 170 mg (0.65 mmol, 30%) as an oil. Rf (0.2% triethylamine
in diethyl ether) = 0.09. 1H NMR (400 MHz, CDCl3): δ = 7.44
(ddd, J = 8.0, J = 1.1 Hz, 1 H, Ar-H6), 7.27 (ddd, J = 7.7, J =
1.4 Hz, 1 H, Ar-H3), 7.21 (ddd, J = 7.3, J = 1.6 Hz, 1 H, Ar-H5),
7.04 (ddd, J = 7.4, J = 1.3 Hz, 1 H, Ar-H4), 5.19 (br.s, 1 H, CH),
4.05 (br.s, 1 H, CH), 2.68 (br.s, 2 H, NH2), 1.38–1.23 (m, 12 H,
4ϫCH3), 0.97–0.95 (m, 2 H, CH2, [cyclopropane]), 0.87–0.84 (m, 2
H, CH2, [cyclopropane]) ppm. 13C NMR (100 MHz, CDCl3): δ =
150.10 (Cq, C2-Ar), 139.12 (+, C4-Ar), 127.57 (+, C6-Ar), 127.42
(Cq, C1-Ar), 124.62 (+, C5-Ar), 116.59 (+, C3-Ar), 49.34 (+, CH),
46.65 (+, CH), 36.28 (Cq, CNH2), 23.91 (+, 2ϫCH3), 19.31 (+,
ν = 3360 (w) [NH ], 3085 (w) [=C–H valence], 3062 (w) [cyclopro-
˜
2
pane], 2973 (m), 2870 (m) [–C–H valence], 1574 (w), 1480 (m), 1414
(m), 1318 (m), 1290 (m) [–C–N valence], 1187 (m), 1107 (m), 1085
(m), 1017 (m), 762 (m) cm–1. MS (70 eV, EI): m/z (%) = 230 (60)
[M+], 215 (16) [C13H17N3+], 202 (36) [C11H14N4+], 201 (100)
[C11H13N4+], 187 (37) [C11H13N3+], 185 (12) [C11H11N3+], 174 (20)
[C10H12N3+]. HR-EIMS (C13H18N4): calcd. 230.1531; found
230.1529; elemental analysis (C13H18N4): calcd. C 67.80, H 7.88, N
24.33; found C 68.18, H 7.88, N 24.06.
(E)-1-[2-(Piperidin-1-yldiazenyl)phenyl]cyclopropanamine (10b): Fol-
lowing general procedure C, compound 9b (529 mg, 2.47 mmol)
was treated with titanium(IV) isopropoxide (0.65 mL, 5.44 mmol),
EtMgBr (3  in diethyl ether, 1.80 mL, 5.22 mmol) and BF3·OEt2
(0.63 mL, 4.94 mmol). After aqueous work up, column chromatog-
raphy (0.2% triethylamine in diethyl ether) on silica yielded 30.2 mg
(0.12 mmol, 5%) as an oil. Rf (0.2% triethylamine in diethyl ether)
2ϫCH ), 14.30 (–, 2ϫCH , [cyclopropane]). IR (KBr): ν = 3363
˜
3
2
(vw) [NH2], 3086 (vw) [=C–H valence], 3062 (vw) [cyclopropane],
2973 (m), 2931 (m), 2931 (m), 2872 (w) [–C–H valence], 1479 (w),
1420 (w), 1364 (w), 1281 (m) [–C–N valence], 1254 (m), 1193 (m),
1
= 0.10. H NMR (400 MHz, CDCl3): δ = 7.39 (ddd, J = 8.0, J =
Eur. J. Org. Chem. 2008, 3314–3327
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3321

S. Bräse et al.
FULL PAPER
1098 (m), 1031 (m), 752 (m) cm–1. MS (70 eV, EI): m/z (%) = 261
[C4H11N2+], 86 (16) [C4H10N2+], 58 (12), 57 (15) [C3H7N+]. HR-
(2) [M + 1], 260 (7) [M+], 189 (21) [C11H15N3+], 159 (10) EIMS (C14H19F3N4): calcd. 300.1562; found 300.1558.
[C9H9N3+], 147 (100) [C8H9N3+], 145 (55) [C8H7N3+], 132 (30)
1,3-Dimethyl-1H-indazole (11): Following general procedure D,
compound 9a (500 mg, 2.50 mmol) was treated with MeMgBr (3 
in Et2O, 3.33 mL, 9.98 mmol) in THF (8 mL). Column chromatog-
[C9H10N+], 130 (87) [C9H8N+], 117 (24) [C9H9+], 115 (85) [C9H7+],
106 (24) [C6H6N2+], 91 (14) [C6H5N+], 77 (13) [C6H5+], 73 (21), 43
(62) [C3H7+]. HR-EIMS (C15H24N4): calcd. 260.2001; found
raphy (EtOAc) on silica yielded 44.0 mg (0.30 mmol, 12%) of a
260.2004; elemental analysis (C15H24N4): calcd. C 69.19, H 9.29, N
21.52; found C 69.26, H 9.55, N 20.68.
1
white solid. Rf (EtOAc) = 0.29. H NMR (400 MHz, CDCl3): δ =
δ = 7.61 (td, J = 8.7, J = 0.9 Hz, 1 H, Ar-H6), 7.54 (td, J = 8.4, J
= 1.0 Hz, 1 H, Ar-H7), 7.25 (ddd, J = 6.6, J = 1.0 Hz, 1 H, Ar-
(E)-1-[2-(3,3-Diisopropyltriaz-1-enyl)-3-(trifluoromethyl)phenyl]cy-
H8), 7.01 (ddd, J = 6.6, J = 0.8 Hz, 1 H, Ar-H5), 4.08 (s, 3 H,
clopropanamine (10e): Following general procedure C, compound
NCH3), 2.59 (s, 3 H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ
9e (597 mg, 2.00 mmol) was treated with titanium(IV) isopropoxide
= 147.77 (Cq, C9-Ar), 131.36 (Cq, C3-Ar), 125.98 (Cq, C4-Ar),
(0.71 mL, 2.40 mmol), EtMgBr (3  in diethyl ether, 1.60 mL,
4.80 mmol) and BF3·OEt2 (0.51 mL, 4.00 mmol). After aqueous
121.08 (+, C5-Ar), 120.31 (+, C7-Ar), 119.56 (+, C6-Ar), 116.89 (+,
C8-Ar), 37.31 (+, NCH ), 9.93 (+, CH ) ppm. IR (KBr): ν = 3048
˜
3
3
work up, column chromatography (diethyl ether) on silica yielded
255 mg (0.78 mmol, 39%) as an oil. Rf (diethyl ether) = 0.18. 1H
NMR (400 MHz, CDCl3) = δ = 7.56–7.53 (m, 2 H, Ar-H6, Ar-H4),
7.14 (dt, J = 7.8, J = 0.7 Hz, 1 H, Ar-H5), 5.20 (sept, J = 6.8 Hz,
1 H, CH), 4.05 (sept, J = 6.7 Hz, 1 H, CH), 2.16 (br.s, 2 H, NH2),
1.37 (d, J = 6.7 Hz, 6 H, 2ϫCH3), 1.31 (d, J = 6.8 Hz, 6 H,
2ϫCH3), 0.91–0.88 (m, 2 H, CH2, [cyclopropane]), 0.72–0.69 (m, 2
H, CH2, [cyclopropane]) ppm. 13C NMR (100 MHz, CDCl3): δ =
150.46 (Cq, C2-Ar), 139.30 (+, C6-Ar), 132.93 (Cq, C1-Ar), 125.22
(+, J = 5.5 Hz, q, C4-Ar), 124.16 (+, q, CF3, J = 273.4 Hz), 124.00
(+, C5-Ar), 123.67 (+, q, C3-Ar, J = 29.6 Hz), 49.46 (+, CH), 45.98
(+, CH), 35.71 (Cq, CNH2), 23.33 (+, 2ϫCH3), 19.27 (+, 2ϫCH3),
15.27 (–, 2ϫCH2 [cyclopropane]) ppm. 19F NMR (376 MHz,
(m), 2946 (m) [=C–H valence], 2923 (m) [–CH3 valence], 2738 (w),
2565 (w), 1937 (w), 1912 (w), 1809 (w), 1788 (w), 1688 (w), 1629
(m) [–C=N valence], 1504 (m), 1453 (m), 1367 (m) 1286 (m) [–C–
N valence], 1031 (m), 854 (m), 762 (m), 744 (s), 718 (m) cm–1. MS
(70 eV, EI): m/z (%) = 146 (100) [M+], 145 (64) [C9H9N2+], 117 (5)
[C4H5N2+], 103 (47) [C7H5N+], 91 (10) [C7H7+], 77 (20) [C6H5+],
51 (10) [C4H3+]. HR-EIMS (C9H10N2): calcd. 146.0844;
found 146.0846.
(E)-1-[2-(Pyrrolidin-1-yldiazenyl)phenyl]ethanone (13a): CeCl3·
7H2O was dried in high vacuum at 150 °C for 5 h while stirring.
