New C-arylation reaction found during a study on the interaction of aldohydrazones and arenediazonium chlorides

Article abstract of DOI:10.1070/MC2006v016n05ABEH002397

The interaction of 2-pyridinecarboxaldehyde phenylhydrazone 1a with aryldiazonium chlorides furnished in complex mixtures, from which (E)-phenylhydrazones of 2-pyridylarylketones 3a-c were isolated as the main products.

Full text of DOI:10.1070/MC2006v016n05ABEH002397

Mendeleev
Communications
Mendeleev Commun., 2006, 16(5), 251–254
New C-arylation reaction found during a study on the interaction of
aldohydrazones and arenediazonium chlorides
Natalia A. Frolova, Sergey Z. Vatsadze,* Natalia Yu. Vetokhina, Valery E. Zavodnik and Nikolay V. Zyk
Department of Chemistry, M. V. Lomonosov Moscow State University, 119992 Moscow, Russian Federation.
Fax: +7 495 932 8846; e-mail: szv@org.chem.msu.ru
DOI: 10.1070/MC2006v016n05ABEH002397
The interaction of 2-pyridinecarboxaldehyde phenylhydrazone 1a with aryldiazonium chlorides furnished in complex mixtures,
from which (E)-phenylhydrazones of 2-pyridylarylketones 3a–c were isolated as the main products.
1,3,5-Triarylformazanes 2 are very useful substrates for the
creation of heterocycles such as verdazyl radicals1–5 and tetra-
zolium salts.6–9 Owing to the presence of a chelating moiety in
their structure, formazanes are also known to form metallo-
chelates as a result of reactions with metal salts.10–16 Attaching
to the formazane metal complex molecules the donating units
(i.e., pyridines) could lead to a group of promising exo-poly-
dentate metalloligands, which combine in their structure the
intrinsic property of metal ion (redox, luminescent, catalytic,
etc.) together with the ability of the whole molecule to act as a
Mendeleev Commun. 2006 251

