Cycloadditions of aryl-substituted 1,2,4-triazines with 2-cyclopropylidene-1,3-dimethylimidazolidine - Zwitterions as discrete intermediates

Article abstract of DOI:10.1002/hlca.200590120

Cycloadditions of 2-cyclopropylidene-1,3-dimethylimidazolidine (1), a strong, electron-rich C-nucleophile, with a variety of aryl-substituted 1,2,4-triazines occur at temperatures between -100 and +100°, depending on the substitution pattern. At low tempe

Full text of DOI:10.1002/hlca.200590120

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Cycloadditions of Aryl-Substituted 1,2,4-Triazines with 2-Cyclopropylidene-
1,3-dimethylimidazolidine ± Zwitterions as Discrete Intermediates
by Michael Ernd1), Manfred Heuschmann*, and Hendrik Zipse*
Department Chemie und Biochemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5 ± 13,
D-81377 München
(phone: ‡ 49-(0)89-2180-77735; fax: ‡ 49-(0)89-2180-77736; e-mail: Manfred.Heuschmann@cup.uni-muenchen.de,
Hendrik.Zipse@cup.uni-muenchen.de)
Dedicated to Professor Rolf Huisgen on the occasion of his 85th birthday
Cycloadditions of 2-cyclopropylidene-1,3-dimethylimidazolidine (1), a strong, electron-rich C-nucleophile,
with a variety of aryl-substituted 1,2,4-triazines occur at temperatures between À 100 and ‡ 1008, depending on
the substitution pattern. At low temperatures, zwitterions, formed by nucleophilic attack of 1 on the triazines,
could be detected spectroscopically and, in some cases, isolated. Two types of zwitterions were found: 1) those
where the new bond was linked to C(5) of the triazine and which were formed in a reversible dead-end
equilibrium, and 2) those where the new bond was linked either to C(3) or C(6). The latter exhibited the same
regiochemistry as the final cycloadducts, and might be intermediates of a two-step Diels ± Alder reaction.
Energies and structural characteristics for stationary points in the reaction of monosubstituted triazines with 1 in
the gas phase and in CH2Cl2 solution were calculated at the Becke3LYP/6-311 ‡ G(d,p)//Becke3LYP/6-31G(d)
level of theory. Different reaction mechanisms are discussed on the basis of steric, electronic, and solvent effects.
1. Introduction. ± 3,6-Disubstituted 1,2,4,5-tetrazines react rapidly at room temper-
ature with 2-cyclopropylidene-1,3-dimethylimidazolidine (1) to give dispiro adducts via
[4 ‡ 2] cycloaddition and consecutive elimination of N2, in accordance with a generally
accepted mechanism [1 ± 3]. The high reactivity of the dienophile [4] in inverse-
electron-demand Diels ± Alder reactions [5] allowed the addition to be performed at
low temperatures, and, thus, zwitterions could be isolated as intermediates. A detailed
study of unsymmetrically substituted tetrazines showed the importance of steric
hindrance in the second step, which determined the overall regiochemistry of the
cycloaddition [2]. Similar Diels ± Alder reactions of electron-rich alkenes with 1,2,4-
triazines are known in a large variety, and are regularly used in synthesis [3]. Previous
investigations [3][6][7] confirm the strong dependence of the regiochemistry on the
substitution pattern of both partners, and on the solvent polarity, but not all effects are
well-understood. In some cases, indications for the presence of intermediates in these
reactions were found [7]. Here, we report the isolation and characterization of
zwitterions as intermediates in [4 ‡ 2] cycloadditions of 1 with 1,2,4-triazines, and the
effect of the substitution pattern on the formation of zwitterions and cycloadducts.
2. Results. ± 2.1. Preparation of Triazines. The triazines required for our
investigation were prepared by two routes. The method of Saraswathi and Srinavasan
1
)
Current address: Allergika GmbH, Bürgermeister-Seidl-Str. 8, D-82515 Wolfratshausen, Germany.
ꢀ 2005 Verlag Helvetica Chimica Acta AG, Zürich

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[8], improved by Zaschke and co-workers [9], starting with b-halogeno ketones and
2 equiv. of acid hydrazides, was best suited for 3,6-disubstituted 1,2,4-triazines 2
(Route A, Table 1). Condensation of 1,2-diketones and amidrazones by the method of
Rätz and Schroeder [10], and of Neunhoeffer et al. [11], yielded 6-substituted triazines
3, 5-substituted triazines 4, and 3,5-disubstituted triazines 5 (Route B, Table 1).
Triazines 4 were usually contaminated with their 6-substituted isomers and 1,2,4,5-
tetrazines, but could be separated easily by column chromatography.
Table 1. Preparation of Different Triazines
Triazine
R3
R5
R6
Routea)
Yield [%]
2b
2c
2e
2f
2g
2i
2j
2k
2l
2m
2n
3b
3c
4b
4c
4d
4e
5c
19b
C6H5
C6H5
H
H
H
H
H
H
H
H
H
H
H
H
H
2-Tol
2-Me-C6H4
4-MeO-C6H4
C6H5
C6H5
C6H5
A
A
A
A
A
A
A
A
A
A
A
B
B
B
B
B
B
B
A
63
42
16
37
29
38
39
44
36
95
54
3
2-Me-C6H4
4-CF3-C6H4
4-NO2-C6H4
4-Me2N-C6H4
4-CF3-C6H4
4-NO2-C6H4
4-MeO-C6H4
4-Me2N-C6H4
C6H5
H
H
H
H
C6H5
4-MeO-C6H4
4-MeO-C6H4
4-NO2-C6H4
4-NO2-C6H4
4-NO2-C6H4
4-MeO-C6H4
4-NO2-C6H4
H
H
H
H
H
59b)
16
7
2,4,6-Me3-C6H2
4-NO2-C6H4
4-MeO-C6H4
4-MeO-C6H4
H
H
H
59b)
4
54
85
C6H5
4-NO2-C6H4
H
a) See Exper. Part. b) Combined yield.
2.2. Cycloaddition of 3,5,6-Triphenyl-1,2,4-triazine (6a). 3,5,6-Triphenyl-1,2,4-
triazine (6a) reacted rapidly with 1 at room temperature in (D6)benzene (Scheme 1).
Apparently, in a Diels ± Alder reaction, the so-far elusive bicyclic intermediate 7a is
formed, which loses N2 in a fast, consecutive [4 ‡ 2] cycloreversion. After a few
minutes, the N2 evolution was finished, and the dispiropyridine 8a was identified by
1
means of H- and 13C-NMR spectroscopy [12]. The substitution pattern of 8a was
corroborated after rearrangement to the pyrrolo[3,2-c]pyridine 9a, a thermal
rearrangement combined with a fragmentation typical for dispiro systems like 8,
leading to N-methylaziridine as the second product [12][13]. The regiochemistry of 9a

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(and, thus, that of 8a) could easily be determined by NOE and other 2D-NMR
experiments. When 6a and 1 were mixed slowly in CD2Cl2 at À 408, a clear solution
resulted, which was analyzed by 1H- and 13C-NMR. After 90 min, the mixture consisted
of starting materials (53% of 6a and 41% of 1), cyloadduct 8a (18%), and a new
substance (29%) to which we assigned the zwitterionic structure 10a on the basis of
spectral similarities [2] to related zwitterions (see below). On stepwise warming to
À 308, and then to 08, the proportion of 10 was reduced to 10 and 0%, and the amount of
cycloadduct 8a increased to 33 and 75%, respectively. The only other products were
triazine 6a (25%) and the reaction product of CD2Cl2 with 1, which, like other 2-
alkylidene imidazolidines, is not stable in this solvent for a longer period at
temperatures above À 208 [2][4]. Unfortunately, we could not find conditions that
led to higher concentrations of 10a to allow the acquisition of unambiguously
interpretable 2D-NMR spectra. Thus, structural assignment was based only upon
chemical-shift comparisons, and not upon clear connectivities.
Scheme 1
2.3. Cycloaddition of 5,6-Diphenyl-1,2,4-triazine (6b). Triazine 6b reacted smoothly
with imidazolidine 1 in benzene solution at room temperature to yield 8b as a single
regioisomer in 93% yield (Scheme 1). In CH2Cl2 solution, 8b isomerized quantitatively
to yield the pyrrolo[3,2-c]pyridine 9b, whose structure was unambiguously identified by
COLOCS, HETCOR, and NOE measurements. NMR Investigation of the low-
temperature reaction at À 308 in CD2Cl2 showed, besides 6b (33%) and 8b (5%), the
zwitterion 10b (62%). The proportion of the latter could be increased to 70% on
warming to À 208. Again 2D-NMR spectra unambiguously corroborated the structure
3
of the 3-regioisomer. Especially the J(C,H) couplings of the characteristic CH group
between the two neighboring N-atoms, and NOE effects were very convincing. After

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warming the solution to room temperature, 80% of the dispiropyridine 8b were
identified, and after seven days, 8b had rearranged quantitatively to 9b, with an isolated
yield of 80%. In other experiments, we observed that N2 evolution already starts at
temperatures as low as À 508.
2.4. Cycloadditions of 3,5-Disubstituted Triazines 5. 3,5-Diphenyl-1,2,4-triazine (5a)
formed a precipitate with imidazolidine 1 at room temperature in toluene (Scheme 2).
Within 20 min, the precipitate dissolved under vigorous N2 evolution to afford the
dispiropyridine 11a in 99% yield after distillation. Similarly, the tolyl and anisyl
derivatives 5b and 5c, respectively, readily reacted at room temperature under
evolution of N2 to afford 11b and 11c in high yields.
Scheme 2
At À 758, the orange-yellow precipitate 12a formed within a few minutes, as above,
but no gas evolution occurred. As this precipitate was not soluble in CD2Cl2, AcOH
was added, and the resulting acetate, which was stable at room temperature, was
dissolved in CDCl3. Careful 2D-NMR analysis revealed the structure of the protonated
zwitterion 13a as the main product (97%; Scheme 2). Triazine 5c was treated with 1 in
CD2Cl2 at À 408, and after a few minutes, CD3COOD was added, and the resulting
clear solution was investigated by NMR. Now, the deuterated zwitterion 13c (61%) was
detected, together with starting material and the dispiro adduct 11c (15%), which was
formed even at such low temperature. In both cases, 13a and 13c, the cyclopropyl group
was undoubtedly connected to the nonsubstituted C-atom of the dihydrotriazine
moieties, corroborating the connectivity of the initially precipitating zwitterions 12.
2.5. Cycloadditions of 3,6-Disubstituted 1,2,4-Triazines 2. Triazines 2 are clearly the
least reactive regioisomers of this series with regard to cycloaddition. Gas evolution did

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not occur below 508, and to achieve a reasonable reaction rate, temperatures typically
of ca. 1008 were necessary. Thus, all Diels ± Alder reactions were run at 1088 in sealed
tubes. In all cases, regioisomeric mixtures of the dispiropyridines 14 and 15 were found
in a ratio of 93 :7 to 48 :52, usually with preferred attack of the cyclopropyl C-atom of 1
at the 3-position of 2 (Scheme 3, Table 2).
Scheme 3
When 1 was added at À 408 to the yellow solutions of triazines 2 in THF or toluene,
the orange zwitterions 16 rapidly precipitated. The zwitterions 16a,g,h were isolated
under Ar atmosphere at À 408. Compounds 16a and 16h were dissolved in CD2Cl2, the
insoluble 16g was treated with CDCl3 containing 4 equiv. of CD3COOD to achieve a
clear solution of 17g, which is probably the most-stable tautomer [14]. The zwitterions
16d,e,i were protonated in the reaction mixture by AcOH without prior isolation, and,
after removal of the solvent in vacuo, the resulting acetates 17d,e,i gave clear solutions
in CDCl3. NMR Studies of the solutions of the zwitterions at À 208, and of the
protonated or deuterated zwitterions at room temperature, indicated that all
nucleophilic additions had occurred at the 5-position of the triazines. Apparently,
compound 1 prefers to attack the 5-position of 2 with its nucleophilic b-C-atom to give
zwitterions 16, while, at high temperatures, C(3) and C(6) of 2 form bonds with the
same b-C-atom to afford the final products 14 or 15 after elimination of N2. The
reversibility of the nucleophilic addition was verified by two experiments. While the
protonated zwitterions 17 were stable at temperatures below 708, the zwitterions 16
decomposed below room temperature. Thus, when a CD2Cl2 solution of isolated 16h

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Table 2. Isomer Distribution in the Reactions of Triazines 2 with 1. Conditions: solvent, 19 h, 1088, sealed tube.
Triazine
R3
R6
Solventa)
Yield [%]
14/15b)
2a
2a
2b
2c
2c
2d
2e
2e
2e
2f
2g
2g
2h
2h
2i
C6H5
C6H5
Toluene
DMF
100
78
88 : 12
69 : 31
80 : 20
88 : 12
87 : 13
89 : 11
83 : 17
88 : 12
81 : 19
70 : 30
48 : 52
49 : 51
90 : 10
89 : 11
93 : 7
C6H5
C6H5
2-Me-C6H4
4-MeO-C6H4
Benzene
Benzene
Toluene
Toluene
Benzene
Benzene
Toluene
Benzene
Benzene
Toluene
Benzene
Toluene
Benzene
Benzene
Benzene
57c)
82
65
4-Me-C6H4
2-Me-C6H4
C6H5
C6H5
100
48
65c)
80
4-CF3-C6H4
4-NO2-C6H4
C6H5
C6H5
100
100
100
52
4-MeO-C6H4
C6H5
93
4-Me2N-C6H4
4-CF3-C6H4
4-NO2-C6H4
C6H5
4-MeO-C6H4
4-MeO-C6H4
100
100
88
2j
2k
75 : 25
52 : 48
a) Fully deuterated in each case. b) Determined by 1H-NMR analysis. c) Heating for 2 h (instead of 19 h).
was allowed to warm to room temperature, only triazine 2h and the reaction products of
1 with CD2Cl2 [2][4] were detected in the 1H-NMR spectrum. In a second experiment,
zwitterion 16h was suspended in a (D6)benzene solution of 3,6-diphenyl-1,2,4,5-
tetrazine, which reacts rapidly with 1 at room temperature [1][2]. No reaction occurred
at room temperature, but on heating above 508, slow evolution of gas started. After
heating to 808 for some hours, the purple color of the tetrazine had vanished, and the
1H-NMR spectrum showed a 1:1 mixture of 2h and 18 (Scheme 3) [1][2].
2.6. Cycloadditions of 3-Substituted Triazines. When the 3-aryl-substituted triazines
19a and b were treated with 1 in (D6)benzene at room temperature, a yellow-brown
solid precipitated (Scheme 4). After heating the mixtures in a sealed tube at 1058 for
2 h, clear solutions were formed, and the products were identified by 2D-1H- and -
13C-NMR spectroscopy. Thus, the dispiropyridine 20a (90%) and its nitro derivative
20b (40%) were identified. We found no indication for the other possible regioisomers.
Scheme 4
The triazines 19a and b readily reacted with the imidazolidine 1 at temperatures as
low as À 708. The precipitates, supposed to be zwitterions 21a and b, respectively, were

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not soluble in THF, CH2Cl2, or CHCl3. After addition of CD3COOD, a clear orange
solution (in CD2Cl2) was obtained, which allowed a detailed 2D-NMR investigation. In
addition to small amounts of the triazines, the deuterated cations 22a (88%) and 22b
(90%) were identified as the only products. Again, the imidazolidine 1 prefers to attack
the 5-position of triazines 19 with its nucleophilic b-C-atom to give zwitterions 21,
while, at high temperatures, C(6) of 19 gets bonded to the b-C-atom of 1 to provide 20.
2.7. Cycloadditions of 5-Substituted Triazines 4. Dropwise addition of a toluene
solution of 1, pre-cooled to À 788, to a solution of 5-phenyl-1,2,4-triazine (4a) at À 858
resulted in the formation of an orange-red precipitate, which dissolved within minutes
under rapid gas evolution. After distillation, a yellow oil, consisting of a 60 :40 mixture
of the dispiropyridines 23a and 24a, was isolated in 70% yield. In CD2Cl2, no precipitate
was formed, but gas evolution occurred rapidly on mixing. When different solvents
were used at different temperatures (Table 3), some variation of the isomer
distribution resulted, which, however, was marginal in terms of energy differences.
Table 3. Isomer Distribution in the Reactions of Triazines 4 with 1
Triazinea)
R5
Solventb)
T [8]
25
À 78
À 78
À 100
25
Yield [%]
23/24c)
4a
C6H5
Toluene
Toluene
Toluened)
Et2O
THF
CD2Cl2
DMF
DMF
CD3CN
C6D6
C6D6
C6D6
76
84
83
100
100
48
92
57
30
100
100
100
95
85 : 15
77: 23
60 : 40
80 : 20
83 : 17
60 : 40
70 : 30
53 : 47
71 : 29
83 : 17
92 : 8
À 60
25
À 50
25
25
25
25
4b
4c
4d
4e
2-Me-C6H4
2,4,6-Me3-C6H2
4-NO2-C6H4
4-MeO-C6H4
100 : 0
73 : 27
86 : 14
C6D6
C6D6
25
25
100
c
a) 0.1 ± 0.3m solution. b) Fully deuterated in each case. ) Determined by 1H-NMR analysis. d) Dilute solution.
Similar results were achieved with the other 5-aryl-substituted triazines 4b ± e.
While donor (4e) or acceptor (4d) substitution did not influence the isomer distribution
noticeably, steric hindrance (e.g., in 4b and c) seems to be of stronger influence. In
terms of energy, the introduction of a mesityl (ˆ2,4,6-trimethylphenyl) group clearly
makes a difference between both pathways. In all cases, we never succeeded to record