After cooling down the anhydrous CeCl3 (1.15 g, 4.67 mmol) was
suspended in dry THF (8 mL). At –50 °C, methyllithium (1.6  in
diethyl ether, 1.94 mL, 3.10 mmol) was added. After 30 min com-
pound 9a (200 mg, 1.00 mmol) dissolved in THF (2 mL) was added
at –65 °C. The resulting violet mixture was stirred for 7 h at this
temperature before a NH4OH solution (25% in water, 2.50 mL)
was added and the reaction was warmed to room temp. within
16 h. The residue was filtered off over celite® 545, washed with
dichloromethane and the filtrate was concentrated in vacuo. Col-
umn chromatography on silica (n-pentane/diethyl ether, 3:1) yielded
50.0 mg (0.23 mmol, 23%) as a white solid. Rf (n-pentane/diethyl
CDCl ): δ = –58.6 (m, CF ) ppm. IR (KBr): ν = 3369 (vw) [NH ],
˜
3
3
2
3087 (vw) [cyclopropane], 2976 (m) [–C–H valence], 2935 (w), 1585
(w), 1469 (w), 1431 (m), 1404 (m), 1368 (m), 1333 (m), 1306 (m),
1228 (m) [–C–N valence], 1158 (m), 1130 (s) [CF3], 1093 (m), 844
(w), 768 (w) cm–1. MS (70 eV, EI): m/z (%) = 328 (4) [M+], 257 (11)
[C12H14F3N3+], 216 (11), 215/214 (100/13), [C9H8F3N3+], 200 (16)
[C10H9F3N+], 198 (19) [C8H3F3N3+], 130 (10) [C7H4N3+], 115 (29)
[C6H15N2+], 73 (16) [C4H11N+], 43 (51) [C2H5N+], 42 (12)
[C2H4N+]. HR-EIMS (C16H23F3N4): calcd. 328.1875; found
328.1873.
1
ether, 3:1) = 0.16. H NMR (250 MHz, CDCl3): δ = 7.54 (ddd, J
= 7.7, J = 1.4 Hz, 1 H, Ar-H6), 7.47 (ddd, J = 8.2, J = 1.4 Hz, 1
H, Ar-H3), 7.39 (ddd, J = 7.2, J = 1.6 Hz, 1 H, Ar-H4), 7.14 (ddd,
J = 7.2, J = 1.4 Hz, 1 H, Ar-H5), 3.81 (bd, 4 H, 2ϫNCH2), 2.62
(s, 3 H, CH3), 2.05 (br.s, 4 H, 2ϫCH2) ppm. 13C NMR (100 MHz,
CDCl3): δ = 202.15 (Cq, C=O), 153.83 (Cq, C2-Ar), 132.30 (+, C6-
Ar), 124.53 (+, C3-Ar), 118.08 (+, C5-Ar), 117.27 (Cq, C1-Ar),
107.15 (+, C2-Ar), 51.28 (–, 2ϫNCH2), 47.05 (+, CO-CH3), 23.92
(E)-1-[2-(3,3-Diethyltriaz-1-enyl)-3-(trifluoromethyl)phenyl]cyclo-
propanamine (10f): Following general procedure C, compound 9f
(540 mg, 2.00 mmol) was treated with titanium(IV) isopropoxide
(0.71 mL, 2.40 mmol), EtMgBr (3  in diethyl ether, 1.60 mL,
4.80 mmol) and BF3·OEt2 (0.51 mL, 4.00 mmol). After aqueous
work up, column chromatography (ethyl acetate) on silica yielded
210 mg (0.70 mmol, 35%) as an oil. Rf (ethyl acetate) = 0.11. 1H
NMR (400 MHz, CDCl3): δ = 7.58 (dd, J = 7.6 Hz, 1 H, Ar-H6),
7.54 (dd, J = 7.8, J = 1.0 Hz, 1 H, Ar-H4), 7.14 (dt, J = 7.7, J =
0.6 Hz, 1 H, Ar-H5), 3.80 [quin, J = 6.9 Hz, 4 H, N(CH2)2], 2.18
(br.s, 2 H, NH2), 1.34 (t, J = 7.1 Hz, 3 H, CH3), 1.27 (t, J = 6.9 Hz,
3 H, CH3), 0.91–0.88 (m, 2 H, CH2, [cyclopropane]), 0.68–0.66 (m,
2 H, CH2, [cyclopropane]) ppm. 13C NMR (100 MHz, CDCl3): δ
= 149.54 (Cq, C2-Ar), 138.98 (+, C6-Ar), 133.68 (Cq, C1-Ar), 125.15
(+, J = 5.6 Hz, q, C4-Ar), 124.16 (+, C5-Ar), 124.16 (+, J =
273.5 Hz, q, CF3), 123.74 (+, q, C3-Ar, J = 29.5 Hz), 48.98 (–,
NCH2), 41.02 (–, NCH2), 35.82 (Cq, CNH2), 15.77 (–, 2ϫCH2,
[cyclopropane]), 14.50 (+, CH3), 11.24 (+, CH3) ppm. 19F NMR
(–, CH ), 23.38 (–, CH ) ppm. IR (KBr): ν = 3304 (w), 3053 (w),
˜
2
2
2974 (m), 2924 (m) [C–H valence], 2875 (m) [–CH3 valence], 2702
(w), 1953 (w), 1668 (m) [C=O], 1589 (m), 1568 (m), 1471 (m), 1442
(m), 1406 (s), 1353 (m), 1281 (m) [–C–N valence], 1155 (m), 967
(m), 774 (m), 596 (m), 540 (m) cm–1. MS (70 eV, EI): m/z (%) =
217 (11) [M+], 147 (74) [C8H7N2O+], 119 (13) [C8H7O+], 91 (100)
[C7H7+], 77 (9) [C6H5+], 70 (6) [C4H8N+], 43 (22) [C2H5N+]. HR-
EIMS (C12H15N3O): calcd. 217.1215; found 217.1218; elemental
analysis (C12H15N3O): calcd. C 66.34, H 6.96, N 19.34; found C
66.46, H 6.90, N 18.46.
(E)-1-[2-(3,3-Diethyltriaz-1-enyl)phenyl]ethanone (13c): Following
general procedure D, methylmagnesium bromide (3  in diethyl
ether, 6.70 mL, 20.0 mmol) was added to a solution of compound
(376 MHz, CDCl ): δ = –58.9 (m, CF ) ppm. IR (KBr): ν = 3370
˜
3
3
(vw) [NH2], 3086 (vw) [cyclopropane], 2978 (w), 2938 (w) [–C–H
valence], 2876 (w), 1584 (w), 1469 (w), 1435 (m), 1339 (m), 1305 9c (404 mg, 2.00 mmol) in dry THF (5 mL) and the mixture was
(m) [–C–N valence], 1160 (m), 1130 (m) [CF3], 1092 (m), 1078 (m)
heated to 60 °C for 7 h. After cooling down to room temp. the
reaction was quenched with water (10 mL) and the aqueous layer
cm–1. MS (70 eV, EI): m/z (%) = 300 (4) [M+], 243 (12), 215 (26)
[C10H10F3N2+], 214 (18) [C10H9F3N2+], 213 (19) [C10H8F3N2+], 200 was extracted with diethyl ether (3ϫ30 mL). Column chromatog-
(15) [C10H9F3N+], 199 (14) [C10H8F3N+], 198 (39) [C10H7F3N+],
172 (10) [C8H5F3N+], 170 (11) [C8H3F3N+], 130 (18), 87 (100)
raphy on silica (n-pentane/diethyl ether, 4:1) gave 273 mg
(1.24 mmol, 62%) of a yellow oil. Rf (n-pentane/diethyl ether, 4:1)
3322
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2008, 3314–3327

Particularly Stable Triazenes
1
= 0.18. H NMR (400 MHz, CDCl3): δ = 7.50 (ddd, J = 7.7, J =
172 (15) [C8H3F3O+], 166 (54), 159 (100) [C7H4F3N+], 145 (11)
[C7H4F3+], 100 (51) [C6H14N+], 58 (25) [C3H8N+], 43 (56) [C3H7+].
1.4 Hz, 1 H, Ar-H6), 7.47 (ddd, J = 8.1, J = 0.9 Hz, 1 H, Ar-H3),
7.39 (ddd, J = 7.2, J = 1.6 Hz, 1 H, Ar-H4), 7.14 (ddd, J = 7.4, J HR-EIMS (C15H20F3N3O): calcd. 315.1558; found 315.1556; ele-
= 1.2 Hz, 1 H, Ar-H5), 3.77 (q, J = 6.8 Hz, 4 H, 2ϫCH2), 2.57 (s,
mental analysis (C15H20F3N3O): calcd. C 57.13, H 6.39, N 13.33;