Mendeleev Commun., 2006, 16(5), 251–254
building block spanning two external metal centres. The neces-
sary stage in the design of such metalloligands is the synthesis
of respective hetaryl-substituted formazanes.
Compound 3a was obtained in two forms (3a' and 3a'') as
yellow and red crystals by crystallization from hexane–ethyl
acetate (3:1). Although we were unable to separate these forms
into individual components, we can state that the red form
Ph
‡
Formazanes 2a–k were obtained by a typical experimental procedure.19
N
H
N
O
H
1,5-Diphenyl-3-(2-thienyl)formazane 2a: 1H NMR, d: 14.29 (s, 1H,
NH), 7.74–7.64 (m, 5H, o-HPh, α-HThienyl), 7.48 (t, 4H, m-HPh, J 7.8 Hz),
7.35–7.25 (m, 3H, p-HPh, β'-HThienyl), 6.89 (dd, 1H, β-HThienyl, J1 5.1 Hz,
J2 3.5 Hz).
R
R
H2N NH Ph
H
Py, 0 °C, 2 h
1a–d
3,5-Di(3-pyridyl)-1-phenylformazane 2b: 1H NMR, d: 15.39 (s, 1H,
NH), 9.37 (s, 1H, α'-HPy(2)), 8.84 (s, 1H, α'-HPy(1)), 8.62 (s, 1H, α-HPy(2)),
8.52 (d, 1H, α-HPy(1), J 4.1 Hz), 8.36 (d, 1H, γ-HPy(2), J 7.9 Hz), 8.05 (d,
a R = 2-Py
b R = 3-Py
c R = 4-Py
d R = 2-Thienyl
Scheme 1
1H, γ-HPy(1), J 8.2 Hz), 7.76 (d, 2H, o-HPh, J 7.3 Hz), 7.52 (t, 2H, m-HPh
J 7.4 Hz), 7.39 (m, 3H, β-HPy(2), β-HPy(1), p-HPh).
3-(3-Pyridyl)-1-phenyl-5-(3-bromophenyl)formazane 2c: H NMR, d:
15.33 (s, 1H, NH), 9.36 (s, 1H, α'-HPy), 8.62 (d, 1H, α-HPy, J 3.8 Hz),
8.37 (d, 1H, γ-HPy, J 7.7 Hz), 7.83–7.74 (m, 3H, α'-HPh(2), o-HPh(1)),
,
Here, we describe a study on the interaction of phenylhydra-
zones 1a–d with aryldiazonum salts. This reaction is a well
known way to formation of hetarylformazanes. By using of a
general synthetic scheme, formazanes 2a–k were synthesised.
Starting phenylhydrazones of 2-thienyl, 2-, 3- and 4-pyridine
carboxaldehydes† 1a–d were obtained by interaction of phenyl-
hydrazone with suitable hetarylcarboxaldehydes in pyridine
(Scheme 1, Table 1).
1
7.53 (m, 3H, α-HPh(2), m-HPh(1)), 7.45–7.30 (m, 4H, β-HPh(2), γ-HPh(2)
β-HPy, p-HPh(1)).
,
3-(3-Pyridyl)-1-phenyl-5-(4-methylphenyl)formazane 2d: 1H NMR, d:
15.50 (s, 1H, NH), 9.37 (s, 1H, α'-HPy); 8.58 (d, 1H, α-HPy, J 4.0 Hz),
8.39 (d, 1H, γ-HPy, J 8.3 Hz), 7.70 (d, 2H, o-HPh(2), J 8.6 Hz), 7.59 (d,
2H, o-HPh(1), J 8.3 Hz), 7.43 (t, 2H, m-HPh(1), J 7.5 Hz), 7.36 (td, 1H,
β-HPy, J1 7.2 Hz, J2 4.6 Hz), 7.32 (t, 2H, m-HPh(2), J 8.1 Hz), 7.23 (t, 1H,
p-HPh(1), J 7.0 Hz), 2.47 (s, 3H, Me).
Ph
N
N
N
N
N2
R1
3-(3-Pyridyl)-1-phenyl-5-(3,5-dimethylphenyl)formazane 2e: 1H NMR,
d: 15.50 (s, 1H, NH), 9.40 (s, 1H, α'-HPy), 8.60 (d, 1H, α-HPy, J 5.2 Hz),
8.41 (d, 1H, γ-HPy, J 8.1 Hz), 7.71 (d, 2H, o-HPh(1), J 8.1 Hz), 7.49 (t, 2H,
m-HPh(1), J 7.6 Hz), 7.38 (dd, 1H, β-HPy, J1 8.3 Hz, J2 4.9 Hz), 7.35–7.30
(m, 3H, o-HPh(2), p-HPh(1)), 6.99 (s, 1H, p-HPh(2)), 2.44 (s, 6H, Me).
3-(3-Pyridyl)-1-phenyl-5-(4-nitrophenyl)formazane 2f: 1H NMR, d: 14.79
(s, 1H, NH), 9.36 (s, 1H, α'-HPy), 8.67 (d, 1H, α-HPy, J 3.2 Hz), 8.37 (dt,
1H, γ-HPy, J1 8.1 Hz, J2 2.0 Hz), 8.30 (d, 2H, o-HPh(2), J 9.2 Hz), 7.96 (d,
2H, o-HPh(1), J 7.5 Hz), 7.64–7.56 (m, 3H, m-HPh(1), p-HPh(1)), 7.51 (d, 2H,
m-HPh(2), J 9.3 Hz), 7.41 (dd, 1H, β-HPy, J1 7.5 Hz, J2 4.7 Hz).
1b–d
+
Cl
R
H
Py/H2O/AcOH,
0 °C, 1 h
R1