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the NMR spectra of the first reaction product, supposed to be a zwitterion, or to
intercept it by protonation before gas evolution set in.
2.8. Cycloadditions of 6-Substituted Triazines 3. 6-Phenyl-1,2,4-triazine (3a) and its
MeO derivative 3b formed red precipitates with imidazolidine 1 at room temperature
in benzene or toluene (Scheme 5). Within a few minutes, the precipitates dissolved with
concomitant, vigorous gas evolution. 2D-NMR Spectra let no doubt that, in both cases,
only one regioisomer, 25a (100%) and 25b (55%), respectively, was formed in the
cycloaddition. However, we did not succeed in isolating 25a, as it rearranged in solution
to the eight-membered ring system 26a, an often-observed rearrangement of such
dispiro systems [12][13].
Scheme 5
The low-temperature reaction between 3a and 1 in CD2Cl2 solution afforded clear
solutions at temperatures above À 508. At À 608, only one product could be identified
by 2D-NMR after addition of CD3OOD, i.e., the deuterated salt 27a ´ CD3CO2D
(89%), together with unreacted 3a (11%). On mixing 3a and 1 at À 40 or À 158, we
detected the formation of a second zwitterion, 28a, in 8 and 15% yield, respectively.
Compound 28a showed the same regiochemistry as the cycloadduct 25a.
2.9. Structures of Zwitterions. All zwitterions showed characteristic spectroscopic
1
data indicative of their structures. The H- and 13C-NMR spectra of the dihydroimi-
dazolium rings were very similar to related dihydroimidazolium salts [2][13], thus
corroborating the cationic feature of these rings. The anionic dihydrotriazinide rings
showed similarities to related dihydrotetrazinides [2], and, likewise, this moiety in the
protonated zwitterions resembled those of dihydrotriazines [15]. In comparison with

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the starting triazines, significant high-field shifts were found for the 13C-NMR signal of
the C-atom connected to the cyclopropyl group, and the same behavior was found for
the directly attached H-atom. Thus, the 13C-NMR signals were observed between d(C)
49.1 and 56.7 for C(4) and C(5), and between 81.5 and 89.2 for C(3), respectively, with
d(H) values of 3.94 and 5.90. There was one notable exception: HÀC(3) of the 5,6-
diphenyl-substituted zwitterion 10b showed a resonance at d(H) 2.08, a value that
seems to be at too high a field. The reason for this may be that, in this case (and maybe
also for 10a), the two bulky Ph groups in 5- and 6-position, which cannot both be
coplanar with the triazinide ring, force the zwitterion into a different conformation. We
knew from a crystal structure of the thermally stable zwitterion 29, derived from 3,6-
diphenyltetrazine and 1, that its dihydrotetrazinide ring adopts a boat conformation
(Fig. 1) [13]. That this is also a likely option for the dihydrotriazinide ring in our
zwitterions is the result of theoretical studies at the Becke3LYP/SB level of theory (see
below). In such a case, two conformations are possible where the substituents can adopt
either pseudo-axial or pseudo-equatorial positions.
Fig. 1. Boat conformations of zwitterions
As shown in Fig. 1 for the zwitterions 10b and 28a, the latter probably prefers
conformation A, whereas the former adopts conformation B. Van der Plas and co-
workers [16] have shown that the 1H-NMR chemical shifts of the Ha- and Hb-atoms in
dihydrotetrazinide anions 30 can differ by as much as 4.8 ppm, Ha being found at higher
field. A similar effect is probably responsible for the observed shift difference in 10b
(Dd(H) ˆ 2.08) and 28a (5.72). Of course, there are also other conformers to be
considered, especially those arising from rotation about the bond connecting the

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cyclopropyl and triazinide rings. These, however, could hardly rationalize the large
1
differences in H-NMR chemical shifts. For all zwitterions (and protonated zwitter-
ions), we found that the rotation barrier for the bond between the cyclopropyl and the
dihydroimidazolium rings is relatively high. Therefore, the corresponding NMR signals
are not averaged. The two CH2 groups of the cyclopropyl and dihydroimidazolium rings
1
exhibited ABCD spin systems in the H-NMR spectra, and two signals each in the
13C-NMR spectra.
3. Discussion. ± 3.1. Selectivity and Reactivity in Nucleophilic Additions. All triazines
investigated (with the possible exception of 5-aryl-triazines 4) react rapidly with 2-
cyclopropylidene-1,3-dimethylimidazolidine (1) in nucleophilic additions. The substi-
tution pattern strongly influences the selectivity. Whenever possible, H-bearing C-
atoms are attacked preferentially, e.g., in 2, 5, and 6b. When two unsubstituted positions
are available, as in 3 and 19, the reactivity decreased in the order C(5) > C(3) > C(6),
as expected from experimental work on other triazines [17]. The substituent effect is
probably due to steric hindrance at the reaction center, but may also stem from
stabilization of the resulting zwitterions. Electronic effects on the formation of the
zwitterions could not be investigated for the donor- or acceptor-substituted triazines,
because the reaction did not occur at the centers bearing these substituents. The same
was true for steric effects.
3.2. Selectivity and Reactivity in Cycloadditions. All triazines investigated gave
cycloadditions only via atoms C(3) and C(6). We found no indication of the alternative
reaction involving C(5) and N(2), followed by elimination of a nitrile [3]. This means
that nucleophilic addition to C(5) cannot lead to a dispiro adduct and, thus, is a dead-
end equilibrium for the overall reaction. For the cycloaddition reactions at C(3) and
C(6), we found tremendous differences in overall reaction rates. For example,
imidazolidine 1 formed cycloadducts with the 5-phenyl-substituted triazine 4a within a
few minutes at À 1008 (see Table 3), while the Diels ± Alder reaction with 3,6-
diaryltriazines 2 usually required heating for several hours at ‡ 1088 (see Table 1). But
this does not necessarily mean that the actual cycloaddition reaction is slow. It only
shows that it is slower than the (very fast) nucleophilic addition to C(5) of 2 to give 16,
which competes with the cycloaddition products 14 and 15. The rate-determining step
then is the fragmentation of 16 back to the starting materials 2 and 1. That the rate of
the cycloaddition of triazines 2 is probably high is shown by comparison with
triphenyltriazine 6a, which reacts quickly at room temperature, although it exhibits the
same (or even stronger) steric hindrance at the reacting centers C(3) and C(6), but
does not undergo nucleophilic addition at C(5) in a dead-end equilibrium.
The 3,6-diaryl-triazines 2 and 5-aryl-triazines 4 offered a chance to investigate the
influence of electronic, steric, and solvent effects upon cycloaddition. For the para-
substituted derivatives of 2, the steric influence can be neglected. Donors in para-
position of the 3-substituent (2d,h,i) increased the ratio of 14/15 slightly (93 :7 for 2i) in
comparison to the diphenyltriazine (88 :12), and acceptors (2f,g) showed the opposite
effect (48 :52 for 2g) (see Table 2). A MeO group in para-position of the 6-substituent
(2c) had no influence at all, and donor/acceptor combinations (2j,k) showed no
enhanced effect. All effects can be rationalized by electronic stabilization or
destabilization of potential zwitterionic intermediates. As electronic effects are small

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and negligible for a Me group in para-position, the effects of ortho-Me groups may be
seen as merely steric. ortho-Tolyl groups in 3-position (2e) or 6-position (2b) both
reduce the ratio of 14/15 slightly to 83 :17 and 80 :20, respectively. For 2e, this might be
interpreted as a sterically hindered addition to C(3). For 2c, one would expect the
opposite behavior, with the same argumentation. In this case, the second step of a
potential two-step Diels ± Alder reaction may determine the overall regioselectivity, as
corroborated for related sterically hindered tetrazines [2]. However, as we could not
isolate 3- or 6-substituted zwitterions in these cases, it remains speculation.
A small solvent effect was found for the 3,6-diphenyl-triazine 2a. While in
(D8)toluene, the ratio 14a/15a was 88 :12, it dropped to 69 :31 in (D7)DMF. All effects
are relatively small in terms of energy differences in the transition states (ꢀ 5 kJ/mol).
For 5-phenyltriazine 4a, we found a 83 :17 ratio of cycloadducts 23/24 in (D6)benzene at
258 (see Table 3). This ratio was reduced in more-polar solvents like CD3CN (71:29) or
(D7)DMF (70 :30). There was also a dependence on temperature. At lower temper-
atures, the proportion of 24 increased in toluene (40% at À 858) or (D7)DMF (47% at
À 508). A MeO substituent in para-position of the 5-aryltriazine 4e increased the ratio
23/24 (86 :14), a NO2 group (4d) reduced it (73 :27). Again, these effects can be
rationalized by stabilization or destabilization of the potential (but not identified)
zwitterionic intermediates of a two-step Diels ± Alder reaction. While donor or acceptor
substitution (4e vs. 4d) did not influence the isomer distribution noticeably, steric
hindrance (4b,c) seems to be of stronger influence. The ortho-tolyl substituent favored
cycloadduct 23b over 24b by 92 :8; in case of a mesityl group, only one isomer was be
detected (23c). In terms of energy, the introduction of a mesityl group clearly makes a
difference between both pathways. One can assume that the ortho-tolyl and mesityl
groups in 5-position are not coplanar with the triazine on the time average and, thus,
impede nucleophilic attack at the neighboring C(6)-atom: ortho-tolyl from one side,
mesityl from both sides.
Two conclusions can be drawn unambiguously: if no 3- or 6-substituents hamper the
cycloaddition by steric hindrance, the reaction occurs very fast. If zwitterions in 3- or 6-
positions could be detected at low temperatures, the regioselectivity for zwitterion and
cycloadduct formation was identical. For example, the cyclopropyl C-atom of 1 was
bound to the more-reactive and usually unsubstituted C-atom of the triazines. Except
for a few cases, we could not correlate the regioisomeric ratios with the size of orbital
coefficients of the triazine LUMOs (lowest-unoccupied molecular orbitals). It seems,
that steric or other effects overwhelm the effect of orbital interactions of the starting
materials. It may well be that the regiochemistry is not determined in the first, but
rather in the second (or maybe even in the third) transition state of these reaction
series, such as the elimination of N2, as calculated for cycloadditions of tetrazines [2].
3.3. One- or Two-Step Diels ± Alder Reaction? To sum up all considerations, there is
no definite proof for a one-step or two-step reaction mechanism of the above
cycloadditions. All arguments favoring the two-step path ± the very existence of
zwitterions, the same regiochemistry for the nucleophilic addition and the cyclo-
addition, the influence of steric or electronic effects on regioselectivities and reaction
rates in the first and/or second step ± cannot exclude the possibility that a concerted
reaction competes with nucleophilic addition. However, there is one argument that
makes this possibility very unlikely, at least in the case of the monosubstituted triazines

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Scheme 6. Mechanistic Overview of Triazine Cycloadditions
31a ± c (Scheme 6)2). The imidazolidine 1 and the 5-phenyltriazine 31b first form a
precipitate at À 1008, which rapidly dissolves under gas evolution. With very high
probability, this precipitate is a mixture of the two zwitterions 32b and 33b. If one
assumes that the cycloaddition occurs in a concerted reaction, these zwitterions need to
fragment back to starting materials, and this fragmentation has to be fast even at
2
)
Some of the structures of Scheme 6 correspond to compounds specifically numbered before (e.g., 31a ˆ
19a). However, for a general discussion, a superior, new numbering is introduced.

Helvetica Chimica Acta ± Vol. 88 (2005)
1503
À 1008. 3-Phenyltriazine 31a and 6-phenyltriazine 31c also form zwitterions at low
temperatures, both by attack at the 5-position. The fragmentation of the zwitterion 34a
back to 31a can be observed at ca. 1008. It is hard to imagine, that two isomeric
zwitterions, e.g., 33b and 34a, that should be comparable in energy, would show such
differences in fragmentation rates.
Overall, it seems reasonable to assume that the three types of zwitterions 32 ± 34 are
formed in all reactions of triazines with 1 (Scheme 6). While 34 is trapped in a dead-end
equilibrium, the other two isomers can react further to the cycloadducts 35 and 36,
respectively, and finally, after loss of N2, to the dihydropyridines 37 and 38. Whether the
zwitterions can be detected, or even isolated, is partly a question of their relative and
absolute stabilities, but also depends on the activation barriers of the following reaction
steps. For a deeper understanding of the deciding factors of these multi-step reactions,
we decided to carry out calculations for conceivable intermediates in the reactions of
the monophenyl-substituted triazines 31a, 31b, and 31c.
4. Calculations. ± As anticipated in Scheme 6, the first step of the overall
cycloaddition reactions of triazines 31 proceeds through the zwitterionic structures 32,
33, and 34. All of these zwitterions can be identified as true minima on the Becke3LYP/
SB potential-energy surface for all three triazines. The relative enthalpies of these
intermediates, calculated at the Becke3LYP/LB//Becke3LYP/SB level, strongly depend
on the substitution pattern of the parent triazines. For 3-phenyltriazine (31a), addition
to C(6) and C(5) is energetically comparable, while addition to the (substituted!) C(3)
position is less-favorable by more than 40 kJ/mol (Table 4). Similarly, reaction of 5-
phenyl-1,2,4-triazine (31b) is least favorable at the substituted C(5)-atom, while
addition to C(6) and, in particular, to C(3) are more favorable. Finally, the reaction of 1
with the 6-phenyl congener 31c yields the C(3)-adduct 33c as the most-stable
zwitterion, closely followed by the C(5)-adduct 34c. Both of these zwitterions are much
more stable than the C(6)-adduct 32c.
The formation of all zwitterions is calculated to be accompanied by a substantial
increase in the molecular dipole moment (Table 4). This is a consequence of the charge
separation indicated in the Lewis structures (see Scheme 6). Taking the reaction of 31a
as an example, the overall NPA charge of the triazine moiety amounts to 0.0 in reactant
31a, À 0.71 in 32a, À 0.68 in 33a, and À 0.77 in 34a (gas-phase values). The absolute
and relative energetics of the formation of these species are, therefore, substantially
influenced by solvent effects, even in a medium of intermediate polarity such as
CH2Cl2. Relative to the two reactants 1 and 31, the reaction enthalpies become more
favorable on inclusion of solvent effects. However, even after consideration of such
effects through CPCM single-point calculations, all reaction enthalpies for the
formation of zwitterionic intermediates 32 ± 34 remain positive3) (Table 4).
The conformational space available to the zwitterions is quite significant due to
rotation about the newly formed CÀC bond. On reaction with 1, the former triazine
ring deforms into a boat-like structure, providing a pseudo-axial and pseudo-equatorial
3
)
Full geometry optimization in the presence of the solvent reaction field was explored for zwitterion 32a.
For this system the solvation free energy calculated for the solution-optimized geometry is 1 kJ/mol larger
as compared to the free energy of solvation using the gas-phase structure.

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Table 4. Energies and Structural Characteristics for Stationary Points in the Reaction of Triazines 31a ± c with 1 at
298.15 K (in the gas phase or in solution). All values were calculated at the Becke3LYP/LB//Becke3LYP/SB
level of theory. The gas-phase dipole moment m was obtained at the Becke3LYP/SB level. For conformations,
see Figs. 2 and 3.
Stationary point
DH298 (gas)
[kJ/mol]
DH298 (CH2Cl2)
[kJ/mol]
m [D]
Conformer
r(CÀC) [pm]
3-Phenyl:
31a ‡ 1
32a
33a
34a
35a
36a
37a
38a
0.0
‡ 44.3
‡ 88.1
‡ 47.1
‡ 72.5
‡ 60.6
À 129.9
À 140.2
‡ 63.5
0.0
‡ 39.0
‡ 79.0
‡ 33.4
‡ 93.0
‡ 75.8
À 105.4
À 117.1
‡ 83.8
±
±
±
9.2
9.3
11.1
4.7
3.3
2.5
2.1
2.2
E
A
C
±
±
±
159.6
163.8
162.9
153.8
156.5
147.6
150.3
154.9
±
±
39a
5-Phenyl:
31b ‡ 1
32b
33b
34b
35b
36b
37b
38b
0.0
‡ 47.1
‡ 29.6
‡ 87.9
‡ 35.7
‡ 29.6
À 157.3
À 162.4
‡ 101.4
0.0
‡ 39.9
‡ 21.5
‡ 59.6
‡ 57.6
‡ 50.0
À 135.8
À 139.7
‡ 119.6
±
±
±
8.9
11.2
13.3
3.1
3.6
3.0
2.8
2.5
E
B
C
±
±
±
159.9
153.6
167.9
154.2
154.0
147.8
147.9
158.4
±
±
39b
6-Phenyl:
31c ‡ 1
32c
33c
34c
35c
36c
37c
38c
0.0
‡ 115.1
‡ 19.2
‡ 26.3
‡ 57.9
‡ 61.8
À 140.0
À 145.1
‡ 62.6
0.0
‡ 92.7
‡ 5.4
±
±
±
12.3
11.7
9.3
2.4
3.8
2.6
2.8
2.5
E
B
C
±
±
±
172.3
153.5
160.4
156.9
153.4
155.5
147.8
155.2
‡ 13.5
‡ 74.7
‡ 82.3
À 118.3
À 121.2
‡ 80.5
±
±
39c
position at the reaction center. The zwitterionic intermediates 33 obtained through
addition to C(3) of the triazine ring can, thus, be classified as being either of the axial
(A) or equatorial (B) type (Fig. 2). The conformers of intermediates 32 and 34 can be
classified accordingly. Reviewing the results described in Table 4, we note that the
most-favorable conformers of the zwitterions 32a ± c are all of type E. Similarly, the
most-stable conformers of the zwitterions obtained through addition at C(5), 34, are all
of type C. For zwitterions 33, the conformational preference (A vs. B) depends on the
substitution pattern, and no general rule can be formulated. The structures of the most-
stable conformers of each type are shown in Fig. 3. One notable feature of the
structures of type B for 33b and 33c are the much smaller distances of the newly formed
CÀC bonds of 153.6 and 153.5 pm, respectively. In all other structures in which the
newly formed CÀC bond occupies the pseudo-axial position, significantly larger bond
distances (ꢁ159.6 pm) are obtained (Table 4).