3 H, CH3), 1.30–1.23 (m, 6 H, 2ϫCH3) ppm. 13C NMR (100 MHz, found C 56.89, H 6.17, N 14.17.
CDCl3): δ = 203.89 (Cq, C=O), 149.39 (Cq, C2-Ar), 134.88 (+, C6-
(E)-1-[2-(3,3-Diisopropyltriaz-1-enyl)-3-(trifluoromethyl)phenyl]-
Ar), 131.50 (+, C4-Ar), 128.24 (+, C5-Ar), 124.85 (Cq, C1-Ar),
pentan-1-imine (14e): To a solution of compound 9e (597 mg,
2.00 mmol) in dry THF (15 mL) was added n-butyllithium (1.6 
in hexane, 2.00 mL, 3.20 mmol) dropwise at 0 °C. After stirring at
room temp. for 2.5 h, no starting material could be detected via
TLC and the reaction was quenched with saturated NH4Cl solution
(7 mL). The aqueous phase was extracted with EtOAc (3ϫ30 mL),
the organic phase was washed with brine (20 mL) and dried with
Na2SO4. Column chromatography on silica (cyclohexane/ethyl ace-
tate, 1:1) yielded 570 mg (1.60 mmol, 80%) of the product. Rf (cy-
118.48 (+, C3-Ar), 48.99 (–, CH2), 41.58 (–, CH2), 32.08 (+, CO-
CH ), 14.51 (+, CH ), 11.24 (+, CH ) ppm. IR (KBr): ν = 3471
˜
3
3
3
(vw), 3065 (vw), 2977 (m) [–C–H valence], 2935 (w), 2875 (w)
[–CH3 valence], 1681 (m) [C=O], 1593 (w), 1467 (m), 1407 (m),
1352 (m) 1282 (m) [–C–N valence], 1246 (m), 1104 (m), 762 (m),
595 (w) cm–1. MS (70 eV, EI): m/z (%) = 219 (18) [M+], 147 (36)
[C8H7N2O+], 119 (11) [C8H7O+], 91 (100) [C7H7+], 77 (6) [C6H5+],
43 (12) [C2H5N+]. HR-EIMS (C12H17N3O): calcd. 219.1372; found
219.1375; elemental analysis (C12H17N3O): calcd. C 65.73, H 7.81,
N 19.16; found C 65.98, H 7.70, N 18.06.
1
clohexane/ethyl acetate, 1:1) = 0.29. H NMR (400 MHz, CDCl3):
δ = 9.26 (br.s, 1 H, NH), 7.64 (dd, J = 7.8, J = 1.0 Hz, 1 H, Ar-
H6), 7.35 (dd, J = 7.5 Hz, 1 H, Ar-H4), 7.18 (dt, J = 7.7, J = 0.5 Hz,
1 H, Ar-H5), 5.09 (sept, J = 6.8 Hz, 1 H, CH), 3.99 (sept, J =
6.6 Hz, 1 H, CH), 2.34 (t, J = 7.9 Hz, 2 H, CH2C=NH), 1.48–1.40
(m, 2 H, CH2), 1.33–1.21 (m, 2 H, CH2), 1.29 (d, J = 6.6 Hz, 6 H,
2ϫCH3), 1.27 (d, J = 6.8 Hz, 6 H, 2ϫCH3), 0.85 (t, J = 7.3 Hz, 3
H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ = 205.88 (Cq,
(E)-1-[2-(3,3-Diisopropyltriaz-1-enyl)phenyl]ethanone (13d): Follow-
ing general procedure D, compound 9d (230 mg, 1.00 mol) was
treated with MeMgBr (3  in Et2O, 1.00 mL, 1.60 mmol) in THF
(10 mL). Column chromatography (n-pentane/diethyl ether, 4:1) on
silica yielded 168 mg (0.68 mmol, 68%) of a white solid. Rf (n-pen-
tane/diethyl ether, 4:1) = 0.18. 1H NMR (400 MHz, CDCl3): δ =
7.51 (ddd, J = 7.7, J = 1.1 Hz, 1 H, Ar-H6), 7.47 (ddd, J = 8.2, J C=NH), 135.38 (Cq, C2-Ar), 134.66 (+, C1-Ar), 132.06 (+, C6-Ar),
= 1.2, J = 0.8 Hz, 1 H, Ar-H3), 7.39 (ddd, J = 7.1, J = 1.5 Hz, 1
H, Ar-H4), 7.13 (ddd, J = 7.7, J = 1.2, J = 0.5 Hz, 1 H, Ar-H5),
5.25 (br.s, 1 H, CH), 4.02 (br.s, 1 H, CH), 2.57 (s, 3 H, CH3), 1.39
(d, J = 4.8 Hz, 6 H, 2ϫCH3), 1.26 (bd, 6 H, 2ϫCH3) ppm. 13C
126.68 (+, q, C4-Ar, J = 5.6 Hz), 124.04 (+, q, CF3, J = 273.5 Hz),
123.88 (+, q, CCF3, J = 29.7 Hz), 123.77 (+, C5-Ar), 50.11 (+,
CH), 47.00 (+, CH), 39.48 (–, CH2C=NH), 28.42 (–, CH2), 23.34
(+, 2ϫCH3), 22.45 (–, CH2), 19.15 (+, 2ϫCH3), 13.83 (+, CH3).
NMR (100 MHz, CDCl3): δ = 204.01 (Cq, C=O), 150.00 (Cq, C2- 19F NMR (376 MHz, CDCl3): δ = –59.4 (m, CF3) ppm. IR (KBr):
Ar), 134.73 (+, C6-Ar), 131.45 (+, C4-Ar), 128.48 (+, C5-Ar),
ν = 2972 (m) 2934 (m) [–C–H valence], 2873 (w), 1691 (w) [C=NH],
124.53 (Cq, C1-Ar), 118.49 (+, C3-Ar), 49.16 (+, CH), 41.58 (–, 1626 (w), 1584 (w), 1405 (s), 1315 (m), 1229 (m) [–C–N valence],
˜
CH2), 46.68 (+, CH), 32.21 (+, CO-CH3), 23.92 (+, CH3), 19.41
1134 (s) [CF3], 1032 (w), 775 (w), 753 (w) cm–1. MS (70 eV, EI):
(+, CH ) ppm. IR (KBr): ν = 3335 (w), 3067 (m), 2977 (m) [–C–H m/z (%) = 356 (28) [M+], 299 (26) [C14H18F3N4+], 285 (9)
˜
3
valence], 1952 (w), 1923 (w), 1676 (m) [C=O], 1591 (m), 1472 (m), [C14H18F3N3 + ], 243 (100) [C11H12F3N3+], 228 (14) [C12H13F3N+],
1403 (s), 1368 (m), 1285 (m) [–C–N valence], 1238 (m), 1220 (m), 223 (28), 208 (11), 201 (42) [C11H13N4+], 200 (38) [C8H5F3N3+],
1156 (m), 753 (m) cm–1. MS (70 eV, EI): m/z (%) = 247 (15) [M+],
188 (10) [C10H12N4+], 187 (13) [C10H11N4+], 173 (37) [C7H4F3N2+],
147 (15) [C8H7N2O+], 120 (9) [C8H7O+], 119 (25) [C8H7O+], 105 172 (81) [C8H5F3N+], 166 (17), 145 (12) [C7H4F3+], 100 (16)
(27) [C7H5O+], 100 (36) [C6H14N+], 92 (8), 91 (100) [C6H5N+], 77
(6) [C6H5+], 58 (6) [C3H8N+], 43 (20) [C3H7+]. HR-EIMS
(C14H21N3O): calcd. 247.1685; found 247.1683; elemental analysis
(C14H21N3O): calcd. C 67.98, H 8.56, N 16.99; found C 67.62, H
8.34, N 16.93.
[C6H14N+], 84 (12) [C5H10N+], 58 (16) [C3H8N+], 43 (52) [C3H7+].
HR-EIMS (C18H27F3N4): calcd. 356.2188; found 356.2186.
(E)-[2-(3,3-Diisopropyltriaz-1-enyl)-3-(trifluoromethyl)phenyl]-
(phenyl)methanimine (16e): To a solution of compound 9e (597 mg,
2.00 mol) in dry THF (15 mL) was added phenyllithium (2.0  in
(E)-1-[2-(3,3-Diisopropyltriaz-1-enyl)-3-(trifluoromethyl)phenyl]- dibutyl ether, 1.60 mL, 3.20 mmol) dropwise at 0 °C. After stirring
ethanone (13e): Following general procedure D, compound 9e
(597 mg, 2.00 mmol) was treated with MeMgBr (3  in Et2O,
2.00 mL, 3.20 mmol) in THF (15 mL). Column chromatography on
at room temp. for 2.5 h, no starting material could be detected via
TLC and the reaction was quenched with saturated NH4Cl solution
(7 mL). The aqueous phase was extracted with EtOAc (3ϫ30 mL),
silica (n-pentane/diethyl ether, 3:1) yielded 493 mg (1.56 mmol, the organic phase was washed with brine (20 mL) and dried with
1
78%) of a white solid. Rf (n-pentane/diethyl ether, 3:1) = 0.35. H
NMR (400 MHz, CDCl3): δ = 7.65 (dd, J = 7.8, J = 0.9 Hz, 1 H,
Ar-H6), 7.40 (dd, J = 7.1 Hz, 1 H, Ar-H4), 7.18 (dt, J = 7.7, J =
0.6 Hz, 1 H, Ar-H5), 5.13 (sept, J = 6.8 Hz, 1 H, CH), 4.00 (sept,
J = 6.6 Hz, 1 H, CH), 2.12 (s, 3 H, CH3), 1.31 (d, J = 6.6 Hz, 6
H, 2ϫCH3), 1.28 (d, J = 6.8 Hz, 6 H, 2ϫCH3) ppm. 13C NMR
(100 MHz, CDCl3): δ = 202.46 (Cq, C=O), 179.29 (Cq, C2-Ar),
Na2SO4. Column chromatography on silica (cyclohexane/ethyl ace-
tate, 3:1) yielded 734 mg (1.95 mmol, 95%) of the product. Rf (cy-
clohexane/ethyl acetate, 1:1) = 0.56. H NMR (400 MHz, CDCl3):
δ = 9.52 (br.s, 1 H, NH), 7.73 (dd, J = 7.8, J = 1.0 Hz, 1 H, Ar-
H4), 7.62 (d, J = 7.3 Hz, 2 H, Aro-H), 7.42 (d, J = 7.5 Hz, 1 H,
Arp-H), 7.39–7.35 (m, 1 H, Ar-H6), 7.33–7.28 (m, 2 H, Arm-H) 7.23
(dt, J = 7.7, J = 0.5 Hz, 1 H, Ar-H5), 4.63 (sept, J = 6.8 Hz, 1 H,
1
131.62 (+, C6-Ar), 128.02 (+, J = 5.4 Hz, q, C4-Ar), 126.77 (+, q, CH), 3.77 (sept, J = 6.6 Hz, 1 H, CH), 1.03 (d, J = 6.7 Hz, 6 H,
C1-Ar, J = 5.4 Hz), 124.08 (+, q, CCF3, J = 29.8 Hz), 124.03 (+, 2ϫCH3), 1.00 (d, J = 6.8 Hz, 6 H, 2ϫCH3) ppm. 13C NMR
q, CF3, J = 273.5 Hz), 123.82 (+, C5-Ar), 50.11 (+, CH), 47.15
(100 MHz, CDCl3): δ = 177.33 (Cq, C=NH), 148.22 (Cq, C2-Ar),
(+, CH), 23.42 (+, COCH3), 19.18 (+, 4ϫCH3) ppm. 19F NMR 137.75 (+, Ci-Ar), 133.38 (+, Co-Ar), 133.05 (+, C6-Ar), 130.24 (+,
(376 MHz, CDCl ): δ = –58.2 (m, CF ) ppm. IR (KBr): ν = 2976
Cp-Ar), 128.08 (+, C1-Ar), 127.99 (+, Cm-Ar), 127.08 (+, J =
5.5 Hz, q, C4-Ar), 124.07 (+, q, CF3, J = 273.5 Hz), 124.00 (+, q,
CCF3, J = 29.6 Hz), 123.64 (+, C5-Ar), 50.47 (+, CH), 47.18 (+,
˜
3
3
(w), 2935 (w), 1694 (w) [C=O], 1629 (w), 1583 (w), 1405 (m), 1368
(m), 1312 (s), 1229 (m) [–C–N valence], 1133 (s) [CF3] cm–1. MS
(70 eV, EI): m/z (%) = 315 (18) [M+], 215 (8) [C9H6F3N2O+], 201
CH), 22.81 (+, CH ), 18.71 (+, CH ) ppm. IR (KBr): ν = 2975 (m),
˜
3
3
(39) [C9H6F3NO+], 187 (28) [C9H6F3O+], 173 (22) [C7H4F3N2+], 2935 (w) [–C–H valence], 1603 (w) [C=NH], 1405 (s), 1367 (m),
Eur. J. Org. Chem. 2008, 3314–3327
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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3323

S. Bräse et al.
FULL PAPER
1316 (s), 1278 (m) [–C–N valence], 1133 (s) [CF3], 1031 (w), 939 1283 (m) [–C–N valence], 1228 (s), 1151 (m), 1030 (m), 898 (w),
(w), 883 (w), 768 (w), 698 (m) cm–1. MS (70 eV, EI): m/z (%) = 376/ 760 (s), 640 (w), 542 (w) cm–1. MS (70 eV, EI): m/z (%) = 234 (100)
377 (65/15) [M+ ], 305 (8) [C1 9 H2 1 N4 + ], 263/264 (57/9) [M+], 218 (3) [C13H20N4+], 134 (6) [C7H8N3]. HR-EIMS
[ C1 4 H1 0 F3 N2 + ] , 24 8 / 2 4 9 ( 1 0 0 / 1 7 ) [ C 1 4 H 9 F 3 N + ] , 2 4 3 (C13H22N4): calcd. 234,1844; found 234.1841; elemental analysis
(22)[C11H12F3N3+], 228 (29) [C10H8F3N3+], 104 (10), 100 (24) (C13H22N4): calcd. C 66.63, H 9.46, N 23.91; found C 66.26,
[C6H14N+], 74 (14) [C4H12N+], 59 (31) [C3H9N+], 43 (20) [C3H7+]. H 9.27, N 23.36.
HR-EIMS (C20H23F3N4): calcd. 376.175; found 376.1877; elemen-
tal analysis (C20H23F3N4): calcd. C 63.82, H 6.16, N 14.88; found
C 63.88, H 6.06, N 14.65.
(E)-[2-(3,3-Diisopropyltriaz-1-enyl)-3-(trifluoromethyl)phenyl]-
methanamine (18e): Following general procedure F, compound 9e
(2.22 g, 7.44 mmol) was reduced by a LiAlH4 solution (1  in THF,
(E)-[2-(Pyrrolidin-1-yldiazenyl)phenyl]methanamine (18a): Follow-
ing general procedure E, compound 9a (200 mg, 1.00 mol) was re-
14.9 mL, 14.9 mmol) to yield 1.28 g (4.23 mmol, 57%) of a yellow
oil after column chromatography on silica (CH2Cl2/methanol with
duced by LiAlH4 (76.0 mg, 2.00 mmol) to yield 183 mg (0.90 mmol,
1% of triethylamine, 19:1). Rf (CH2Cl2/methanol with 1% of trieth-
1
1
90%) of a yellow oil. H NMR (400 MHz, CDCl3): δ = 7.42 (ddd, ylamine, 9:1) = 0.33. H NMR (400 MHz, CDCl3): δ = 7.57 (dd, J
J = 7.2, J = 1.4, J = 0.9 Hz, 1 H, Ar-H3), 7.22–7.19 (m, 2 H, Ar- = 7.8, J = 0.9 Hz, 1 H, Ar-H4), 7.50 (dd, J = 7.6 Hz, 1 H, Ar-H6),
H4, Ar-H5), 7.07 (ddt, J = 7.4, J = 1.2 Hz, 1 H, Ar-H6), 3.96 (s, 2
H, CH2-NH2), 3.80 [br.s, 4 H, N(CH2)2], 2.28 (br.s, 2 H, NH2),
2.05–2.01 (m, 4 H, 2ϫCH2) ppm. 13C NMR (100 MHz, CDCl3): δ
7.17 (dt, J = 7.6 Hz, 1 H, Ar-H5), 5.19 (sept, J = 6.8 Hz, 1 H, CH),
4.03 (sept, J = 6.7 Hz, 1 H, CH), 3.75 (s, 2 H, CH2), 2.33 (br.s, 2
H, NH2), 1.35 (d, J = 6.7 Hz, 6 H, 2ϫCH3), 1.28 (d, J = 6.8 Hz,
= 148.85 (Cq, C2-Ar), 137.16 (+, C4-Ar), 128.54 (+, C6-Ar), 127.66 6 H, 2ϫCH3) ppm. 13C NMR (100 MHz, CDCl3): δ = 149.06 (Cq,
(Cq, C1-Ar), 125.28 (+, C5-Ar), 116.48 (+, C3-Ar), 77.27 [–, C2-Ar), 136.10 (+, C5-Ar), 132.54 (+, C6-Ar), 125.46 (+, q, C5-Ar,
N(CH ) ], 44.45 (–, CH –NH ), 23.79 (–, 2ϫCH ). IR (KBr): ν =
J = 5.6 Hz), 124.23 (+, C4-Ar), 124.19 (+, q, CF3, J = 273.6 Hz),
123.35 (+, q, C3-Ar, J = 29.7 Hz), 49.25 (+, CH), 46.22 (+, CH),
43.43 (–, CH2), 23.36 (+, CH3), 19.19 (+, CH3) ppm. 19F NMR
˜
2 2
2
2
2
3299 (vw) [NH2], 3063 (w), 3028 (w), 2971 (m), 2870 (m) [–C–H
valence], 1712 (w), 1662 (m) [NH2], 1595 (w), 1580 (w), 1480 (m),
1413 (m), 1318 (m), 1222 (m) [–C–N valence], 1161 (w), 1104 (w),
(376 MHz, CDCl ): δ = –58.6 (m, CF ) ppm. IR (KBr): ν = 3363
˜
3
3
761 (m), 561 (w) cm–1. MS (70 eV, EI): m/z (%) = 204 (8) [M+], 148 (w) [NH2], 3074 (w), 2976 (m), 2935 (m) [–C–H valence], 2874 (m)
(8) [C7H8N4+], 133 (19) [C7H7N3+], 106 (100) [C7H8N+], 105 (9)
[C7H7N+], 104 (11) [C7H6N+], 84 (15) [C4H8N2+], 77 (24) [C6H5+],
[CH2 valence], 1639 (w) [NH2], 1596 (m), 1426 (m), 1405 (m), 1367
(m), 1318 (m) [–C–N valence], 1129 (m) [CF3], 779 (m) cm–1. MS
70 (8) [C4H8N+], 56 (5) [C3H6N+], 43 (11) [C2H5N+]. HR-EIMS (70 eV, EI): m/z (%) = 302 (8) [M+], 215 (28), 201 (16) [C8H6F3N3+],
(C11H16N4): calcd. 204.1375; found 204.1378.