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Fig. 2. Principal conformations of zwitterions 32 ± 34
Cyclization of the zwitterionic intermediates to the fully cyclized adducts 35, 36, and
39 is an endothermic process in all cases, and adducts of type 39 (see Scheme 6) are not
dramatically less stable than either 35 or 36. The energetically least-favorable mode of
cyclization always occurs onto a phenyl-substituted center, as in the conversion of 32a
to 35a, or in the conversion of 33c to 36c. Due to the charge-neutralizing character of
these cyclization reactions, the consideration of solvent effects now leads to much less-
favorable reaction energetics widening the energy difference to the preceding
zwitterionic intermediates. The final elimination of N2 is strongly exothermic in all
cases. The most-stable products formed in the reactions of triazines 31a ± c are 38a ± c.
However, the energy differences between the products 37b/38b and 37c/38c are rather
small, and product mixtures would have to be expected in case the reaction outcome is
based on product stability. This is clearly not the case due to the strongly exothermic
nature of the final reaction step. The outcome of the reaction is, thus, most likely
determined by the relative heights of the N2 elimination barriers.
We are indebted to Mr. H. Schulz for elemental analyses, Mr. G. Seidl and Dr. W. Spahl for the acquisition
of mass spectra, and to Dr. D. Stephenson for the acquisition of NMR spectra. We thank the Deutsche
Forschungsgemeinschaft and the Fonds der Chemischen Industrie for financial support.
Experimental Part
1. General. Abbreviations: Ar, aryl, Ph, phenyl; Tol, tolyl; cPr, cyclopropyl; Im, imidazole or imidazolium
based moieties. 3,5-Diphenyl-1,2,4-triazine (5a) [18][19], 5-(2-methylphenyl)-3-phenyl-1,2,4-triazine (5b) [20],
3-(4-methylphenyl)-6-phenyl-1,2,4-triazine (2d) [8], 3-(4-methoxyphenyl)-6-phenyl-1,2,4-triazine (2h) [8], 6-
phenyl-1,2,4-triazine (3a) [18], 5-phenyl-1,2,4-triazine (4a) [19], 3-phenyl-1,2,4-triazine (19a) [19], 3,5,6-

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Fig. 3. Three-dimensional structures of the most-stable zwitterions 32 ± 34
triphenyl-1,2,4-triazine (6a) [18][19], and 5,6-diphenyl-1,2,4-triazine (6b) [21] were prepared according to
literature procedures. All cycloaddition reactions were performed in oven-dried glassware with anh. solvents
under Ar gas. For all distillations, a Kugelrohr apparatus was used. UV Spectra: Perkin-Elmer Lambda-3 and
Zeiss PMQ II; lmax (log e) in nm. IR Spectra: Perkin-Elmer 1420 and IFS 45; in cmÀ1. NMR Spectra: Varian VXR
400S or Bruker WP 80; if not specified otherwise, 1H- and 13C-NMR chemical shifts d (in ppm) of Ph groups are
listed in the order (ipso), ortho, meta, para. EI-MS: Finnigan MAT 90; in m/z (rel. %)
2. Synthesis of Triazines. General Procedure A (GP A). The appropriate arylcarboxylic hydrazide (n g,
2m mmol) was heated in a mixture of EtOH (3m ml) and glacial AcOH (m ml) to 608, until a clear soln.
resulted. AcONa (1.1m mmol) and 2-bromo-1-phenylethanone (p g, m mmol) were added, and the mixture was
heated at reflux for 3 h. Crystalline precipitates were collected by filtration, solns. were poured on ice/H2O and
neutralized with NaHCO3. After extraction with Et2O (3 Â 20 ml) and drying (MgSO4), the solvent was
removed, and the residue was crystallized from EtOH or glacial AcOH.
General Procedure B (GP B). To a pre-cooled mixture of formamidine acetate (r g, s mmol) in anh. MeOH
(20 ml), anh. hydrazine (t g, u mmol) was added at À 108 under Ar gas, and the mixture was stirred for 5 min.
Slowly, a soln. of freshly distilled 2-aryl-2-oxoethanal (v g, s mmol) in anh. MeOH (10 ml), and, after 10 min,
Et3N (w g, s mmol) were added. After stirring at 208 for 24 h, the solvent was removed in vacuo, the residue was

Helvetica Chimica Acta ± Vol. 88 (2005)
1507
extracted with Et2O (3 Â 20 ml), the combined org layers were washed with brine, dried (MgSO4), and
concentrated. The resulting residue was separated by column chromatography (CC).
5-(4-Methoxyphenyl)-3-phenyl-1,2,4-triazine (5c). To a pre-cooled slurry of benzenecarboxamidine hydro-
chloride ´ 1.8 H2O (1.55 g, 9.89 mmol) and Na2SO4 (1.42 g, 10.0 mmol) in anh. MeOH (50 ml), anh. hydrazine
(0.475 g, 14.8 mmol) was added at 08, and the mixture was stirred for 2 h, until NH3 evolution ceased. Slowly, a
soln. of freshly distilled 2-(4-methoxyphenyl)-2-oxoethanal (1.09 g, 6.72 mmol) in anh. MeOH (10 ml) and, after
10 min, Et3N (1.00 g, 9.9 mmol) were added. After stirring at 208 for 24 h, the solvent was removed in vacuo, and
the residue was extracted with Et2O (3 Â 50 ml). The org. layer was washed with brine, dried (MgSO4), and
evaporated. The resulting solid, according to 1H-NMR analysis made of 10% of 3b, 18% of 3,6-bis(4-
methoxyphenyl)tetrazine, and 72% of 5c, was separated by CC (SiO2; toluene/AcOEt 20 :1; Rf 0.14). Orange-
yellow platelets. Yield of 5c: 0.960 g (54%). M.p. 118 ± 1208 (EtOH). UV (CHCl3): 332 (1.24). 1H-NMR
(CDCl3, 400 MHz): 3.90 (MeO); 7.07 (J ˆ 9.0, HÀC(3,5) of 5-Ar); 7.56 (HÀC(3,4,5) of 3-Ph); 8.26 (HÀC(2,6)
of 5-Ar); 8.64 (HÀC(2,6) of 3-Ph); 9.52 (HÀC(6)). 13C-NMR (CDCl3, 100 MHz): 55.5 (MeO); 114.9 (C(3,5)
of 5-Ar); 125.9 (C(1) of 5-Ar); 128.3 (C(3,5) of 3-Ph); 128.8 (C(2,6 of 3-Ph); 129.4 (C(2,6) of 5-Ar); 131.5
(C(1) of 3-Ph); 135.5 (C(4) of 3-Ph); 143.7 (C(6)); 154.6 (C(5)); 163.3 (C(4) of 6-Ar); 163.2 (C(3)). EI-MS: 263
‡
(23, M ). Anal. calc. for C16H13N3O (263.3): C 72.99, H 4.98, N 15.96; found: C 72.84, H 4.92, N 16.11.
6-(2-Methylphenyl)-3-phenyl-1,2,4-triazine (2b). GP A (n ˆ 0.980, m ˆ 7.18, p ˆ 0.770). Yield: 0.772 g
(63%). M.p. 968 (EtOH). UV (CHCl3): 275 (1.80). IR: 3052, 2964, 2924, 1602,1581,1495, 1439, 1403, 767, 726,
695. 1H-NMR (CDCl3, 400 MHz): 2.51 (Me); 7.40 (HÀC(3,4,5) of 6-Ar); 7.53 (HÀC(6)); 7.57 (HÀC(3,4,5) of
3-Ph); 8.61 (HÀC(2,6) of 3-Ph); 8.79 (HÀC(5)). 13C-NMR (CDCl3, 100 MHz): 20.5 (Me); 126.5 (C(6) of 6-
Ar); 128.2 (C(3,5) of 3-Ph); 128.9 (C(2,6) of 3-Ph); 129.8 (C(3) of 6-Ar); 130.0 (C(5) of 6-Ar); 131.5 (C(4) of
6-Ar); 131.7 (C(4) of 3-Ph); 133.6 (C(1) of 3-Ph); 136.8 (C(2) of 6-Ar); 134.7 (C(1) of 6-Ar); 149.1 (C(5));
‡
158.2 (C(6)); 161.9 (C(3)). EI-MS: 247 (44, M ). Anal. calc. for C16H13N3 (247.3): C 77.71, H 5.30, N 16.99;
found: C 77.56, H 5.26, N 16.72.
6-(4-Methoxyphenyl)-3-phenyl-1,2,4-triazine (2c) [8b]. GP A (n ˆ 1.50, m ˆ 11.0, p ˆ 1.26). Yield: 0.610 g
(42%). M.p. 161 ± 1648 (AcOH). UV (CHCl3): 447 (1.91). 1H-NMR (CF3COOD, 400 MHz): 4.07 (MeO); 7.31
(J ˆ 8.3, HÀC(3,5) of 6-Ar); 7.77 (HÀC(3,5 of 3-Ph); 7.91 (HÀC(4) of 3-Ph); 8.26 (HÀC(2,6) of 6-Ar); 8.50
(HÀC(2,6) of 3-Ph); 9.96 (HÀC(5)). 13C-NMR (CF3COOD, 100 MHz): 54.9 (MeO); 118.1 (C(3,5) of 6-Ar);
130.0 (C(1) of 6-Ar); 131.1 (C(3,5) of 3-Ph); 132.0 (C(2,6) of 3-Ph); 132.3 (C(2,6) of 6-Ar); 132.4 (C(1) of 3-
Ph); 138.8 (C(4) of 3-Ph); 155.8 (C(5)); 159.7 (C(4) of 6-Ar); 162.4 (C(6)); 167.2 (C(3)). EI-MS (1308, 70 eV):
‡
263 (17, M ). Anal. calc. for C16H13N3O (263.3): C 72.99, H 4.98, N 15.96; found: C 73.00, H 5.07, N 15.83.
3-(2-Methylpenyl)-6-phenyl-1,2,4-triazine (2e). GP A (n ˆ 17.8, m ˆ 11.9, p ˆ 10.1; 18 h reflux). Yield:
3.66 g (25%). M.p. 118 ± 1208 (EtOH). IR: 3052, 2964, 2924, 1602,1581,1495, 1439, 1403, 767, 726, 695. UV
(CHCl3): 278 (1.40). 1H-NMR (CDCl3, 400 MHz): 2.68 (Me); 7.37 ± 7.41 (HÀC(3,4,5) of 3-Ar); 7.57
(HÀC(3,4,5) of 6-Ph); 8.03 (HÀC(6) of 3-Ar); 8.19 (HÀC(2,6) of 6-Ph); 9.09 (HÀC(5)). 13C-NMR (CDCl3,
100 MHz): 21.6 (Me); 126.2 (C(4) of 6-Ph); 126.8 (C(3,5) of 6-Ph); 129.4 (C(2,6) of 6-Ph); 134.8 (C(1) of 6-
Ph); 130.4 (C(3) of 3-Ar); 130.9 (C(4) of 3-Ar); 130.9 (C(5) of 3-Ar); 131.7 (C(6) of 3-Ar); 133.3 (C(2) of 3-
‡
Ar); 138.3 (C(1) of 3-Ar); 145.9 (C(5)); 154.3 (C(6)); 165.3 (C(3)). EI-MS (908, 70 eV): 247 (54, M ). Anal.
calc. for C16H13N3 (247.3): C 77.71, H 5.30, N 16.99; found: C 77.57, H 5.27, N 17.02.
6-Phenyl-3-[4-(trifluoromethyl)phenyl]-1,2,4-triazine (2f). GP A (n ˆ 0.200, m ˆ 0.41, p ˆ 0.160). Yield:
0.110 g (37%). M.p. 194 ± 1978 (AcOH). UV (CHCl3): 320 (1.20). 1H-NMR (CF3COOD, 400 MHz): 7.78
(HÀC(3,5) of 6-Ph); 8.04 (J ˆ 8.3, HÀC(2,6) of 3-Ar); 8.25 (HÀC(2,6) of 6-Ph); 7.89 (HÀC(4) of 6-Ph); 8.70
(HÀC(3,5) of 3-Ar); 10.10 (HÀC(5)). 13C-NMR (CF3COOD, 100 MHz): 125.3 (J(C,F) ˆ 273.1, F3C); 128.5
(C(1) of 3-Ar); 129.1 (J(C,F) ˆ 3.8, C(3,5) of 3-Ar); 130.1 (C(3,5) of 6-Ph); 131.8 (C(2,6) of 6-Ph); 132.6
(C(2,6) of 3-Ar); 132.9 (C(1) of 6-Ph); 137.1 (C(4) of 6-Ph); 140.1 (J(C,F) ˆ 32.3, C(4) of 3-Ar); 156.2 (C(5));
‡
160.6 (C(6)). EI-MS (1308, 70 eV): 301 (10, M ). Anal. calc. for C16H10F3N3 (301.3): C 64.74, H 3.62, N 13.94;
found: C 65.07, H 3.56, N 13.73.
3-(4-Nitrophenyl)-6-phenyl-1,2,4-triazine (2g). GP A (n ˆ 3.71, m ˆ 21.0, p ˆ 2.04). Yield: 0.852 g (29%).
1
M.p. > 2208 (AcOH). UV (CHCl3): 316 (0.45). H-NMR (CF3COOD, 400 MHz): 7.84 (HÀC(3,5) of 6-Ph);
7.95 (HÀC(4) of 6-Ph); 8.26 (HÀC(2,6) of 6-Ph); 8.61 (J ˆ 9.1, HÀC(3,5) of 3-Ar); 8.82 (HÀC(2,6) of 3-Ar);
10.20 (HÀC(5)). 13C-NMR (CF3COOD, 100 MHz): 126.8 (C(3,5) of 3-Ar); 127.4 (C(1) of 6-Ph); 130.6 (C(2,6)
of 3-Ar); 132.5 (C(2,6) of 6-Ph); 132.9 (C(3,5) of 6-Ph); 137.4 (C(1) of 3-Ar); 138.3 (C(4) of 6-Ph); 153.6
‡
(C(6)); 154.9 (C(4) of 3-Ar); 160.8 (C(5)); 164.4 (C(3). EI-MS (2008, 70 eV): 278 (29, M ). Anal. calc. for
C15H10N4O2 (278.2): C 64.74, H 3.62, N 20.14; found: C 65.07, H 3.56, N 20.16.
3-[4-(Dimethylamino)phenyl]-6-phenyl-1,2,4-triazine (2i). GP A (n ˆ 2.68, m ˆ 15.0, p ˆ 1.16). Yield:
1
0.781 g (38%). M.p. 208 ± 2108 (EtOH). UV (CHCl3): 368 (0.45). H-NMR (CDCl3, 400 MHz): 3.07 (MeN);