189 (57) [C8H8F3N2+], 188 (17) [C8H7F3N2+], 174 (29) [C8H7F3N+],
172 (11) [C8H5F3N+], 145 (12) [C7H4F3+], 100 (12) [C6H14N+], 58
(25) [C3H8N+], 43 (51) [C3H7+]. HR-EIMS (C14H21F3N4):
calcd. 302.1718; found 302.1716.
(E)-[2-(3,3-Diethyltriaz-1-enyl)phenyl]methanamine (18c): Following
general procedure E, compound 9c (500 mg, 2.47 mmol) was re-
duced by LiAlH4 (190 mg, 5.01 mmol) to yield 478 mg (2.32 mmol,
93%) of a yellow oil. Rf (1% triethylamine in methanol) = 0.14. 1H
(E)-[2-(3,3-Diethyltriaz-1-enyl)-3-(trifluoromethyl)phenyl]methan-
NMR (400 MHz, CDCl3): δ = 7.47 (ddd, J = 7.2 Hz, 1 H, Ar-H3), amine (18f): Following general procedure F, compound 9f (270 mg,
7.28–7.24 (m, 2 H, Ar-H4, Ar-H5), 7.13 (dt, J = 7.3, J = 1.2 Hz, 1
H, Ar-H6), 4.02 (s, 2 H, CH2-NH2), 3.81 [q, J = 7.2 Hz, 4 H,
1.00 mmol) was reduced by a LiAlH4 solution (1  in THF, 2.0 mL,
2.00 mmol) to yield 68.0 mg (0.25 mmol, 25%) of a yellow oil. Rf
N(CH2)2], 2.00 (br.s, 2 H, NH2), 1.32 (t, J = 6.7 Hz, 6 H, 2ϫCH3) (1% triethylamine methanol) = 0.26. 1H NMR (400 MHz, CDCl3):
ppm. 13C NMR (100 MHz, CDCl3): δ = 148.57 (Cq, C2-Ar), 137.45 δ = 7.56 (dd, J = 7.9, J = 0.9 Hz, 1 H, Ar-H4), 7.48 (dd, J = 7.6 Hz,
(+, C4-Ar), 128.46 (+, C6-Ar), 127.59 (Cq, C1-Ar), 126.17 (+, C5- 1 H, Ar-H6), 7.18 (dt, J = 7.6, J = 0.5 Hz, 1 H, Ar-H5), 3.77 [q, J
Ar), 117.47 (+, C3-Ar), 44.39 [–, N(CH2)2], 22.63 (–, CH2–NH2),
= 6.7 Hz, 4 H, N(CH2)2], 3.70 (s, 2 H, CH2), 1.62 (br.s, 2 H, NH2),
12.11 (+, 2ϫCH ). IR (KBr): ν = 3367 (w) [NH ], 3064 (w), 2974 1.32–1.25 (m, 6 H, 2ϫCH3) ppm. 13C NMR (100 MHz, CDCl3): δ
˜
3
2
(m), 2933 (m) [–C–H valence], 2871 (m), 1581 (w), 1412 (s), 1380 = 148.64 (Cq, C2-Ar), 136.99 (+, C6-Ar), 132.69 (Cq, C1-Ar), 125.27
(s), 1342 (s), 1281 (m) [–C–N valence], 1239 (s), 1201 (m), 1086 (s),
(+, q, C4-Ar, J = 5.5 Hz), 124.44 (+, C5-Ar), 124.17 (+, q, CF3, J
902 (w), 760 (s), 639 (w), 572 (w) cm–1. MS (70 eV, EI): m/z (%) = = 273.5 Hz), 123.51 (+, q, C3-Ar, J = 29.6 Hz), 48.99 (–, CH2CH3),
206 (36) [M+], 190 (47) [C11H16N3+], 149 (16) [C7H9N4+], 134 (8)
43.70 (–, CH2NH2), 41.13 (–, CH2CH3), 14.44 (+, CH3), 11.13 (+,
[C7H8N3+], 132 (19) [C7H6N3+], 106 (100) [C7H8N+], 105 (13) CH ) ppm. IR (KBr): ν = 3440 (br.) [NH ], 2977 (vw), 2937 (vw)
˜
3
2
[C7H7N+], 104 (10) [C7H6N+], 77 (24) [C6H5+]. HR-EIMS [–CH2 valence], 1587 (vw), 1449 (w), 1317 (w) [–C–N valence], 1129
(C12H13F3N4): calcd. 206.1531; found 206.1533; elemental analysis
(C11H18N4): calcd. C 64.05, H 8.79, N 27.16; found C 64.04, H
8.46, N 26.65.
(w) [CF3], 773 (vw), 752 (vw) cm–1. MS (70 eV, EI): m/z (%) = 274
(9) [M+], 200 (10) [C8H5F3N3+], 189 (8) [C8H8F3N2+], 174 (13)
[C8H7F3N+], 173 (10) [C8H6F3N+], 172 (10) [C8H5F3N+], 134 (13)
[C7H8N3+], 127 (20), 87 (14) [C7H3+], 86 (24), 74 (8) [C4H12N+],
57 (9) [C3H7N+]. HR-EIMS (C12H17F3N4): calcd. 274.1405; found
274.1396.
(E)-[2-(3,3-Diisopropyltriaz-1-enyl)phenyl]methanamine (18d): Fol-
lowing general procedure E, compound 9d (500 mg, 2.17 mmol)
was reduced by LiAlH4 (170 mg, 4.48 mmol) to yield 506 mg
(2.16 mmol, quant.) of a yellow oil. Rf (1% triethylamine meth-
1-(Diethylamino)-7-(trifluoromethyl)-1H-indazol-3(2H)-one (19f):
1
anol) = 0.14. H NMR (400 MHz, CDCl3): δ = 7.51–7.49 (m, 1 H,
1H NMR (400 MHz, CDCl3): δ = 7.62 (dd, J = 8.3 Hz, 1 H, Ar-
Ar-H3), 7.30–7.24 (m, 2 H, Ar-H4, Ar-H5), 7.11 (ddd, J = 7.4, J = H10), 7.52 (qdd, J = 7.0, J = 1.0 Hz, 1 H, Ar-H8), 6.83 (ddt, J =
1.3 Hz, 1 H, Ar-H6), 5.22 (br.s, 1 H, CH), 4.07 (br.s, 1 H CH),
7.1, J = 0.6 Hz, 1 H, Ar-H9), 4.51 (br.s, 1 H, NH), 3.56 (q, J =
2.00 (br.s, 2 H, CH2), 1.37 (bd, 12 H, 4ϫCH3) ppm. 13C NMR 4.8 Hz, 2 H, NCH2), 3.10 (q, J = 4.5 Hz, 2 H, NCH2), 0.85 (t, J =
(100 MHz, CDCl3): δ = 149.02 (Cq, C2-Ar), 137.28 (+, C4-Ar), 7.1 Hz, 6 H, 2ϫCH3) ppm. 13C NMR (100 MHz, CDCl3): δ =
128.46 (+, C6-Ar), 127.55 (Cq, C1-Ar), 124.91 (+, C5-Ar), 116.57
165.38 (Cq, C=O), 140.82 (Cq, C6-Ar), 139.63 (+, C8-Ar), 125.20
(+, C3-Ar), 51.98 (+, 2ϫCH), 44.50 (–, CH2–NH2), 20.65 (+, (+, q, C9-Ar, J = 5.4 Hz), 124.21 (+, C10-Ar), 124.21 (+, q, CF3, J
4ϫCH ) ppm. IR (KBr): ν = 3371 (w) [NH ], 3063 (w), 2973 (m),
= 271.8 Hz), 117.25 (Cq, q, CCF3, J = 32.2 Hz), 115.54 (Cq, C5-
˜
3
2
2931 (m) [–C–H valence], 2869 (m), 1580 (w), 1418 (s), 1365 (s) Ar), 51.74 (–, 2ϫCH ), 12.15 (+, 2ϫCH ) ppm. IR (KBr): ν = 3465
˜
2
3
3324
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2008, 3314–3327

Particularly Stable Triazenes
(vw) [N–H], 3154 (w), 3110 (w), 2974 (w) [–C–H valence], 2875 (m), 1031 (w), 780 (w), 671 (w) cm–1. MS (70 eV, EI): m/z (%) =
(vw), 1639 (w) (C=O), 1614 (w), 1309 (w), 1248 (w) [–C–N valence],
1111 (w), 753 (w) cm–1. MS (70 eV, EI): m/z (%) = 273 (7) [M+],
272 (63) [M+ – 1], 253 (8), 201 (18) [C8H4F3N2O+], 172 (9)
[C8H3F3O+], 151 (9), 73 (18) [C4H11N+], 72 (22) [C4H10N+], 58
(100) [C3H8N+]. HR-EIMS (C12H14N3F4O): calcd. 273.1089; found
273.1084; elemental analysis (C12H14N3F4O): calcd. C 52.75, H
5.16, N 15.38; found C 52.28, H 5.01, N 17.77.
359/360 (100) [M + 1], 340 (13) [C17H23F3N4+], 302 (23)
[C14H21F3N4+], 259 (7) [C11H14F3N4+], 246 (19) [C11H15F3N3+],
185 (14) [C8 H4 F3 N2 +], 175 (63), 173 (16) [C7H4F3N2+ ],
159 (8) [C8H6F3+], 155 (26), 127 (15) [C6H13N3+], 115 (27)
[C5H13N3+], 100 (40) [C6H14N+]; elemental analysis (C18H29F3N4):
calcd. C 60.31, H 8.15, N 15.63; found C 60.45, H 8.00,
N 15.56.
(E)-1-[2-(3,3-Diisopropyltriaz-1-enyl)-3-(trifluoromethyl)phenyl]- (E)-[2-(3,3-Diisopropyltriaz-1-enyl)-3-(trifluoromethyl)phenyl]-
ethanamine (20e): Following general procedure G, compound 13e
(140 mg, 0.44 mmol) was reduced with ammonia (2  in methanol,
(phenyl)methanamine (22e): A solution of compound 16e (347 mg,
0.92 mmol) in dry THF (5 mL) was cooled down to 0 °C. At this
1.11 mL, 2.22 mmol), Ti(OiPr)4 (0.20 mL, 0.89 mmol) and LiBH4 temperature lithium borohydride (0.69 mL, 1.38 mmol) was added
(2  in THF, 0.30 mL, 0.67 mmol). Column chromatography (n-
pentane/diethyl ether + 10% triethylamine, 3:1) on silica yielded
80.0 mg (0.25 mmol, 57 %) of a yellow oil. Rf (n-pentane/diethyl
ether + 10 % triethylamine, 3:1) = 0.12. 1H NMR (400 MHz,
CDCl3): δ = 7.66 (dd, J = 6.9 Hz, 1 H, Ar-H6), 7.53 (dd, J = 7.7,
dropwise. The resulting solution was heated up to room temp. and
stirred for 6 h until no more starting material could be detected via
TLC. Then water (5 mL) was added and the aqueous layer was
extracted with EtOAc (3ϫ15 mL), the organic layer washed with
brine (15 mL) and dried with Na2SO4. Column chromatography on
J = 1.0 Hz, 1 H, Ar-H4), 7.22 (dt, J = 7.8 Hz, 1 H, Ar-H5), 5.19 silica (n-pentane/diethyl ether, 1:2 + 0.2% of triethylamine) gave
(sept, J = 6.8 Hz, 1 H, CH), 4.23 (q, J = 6.7 Hz, 1 H, NH2CH),
4.00 (sept, J = 6.6 Hz, 1 H, CH), 1.54 (br.s, 2 H, NH2), 1.34 [d, J
= 6.7 Hz, 6 H, CH(CH3)2], 1.33 (d, J = 6.6 Hz, 3 H, CH3), 1.28 [d,
100 mg (0.26 mmol, 30 %) of a yellow oil. Rf (n-pentane/diethyl
ether, 1:2 + 0.2% of triethylamine) = 0.15. 1H NMR (400 MHz,
CDCl3): δ = 7.55 (dd, J = 7.8, J = 1.1 Hz, 1 H, Ar-H4), 7.46 (dd,
J = 6.8 Hz, 6 H, CH(CH3)2] ppm. 13C NMR (100 MHz, CDCl3): J = 7.7 Hz, 1 H, Ar-H6), 7.33–7.27 (m, 4 H, Aro-H, Arm-H), 7.22–
δ = 159.77 (Cq, C2-Ar), 148.88 (+, C6-Ar), 141.74 (Cq, C1-Ar), 7.15 (m, 2 H, Arp-H, Ar-H5), 5.40 (s, 1 H, CH), 5.17 (sept, J =
128.90 (+, C4-Ar), 124.86 (+, q, C5-Ar, J = 5.5 Hz), 124.22 (+, q, 6.8 Hz, 1 H, CH), 3.94 (sept, J = 6.6 Hz, 1 H, CH), 1.81 (br.s, 2
CF3, J = 273.5 Hz), 122.81 (Cq, q, C3-Ar, J = 29.6 Hz), 49.01 (+,
H, NH2), 1.24 (dd, J = 34.7, J = 6.8 Hz, 6 H, 2ϫCH3), 1.24 (dd,
CH), 45.91 (+, CH), 45.49 (+, NH2CH), 23.99 (+, CHCH3), 23.42 J = 6.8, J = 2.3 Hz, 6 H, 2ϫCH3) ppm. 13C NMR (100 MHz,
(+, 2ϫCH ), 19.31 (+, 2ϫCH ) ppm. IR (KBr): ν = 3373 (br.) CDCl3): δ = 149.37 (Cq, C2-Ar), 144.48 (+, Ci-Ar), 140.23 (+, C6-
˜
3
3
[NH2], 3074 (vw), 2975 (m), 2933 (m) [–C–H valence], 2871 (w)
[–CH3 valence], 1947 (vw), 1668 (w), 1596 (w), 1430 (m), 1403 (m),
1367 (m), 1317 (m) 1226 (m) [–C–N valence], 1128 (m) [CF3], 1031
Ar), 131.26 (+, C1-Ar), 128.33 (+, Co-Ar), 127.06 (+, Cp-Ar),
126.58 (+, Cm-Ar), 125.35 (+, q, C4-Ar, J = 5.5 Hz), 124.30 (+, C5-
Ar), 124.20 (+, q, CF3, J = 273.6 Hz), 122.73 (+, q, CCF3, J =
(w), 922 (vw), 778 (w), 741 (w) cm–1. MS (70 eV, EI): m/z (%) = 29.8 Hz), 53.72 (+, CHNH2), 48.93 (+, CH), 45.83 (+, CH), 23.31
316 (0.5) [M+], 228 (21) [C10H9F3N3+], 203 (100) [C12H17N3+], 186
(80) [C9H7F3N+], 168 (48), 115 (44) [C6H15N2+], 100 (16)
[C6H14N+], 73 (26) [C4H11N+], 43 (54) [C3H7+]; elemental analysis
(+, CH3), 19.27 (+, CH3) ppm. 19F NMR (376 MHz, CDCl3): δ =
–57.8 (m, CF ) ppm. IR (KBr): ν = 3376 (br.) [NH ], 3310 (vw),
˜
3
2
2976 (vw), 2930 (vw) [–C–H valence], 1736 (vw), 1493 (vw), 1428
(C15H23F3N4): calcd. C 56.95, H 7.33, N 17.71; found C 56.79, H (w), 1367 (w), 1317 (w), 1271 (w) [–C–N valence], 1226 (w), 1150
7.22, N 13.79.
(w), 1127 (w) [CF3], 1082 (w), 1030 (vw), 781 (vw), 739 (vw), 700
(w), 672 (vw) cm–1. MS (70 eV, EI): m/z (%) = 378 (84) [M+], 362
(90) [C20H23F3N3+], 341 (13), 281 (17), 227 (17) [C10H7F3N3 + ],
178 (19) [C13H8N+], 153 (17), 127 (21), 100 (27) [C6H14N+], 86 (48)
[C5H12N+], 84 (100) [C5H10N+], 77 (35) [C6H5+], 44 (35), 43 (40)
[C2H5N+], 41 (60) [C2H3N+]. HR-EIMS (C20H25F3N4): calcd.
378.2031; found 378.2030; elemental analysis (C20H25F3N4): calcd.
C 63.48, H 6.66, N 14.80; found C 62.52, H 6.72, N 13.72.