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Helvetica Chimica Acta ± Vol. 88 (2005)
6.81 (J ˆ 8.1, HÀC(3,5) of 3-Ar); 7.54 (HÀC(3,5) of 6-Ph); 7.54 (HÀC(4) of 6-Ph); 8.11 (HÀC(2,6) of 6-Ph);
8.46 (HÀC(2,6) of 3-Ar); 8.91 (HÀC(5)). 13C-NMR (CF3COOD, 100 MHz): 40.1 (MeN); 111.8 (C(3,5) of 3-
Ar); 121.9 (C(1) of 3-Ar); 126.3 (C(2,6) of 3-Ar); 129.2 (C(3,5) of 6-Ph); 129.6 (C(2,6) of 6-Ph); 130.3 (C(4) of
6-Ph); 133.8 (C(1) of 6-Ph); 146.2 (C(5)); 152.7 (C(6)); 153.5 (C(4) of 3-Ar); 162.7 (C(3)). EI-MS (1308,
‡
70 eV): 276 (26, M ). Anal. calc. for C17H16N4 (276.3): C 73.89, H 5.84, N 20.28; found: C 74.04, H 5.82, N 20.21.
6-(4-Methoxyphenyl)-3-[4-(trifluoromethyl)phenyl]-1,2,4-triazine (2j). GP A (n ˆ 0.300, m ˆ 1.47, p ˆ
1
0.161). Yield: 0.090 g (39%). M.p. 1928 (AcOH). UV (CHCl3): 417 (2.70). H-NMR (CF3COOD, 400 MHz):
4.08 (MeO); 7.35 (J ˆ 8.6, HÀC(3,5) of 6-Ar); 7.99 (J ˆ 8.1, HÀC(2,6) of 3-Ar); 8.27 (HÀC(2,6) of 6-Ar); 8.66
(HÀC(3,5) of 3-Ar); 10.09 (HÀC(5)). 13C-NMR (CF3COOD, 100 MHz): 57.4 (MeO); 118.7 (C(3,5) of 6-Ar);
125.4 (J(C,F) ˆ 272.4, F3C); 128.8 (J(C,F) ˆ 3.8, C(3,5) of 3-Ar); 131.3 (C(2,6) of 3-Ar); 132.8 (C(2,6) of 6-
Ar); 132.8 (C(1) of 6-Ar); 133.9 (C(1) of 3-Ar), 139.5 (J(C,F) ˆ 32.3, C(4) of 3-Ar); 153.6 (C(5)); 160.2 (C(4)
‡
of 6-Ar); 163.1 (C(6)); 168.7 (C(3). EI-MS (1308, 70 eV): 331 (18, M ). Anal. calc. for C17H12F3N3O (331.3): C
61.63, H 3.65, N 12.68; found: C 61.66, H 3.41, N 12.71.
6-(4-Methoxyphenyl)-3-(4-nitrophenyl)-1,2,4-triazine (2k). GP A (n ˆ 3.62, m ˆ 20.0, p ˆ 2.29). Yield:
1.26 g (44%). M.p. 2398 (AcOH). UV (CHCl3): 439 (2.37). 1H-NMR (CF3COOD, 400 MHz): 4.09 (MeO); 7.38
(J ˆ 8.3, HÀC(3,5) of 6-Ar); 8.30 (HÀC(2,6) of 6-Ar); 8.56 (J ˆ 8.1, HÀC(2,6) of 3-Ar); 8.76 (HÀC(3,5) of 3-
Ar); 10.12 (HÀC(5)). 13C-NMR (CF3OOD, 100 MHz): 57.5 (MeO); 118.3 (C(3,5) of 6-Ar); 126.7 (C(3,5) of 3-
Ar); 132.0 (C(2,6) of 3-Ar); 133.3 (C(2,6) of 6-Ar); 132.0 (C(1) of 6-Ar); 138.2 (C(1) of 3-Ar); 152.1 (C(4) of
‡
3-Ar); 153.2 (C(5)); 160.6 (C(4) of 6-Ar); 163.6 (C(6)); 169.8 (C(3)). EI-MS (1508, 70 eV): 308 (18, M ). Anal.
calc. for C16H12N4O3 (308.3): C 62.33, H 3.92, N 18.17; found: C 62.11, H 4.05, N 18.10.
3-(4-Methoxyphenyl)-6-(4-nitrophenyl)-1,2,4-triazine (2l). GP A (n ˆ 1.66, m ˆ 10.0, p ˆ 1.01). Yield:
0.550 g (36%). M.p. > 2358 (dec.). UV (CHCl3): 350 (1.30). 1H-NMR (CF3COOD, 400 MHz): 4.05 (MeO);
7.30 (J ˆ 9.2, HÀC(3,5) of 3-Ar); 7.98 (HÀC(2,6) of 3-Ar); 8.30 (J ˆ 8.8, HÀC(3,5) of 6-Ar); 8.48 (HÀC(2,6)
of 6-Ar); 9.93 (HÀC(5)). 13C-NMR (CF3COOD, 100 MHz): 54.3 (MeO); 116.4 (C(3,5) of 3-Ar); 126.5 (C(3,5)
of 6-Ar); 130.6 (C(2,6) of 3-Ar); 132.5 (C(2,6) of 6-Ar); 134.9 (C(1) of 3-Ar); 139.0 (C(1) of 6-Ar); 162.6 (C(4)
‡
‡
of 3-Ar); 160.6 (C(4) of 6-Ar); 163.1 (C(6)); 170.9 (C(3). EI-MS (1758, 70 eV): 308 (13, M , C16H12N4O3 ).
3-[4-(Dimethylamino)phenyl]-6-(4-nitrophenyl)-1,2,4-triazine (2m). GP A (n ˆ 0.500, m ˆ 2.78, p ˆ 0.280).
Yield: 0.440 g (95%). M.p. > 1958 (dec.). UV (CHCl3): 313 (1.65). 1H-NMR (CF3COOD, 400 MHz): 3.55
(MeN); 7.85 (J ˆ 8.8, HÀC(3,5) of 3-Ar); 8.05 (HÀC(2,6) of 3-Ar); 8.19 (J ˆ 9.0, HÀC(3,5) of 6-Ar); 8.48
‡
‡
(HÀC(2,6) of 6-Ar); 9.65 (HÀC(5)). EI-MS (2108, 70 eV): 321 (22, M , C17H15N5O2 ).
6-(4-Nitrophenyl)-3-phenyl-1,2,4-triazine (2n). GP A (n ˆ 0.68, m ˆ 5.00, p ˆ 0.230). Yield: 0.300 g (43%).
M.p. > 2108 (dec.). UV (CHCl3): 320 (1.20). 1H-NMR (CF3COOD, 400 MHz): 7.83 (HÀC(3,5) of 3-Ph); 8.02
(HÀC(4) of 3-Ph); 8.30 (HÀC(3,5) of 6-Ar); 8.51 (HÀC(2,6) of 6-Ar); 8.64 (HÀC(2,6) of 3-Ph); 10.10
(HÀC(5)). 13C-NMR (CF3COOD, 100 MHz): 126.5 (C(3,5) of 3-Ph); 131.0 (C(1) of 6-Ar); 132.5 (C(2,6) of 3-
Ph); 132.7 (C(2,6) of 6-Ar); 130.8 (C(3,5) of 6-Ar), 138.9 (C(1) of 3-Ph); 138.9 (C(4) of 6-Ar); 157.3 (C(6));
‡
‡
152.0 (C(5)). EI-MS (1608, 70 eV): 278 (15, M , C15H10N4O2 †:
6-(4-Methoxyphenyl)-1,2,4-triazine (3b). GP B (rˆ 1.08, s ˆ 10.4, t ˆ 0.340, u ˆ 10.4, v ˆ 1.71, w ˆ 1.05).
Purification by CC (cyclohexane/1,4-dioxane 95 :5; Rf 0.05). Yield: 0.063 g (3%). M.p. 139 ± 1408. UV (CHCl3):
278 (0.82). 1H-NMR (CDCl3, 400 MHz): 3.76 (MeO); 6.93 (J ˆ 8.8, HÀC(3,5) of 6-Ar); 7.94 (HÀC(2,6) of 6-
Ar); 8.84 (HÀC(5)); 9.43 (HÀC(3)). 13C-NMR (CDCl3, 100 MHz): 54.4 (MeO); 113.8 (C(3,5) of 6-Ar); 124.3
(C(1) of 6-Ar); 127.3 (C(2,6) of 6-Ar); 145.0 (C(5)); 156.2 (C(3)); 156.2 (C(6)); 161.1 (C(4) of 6-Ar). EI-MS:
‡
187 (64, M ). Anal. calc. for C10H9N3O (187.1): C 64.16, H 4.85, N 22.45; found: C 63.88, H 5.02, N 20.61.
6-(4-Nitrophenyl)-1,2,4-triazine (3c) [22b]. GP B (rˆ 0.590, s ˆ 5.67, t ˆ 0.284, u ˆ 8.87, v ˆ 1.02, w ˆ 0.573).
1
Mixture: 3c/4d 24 :76. Total yield: 0.680 g (59%). H-NMR (CDCl3, 400 MHz): 8.34 (J ˆ 8.7, HÀC(2,6) of 6-
Ar); 8.45 (HÀC(2,6) of 6-Ar); 9.13 (HÀC(5)); 9.77 (HÀC(3)). 13C-NMR (CDCl3, 100 MHz): 124.6 (C(3,5) of
6-Ar); 127.7 (C(2,6) of 6-Ar); 138.9 (C(1) of 6-Ar); 146.8 (C(5)); 149.5 (C(4) of 6-Ar); 156.1 (C(6)); 156.9
(C(3)).
5-(4-Methylphenyl)-1,2,4-triazine (4b). GP B (rˆ 1.54, s ˆ 14.8, t ˆ 0.470, u ˆ 14.8, v ˆ 2.19, w ˆ 1.50).
Purified by CC (cyclohexane/1,4-dioxane 90 :10; Rf 0.07). Yield: 0.401 g (16%). Glassy solid. B.p. 1208/0.1 mbar.
UV (CHCl3): 286 (1.26). 1H-NMR (CDCl3, 400 MHz): 2.52 (Me); 7.38 (HÀC(3,5) of 5-Ar); 7.46 (HÀC(4) of
5-Ar); 7.56 (HÀC(6) of 5-Ar); 9.45 (J ˆ 2.0, HÀC(6)); 9.71 (HÀC(3)). 13C-NMR (CDCl3, 100 MHz): 20.5
(Me); 126.6 (C(5) of 5-Ar); 130.0 (C(6) of 5-Ar); 131.0 (C(3) of 5-Ar); 131.8 (C(4) of 5-Ar); 133.6 (C(1) of 5-
‡
Ar); 137.2 (C(2) of 5-Ar); 150.0 (C(6)); 156.9 (C(3)); 158.9 (C(5)). EI-MS: 171 (12, M ). Anal. calc. for
C10H9N3 (171.2): C 70.16, H 5.30, N 24.54; found: C 70.23, H 5.26, N 24.15.
5-(2,4,6-Trimethylphenyl)-1,2,4-triazine (4c). GP B (rˆ 1.29, s ˆ 12.4, t ˆ 0.411, u ˆ 12.3, v ˆ 2.20, w ˆ 1.26).
Purified by CC (cyclohexane/1,4-dioxane 95 :5; Rf 0.17). Yield: 0.185 g (7%). Glassy solid. B.p. 1408/0.01 mbar.

Helvetica Chimica Acta ± Vol. 88 (2005)
1509
1H-NMR (C6D6, 400 MHz): 1.81 (2 Me); 2.10 (Me); 6.68 (HÀC(3,5) of 5-Ar); 8.7 (J ˆ 2.1, HÀC(6)); 9.53
(HÀC(3)). 13C-NMR (C6D6, 100 MHz): 19.9 (2 Me); 21.0 (Me); 129.1 (C(3,5) of 5-Ar); 132.0 (C(1) of 5-Ar);
‡
135.9 (C(2,6) of 5-Ar); 139.4 (C(4) of 5-Ar); 157.8 (C(3)); 159.8 (C(5)). EI-MS: 199 (17, M ). Anal. calc. for
C12H13N3 (199.2): C 72.34, H 6.57, N 21.09; found: C 71.92, H 6.57, N 20.27.
5-(4-Nitrophenyl)-1,2,4-triazine (4d). GP B (rˆ 0.590, s ˆ 5.67, t ˆ 0.284, u ˆ 8.87, v ˆ 1.02, w ˆ 0.573).
1
Mixture: 3c/4d 24 :76. Total yield: 0.680 g (59%). H-NMR (CDCl3, 400 MHz): 8.37 (J ˆ 9.0, HÀC(2,6) of 5-
Ar); 8.44 (HÀC(2,6) of 5-Ar); 9.82 (J ˆ 2.0, HÀC(6)); 9.83 (HÀC(3)). 13C-NMR (CDCl3, 100 MHz): 124.6
(C(3,5) of 5-Ar); 128.7 (C(2,6) of 5-Ar); 139.1 (C(1) of 5-Ar); 146.7 (C(6)); 150.3 (C(4) of 5-Ar); 153.2 (C(5));
‡
157.6 (C(3)). EI-MS: 202 (36, M ). Anal. calc. for C9H6N4O2 (202.1): C 53.46, H 2.99, N 27.71; found: C 53.33, H
2.98, N 27.13.
5-(4-Methoxyphenyl)-1,2,4-triazine (4e). GP B (rˆ 1.08, s ˆ 10.4, t ˆ 0.340, u ˆ 10.4, v ˆ 1.71, w ˆ 1.05).
Purified by CC (cyclohexane/1,4-dioxane 95 :5; Rf 0.01). Yield: 0.080 g (4%). M.p. 134 ± 1358. UV (CHCl3): 278
(0.82). 1H-NMR (CDCl3, 400 MHz): 3.77 (MeO); 6.91 (J ˆ 8.9, HÀC(3,5) of 5-Ar); 8.02 (HÀC(2,6) of 5-Ar);
9.43 (J ˆ 1.9, HÀC(6)); 9.51 (HÀC(3)). 13C-NMR (CDCl3, 100 MHz): 54.5 (MeO); 113.9 (C(3,5) of 5-Ar);
127.3 (C(1) of 5-Ar); 128.3 (C(2,6) of 5-Ar); 145.2 (C(6)); 153.8 (C(5)); 156.3 (C(3)); 162.4 (C(4)) of 5-Ar). EI-
‡
MS: 187 (100, M ). Anal. calc. for C10H9N3O (187.1): C 64.16, H 4.85, N 22.45; found: C 63.85, H 4.87, N 21.93.
3-(4-Nitrophenyl)-1,2,4-triazine (19b). To a pre-cooled mixture of 4-nitrobenzenecarboxamidine hydro-
chloride (1.14 g, 5.66 mmol) in anh. MeOH (50 ml), anh. hydrazine (0.270 g, 8.49 mmol) was added at À 108
under Ar gas, and the mixture was stirred for 4 h, until NH3 evolution ceased. Slowly, a soln. of freshly distilled 2-
(4-methoxyphenyl)-2-oxoethanal (0.370 g, 6.38 mmol) in anh. MeOH (10 ml) and, after 10 min, Et3N (0.740 g,
7.33 mmol ) were added. After stirring at 208 for 24 h, the solvent was removed in vacuo, and the residue was
extracted with Et2O (3 Â 50 ml). After washing with brine and drying (MgSO4), the solvent was removed, and
the resulting solid was crystallized from AcOH. Yellow platelets. Yield: 0.970 g (85%). M.p. 1618 (lit. 176 ± 1788
[19]). UV (CHCl3): 284 (0.43). 1H-NMR (CDCl3, 400 MHz): 8.40 (J ˆ 9.1, HÀC(2,6) of 3-Ar); 8.76 (HÀC(3,5)
of 3-Ar); 8.77 (J ˆ 2.5, HÀC(5)); 9.28 (HÀC(6)). 13C-NMR (CDCl3, 100 MHz): 124.0 (C(3,5) of 3-Ar); 129.3
(C(2,6) of 3-Ar); 140.4 (C(1) of 3-Ar); 148.4 (C(5)); 148.5 (C(6)); 150.1 (C(4) of 3-Ar); 162.6 (C(3)). EI-MS
‡
(958, 70 eV): 202 (26, M ). Anal. calc. for C9H6N4O2 (202.1): C 53.46, H 2.99, N 27.71; found: C 53.53, H 2.96, N
27.36.
3. Addition Reactions to 3,5,6-Triphenyl-1,2,4-triazine (6a). 5,8-Dimethyl-9,10,12-triphenyl-5,8,11-triazadi-
spiro[2.0.4.4]dodeca-9,11-diene (8a) [12]. Compound 1 (24 mg, 0.174 mmol) was added to a soln. of 6a (50.0 mg,
0.161 mmol) in C6D6 (1 ml). Vigorous gas evolution set in, which was finished after a few minutes. By NMR,
74% of 8a were identified. 1H-NMR (C6D6, 400 MHz): 1.05 (2 H of cPr); 1.19 (2 H of cPr); 2.27 (2 MeN); 2.76
(2 NCH2); 7.03 ± 7.66 (3 Ph). 13C-NMR (C6D6, 100 MHz): 11.3 (C(1,2)); 26.9 (C(3)); 36.5 (2 MeN); 52.5
(C(6,7)); 81.5 (C(4)); 125.6 (C(9)); 144.8 (C(10)); 173.1 (C(12); 141.2, 132.7, 127.42, 126.9 (9-Ph); 141.2, 130.8,
127.44, 126.6 (10-Ph); 139.5, 129.4, 127.9, 126.8 (12-Ph).
2,3-Dihydro-1-methyl-4,6,7-triphenyl-1H-pyrrolo[3,2-c]pyridine (9a). To 6a (100 mg, 0.323 mmol) in
CD2Cl2 (1 ml) under Ar gas, compound 1 (53.0 mg, 0.383 mmol) was added slowly via syringe at À 608. The
orange-brown soln. was allowed to slowly warm up, and at ca. À 258, vigorous gas evolution started. After 14 h
at r.t., the solvent was removed in vacuo, and the residue was purified by prep. TLC (Al2O3; petroleum ether/
AcOEt 30 :1; Rf 0.16). Yellow solid. Yield 119 mg (42%). M.p. > 2008 (dec.). 1H-NMR (CDCl3, 400 MHz):
2.24 (MeN); 3.20 (HÀC(3)); 3.44 (HÀC(2)); 7.00 ± 7.83 (3 Ph). 13C-NMR (CD2Cl2, 100 MHz): 27.5 (C(3)); 37.7
(MeN); 57.0 (C(2)); 116.3 (C(7)); 122.4 (C(3a)); 150.8 (C(7a)); 157.4 (C(6)); 158.1 (C(4)); 137.1, 128.4, 128.1,
127.9 (4-Ph); 139.9, 129.9, 127.2, 126.9 (6-Ph); 141.1, 131.6, 127.7, 126.7 (7-Ph).
3-[1-(4,5-Dihydro-1,3-dimethyl-1H-imidazol-3-ium-2-yl)cyclopropyl]-3,5,6-triphenyl-3H-1,2,4-triazin-2-ide
(10a)4). To a soln. of 6a (71 mg, 0.23 mmol) in CD2Cl2 (1 ml) under Ar gas, compound 1 (38 mg, 0.28 mmol) was
carefully added at À 408. NMR Spectra were then recorded at À 40, À 20, 0, and ‡ 258. The following product
distribution was found: a) Tˆ À408, 1.5 h: 6a/1/8/9/10 53 :41:18 :0 :29; b) Tˆ À308, 1 h: 57:44 :33 :0 :10; c)
Tˆ 08, 1 h: 25 :6 :75 :0 :0; d) Tˆ 258, 48 h: 25 :0 :0 :75 :0.
1
Data of 10a. H-NMR (CD2Cl2, 400 MHz, Tˆ À408): 0.70 ± 0.95 (4 H of cPr); 2.52 (MeN); 2.73 (MeN);
3.55 (mc, 2 NCH2); 6.70 ± 7.30 (3 Ph). 13C-NMR (CD2Cl2, 100 MHz): 10.8 (2 CH2 of cPr); 24.8 (cPr); 35.5
(MeN); 35.7 (MeN); 52.4 (NCH2); 52.9 (NCH2); 81.5 (C(3)); 146.8 (C(5)); 148.6 (C(6)); 168.6 (C(2) of Im);
137.9, 127.0, 126.8, 121.7 (3-Ph); 139.6, 127.1, 126.9, 126.3 (5-Ph); 140.9, 130.3, 127.1, 128.3 (6-Ph).
4. Addition Reactions to 5,6-Diphenyl-1,2,4-triazine (6b). 5,8-Dimethyl-9,10-diphenyl-5,8,11-triazadispiro-
[2.0.4.4]dodeca-9,11-diene (8b) [12]. Compound 1 (36 mg, 0.251 mmol) was added to a soln. of 6a (75.0 mg,
4
)
Systematic name of one single resonance structure out of several possible ones.