(E)-1-[2-(3,3-Diisopropyltriaz-1-enyl)-3-(trifluoromethyl)phenyl]-
pentan-1-amine (21e): A solution of compound 14e (170 mg,
0.48 mmol) in dry THF (5 mL) was cooled down to 0 °C. At this
temperature lithium borohydride (0.36 mL, 0.72 mmol) was added
dropwise. The resulting solution was heated up to room temp. and
stirred for 6 h until no more starting material could be detected via
TLC. Then water (5 mL) was added and the aqueous layer was
extracted with EtOAc (3ϫ15 mL), the organic layer was washed
with brine (15 mL) and dried with Na2SO4. Column chromatog-
raphy on silica (n-pentane/diethyl ether, 5:1 + 0.2 % of triethyl-
amine) gave 88.0 mg (0.25 mmol, 51%) of a yellow oil. Rf (n-pen-
(E)-1-[2-(3,3-Diisopropyltriaz-1-enyl)phenyl]ethanamine (23d): Fol-
lowing general procedure G, compound 13d (150 mg, 0.61 mmol)
was reduced with ammonia (2  in methanol, 1.50 mL, 3.03 mmol),
Ti(OiPr)4 (0.40 mL, 1.21 mmol) and LiBH4 (2  in THF, 0.50 mL,
0.91 mmol). Column chromatography (n-pentane/diethyl ether, 1:1)
1
tane/diethyl ether, 5:1 + 0.2% of triethylamine) = 0.21. H NMR
(400 MHz, CDCl3): δ = 7.60 (dd, J = 7.7 Hz, 1 H, Ar-H6), 7.52
on silica yielded 59.1 mg (0.24 mmol, 39%) of a yellow oil. Rf (n-
(dd, J = 7.9 Hz, 1 H, Ar-H4), 7.21 (dt, J = 7.8 Hz, 1 H, Ar-H5), pentane/diethyl ether, 1:1) = 0.15. H NMR (400 MHz, CDCl3): δ
5.18 (sept, J = 6.8 Hz, 1 H, CH), 4.04 (m, 1 H, CHNH2), 3.99 = 7.43 (ddd, J = 7.9, J = 1.2 Hz, 1 H, Ar-H3), 7.35 (ddd, J = 7.6,
1
(sept, J = 6.6 Hz, 1 H, CH), 1.69–1.54 (m, 2 H, CHCH2), 1.50
(br.s, 2 H, NH2), 1.36–1.23 (m, 16 H, 2ϫCH2, 4ϫCH3), 0.85 (t, J 7.0, J = 1.9 Hz, 1 H, Ar-H4), 5.14 (br.s, 2 H, 2ϫCH), 4.62 (q, J =
= 7.2 Hz, 3 H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ =
6.8 Hz, 1 H, CHNH2), 1.45 (d, J = 6.8 Hz, 3 H, CH3), 1.33–1.29
148.66 (Cq, C2-Ar), 138.59 (+, C6-Ar), 130.17 (Cq, C1-Ar), 125.76 (m, 14 H, NH2, 4ϫCH3) ppm. 13C NMR (100 MHz, CDCl3): δ =
(+, q, C4-Ar, J = 5.6 Hz), 124.30 (+, C5-Ar), 124.18 (+, q, CF3, J 148.31 (Cq, C2-Ar), 128.86 (Cq, C1-Ar), 127.01 (+, C6-Ar), 125.24
= 273.5 Hz), 122.84 (+, q, CCF3, J = 29.9 Hz), 49.29 (+, CH), (+, C4-Ar), 124.96 (+, C5-Ar), 116.45 (+, C3-Ar), 56.71 (+, CH),
46.20 (+, CH), 37.10 (+, CHNH2), 28.47 (–, CHCH2), 23.28 (–, 50.74 (+, CH), 47.41 (+, NH2CH), 23.52 (+, CH-CH3), 17.46 (+,
CH2), 23.20 (–, CH2), 22.65 (+, 2ϫCH3), 19.27 (+, 2ϫCH3), 14.02 4ϫCH ) ppm. IR (KBr): ν = 3064 (w), 2973 (m) 2931 (m) [–C–H
J = 1.5 Hz, 1 H, Ar-H6), 7.24–7.21 (m, 1 H, Ar-H5), 7.11 (dt, J =
˜
3
(+, CH3) ppm. 19F NMR (376 MHz, CDCl3): δ = –59.9 (m, CF3)
valence], 2871 (w) [–CH3 valence], 2361 (w), 2315 (w), 1467 (w),
ppm. IR (KBr): ν = 3404 (br.) [NH ], 3076 (w), 2973 (m), 2934 (m) 1416 (s), 1364 (m) 1226 (m) [–C–N valence], 1154 (m), 1030 (w),
˜
2
[–C–H valence], 2873 (m), 1597 (w), 1431 (m), 1367 (m), 1318 (m),
757 (w), 547 (vw) cm–1. MS (70 eV, EI): m/z (%) = 248 (10) [M+],
1266 (m) [–C–N valence], 1226 (m), 1193 (m), 1129 (m) [CF3], 1098 232 (99) [C14H22N3+], 177 (55) [C10H15N3+], 160 (35) [C9H10N3+],
Eur. J. Org. Chem. 2008, 3314–3327
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3325

S. Bräse et al.
FULL PAPER
135 (97) [C8H11N2+], 120 (78) [C8H10N+], 118 (100) [C8H8N+], 115 1525 (w), 1404 (m), 1364 (m) [tert-butyl], 1322 (m), 1272 (m) [–C–
(28) [C6H15N2+], 103 (47) [C7H5N+], 91 (21) [C7H7+], 77 (20) N valence], 1158 (m), 1130 (m) [CF3], 1082 (m) [S=O] cm–1. MS
[C6H5+], 43 (41) [C3H7+]. HR-EIMS (C14H24N4): calcd. 248.2001; (70 eV, EI): m/z (%) = 418/419 (12/3) [M+], 362/363 (100/18)
found 248.2004.
[C1 5 H2 1F3N4OS+ ], 361 (15) [C1 5H20 F3 N4 OS+], 261 (22)
[C9H6F3N3OS+], 233/234 (80/13) [C9H6F3NOS+], 214 (11)
[C9H6F3N3+], 213 (15) [C9H6F3N3+], 200 (12) [C9H7F3N2+], 187
(11) [C7H4F3N3+], 186 (17) [C7H3F3N3+], 181 (15), 166 (12), 100
(13) [C6H14N+]. HR-EIMS (C19H29F3N4OS): calcd. 418.2014;
found 418.2011; elemental analysis (C19H29F3N4OS): calcd. C
54.53, H 6.98, N 13.39; found C 54.28, H 6.72, N 13.12.
(E)-N-(1-{2-[(E)-3,3-Diisopropyltriaz-1-enyl]phenyl}ethylidene)-2-
methylpropane-2-sulfinamide (24d): To a solution of compound 9d
(500 mg, 2.17 mmol) in dry THF (5 mL), methyllithium (1.6  in
diethyl ether, 1.76 mL, 2.82 mmol) was added at 0 °C. After stirring
for 30 min at this temperature, the mixture was cooled down to
–78 °C and tert-butylsulfinyl chloride (638 mg, 4.54 mmol) was
added at once. After 10 min the reaction was warmed to 0 °C with
the help of an ice bath and saturated NH4Cl solution (50 mL) was
added after 60 min at this temperature. The aqueous phase was
extracted with EtOAc (3ϫ40 mL), the organic phase washed with
brine (30 mL) and dried with MgSO4. The crude product was puri-
fied via column chromatography on silica (n-pentane/ethyl acetate,
7:3) to give 360 mg (1.03 mmol, 47%) of a yellow oil. Rf (n-pentane/
(E)-N-{1-[2-(3,3-Diisopropyltriaz-1-enyl)phenyl]-1-phenylethyl}-2-
methylpropane-2-sulfinamide (25): To a solution of compound 24d
(165 mg, 0.47 mmol) in toluene (2 mL), a AlMe3 solution (2  in
toluene, 0.26 mL, 0.52 mmol) was added at –78 °C and the re-
sulting mixture was stirred for 5 min. The mixture was then added
to a solution of phenyllithium (2  in dibutyl ether, 0.52 mL,
0.26 mmol) in toluene (1.5 mL) and also cooled to –78 °C within
10 to 15 min. The reaction was stirred for 3.5 h at this temperature,
warmed to 0 °C and saturated Na2SO4 solution (2 mL) was added.
The aqueous phase was separated and the organic phase was dried
with MgSO4. Purification of the crude product on silica (n-pentane/
ethyl acetate, 2:1) gave 116 mg (0.27 mmol, 58%) of a yellow solid.
Rf (n-pentane/ethyl acetate, 2:1) = 0.15. 1H NMR (400 MHz,
CDCl3): δ = 7.51–7.49 (m, 1 H, Ar-H3), 7.36–7.25 (m, 4 H, Ar-H6,
Ar-H5, Ar-Ho), 7.18–7.11 (m, 3 H, Ar-Hm, Ar-Hp), 7.03 (tt, J =
7.3, J = 1.2 Hz, 1 H, Ar-H4), 4.62 (sept, J = 6.6 Hz, 1 H, CH),
3.74 (sept, J = 6.4 Hz, 1 H, CH), 2.01 (s, 3 H, NC-CH3), 1.81 (br.s,
1 H, NH), 1.28 (d, 3 H, CH3), 1.09 (d, J = 6.4 Hz, 3 H, CH3), 1.07
(s, 9 H, tBu-H), 1.03 (d, J = 6.8 Hz, 3 H, CH3), 0.67 (d, J = 6.5 Hz,
3 H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ = 150.80 (Cq, C2-
Ar), 139.42 (Cq, Ci-Ar), 131.14 (+, Co-Ar), 127.96 (+, C4-Ar),
127.75 (+, C6-Ar), 126.31 (+, Cp-Ar), 125.73 (+, Cm-Ar), 125.05
(Cq, C1-Ar), 124.30 (+, C5-Ar), 118.31 (+, C3-Ar), 64.68 (Cq,
CNH), 60.41 [Cq, C(CH3)3], 55.76 (+, CH), 45.83 (+, CH), 29.03
(+, NC-CH3), 22.79 [+, C(CH3)3], 19.53 [+, CH(CH3)2] 14.41 [+,
1
ethyl acetate, 3:1) = 0.31. H NMR (400 MHz, CDCl3): δ = 7.49–
7.47 (m, 1 H, Ar-H3), 7.39–7.32 (m, 2 H, Ar-H4, Ar-H5), 7.10 (ddd,
J = 7.4 Hz, 1 H, Ar-H6), 5.18 (br.s, 1 H, CH), 4.00 (br.s, 1 H, CH),
2.69 (s, 3 H, NC-CH3), 1.38 (s, 9 H, tBu-H), 1.30 (m, 6 H, 2 CH3),
1.14 (m, 6 H, 2ϫCH3) ppm. 13C NMR (100 MHz, CDCl3): δ =
182.39 (Cq, C=N), 147.93 (Cq, C2-Ar), 135.11 (+, C4-Ar), 129.19
(Cq, C1-Ar), 127.49 (+, C6-Ar), 123.43 (+, C5-Ar), 116.55 (+, C3-
Ar), 60.41 [Cq, C(CH3)3], 48.15 (+, CH), 45.49 (+, CH), 22.92 [+,
C(CH3)3], 21.76 (+, NC-CH3), 18.37 [+, CH(CH3)2], 13.18 [+,
CH(CH ) ] ppm. IR (KBr): ν = 3442 (br.), 3063 (vw), 2974 (m),
˜
3 2
2929 (m) [–C–H valence], 1607 (m) [–C=N], 1475 (m), 1408 (s),
1364 (m) [tert-butyl], 1222 (s), 1158 (m) [CF3], 1082 (m) [S=O], 758
(m) [–C–S valence] cm–1. MS (70 eV, EI): m/z (%) = 350 (10) [M+],
295 (15), 294 (100) [C14H22N4OS+], 293 (17) [C14H21N4OS+], 167
(13) [C8H9NOS+], 166 (10) [C8H8NOS+], 165 (34) [C8H7NOS+],
146 (29), 137 (11), 133 (51) [C7H3NS+], 132 (11), 123 (13), 119 (22),
118 (26), 117 (13) [C8H7N+], 115 (12) [C5H13N3+], 100 (14)
[C6H14N+], 96 (11), 91 (19) [C7H7+], 57 (25) [C4H9+], 43 (42)
[C2H5N+], 41 (12) [C3H5+]. HR-EIMS (C18H30N4OS): calcd.