1510
Helvetica Chimica Acta ± Vol. 88 (2005)
0.241 mmol) in C6D6 (1 ml). Vigorous gas evolution set in, which was finished after a few minutes. By NMR,
93% of 8b was identified. 1H-NMR (C6D6, 400 MHz): 0.62 (2 H of cPr); 1.10 (2 H of cPr); 2.15 (2 MeN); 2.60,
2.67 (2 NCH2); 7.08 (HÀC(12)); 6.93 ± 7.53 (2 Ph). 13C-NMR (C6D6, 100 MHz): 12.1 (C(1,2)); 26.4 (C(3)); 35.1
(2 MeN); 52.4 (C(6,7)); 80.2 (C(4)); 126.5 (C(9)); 145.0 (C(10)); 167.4 (C(12)); 141.3, 132.8, 127.36, 126.9 (9-
Ph); 141.9, 130.7, 127.42, 126.5 (10-Ph).
2,3-Dihydro-1-methyl-6,7-diphenyl-1H-pyrrolo[3,2-c]pyridine (9b). To compound 6b (143 mg,
0.610 mmol) in CH2Cl2 (2 ml) under Ar gas, compound 1 (93.0 mg, 0.67 mmol) was slowly added via syringe
at À 658. The orange soln. was allowed to warm up, and at ca. À 508, gas evolution started. After 24 h at r.t., the
solvent was removed in vacuo, and the residue was purified by prep. TLC (Al2O3; petroleum ether/AcOEt 6 :1;
Rf 0.1). Colorless solid. Yield: 108 mg (38%). M.p. 1758. UV (CHCl3): 245 (1.40). 1H-NMR (CDCl3, 400 MHz):
2.24 (MeN); 3.05 (4J ˆ 0.9, HÀC(3)); 3.48 (HÀC(2)); 7.09 ± 7.22 (2 Ph); 8.16 (HÀC(4)). 13C-NMR (CDCl3,
100 MHz): 25.3 (C(3)); 37.1 (MeN); 56.7 (C(2)); 117.1 (C(7)); 125.2 (C(3a)); 142.3 (C(4)); 156.3 (C(7a)); 158.2
‡
‡
(C(6)); 141.0, 127.7, 131.6, 126.9 (6-Ph); 136.9, 127.3, 129.6, 126.7 (7-Ph). EI-MS: 286 (68, M , C20H18N2 ).
3-[1-(4,5-Dihydro-1,3-dimethyl-1H-imidazol-3-ium-2-yl)cyclopropyl]-5,6-diphenyl-3H-1,2,4-triazin-2-ide
(10b)4). To a soln. of 6b (75 mg, 0.321 mmol) in CD2Cl2 (1 ml) under Ar gas, compound 1 (43.0 mg, 0.311 mmol)
was carefully added at À 408. Then, NMR spectra were recorded at À 40, À 20, and ‡ 258, giving rise to the
following product distributions: a) Tˆ À408, 1 h: 6b/8b/9b/10b 33 :5 :62 :0; b) Tˆ À208, 7 h: 20 :10 :70 :0; c)
Tˆ 258, 1 h: 20 :0 :80 :0; d) Tˆ 258, 168 h: 20 :0 :0 :80.
Data of 10b. 1H-NMR (CD2Cl2, 400 MHz; Tˆ À208): 1.07 (2 H of cPr); 1.46 (H of cPr); 1.58 (H of cPr);
2.08 (HÀC(3)); 3.42 (MeN); 3.45 (MeN); 3.65 (mc, 2 NCH2); 6.83 ± 7.42 (2 Ph). 13C-NMR (CD2Cl2, 100 MHz):
9.8 (CH2 of cPr); 10.8 (CH2 of cPr); 19.6 (cPr); 34.9 (MeN); 35.3 (MeN); 49.4 (NCH2); 49.5 (NCH2); 89.2
(C(3)); 136.2 (C(5)); 147.9 (C(6)); 168.9 (C(2) of Im); 134.0, 130.4, 127.4, 127.0 (5-Ph); 136.7, 123.9, 127.3, 121.8
(6-Ph).
5. Additions to 3,5-Diaryl-1,2,4-triazines 5. 5,8-Dimethyl-9,11-diphenyl-5,8,10-triazadispiro[2.0.4.4]dodeca-
9,11-diene (11a). Compound 1 (61 mg, 0.44 mmol) was slowly added to a soln. of 5a (86.0 mg, 0.365 mmol) in
toluene (3 ml). A vigorous gas evolution set in, and the initially formed precipitate dissolved again. After
20 min, the solvent was removed in vacuo, and the residue was distilled at 2508/0.01 mbar. Yellow glass. Yield:
126 mg (99%). 1H-NMR (C6D6, 400 MHz): 0.58 (2 H of cPr); 1.12 (2 H of cPr); 2.16 (2 MeN); 2.70, 2.82
(2 NCH2); 5.58 (HÀC(12)); 7.26 ± 7.30, 8.02 ± 8.08 (2 Ph). 13C-NMR (C6D6, 100 MHz): 13.3 (C(1)); C(2)), 22.0
(C(3)), 35.4 (2 MeN); 52.3 (C(6,7)); 78.6 (C(4)); 120.5 (C(12)); 144.1 (C(11)); 164.8 (C(9)); 140.3, 129.6, 128.1,
‡
128.2 (9-Ph); 138.9, 127.3, 125.1, 126.9 (11-Ph). EI-MS: 343 (100, M ). Anal. calc. for C23H25N3 (343.4): C 80.43,
H 7.34, N 12.23; found: C 80.07, H 7.21, N 12.35.
5,8-Dimethyl-11-(2-methylphenyl)-9-phenyl-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (11b). Com-
pound 1 (44 mg, 0.32 mmol) was slowly added to a soln. of 5b (76.0 mg, 0.307 mmol) in toluene (3 ml). A
vigorous gas evolution set in. After 20 min, the solvent was removed in vacuo, and the residue was distilled at
2508/0.01 mbar. Yellow glass. Yield: 103 mg (92%). 1H-NMR (C6D6, 400 MHz): 0.51 (2 H of cPr); 1.07 (2 H of
cPr); 2.18 (2 MeN); 2.52 (Me of Tol); 2.67, 2.80 (2 NCH2); 5.11 (HÀC(12); 7.13 (HÀC(3,4,5) of Tol); 7.19
(HÀC(3,4,5) of Ph); 7.51 (HÀC(6) of Tol); 7.97 (HÀC(2,6) of Ph). 13C-NMR (C6D6, 100 MHz): 13.4 (C(1,2));
21.4 (Me of Tol); 22.2 (C(3)); 35.9 (2 MeN); 52.7 (C(6,7)); 78.5 (C(4)); 124.9 (C(12)); 143.5 (C(11)); 164.3
(C(9)); 144.3, 129.9, 127.7, 128.5 (9-Ph); 140.6 (C(1) of Tol); 136.5 (C(2) of Tol); 130.9 (C(3) of Tol); 127.4 (C(4)
‡
of Tol); 125.8 (C(5) of Tol); 129.3 (C(5) of Tol); 129.3 (C(6) of Tol). EI-MS: 357 (92, M ). Anal. calc. for
C24H27N3 (358.5): C 80.63, H 7.61, N 11.75; found: C 79.69, H 7.41, N 11.67.
11-(4-Methoxyphenyl)-5,8-dimethyl-9-phenyl-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (11c). Com-
pound 1 (27 mg, 0.11 mmol) was slowly added to a soln. of 5c (27.0 mg, 0.103 mmol) in C6D6 (1 ml). A
vigorous gas evolution set in. After 20 min, the solvent was removed in vacuo, and the residue was distilled at
2508/0.01 mbar. Yellow glass. Yield 35.1 mg (91%). 1H-NMR (C6D6, 400 MHz): 0.56 (2 H of cPr); 1.20 (2 H of
cPr); 2.14 (2 MeN); 2.68, 2.80 (2 NCH2); 3.33 (MeO); 5.73 (HÀC(12)); 6.90 (J ˆ 9.0, HÀC(2,6)) of 11-Ar);
7.30 ± 7.45 (HÀC(3,4,5) of 9-Ph); 7.99 (HÀC(3,5) of 11-Ar); 8.05 (HÀC(2,6) of 9-Ph). 13C-NMR (C6D6,
100 MHz): 13.6 (C(1,2)); 22.4 (C(3)); 35.9 (2 MeN); 52.7 (C(6,7)); 54.8 (MeO); 79.2 (C(4)); 118.8 (C(12));
144.7 (C(11)); 164.3 (C(9)); 140.4, 130.0, 127.7, 128.5 (9-Ph); 132.0, 126.7, 114.0, 159.8 (11-Ar). EI-MS: 373 (100,
‡
M ). Anal. calc. for C24H27N3O (373.5): C 77.18, H 7.29, N 11.25; found: C 76.74, H 6.98, N 11.37.
4,5-Dihydro-2-[1-(1,6-dihydro-3,5-diphenyl-1,2,4-triazin-6-yl)cyclopropyl]-1,3-dimethyl-1H-imidazolium
Acetate (13a). To compound 5a (79 mg, 0.34 mmol) in toluene (2 ml) under Ar gas, compound 1 (56 mg,
0.41 mmol) was slowly added via syringe at À 758 with stirring. After 15 min, AcOH (21 mg, 0.35 mmol) was
added to the suspension, and the orange soln. was allowed to warm to r.t. After removal of the solvent in vacuo,
1
the residue (97% of 13a) was analyzed by NMR. H-NMR (CDCl3, 400 MHz): 0.86 (2 H of cPr); 1.15 (H of

Helvetica Chimica Acta ± Vol. 88 (2005)
1511
cPr); 2.86 (MeN); 3.20 (MeN); 3.54, 3.78 (mc, 2 NCH2); 5.09 (HÀC(6) of triazine); 7.37 (HÀC(3,4,5 of 3-Ph);
7.49 (HÀC(3,4,5) of 5-Ph); 8.03 (HÀC(2,6) of 3-Ph); 8.16 (HÀC(2,6) of 5-Ph). 13C-NMR (CDCl3, 100 MHz):
10.7 (CH2 of cPr); 11.9 (CH2 of cPr); 16.8 (C of cPr); 34.6 (MeN); 34.9 (MeN); 49.2 (C(6) of triazine); 49.6
(NCH2); 49.8 (NCH2); 147.1 (C(3) of triazine); 147.6 (C(5) of triazine); 165.8 (C(2) of Im); 135.2, 124.2, 128.7,
128.7 (3-Ph); 135.3, 127.5, 129.3, 131.8 (5-Ph).
4,5-Dihydro-2-{1-[1,6-dihydro-5-(4-methoxyphenyl)-3-phenyl-[1-2H]-1,2,4-triazin-6-yl]cyclopropyl}-1,3-di-
methyl-1H-imidazolium [2,2,2-2H3]Acetate (13c). To 5c (88 mg, 0.33 mmol) in CD2Cl2 (1 ml) under Ar gas,
compound 1 (51 mg, 0.37 mmol) was slowly added via syringe at À 408. After 15 min, CD3COOD (30 mg,
1
0.49 mmol) was added to the suspension, and the orange soln. (61% of 13c) was analyzed by NMR H-NMR
(CD2Cl2, 400 MHz; Tˆ À308): 0.77 (2 H of cPr); 1.15 (H of cPr); 2.74 (MeN); 3.16 (MeN); 3.72 (MeO); 3.83
(mc, 2 NCH2); 4.80 (HÀC(6) of triazine); 6.97 (J ˆ 9.0, HÀC(3,5) of 5-Ar); 7.40 (HÀC(3,4,5) of 3-Ph); 8.06
(HÀC(2,6) of 3-Ph); 8.14 (HÀC(2,6) of 5-Ar). 13C-NMR (CDCl3, 100 MHz; Tˆ À308): 9.7 (2 CH2 of cPr);
16.5 (cPr); 34.3 (MeN); 34.8 (MeN); 49.1(C(6) of triazine); 49.2 (NCH2); 49.3 (NCH2); 149.7 (C(3) of
triazine); 147.0 (C(5) of triazine); 165.5 (C(2) of Im); 134.9, 129.2, 128.7, 129.3 (3-Ph); 126.7, 128.6, 129,3, 131.8
(5-Ar).
6. Additions to 3,6-Diaryl-1,2,4-triazines 2. General Procedure C (GP C). To compound 2 (n mg, m mmol) in
either C6D6 or (D8)toluene (0.6 ml), compound 1 (q mg, p mmol) was added via syringe under Ar gas. The
orange suspension was heated to 1088 in a sealed tube for 19 h, and the resulting yellow-brown soln. was
investigated by NMR. For yields and ratios of regioisomers, see Table 2; for characteristic 1H-NMR (400 MHz)
and 13C-NMR (100 MHz) shifts, see Tables 5 ± 7.
5,8-Dimethyl-9,12-diphenyl-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (14a) and 5,8-Dimethyl-9,12-di-
phenyl-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (15a). GP C (n ˆ 28, m ˆ 120, q ˆ 23, p ˆ 166).
1
Data of 14a. H-NMR ((D8)toluene): 7.14 ± 7.72 (2 Ph). 13C-NMR ((D8)toluene): 141.9, 128.7, 126.7, 126.8
(9-Ph); 138.7, 129.3, 129.1, 128.3 (12-Ph).
Data of 15a. 1H-NMR ((D8)toluene): 7.14 ± 8.00 (2 Ph). 13C-NMR ((D8)toluene): 144.0, 129.9, 129.6, 128.2
(9-Ph); 137.3, 128.0, 127.3, 127.1 (12-Ph).
1
Table 5. Selected H-NMR Chemical Shifts of Compounds 14 and 15
Solvent
14
15
cPra)
MeN
CH2N
HÀC(11)
cPr
MeN
CH2N
HÀC(11)
a
b
c
d
e
f
g
h
i
(D8)toluene
C6D6
C6D6
(D8)toluene
C6D6
C6D6
(D8)toluene
(D8)toluene
(D8)toluene
C6D6
0.93, 1.16
1.04, 1.18
0.96, 1.17
0.98, 1.18
1.02, 1.16
0.73, 1.13
0.68, 1.15
1.00, 1.20
1.09, 1.23
0.75, 1.15
0.66, 1.14
2.26
2.44
2.30
2.28
2.24
2.22
2.20
2.28
2.31
2.26
2.23
2.80
2.78
2.80
2.82
2.78
2.77
2.79
2.84
2.87
2.80
2.78
7.38
7.28
7.49
7.39
7.42
7.42
7.31
7.40
7.44
7.44
7.42
0.73, 0.99
0.62, 0.95
0.80, 1.03
0,74, 1.00
0.78, 1.02
0.74, 0.95
0.72, 0.94
0.75, 1.01
0.74, 1.02
0.91, 0.98
0.79, 0.96
2.27
2.44
2.29
2.29
2.30
2.15
2.14
2.31
2.36
2.18
2.13
2.86
2.78
2.80
2.82
2.78
2.77
2.70
2.84
2.86
2.71
2.67
7.03
7.02
7.30
7.03
7.06
7.06
6.97
7.04
7.05
7.12
7.10
j
k
C6D6
a) cPrˆ Cyclopropyl.
5,8-Dimethyl-9-(2-methylphenyl)-12-phenyl-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (14b) and 5,8-
Dimethyl-12-(2-methylphenyl)-9-phenyl-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (15b). GP C (n ˆ 29,
m ˆ 117, q ˆ 20, p ˆ 144).
Data of 14b. 1H-NMR (C6D6): 2.23 (Me of Tol); 7.02 ± 7.53 (9-Ar, 12-Ph). 13C-NMR (C6D6): 20.5 (Me of 9-
Ar); 134.3, 137.1, 131.5, 130.1, 165.5, 125.0 (9-Ar); 126.1, 129.5, 129.1, 128.6 (12-Ph).
1
Data of 15b. H-NMR (C6D6): 7.04 ± 8.00 (12-Ar, 9-Ph). 13C-NMR (C6D6): 20.3 (Me of Tol); 144.0, 129.9,
129.6, 128.2 (9-Ph); 144.4, 136.6, 132.0, 128.1, 127.6, 125.1 (12-Ar).

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Helvetica Chimica Acta ± Vol. 88 (2005)
Table 6. Selected 13C-NMR Chemical Shifts of Compounds 14
Solvent
C(1,2)
C(3)
C(4)
C(6,7)
C(9)
C(10)
C(12)
MeN
14a
14b
14c
14d
14e
14f
14g
14h
14i
(D8)toluene
C6D6
C6D6
(D8)toluene
C6D6
C6D6
(D8)toluene
(D8)toluene
(D8)toluene
C6D6
10.4
10.3
10.8
10.4
11.4
10.9
10.6
10.3
10.5
10.9
10.9
26.4
26.8
26.7
26.5
28.1
26.6
26.1
26.6
26.9
26.3
26.3
80.7
80.7
80.8
80.7
80.5
80.8
80.8
80.8
81.5
80.6
80.5
52.7
53.0
53.0
52.7
52.8
52.9
52.6
52.7
53.1
52.9
52.9
137.1
139.3
129.8
137.1
129.4
128.0
136.8
131.0
128.2
129.4
129.2
138.5
140.1
138.3
138.7
138.3
138.5
138.0
138.8
139.6
137.9
137.7
173.3
173.6
173.2
173.1
173.1
172.3
171.2
173.0
173.7
171.7
171.0
36.4
35.6
36.7
36.4
36.6
36.6
36.2
36.5
37.1
36.6
36.6
14j
14k
C6D6
9-(4-Methoxyphenyl)-5,8-dimethyl-12-phenyl-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (14c) and 12-
(4-Methoxyphenyl)-5,8-dimethyl-9-phenyl-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (15c). GP C (n ˆ 43,
m ˆ 163, q ˆ 23, p ˆ 166).
Data of 14c. 1H-NMR (C6D6): 3.36 (MeO of 9-Ar); 6.81, 7.69 (J ˆ 8.9, 9-Ar); 7.10 ± 7.69 (12-Ph). 13C-NMR
(C6D6): 54.7 (MeO of 9-Ar); 134.4, 130.7, 113.7, 159.5 (9-Ar); 139.3, 129.5, 127.9, 128.4 (12-Ph).
Data of 15c. 1H-NMR (C6D6): 3.32 (MeO of 12-Ar); 7.20 ± 7.32 (9-Ph); 6.72, 8.09 (J ˆ 7.9, 12-Ar) . 13C-
NMR (C6D6): 54.8 (MeO of 12-Ar); 144.3, 131.4, 129.8 128.5 (9-Ph); 135.5, 131.3, 113.7, 159.5 (12-Ar).
Table 7. Selected 13C-NMR Chemical Shifts of Compounds 15
Solvent
C(1,2)
C(3)
C(4)
C(6,7)
C(9)
C(11)
C(12)
MeN
15a
15b
15c
15d
15e
15f
15g
15h
15i
(D8)toluene
C6D6
C6D6
(D8)toluene
C6D6
C6D6
(D8)toluene
(D8)toluene
(D8)toluene
C6D6
10.0
10.2
10.3
10.0
10.3
10.5
10.2
10.0
10.3
10.4
10.5
23.6
24.8
24.1
23.5
23.5
23.8
23.6
23.5
24.0
24.1
24.2
79.5
79.6
79.9
79.3
79.1
79.6
79.4
79.2
79.8
79.8
79.8
52.7
53.0
52.9
52.7
52.9
52.7
52.4
52.6
53.0
52.8
52.7
164.1
164.1
164.2
164.0
164.2
163.2
162.1
162.7
164.3
162.9
162.3
133.1
133.1
132.8
132.6
132.3
132.6
132.2
132.5
133.1
132.5
132.5
135.3
136.9
135.9
137.3
135.9
36.4
35.6
36.8
36.4
36.6
36.6
36.6
36.4
36.9
36.6
36.6
a
)
136.7
136.5
134.5
136.4
133.8
15j
15k
C6D6
a) Signal masked.
5,8-Dimethyl-12-(4-methylphenyl)-9-phenyl-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (14d) and 5,8-
Dimethyl-9-(4-methylphenyl)-12-phenyl-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (15d). GP C (n ˆ 31,
m ˆ 125, q ˆ 21, p ˆ 152).
Data of 14d. 1H-NMR ((D8)toluene): 2.13 (Me of 12-Ar); 7.17 ± 7.74 (9-Ph); 6.96, 7.46 (J ˆ 8.1, 12-Ar).
13C-NMR ((D8)toluene): 20.8 (Me of 12-Ar); 142.0, 128.2, 127.8, 126.7 (9-Ph); 137.9, 129.2, 129.3, 136.1 (12-Ar).
Data of 15d. 1H-NMR ((D8)toluene): 2.19 (Me of 9-Ar); 7.14 ± 7.74 (9-Ar, 12-Ph). 13C-NMR ((D8)toluene):
20.8 (Me of 9-Ar); 141.0, 129.5, 130.0, 136.8 (9-Ar); 137.8, 129.0, 128.0, 127.0 (12-Ph).
5,8-Dimethyl-12-(2-methylphenyl)-9-phenyl-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (14e) and 5,8-
Dimethyl-9-(2-methylphenyl)-12-phenyl-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (15e). GP C (n ˆ 30,
m ˆ 121, q ˆ 19, p ˆ 137).
Data of 14e. 1H-NMR (C6D6): 2.40 (Me of 12-Ar); 7.02 ± 7.90 (12-Ar, 9-Ph). 13C-NMR (C6D6): 19.8 (Me of
12-Ar); 142.3, 129.9, 128.0, 127.2, (9-Ph); 136.9, 138.1, 130.2, 131.0, 124.7, 129.3 (12-Ar).

Helvetica Chimica Acta ± Vol. 88 (2005)
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Data of 15e. 1H-NMR (C6D6): 2.58 (Me of 9-Ar); 7.04 ± 8.20 (9-Ar, 12-Ph). 13C-NMR (C6D6): 23.5 (Me of
9-Ar); 141.3, 137.4, 129.8, 130.3, 124.6, 128.7 (9-Ar); 137.7, 130.6, 129.1, 127.1 (12-Ph).
5,8-Dimethyl-9-phenyl-12-[4-(trifluoromethyl)phenyl]-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (14f)
and 5,8-Dimethyl-12-phenyl-9-(4-(trifluoromethyl)phenyl]-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (15f).
GP C (n ˆ 24, m ˆ 80, q ˆ 11, p ˆ 80).
Data of 14f. 1H-NMR (C6D6): 7.09 ± 7.24, 7.75 (9-Ph); 7.31, 7.35 (J ˆ 8.4, 12-Ar). 13C-NMR (C6D6): 137.3,
129.6, 128.2, 127.4 (9-Ph); 141.9, 129.8, 124.9, 130.3 (12-Ar).
1
Data of 15f. H-NMR (C6D6): 7.31, 7.41 (J ˆ 8.2, 9-Ar); 7.09 ± 7.24, 7.94 (12-Ph). 13C-NMR (C6D6): 142.4,
127.4, 124.7, 130.5 (9-Ar); 144.0, 130.1, 130.1, 127.9 (12-Ph).
5,8-Dimethyl-12-(4-nitrophenyl)-9-phenyl-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (14g) and 5,8-Di-
methyl-9-(4-nitrophenyl)-12-phenyl-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (15g). GP C (n ˆ 26, m ˆ 94,
q ˆ 14, p ˆ 102).
Data of 14g. 1H-NMR ((D8)toluene): 7.12 ± 7.19 (9-Ph); 7.82, 7.91 (J ˆ 9.0, 12-Ar). 13C-NMR ((D8)toluene):
145.5, 129.6, 127.6, 127.1 (9-Ph); 144.0, 129.3, 122.7, 147.9 (12-Ar).
Data of 15g. 1H-NMR ((D8)toluene): 7.21, 7.78 (J ˆ 9.0, 9-Ar); 7.12, 7.68 (12-Ph). 13C-NMR ((D8)toluene):
141.4, 129.7, 122.5, 147.7 (9-Ar); 149.6, 129.7, 127.6, 127.5 (12-Ph).
12-(4-Methoxyphenyl)-5,8-dimethyl-9-phenyl-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (14h) and 9-(4-
Methoxyphenyl)-5,8-dimethyl-12-phenyl-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (15h). GP C (n ˆ 40,
m ˆ 152, q ˆ 21, p ˆ 152).
1
Data of 14h. H-NMR ((D8)toluene): 3.34 (MeO of 12-Ar); 7.19, 7.75 (9-Ph); 6.72, 7.50 (J ˆ 8.9, 12-Ar).
13C-NMR ((D8)toluene): 54.4 (MeO of 12-Ar); 142.1, 129.2, 127.9,126.7 (9-Ph); 129.5, 130.6, 112.9, 160.2 (12-
Ar).
Data of 15h. 1H-NMR ((D8)toluene): 3.38 (MeO of 9-Ar); 6.86, 7.95 (J ˆ 8.7, 9-Ar); 7.15, 7.87 (12-Ph).
13C-NMR ((D8)toluene): 54.5 (MeO of 9-Ar); 137.5, 130.1, 112.8, 160.7 (9-Ar); 135.0, 130.0, 129.0, 126.5 (12-
Ph).
12-(4-(Dimethylamino)phenyl]-5,8-dimethyl-9-phenyl-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (14i)
and 9-[4-(Dimethylamino)phenyl]-5,8-dimethyl-12-phenyl-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (15i).
GP C (n ˆ 32, m ˆ 116, q ˆ 21, p ˆ 152).
Data of 14i. 1H-NMR (C6D6): 2.53 (Me2N of 12-Ar); 7.18, 7.77 (9-Ph) ; 6.47, 7.59 (J ˆ 8.9, 12-Ar). 13C-NMR
(C6D6): 39.8 (Me2N of 12-Ar); 142.7, 129.4, 128.1, 126.8 (9-Ph); 127.0, 130.8, 111.4, 150.9 (12-Ar).
Data of 15i. 1H-NMR (C6D6): 2.53 (Me2N of 9-Ar); 6.56, 7.18 (J ˆ 8.8, 9-Ar); 7.12, 7.98 (12-Ph). 13C-NMR
(C6D6): 39.9 (Me2N of 9-Ar); 138.0, 130.3, 111.5, 149.0 (9-Ar); 138.0, 130.8, 128.0, 127.3 (12-Ph).
9-(4-Methoxyphenyl)-5,8-dimethyl-12-[4-(trifluoromethyl)phenyl]-5,8,11-triazadispiro[2.0.4.4]dodeca-
9,11-diene (14j) and 12-(4-Methoxyphenyl)-5,8-dimethyl-9-[4-(trifluoromethyl)phenyl]-5,8,10-triazadispi-
ro[2.0.4.4]dodeca-9,11-diene (15j). GP C (n ˆ 23, m ˆ 69, q ˆ 10, p ˆ 73).
Data of 14j. 1H-NMR (C6D6): 3.37 (MeO of 9-Ar); 6.80, 7.67 (J ˆ 8.6, 9-Ar); 7.32, 7.36 (J ˆ 8.4, 12-Ar).
13C-NMR (C6D6): 54.8 (MeO of 9-Ar); 124.9 (F3C of 12-Ar); 134.0, 130.7, 113.8, 159.8 (9-Ar); 142.5, 129.8,
124.9 (J(C,F) ˆ 3.8), 130.3 (J(C,F) ˆ 32.0) (12-Ar).
Data of 15j. 1H-NMR (C6D6): 3.32 (MeO); 7.42, 7.92 (J ˆ 8.3, 9-Ar); 6.73, 7.10 (J ˆ 8.6, 12-Ar). 13C-NMR
(C6D6): 54.8 (MeO of 12-Ar); 125.0 (F3C of 9-Ar); 147.8, 130.1, 124.8 (J(C,F) ˆ 3.8), 130.1 (J(C,F) ˆ 32.0) (9-
Ar); 142.5, 131.2, 113.8, 159.8 (12-Ar).
9-(4-Methoxyphenyl)-5,8-dimethyl-12-(4-nitrophenyl)-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (14k)
and 12-(4-Methoxyphenyl)-5,8-dimethyl-9-(4-nitrophenyl)-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (15k).
GP C (n ˆ 24, m ˆ 78, q ˆ 11, p ˆ 80).
1
Data of 14k. H-NMR (C6D6): 3.37 (MeO of 9-Ar); 6.82, 7.66 (J ˆ 9.0, 9-Ar); 7.21, 7.79 (J ˆ 8.8, 12-Ar).
13C-NMR (C6D6): 54.8 (MeO of 9-Ar); 133.8, 130.7, 113.8, 159.8 (9-Ar); 145.3, 130.3, 123.1, 148.2 (12-Ar).
Data of 15k. 1H-NMR (C6D6): 3.33 (MeO); 7.87, 7.93 (J ˆ 9.0, 9-Ar); 6.73, 7.08 (J ˆ 8.9, 12-Ar). 13C-NMR
(C6D6): 54.8 (MeO of 12-Ar); 144.4, 129.9, 122.9, 148.0 (9-Ar); 137.0, 131.2, 113.8, 159.8 (12-Ar).
4,5-Dihydro-2-[1-(2,5-dihydro-3,6-diphenyl-[2-2H]-1,2,4-triazin-5-yl)cyclopropyl]-1,3-dimethyl-1H-imida-
zolium[2,2,2- 2H3]Acetate (17a). To compound 2a (51 mg, 0.22 mmol) in THF (10 ml) under Ar gas, compound 1
(30 mg, 0.22 mmol) was slowly added via syringe at À 408 with stirring. After 1 h, the orange precipitate was
collected by filtration at À 408 under Ar gas, and washed with pentane. After removal of the last traces of
solvent at À 208/0.1 mbar, the remaining solid (75%) was dissolved in CDCl3 (0.6 ml) containing CD3COOD
(0.6 mmol). 1H-NMR (CDCl3, 400 MHz; Tˆ 258): 1.06, 1.08, 1.26, 1.28 (cPr); 3.08 (2 MeN); 3.72 (mc, 2 NCH2);
5.62 (HÀC(5) of triazine); 7.96, 7.50, 7.63 (3-Ph); 7.78, 7.55, 7.50 (6-Ph). 13C-NMR (CDCl3, 100 MHz; Tˆ 258):
10.2 (CH2 of cPr); 10.8 (CH2 of cPr); 18.2 (C of cPr); 34.8 (MeN); 35.0 (MeN); 50.0 (NCH2); 50.1 (NCH2); 51.5