350.2140; found 350.2138.
CH(CH ) ] ppm. IR (KBr): ν = 3318 (w), 3062 (w) [–N–H valence],
˜
3 2
2978 (w), 1598 (vw), 1416 (m), 1284 (w), 1228 (m) [–C–N valence],
1151 (w), 1072 (m) [S=O], 955 (w), 835 (w), 766 (w) [–C–S valence],
709 (w), 545 (w) cm–1. MS (70 eV, EI): m/z (%) = 429 (0.11) [M +
1], 371/372 (89/18) [C20H27N4OS+], 309 (20) [C20H27N3+], 308 (100)
[C20H26N3+], 194 (11) [C14H12N+], 179 (15) [C14H11+], 165 (9)
[C8H7NOS+], 118 (2) [C8H8N+], 103 (2) [C7H5N+], 100 (2)
[C6H14N+], 77 (1) [C6H5+], 57 (4) [C4H9+], 43 (8) [C2H5N+], 41 (2)
[C3H5+]. HR-EIMS (C20H27N4OS): calcd. 371.1906; found
371.1903 (M – tBu).
(E)-N-(1-{2-[(E)-3,3-Diisopropyltriaz-1-enyl]-3-(trifluoromethyl)-
phenyl}ethylidene)-2-methylpropane-2-sulfinamide (24e): To a solu-
tion of compound 9e (895 mg, 3.00 mmol) in dry THF (10 mL),
methyllithium (1.6  in diethyl ether, 2.40 mL, 3.90 mmol) was
added at 0 °C. After stirring for 30 min at this temperature the
mixture was cooled down to –78 °C and tert-butylsulfinyl chloride
(844 mg, 6.00 mmol) was added at once. After 10 min the reaction
was warmed to 0 °C with the help of an ice bath and saturated
NH4Cl solution (50 mL) was added after 60 min at this tempera-
ture. The aqueous phase was extracted with EtOAc (3ϫ40 mL),
the organic phase washed with brine (30 mL) and dried with
MgSO4. The crude product was purified via column chromatog-
raphy on silica (n-pentane/diethyl ether, 3:1) to give 854 mg
(2.04 mmol, 68%) of a yellow oil. Rf (n-pentane/diethyl ether, 3:1)
Crystal Structure Studies: Single-crystal X-ray diffraction studies
were carried out either on a Nonius Kappa-CCD diffractometer
(for 9a, 13d) or a Bruker–Nonius APEXII diffractometer (for 9d,
9e) at 123(2) K using Mo-Kα radiation (λ = 0.71073 Å). Direct
Methods (SHELXS-97[20]) were used for structure solution and re-
finement (SHELXL-97,[21] full-matrix least-squares on F2). The ab-
solute structure could not be determined reliably [refinement of
Flack’s x parameter x = –2(4) (for 9d) and x = –0.6(7) (for 9e)],[22]
and H atoms were refined using a riding model. In 9a the pyrrolid-
ine is disordered. 13d is a non-merohedral twin with 3 domains.[23]
Important data on the data collection and structure solution and
refinement are listed in Table 5.
1
= 0.26. H NMR (400 MHz, CDCl3): δ = 7.70 (dd, J = 7.6 Hz, 1
H, Ar-H4), 7.52 (dd, J = 7.7 Hz, 1 H, Ar-H6), 7.19 (dt, J = 7.7 Hz,
1 H, Ar-H5), 5.00 (sept, J = 6.7 Hz, 1 H, CH), 4.05 (sept, J =
6.6 Hz, 1 H, CH), 2.31 (s, 3 H, NC-CH3), 1.31 (s, 9 H, tBu-H),
1.20 (m, 6 H, 2ϫCH3), 1.14 (m, 6 H, 2ϫCH3) ppm. 13C NMR
(100 MHz, CDCl3): δ = 182.29 (Cq, C=N), 148.45 (Cq, C2-Ar),
134.71 (Cq, C1-Ar), 133.11 (+, C6-Ar), 127.69 (+, q, C4-Ar, J =
5.0 Hz), 123.97 (+, q, CF3, J = 273.5 Hz), 123.53 (+, C5-Ar), 124.39
CCDC-670842 (for 9a), -670843 (for 9d), -670844 (for 9e), and
(+, q, C3-Ar, J = 29.8 Hz), 60.37 [Cq, C(CH3)3], 51.00 (+, CH), -670845 (for 13d) contain the supplementary crystallographic data
48.07 (+, CH), 23.45 [+, C(CH3)3], 21.03 (+, NC-CH3), 19.12 [+,
for this paper. These data can be obtained free of charge from The
CH(CH ) ], 14.17 [+, CH(CH ) ] ppm. IR (KBr): ν = 3451 (vw), Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
˜
3 2
3 2
3189 (br.), 2975 (m) [–CH3 valence], 2931 (w), 1739 (w), 1587 (w),
data_request/cif.
3326
www.eurjoc.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2008, 3314–3327

Particularly Stable Triazenes
Table 5. Crystallographic data, structure solution and refinement of 9a, 9d, 9e, 13d.
9a
9d
9e
13d
Empirical formula
Formula weight
Temperature [K]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
C11H12N4
200.25
123(2)
monoclinic
P21/c (No. 14)
8.9317(6)
11.2714(4)
10.9547(8)
90
109.731(3)
90
1038.09(11)
4
1.281
0.082
C13H18N4
230.31
123(2)
monoclinic
P21 (No. 4)
7.7651(5)
10.6314(8)
8.2078(6)
90
100.803(4)
90
665.58(8)
2
1.149
0.072
C14H17F3N4
298.32
123(2)
orthorhombic
P212121 (No. 19)
9.0195(2)
10.2052(3)
16.3904(4)
90
C14H21N3O
247.34
123(2)
triclinic
¯
P1 (No. 2)
7.8841(6)
12.0150(8)
15.0091(13)
88.366(5)
87.199(4)
89.964(5)
1419.50(9)
4
90
90
γ [°]
V [Å3]
1508.67(7)
4
1.313
0.107
624
Z
Dcalcd. [gcm–3]
Abs. coeff. [mm–1]
F[000]
1.157
0.075
536
424
248
Crystal size [mm]
θ range for data collection [°] 3.02 to 25.03
Limiting indices
0.40ϫ0.30ϫ0.15
0.40ϫ0.05ϫ0.05
3.17 to 24.98
–9ՅhՅ9
–12ՅkՅ12
–9ՅlՅ9
10686
0.20ϫ0.15ϫ0ϫ10
3.01 to 25.02
–10ՅhՅ10
–12ՅkՅ12
–19ՅlՅ19
22862
0.40ϫ0.30ϫ0.20
2.98 to 25.03
–9ՅhՅ9
–14ՅkՅ14
–17ՅlՅ17
4907
–9ՅhՅ10,
–13ՅkՅ13
–13ՅlՅ12
6607
1828
0.0272
Reflections collected
Unique reflections
Rint
2342
0.0692
2665
0.0476
4907
0.0000
Data/restraints/parameters
1828/17/135
1.036
2342/1/154
1.176
2665/0/190
1.137
4907/0/330
0.998
GOF on F2
R1 [IϾ2σ(I)]
wR2 (all data)
0.0536
0.1473
0.0508
0.1046
0.0355
0.0708
0.1200
0.4303
Largest difference map peak/
0.389/
–0.316
0.160/
–0.180
0.127/
–0.156
0.680/
–0.640
hole [eA–3]
[9] a) M. D. Threadgrill, M. F. G. Stevens, Synthesis 1983, 289–
291; b) H. N. E. Stevens, M. F. G. Stevens, J. Chem. Soc. C
1970, 2284–2289.
[10] a) M. E. P. Lormann, S. Dahmen, F. Avemaria, F. Lauter-
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Acknowledgments
We thank the Bayer CropScience AG, the Bundesministerium für
Bildung und Forschung and the Landesgraduiertenförderung
Baden-Württemberg (grant to R. R.) for financial support.
[11] K. Nishiwaki, T. Ogawa, K. Shigeta, K. Takahashi, K. Matsuo,
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Received: February 8, 2008
Published Online: May 9, 2008
Eur. J. Org. Chem. 2008, 3314–3327
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