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Helvetica Chimica Acta ± Vol. 88 (2005)
(C(5) of triazine); 144.8 (C(6) of triazine); 156.4 (C(3) of triazine); 164.5 (C(2) of Im); 128.5, 127.8, 129.4, 133.2
(3-Ph); 133.5, 126.2, 129.5, 131.2 (6-Ph).
2,5-Dihydro-2-{1-[1,6-Dihydro-3-(2-methylphenyl)-6-phenyl-1,2,4-triazin-5-yl]cyclopropyl}-1,3-dimethyl-
1H-imidazolium Acetate (17e). To compound 2e (143 mg, 0.58 mmol) in toluene (10 ml) under Ar gas,
compound 1 (95 mg, 0.69 mmol) was slowly added via syringe at À 408 with stirring. After 1 h, AcOH
(1.2 mmol) was added to the orange precipitate, which dissolved within 30 min. The solvent was removed at
0.1 mbar, the residue (76%) was dissolved in CDCl3 (0.6 ml), and investigated by NMR. 1H-NMR (CDCl3,
400 MHz; Tˆ 258): 1.05, 1.10, 1.30, 1.42 (cPr); 2.38 (Me of 3-Ar); 2.99 (MeN); 3.14 (MeN); 3.78 (mc, 2 NCH2);
5.42 (HÀC(5) of triazine); 7.20 ± 7.60 (3-Ar); 7.76, 7.15, 7.45 (6-Ph). 13C-NMR (CDCl3, 100 MHz; Tˆ 258): 8.3
(CH2 of cPr); 10.2 (CH2 of cPr); 18.5 (C of cPr); 19.9 (Me of 3-Ar); 34.7 (MeN); 34.9 (MeN); 49.4 (NCH2); 49.7
(NCH2); 51.3 (C(5) of triazine); 137.9 (C(6) of triazine); 157.7 (C(3) of triazine); 165.5 (C(2) of Im); 128.3, 131.8
130.2, 131.2 (3-Ar); 141.5, 125.3, 129.0, 129.1 (6-Ph).
2,5-Dihydro-2-{1-[1,6-dihydro-3-(4-methylphenyl)-6-phenyl-1,2,4-triazin-5-yl]cyclopropyl}-1,3-dimethyl-
1H-imidazolium Acetate (17d). To compound 2d (100 mg, 0.41 mmol) in toluene (10 ml) under Ar gas,
compound 1 (67 mg, 0.48 mmol) was slowly added via syringe at 258 with stirring. After 1 h, AcOH (1.2 mmol)
was added to the orange precipitate, which dissolved within 30 min. The solvent was removed at 0.1 mbar, the
residue (75%) was dissolved in CDCl3 (0.6 ml), and investigated by NMR. 1H-NMR (CDCl3, 400 MHz; Tˆ
258): 0.96, 0.99, 1.32, 1.33 (cPr); 2.36 (Me of 3-Ar); 2.96 (MeN); 2.99 (MeN); 3.68 (mc, 2 NCH2); 5.08 (HÀC(5)
of triazine); 7.97, 7.23 (J ˆ 8.3, 3-Ar); 7.77, 7.40, 7.40 (6-Ph). 13C-NMR (CDCl3, 100 MHz; Tˆ 258): 10.1 (CH2 of
cPr); 11.1 (CH2 of cPr); 18.6 (C of cPr); 21.4 (Me of 3-Ar); 34.7 (MeN); 34.9 (MeN); 49.7 (NCH2); 49.8
(NCH2); 53.7 (C(5) of triazine); 146.5 (C(6) of triazine); 154.8 (C(3) of triazine); 165.2 (C(2) of Im); 135.0,
125.6, 129.0, 141.5 (3-Ar); 141.9, 129.5, 126.9, 129.7 (6-Ph).
4,5-Dihydro-2-{1-[2,5-dihydro-3-(4-nitrophenyl)-6-phenyl-[2-2H]-1,2,4-triazin-5-yl]cyclopropyl}-1,3-di-
methyl-1H-imidazolium [2,2,2-2H3]Acetate (17g). To compound 2g (220 mg, 0.79 mmol) in THF (10 ml) under
Ar gas, compound 1 (181 mg, 1.31 mmol) was slowly added via syringe at À 408 with stirring. After 1 h, the
orange precipitate was collected by filtration under Ar gas, and washed with pentane. After removal of last
traces of solvent at 0.1 mbar, the resulting solid (66%) was dissolved in CDCl3 (0.6 ml) containing CD3COOD
1
(3.9 mmol). H-NMR (CDCl3, 400 MHz; Tˆ 258): 1.15, 1.15, 1.45, 1.60 (cPr); 3.12 (MeN); 3.13 (MeN); 3.40,
3.70 (2 NCH2); 5.93 (HÀC(5) of triazine); 7.98, 7.44 (J ˆ 8.4, 3-Ar); 7.98, 7.56, 7.56 (6-Ph). 13C-NMR (CDCl3,
100 MHz; Tˆ 258): 10.3 (CH2 of cPr); 10.5 (CH2 of cPr); 18.1 (C of cPr); 34.8 (MeN); 35.0 (MeN); 48.2 (C(5) of
triazine); 49.8 (2 NCH2); 147.8 (C(6) of triazine); 155.5 (C(3) of triazine); 163.6 (C(2) of Im); 130.7, 129.2 126.7
146.8 (3-Ar); 132.3, 129.7, 130.7, 132.1 (6-Ph).
4,5-Dihydro-2-{1-[2,5-dihydro-3-(4-methoxyphenyl)-6-phenyl-[2-2H]-1,2,4-triazin-5-yl]cyclopropyl}-1,3-di-
methyl-1H-imidazolium [2,2,2-2H3]Acetate (17h). To compound 2h (202 mg, 0.77 mmol) in THF (10 ml) under
Ar gas, compound 1 (129 mg, 0.93 mmol) was slowly added via syringe at À 408 with stirring. After 1 h, the
orange precipitate was collected by filtration under Ar gas, and washed with pentane. After removal of last
traces of solvent at 0.1 mbar, the resulting solid (67%) was dissolved in CDCl3 (0.6 ml) containing CD3COOD
(2.8 mmol). 1H-NMR (CDCl3, 400 MHz; Tˆ 258): 1.14, 1.14, 1.40, 1.54 (cPr); 3.07 (2 MeN); 3.40, 3.70
(2 NCH2); 3.78 (MeO of 3-Ar); 5.97 (HÀC(5) of triazine); 8.08, 7.10 (J ˆ 8.1, 3-Ar); 7.98, 7.54, 7.54 (6-Ph).
13C-NMR (CDCl3, 100 MHz; Tˆ 258): 10.4 (CH2 of cPr); 10.7 (CH2 of cPr); 18.5 (C of cPr); 34.9 (MeN); 35.1
(MeN); 49.4 (C(5) of triazine); 50.0 (NCH2); 50.1 (NCH2); 55.8 (MeO of 3-Ar); 147.4 (C(6) of triazine); 155.7
(C(3) of triazine); 165.3 (C(2) of Im); 133.3, 131.4, 115.5, 164.2 (3-Ar); 130.4, 129.8, 126.8, 132.1 (6-Ph).
4,5-Dihydro-2-(1-{2,5-dihydro-3-[4-(dimethylamino)phenyl]-6-phenyl-[2-2H]-1,2,4-triazin-5-yl}cycloprop-
yl)-1,3-dimethyl-1H-imidazolium [2,2,2-2H3]Acetate (17i). To compound 2i (95 mg, 0.34 mmol) in toluene
(10 ml) under Ar gas, compound 1 (57 mg, 0.41 mmol) was slowly added via syringe at À 408 with stirring. After
1 h, CD3COOD (1.2 mmol) was added to the orange precipitate, which dissolved within 30 min. The solvent was
removed at 0.1 mbar, and the residue (25%) was dissolved in CDCl3 (0.6 ml), and investigated by NMR.
1H-NMR (CDCl3, 400 MHz; Tˆ 258): 1.00, 1.00, 1.35, 1.45 (cPr); 3.17 (2 MeN); 3.19 (Me2N of 3-Ar); 3.75 (mc,
2 NCH2); 5.16 (HÀC(5) of triazine); 7.97, 6.70 (J ˆ 9.0, 3-Ar); 7.82 ,7.40, 7.40 (6-Ph). 13C-NMR (CDCl3,
100 MHz; Tˆ 258): 10.4 (CH2 of cPr); 11.3 (CH2 of cPr); 18.5 (C of cPr); 34.8 (MeN); 35.1 (MeN); 49.4 (C(5) of
triazine); 49.8 (NCH2); 49.9 (NCH2); 53.3 (Me2N of 3-Ar); 142.5 (C(6) of triazine); 154.9 (C(3) of triazine);
165.1 (C(2) of Im); 116.5, 125.7, 111.6, 152.7 (3-Ar); 134.8, 128.2, 129.0, 129.9 (6-Ph).
5-[1-(4,5-Dihydro-1,3-dimethyl-1H-imidazol-3-ium-2-yl)cyclopropyl]-3,6-diphenyl-5H-1,2,4-triazin-2-ide
(16a)4). To a yellow soln. of compound 2a (273 mg, 1.17 mmol) in toluene (10 ml), compound 1 (193 mg,
1.40 mmol) was slowly added at À 408. After 1 h, the orange precipitate was collected by filtration at À 408
under Ar gas. After washing with pentane and removal of last traces of solvent at À 208/0.1 mbar, the solid

Helvetica Chimica Acta ± Vol. 88 (2005)
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(100% of 16a) was dissolved in CD2Cl2 (0.6 ml), and analyzed by NMR. 1H-NMR (CD2Cl2, 400 MHz; Tˆ
À208): 0.56, 0.64, 1.26, 1.34 (cPr); 2.94 (MeN); 2.98 (MeN); 3.45 (mc, 2 NCH2); 4.86 (HÀC(5)); 7.87, 7.29, 7.17
(3-Ph); 8.29, 7.29, 7.29 (6-Ph). 13C-NMR (CD2Cl2, 100 MHz; Tˆ À208): 9.4 (CH2 of cPr); 11.0 (CH2 of cPr); 19.8
(C of cPr); 35.1 (MeN); 35.2 (MeN); 49.7 (2 NCH2); 56.9 (C(5) of triazine); 140.1 (C(6) of triazine); 160.3
(C(3) of triazine); 166.9 (C(2) of Im); 134.7, 124.3, 129.7, 126.7 (3-Ph); 139.7, 127.2, 128.9, 127.8 (6-Ph).
5-[1-(4,5-Dihydro-1,3-dimethyl-1H-imidazol-3-ium-2-yl)cyclopropyl]-3-(4-methoxyphenyl)-6-phenyl-5H-
1,2,4-triazin-2-ide (16h)4). To a yellow soln. of compound 2h (0.186 g, 0.710 mmol) in THF (10 ml), compound 1
(0.980 g, 710 mmol) was added at À 408. After 1 h, the orange precipitate was collected by filtration at À 408
under Ar gas. After removal of last traces of solvent at À 208/0.1 mbar, the solid (79% of 16h) was dissolved in
CD2Cl2 (0.6 ml) and analyzed by NMR. 1H-NMR (CD2Cl2, 400 MHz; Tˆ À308): 0.7 ± 1.3 (4 H of cPr); 2.91
(MeN); 2.93 (MeN); 3.43 (mc, 2 NCH2); 3.75 (MeO); 4.81 (HÀC(5)); 8.14, 6.80 (J ˆ 8.1, 3-Ph); 7.78, 7.29, 7.15
(6-Ph). 13C-NMR (CD2Cl2, 100 MHz; Tˆ À308): 8.2 (CH2 of cPr); 9.8 (CH2 of cPr); 18.4 (C of cPr); 33.9
(MeN); 34.1 (MeN); 48.5 (NCH2); 48.9 (NCH2); 53.8 (C(5) of triazine); 54.4 (MeO of 3-Ar); 165.6 (C(2) of
Im); 134.1, 127.6, 111.7, 158.9 (3-Ph); 125.7, 123.2, 127.7, 125.6 (6-Ph).
7. Addition Reactions to 3-Aryl-1,2,4-triazines 19. 5,8-Dimethyl-9-phenyl-5,8,10-triazadispiro[2.0.4.4]do-
deca-9,11-diene (20a). Compound 1 (48 mg, 0.35 mmol) was slowly added to a soln. of 19a (45 mg, 0.29 mmol) in
C6D6 (0.6 ml). The resulting suspension (yellow precipitate) was heated in a sealed tube at 1058 for 2 h. A clear
yellow-brown soln resulted (90% of 20a), which was analyzed by NMR. 1H-NMR (C6D6, 400 MHz): 0.43, 1.01
(4 H of cPr); 2.13 (2 MeN); 2.63, 2.77 (2 NCH2); 4.88 (J ˆ 6.7, HÀC(12)); 7.00 (HÀC(11)); 7.96, 7.18, 7.18 (9-
Ph). 13C-NMR (C6D6, 100 MHz): 13.2 (2 CH2 of cPr); 21.8 (C(3)); 35.7 (2 MeN); 52.7 (2 NCH2); 79.4 (C(4));
126.6 (C(12)); 132.7 (C(11)); 165.2 (C(9)); 144.4, 129.9, 127.6, 128.4 (9-Ph).
5,8-Dimethyl-9-(4-nitrophenyl)-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (20b). Compound 1 (46 mg,
0.33 mmol) was slowly added to a soln. of 19b (56 mg, 0.28 mmol) in C6D6 (0.6 ml). The suspension (brown
precipitate) was heated in a sealed tube at 1058 for 2 h. A clear yellow-brown soln. resulted (40% of 20a), which
was analyzed by NMR. 1H-NMR (C6D6, 400 MHz): 0.42, 0.95 (4 H of cPr); 1.98 (2 MeN); 2.54 (2 NCH2); 4.85
(J ˆ 6.8, HÀC(12)); 6.95 (HÀC(11)); 7.72, 7.91 (9-Ar). 13C-NMR (C6D6, 100 MHz): 13.4 (2 CH2 of cPr); 21.9
(C(3)); 36.0 (2 MeN); 53.5 (2 NCH2); 79.5 (C(4)); 127.4 (C(12)); 132.4 (C(11)); 163.3 (C(9)); 140.5, 130.6, 122.7,
150.2 (9-Ar).
4,5-Dihydro-2-[1-(2,5-dihydro-3-phenyl-[2-2H]-1,2,4-triazin-5-yl)cyclopropyl]-1,3-dimethyl-1H-imidazoli-
um[2,2,2- 2H3]Acetate (22a). To compound 19a (53 mg, 0.34 mmol) in CD2Cl2 (1 ml) under Ar gas, compound 1
(56 mg, 0.41 mmol) was slowly added via syringe at À 708. After addition of CD3COOD (30 mg, 0.49 mmol) to
the orange precipitate, a clear soln. resulted, which was analyzed by NMR at temps. between À 708 and ‡ 258.
1
At all temps., 85 ± 88% of 22a were identified. H-NMR (CD2Cl2, 400 MHz; Tˆ 258): 1.15, 1.40 (4 H of cPr);
3.14 (MeN); 3.16 (MeN); 3.84 (mc, 2 NCH2); 3.94 (J ˆ 2.7, HÀC(5) of triazine); 6.78 (HÀC(6) of triazine); 7.97,
7.43, 7.43 (3-Ph). 13C-NMR (CD2Cl2, 100 MHz; Tˆ 258): 9.8 (CH2 of cPr); 9.9 (CH2 of cPr); 19.4 (C of cPr); 33.2
(MeN); 34.4 (MeN); 50.3 (NCH2); 50.4 (NCH2); 56.7 (C(5) of triazine); 134.5 (C(6) of triazine); 154.6 (C(3) of
triazine); 165.9 (C(2) of Im); 132.1, 127.1, 129.0, 131.5 (3-Ph).
4,5-Dihydro-2-{1-[2,5-dihydro-3-(4-nitrophenyl)-[2-2H]-1,2,4-triazin-5-yl]cyclopropyl}-1,3-dimethyl-1H-
imidazolium [2,2,2-2H3]Acetate (22b). To compound 19b (30 mg, 0.15 mmol) in toluene (4 ml) under Ar gas,
compound 1 (21 mg, 0.15 mmol) was slowly added via syringe at À 208. After 30 min, the dark-brown
precipitate was collected at À 208, and washed with pentane. After removal of the solvent at À 208/0.01 mbar,
the solid (90% of 22b) was dissolved in CD2Cl2 (1 ml) containing CD3COOD (16 mg, 0.27 mmol), and analyzed
by NMR at À 308. 1H-NMR (CD2Cl2, 400 MHz; Tˆ À308): 1.04, 1.44 (4 H of cPr); 3.05 (MeN); 3.14 (MeN);
3.75 (mc, 2 NCH2); 3.93 (J ˆ 2.5, HÀC(5) of triazine); 6.84 (HÀC(6) of triazine); 8.15 (J ˆ 8.3, C(2,6) of 3-Ar);
8.24 (C(3,5) of 3-Ar). 13C-NMR (CD2Cl2, 100 MHz; Tˆ À308): 9.8 (CH2 of cPr); 10.8 (CH2 of cPr); 18.6 (C of
cPr); 34.7 (MeN); 35.2 (MeN); 49.6 (NCH2); 49.8 (NCH2); 56.6 (C(5) of triazine); 134.3 (C(6) of triazine);
153.3 (C(3) of triazine); 164.5 (C(2) of Im); 137.1, 128.1, 123.8, 149.0 (3-Ar).
8. Addition Reactions to 5-Aryl-1,2,4-triazines (4). 5,8-Dimethyl-10-phenyl-5,8,11-triazadispiro[2.0.4.4]do-
deca-9,11-diene (23a) and 5,8-Dimethyl-11-phenyl-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (24a). Meth-
od 1. Compound 1 (26 mg, 0.19 mmol) was added to a soln. of 4a (30 mg, 0.19 mmol) in C6D6 (0.6 ml). The
vigorous gas evolution was finished after a short time, and a clear soln. resulted, which was analyzed by NMR:
23a/24a 83 :17 (total yield: 58%).
Method 2. Compound 1 (57 mg, 0.41 mmol) was slowly added to a soln. of 4a (59 mg, 0.38 mmol) in toluene
(15 ml) at À 788. After a few minutes, gas evolution ceased, and after 30 min, the soln. was allowed to warm to
r.t. Distillation at 2108/0.01 mbar yielded a yellow oil (70 mg, 70%).

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Data of 23a. 1H-NMR (C6D6, 400 MHz): 0.65, 1.57 (4 H-cPr), 2.14 (2 MeN), 2.55, 2.86 (2 NCH2), 5.77
(HÀC(9)), 6.97 (HÀC(12); 8.15, 7.28, 7.10 (10-Ph). 13C-NMR (C6D6, 100 MHz): 12.8 (2 CH2 of cPr); 24.7
(C(3)); 35.4 (2 MeN); 50.9 (2 NCH2); 77.6 (C(4)); 107.0 (C(9)); 146.8 (C(10)); 170.2 (C(12)); 139.6, 126.3, 128.3,
128.0 (10-Ph).
1
Data of 24a. UV (CHCl3): 255 (0.80). H-NMR (C6D6, 400 MHz): 0.55, 1.35 (4 H of cPr); 2.24 (2 MeN);
2.62, 2.87 (2 NCH2); 5.39 (HÀC(12)); 7.52 (HÀC(9); 8.02, 7.16, 7.15 (10-Ph). 13C-NMR (C6D6, 100 MHz): 13.7
(2 CH2 of cPr); 20.7 (C(3)); 35.3 (2 MeN); 51.8 (2 NCH2); 76.1 (C(4)); 122.0 (C(12)); 140.8 (C(11)); 156.1
‡
(C(9)); 139.3, 125.5, 128.3, 127.3 (9-Ph). EI-MS: 267 (100, M ). Anal. calc. for C17H21N3 (267.3): C 76.37, H 7.92,
N 15.71; found: C 76.13, H 7.60, N 15.25.
5,8-Dimethyl-10-(4-methylphenyl)-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (23b) and 5,8-Dimethyl-
11-(4-methylphenyl)-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (24b). Compound 1 (36 mg, 0.26 mmol) was
added to a soln. of 4b (40 mg, 0.23 mmol) in C6D6 (0.6 ml). After a short time, the vigorous gas evolution was
1
finished, and a clear soln. resulted, which was analyzed by NMR: 23b/24b 92 :8 (total yield: 100%). H-NMR
(C6D6, 400 MHz): 0.65, 1.58 (4 H of cPr); 2.19 (2 MeN); 2.44, 2.86 (2 NCH2); 2.50 (Me of 10-Ar); 5.16 (J ˆ 0.9,
HÀC(9)); 6.78 (HÀC(12); 7.08 (C(3,4,5) of 10-Ar); 7.48 (C(6) of 10-Ar). 13C-NMR (C6D6, 100 MHz): 12.7
(2 CH2 of cPr); 21.1 (Me of 10-Ar); 24.4 (C(3)); 35.4 (2 MeN); 50.7 (2 NCH2); 77.6 (C(4)); 110.3 (C(9)); 150.0
(C(10)); 169.1 (C(12)); 141.4, 136.4, 129.5, 130.6 (10-Ar).
1
Data of 24b. UV (CHCl3): 264 (0.85). H-NMR (C6D6, 400 MHz): 0.57, 1.37 (4 H of cPr); 2.35 (2 MeN);
2.49 (Me of 9-Ar); 2.64, 2.82 (2 NCH2); 4.97 (J ˆ 1.1, HÀC(12)); 7.45 (HÀC(9); 7.20 (C(3,4,5) of 9-Ar); 7.52
(C(6) of 9-Ar). 13C-NMR (C6D6, 100 MHz): 12.9 (2 CH2 of cPr); 19.2 (C(3)); 20.8 (Me of 9-Ar); 35.0 (2 MeN);
51.4 (2 NCH2); 75.8 (C(4)); 125.6 (C(12)); 143.2 (C(11)); 154.8 (C(9)); 140.3, 136.0, 128.9, 130.4, 125.5, 127.2 (9-
‡
‡
Ar). EI-MS: 281 (31, M , C18H23N3 ).
5,8-Dimethyl-10-(2,4,6-trimethylphenyl)-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (23c). Compound 1
(43 mg, 0.31 mmol) was added to a soln. of 4c (61 mg, 0.31 mmol) in C6D6 (0.6 ml). After a short time, the
vigorous gas evolution was finished, and a clear soln. resulted, which was analyzed by NMR: 23c/24c 100 :0 (total
yield: 100%). 1H-NMR (C6D6, 400 MHz): 0.64, 1.63 (4 H of cPr); 2.22 (4-Me of 10-Ar); 2.24 (2 MeN); 2.38, 2.82
(2 NCH2); 2.43 (2,6-Me2 of 10-Ar); 5.01 (J ˆ 1.0, HÀC(9)); 6.85 (HÀC(12)); 6.90 (HÀC(3,5) of 10-Ar).
13C-NMR (C6D6, 100 MHz): 12.5 (2 CH2 of cPr); 20.7 ((2,6-Me2 of 10-Ar); 20.8 (4-Me of 10-Ar); 24.1 (C(3));
35.4 (2 MeN); 50.4 (2 NCH2); 77.1 (C(4)); 111.1 (C(9)); 147.4 (C(10)); 169.6 (C(12)); 136.0, 135.7, 128.2, 138.4
(10-Ar).
5,8-Dimethyl-10-(4-nitrophenyl)-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (23d) and 5,8-Dimethyl-11-
(4-nitrophenyl)-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (24d). Compound 1 (7 mg, 0.05 mmol) was
added to a soln. of 4d (19 mg, 0.10 mmol) in C6D6 (0.6 ml). A brown precipitate formed immediately, and
dissolved again under vigorous gas evolution, which was finished after a few minutes. The resulting clear soln.
was analyzed by NMR: 23d/24d 73 :27 (total yield 95%).
Data of 23d. 1H-NMR (C6D6, 400 MHz): 0.64, 1.53 (4 H of cPr); 2.11 (2 MeN); 2.56, 2.85 (2 NCH2); 5.75
(J ˆ 0.9, HÀC(9)); 7.35 (HÀC(12)); 8.04 (J ˆ 9.0, 10-Ar); 7.86 (10-Ar). 13C-NMR (C6D6, 100 MHz): 12.5
(2 CH2 of cPr); 24.3 (C(3)); 34.8 (2 MeN); 50.6 (2 NCH2); 76.9 (C(4)); 110.6 (C(9)); 144.2 (C(10)); 170.3
(C(12)); 144.4, 126.1, 123.4 147.4 (10-Ar).
Data of 24d. 1H-NMR (C6D6, 400 MHz): 0.59, 1.40 (4 H of cPr); 2.20 (2 MeN); 2.61, 2.76 (2 NCH2); 5.35
(J ˆ 0.9, HÀC(12)); 7.46 (HÀC(9)); 8.07 (J ˆ 8.9, 11-Ar); 7.74 (11-Ar). 13C-NMR (C6D6, 100 MHz): 0.59, 1.40
(4 H- of cPr); 2.20 (2 MeN); 2.61, 2.76 (2 NCH2); 5.35 (J ˆ 0.9, HÀC(12)); 7.46 (HÀC(9); 8.07 (J ˆ 8.9, 11-Ar);
7.74 (11-Ar). 13C-NMR (C6D6, 100 MHz): 13.9 (2 CH2, cPr), 19.9 (C(3)), 34.7 (2 NMe), 51.4 (2 NCH2), 75.5
(C(4)), 123.4 (C(12)), 138.7 (C(11)), 156.3 (C(9)); 146.3, 124.9, 127.9, 146.8 (9-Ar).
10-(4-Methoxyphenyl)-5,8-dimethyl-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (23e) and 11-(4-Methoxy-
phenyl)-5,8-dimethyl-5,8,10-triazadispiro[2.0.4.4]dodeca-9,11-diene (24e).Compound 1 (17 mg, 0.14 mmol) was
added to a soln. of 4e (19 mg, 0.10 mmol) in C6D6 (0.6 ml). The vigorous gas evolution was finished after a short
time, and a clear soln. resulted, which was analyzed by NMR: 23e/24e 86 :14 (total yield: 100%).
1
Data of 23e. H-NMR (C6D6, 400 MHz): 0.67, 1.62 (4 H of cPr); 2.20 (2 MeN); 2.60, 2.91 (2 NCH2); 3.37
(MeO of 10-Ar); 5.74 (J ˆ 0.8, HÀC(9)); 7.03 (HÀC(12); 8.16 (J ˆ 8.9, 10-Ar); 6.96 (10-Ar). 13C-NMR (C6D6,
100 MHz):12.4 (2 CH2 of cPr); 24.4 (C(3)); 35.1 (2 MeN); 50.6 (2 NCH2); 54.4 (MeO); 77.4 (C(4)); 104.5
(C(9)); 146.0 (C(10)); 169.6 (C(12)); 131.9, 127.2, 113.7, 159.8 (10-Ar).
Data of 24e. 1H-NMR (C6D6, 400 MHz): 0.60, 1.39 (4 H of cPr); 2.30 (2 MeN); 2.65, 2.82 (2 NCH2); 3.38
(MeO of 11-Ar); 5.35 (J ˆ 1.1, HÀC(12)); 7.59 (HÀC(9)); 8.03 (J ˆ 8.9, 11-Ar); 6.94 (11-Ar). 13C-NMR (C6D6,
100 MHz):13.2 (2 CH2 of cPr); 19.2 (C(3)); 35.0 (2 MeN); 51.5 (2 NCH2); 54.1 (MeO); 75.8 (C(4)); 119.6
(C(12)); 140.0 (C(11)); 155.7 (C(9)); 131.9, 126.1, 127.9, 159.5 (11-Ar).

Helvetica Chimica Acta ± Vol. 88 (2005)
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9. Addition Reactions to 6-Aryl-1,2,4-triazines 3. 5,8-Dimethyl-9-phenyl-5,8,11-triazadispiro[2.0.4.4]dodeca-
9,11-diene (25a). Compound 1 (94 mg, 0.68 mmol) was slowly added to a soln. of 3a (90.0 mg, 0.57 mmol) in
toluene (3 ml). A dark-red precipitate formed, which dissolved again under gas evolution. After 15 min, the
solvent was removed in vacuo, and full conversion was verified by NMR. Distillation at 2508/0.01 mbar afforded
25a as an oil (115 mg, 76%). UV (CHCl3): 280 (0.22). 1H-NMR (CDCl3, 400 MHz): 0.92, 1.30 (4 H of cPr); 2.19
(2 MeN); 2.90 (mc, 2 NCH2); 6.85 (HÀC(12)); 7.05 (HÀC(10)); 7.60, 7.25, 7.25 (9-Ph). 13C-NMR (CDCl3,
100 MHz): 12.0 (2 CH2 of cPr); 26.4 (C(3)); 35.0 (MeN); 52.5 (NCH2); 79.1 (C(4)); 130.8 (C(9)); 137.3 (C(10));
‡
‡
168.9 (C(12)); 141.3, 129.7, 127.6, 127.0 (9-Ph). EI-MS: 267 (50, M , C17H21N3 ).
9-(4-Methoxyphenyl)-5,8-dimethyl-5,8,11-triazadispiro[2.0.4.4]dodeca-9,11-diene (25b). Compound
1
(19 mg, 0.14 mmol) was added slowly to a soln. of 3b (25 mg, 0.13 mmol) in C6D6 (0.6 ml). A slow gas
evolution started, which was finished after 15 min. By NMR, 55% of 25b were identified. 1H-NMR (C6D6,
400 MHz): 0.54, 1.10 (4 H of cPr); 2.16 (2 MeN); 2.62 (NCH2); 2.73 (NCH2); 3.35 (MeO of 9-Ar); 6.78 (J ˆ 7.7,
HÀC(3,5) of 9-Ar); 6.94 (HÀC(12)); 7.25 (HÀC(10)); 7.57 (HÀC(2,6) of 9-Ar). 13C-NMR (C6D6, 100 MHz):
11.8 (2 CH2 of cPr); 26.3 (C(3)); 35.2 (2 MeN); 52.6 (2 NCH2); 54.6 (MeO of 9-Ar); 79.4(C(4)); 130.0 (C(9));
138.0 (C(10)); 167.6 (C(12)); 141.8, 130.6, 113.5, 159.6 (9-Ar).
1,2,3,4,5,6-Hexahydro-1,4-dimethyl-10-phenylpyrido[4,3-e][1,4]diazocine (26a), 5-[1-(4,5-Dihydro-1,3-di-
methyl-1H-imidazol-3-ium-2-yl)cyclopropyl]-6-phenyl-5H-1,2,4-triazin-2-ide (27a), and 3-[1-(4,5-Dihydro-1,3-
dimethyl-1H-imidazol-3-ium-2-yl)cyclopropyl]-6-phenyl-5H-1,2,4-triazin-2-ide (28a). To a soln. of compound
3a (40 mg, 0.25 mmol) in CD2Cl2 (1 ml) under Ar gas, compound 1 (42 mg, 0.31 mmol) was carefully added at
À 408. Both at À 408 and, after 30 min, at 258, NMR spectra were recorded. Product distribution: at Tˆ À408:
3a/27a/28a/25a/26a 5 :87:8 :0 :0; at Tˆ 258: 33 :33 :0 :0 :34. The experiment was repeated with mixing, and
taking the first NMR spectrum at À 158. Here, the following distributions were found: at Tˆ À158: 3a/27a/28a/
25a/26a 0 :85 :15 :0 :0; at Tˆ ‡258: 30 :30 :0 :16 :24.
Data of 26a. 1H-NMR (CD2Cl2, 400 MHz; Tˆ 258): 2.37 (MeN); 2.41 (MeN); 2.65, 2.77, 3.45, 3.58 (4 CH2);
7.66 (mc 10-Ph); 8.21 (C(7)); 8.65 (C(9)). 13C-NMR (CD2Cl2, 400 MHz; Tˆ 258): 36.7, 36.8 (2 MeN); 47.8, 49.9,
50.3, 51.7 (4 CH2); 89.1 (C(3)); 128.6, 129.0 (2 CH); 156.1 (C(9)); 157.8 (C(7)).
Data of 27a. 1H-NMR (CD2Cl2, 400 MHz; Tˆ À408): 0.60, 0.67, 1.15, 1.28 (4 H of cPr); 2.88 (MeN); 3.08
(MeN); 3.33 (NCH2); 3.48 (NCH2); 4.61 (HÀC(5)); 7.36 (HÀC(3); 7.75, 7.32, 7.24 (6-Ph). 13C-NMR (CD2Cl2,
100 MHz; Tˆ À408): 9.8 (CH2 of cPr); 10.8 (CH2 of cPr); 19.3 (C of cPr); 35.1 (MeN); 35.2 (MeN); 49.5
(NCH2); 49.6 (NCH2); 54.8 (C(5)); 139.1 (C(6); 155.1 (C(3); 166.2 (C(2) of Im); 135.1, 124.3, 128.9, 127.4
(6-Ph).
Data of 28a. 1H-NMR (CD2Cl2, 400 MHz; Tˆ À408): 1.77, 1.85 (4 H of cPr); 2.91 (MeN); 3.16 (MeN); 3.45
(2 NCH2); 5.72 (HÀC(3)); 7.28 (HÀC(5)); 7.61, 7.46, 7.46 (6-Ph). 13C-NMR (CD2Cl2, 100 MHz; Tˆ À408): 11.0
(CH2 of cPr); 11.2 (CH2 of cPr); 22.0 (C of cPr); 34.5 (MeN); 36.2 (MeN); 47.8 (2 NCH2); 89.1 (C(3)); 129.1
(C(5)); 155.7 (C(3)); 164.7 (C(2) of Im); 137.6, 126.8, 128.6, 128.2 (6-Ph).
10. Computations. All structures were optimized at the Becke3LYP/6-31G(d) level of theory. Enthalpies at
298.15 K were calculated for each conformer based on its harmonic vibrational frequencies. Single-point-energy
calculations were also performed at the Becke3LYP/6-311 ‡ G(d,p) level of theory. Combination of these single-
point energies with the enthalpy values calculated at the Becke3LYP/6-31G(d) level allows the calculation of
Becke3LYP/6-311 ‡ G(d,p)//Becke3LYP/6-31G(d) reaction enthalpies at 298.15 K. Solvent effects in CH2Cl2
were estimated through single-point calculations with the CPCM continuum solvation model at the Becke3LYP/
6-31G(d) level of theory using UAKS radii, and the gas phase Becke3LYP/6-31G(d) geometries [22]. Atomic
charges were calculated with the Natural Population Analysis (NPA) scheme at the Becke3LYP/6-31G(d) level
of theory [23]. Throughout the manuscript, the 6-31G(d) basis is abbreviated as ꢁSBꢂ (small basis), and the 6-
311 ‡ G(d,p) basis set as ꢁLBꢂ (large basis). All calculations were performed with the Gaussian 03 software [24].
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Received March 3, 2005