– HCl
2a–k
2a R = 2-Thienyl, R1 = Ph
2b R = R1 = 3-Py
2g R = 4-Py, R1 = 3-Py
2h R = 4-Py, R1 = 3-BrC6H4
2i R = 4-Py, R1 = 4-MeC6H4
2j R = 4-Py, R1 = 3,5-Me2C6H3
2c R = 3-Py, R1 = 3-BrC6H4
2d R = 3-Py, R1 = 3-MeC6H4
2e R = 3-Py, R1 = 3,5-Me2C6H3 2k R = 4-Py, R1 = 4-NO2C6H4
2f R = 3-Py, R1 = 4-NO2C6H4
3-(4-Pyridyl)-5-(3-pyridyl)-1-phenylformazane 2g: 1H NMR, d: 15.64
(s, 1H, NH), 8.86 (s, 1H, α'-HPy(2)), 8.71 (d, 2H, α-HPy(1), J 6.0 Hz), 8.56
(s, 1H, α-HPy(2)), 8.06 (d, 1H, γ-HPy(2), J 7.3 Hz), 8.00 (d, 2H, β-HPy(1)
Scheme 2
,
J 6.0 Hz), 7.74 (d, 2H, o-HPh, J 7.4 Hz), 7.52 (t, 2H, m-HPh, J 7.6 Hz),
7.39 (m, 3H, β-HPy(2), p-HPh).
The reactions of hydrazones 1b–d with aryldiazonium chlorides
were performed under standard conditions. Formazanes 2a–k
were formed as single products (TLC monitoring) in good yields
(Scheme 2, Table 1).‡
Contrary to the above data, the reactions of hydrazone 1a
with arenediazonium chlorides resulted in complex mixtures of
several products (TLC monitoring). We successively found the
procedure that allowed us to isolate major crystalline products
from these reaction mixtures. Products 3a–c were characterised
by 1H NMR§ spectra (Scheme 3, Table 1) and, in the case of 3a,
additionally, by a single-crystal X-ray diffraction study (vide infra).
A chromatographic study of the reaction mixtures¶ showed the
presence of target formazanes, starting hydrazone 1a, and other
unidentified products.
3-(4-Pyridyl)-1-phenyl-5-(3-bromophenyl)formazane 2h: 1H NMR, d:
15.60 (s, 1H, NH), 8.69 (d, 2H, α-HPy, J 5.0 Hz), 8.13 (d, 2H, β-HPy
,
J 5.9 Hz), 7.83 (s, 1H, α'-HPh(2)), 7.78 (d, 2H, o-HPh(1), J 8.1 Hz), 7.60–
7.50 (m, 3H, α-HPh(2), m-HPh(1)), 7.43 (m, 2H, β-HPh(2), γ-HPh(2)), 7.36 (t,
1H, p-HPh(1), J 8.0 Hz).
1
3-(4-Pyridyl)-1-phenyl-5-(4-methylphenyl)formazane 2i: H NMR, d:
15.75 (s, 1H, NH), 8.66 (d, 2H, α-HPy, J 5.4 Hz), 8.03 (d, 2H, β-HPy
,
J 6.1 Hz), 7.72 (d, 2H, o-HPh(2), J 8.5 Hz), 7.65 (d, 2H, o-HPh(1), J 7.6 Hz),
7.47 (t, 2H, m-HPh(1), J 7.4 Hz), 7.32 (d, 2H, m-HPh(2), J 8.0 Hz), 7.27 (t,
1H, p-HPh(1), J 7.0 Hz), 2.47 (s, 3H, Me).
3-(4-Pyridyl)-1-phenyl-5-(3,5-dimethylphenyl)formazane 2j: 1H NMR,
d: 15.73 (s, 1H, NH), 8.66 (d, 2H, α-HPy, J 4.9 Hz), 8.01 (d, 2H, β-HPy
,
J 4.6 Hz), 7.70 (d, 2H, o-HPh(1), J 7.3 Hz), 7.49 (t, 2H, m-HPh(1), J 7.5 Hz),
7.38–7.25 (m, 3H, o-HPh(2), p-HPh(1)), 6.98 (s, 1H, p-HPh(2)), 2.44 (s, 6H, Me).
3-(4-Pyridyl)-1-phenyl-5-(4-nitrophenyl)formazane 2k: 1H NMR, d: 15.24
(s, 1H, NH), 8.66 (d, 2H, α-HPy, J 5.4 Hz), 8.03 (d, 2H, β-HPy, J 6.1 Hz),
8.30 (d, 2H, o-HPh(2), J 9.2 Hz), 7.95 (d, 2H, o-HPh(1), J 7.5 Hz), 7.63–7.53
(m, 3H, m-HPh(1), p-HPh(1)), 7.50 (d, 2H, m-HPh(2), J 9.3 Hz).
Ph
N
R
N
N2
R1
1b–d
+
Cl
H
Py/H2O/AcOH,
0 °C, 1 h
§
Hydrazones 3a–c were obtained by an analogous experimental proce-
N
dure as for 2. Compounds 3a–c were separeted for admixture by ablution
of reaction mixture by diethyl ether.
–N2, – HCl
3a R = Ph
(E)-phenylhydrazone of 2-pyridyl phenyl ketone 3a: 1H NMR, d: 8.52
(d, 1H, α-HPy, J 4.9 Hz), 8.19 (d, 1H, β'-HPy, J 8.1 Hz), 7.80 (s, 1H, NH),
7.73 (td, 1H, γ-HPy, J1 7.9 Hz, J 1.6 Hz), 7.61 (t, 2H, m-HPh(2), J 7.3 Hz),
7.53 (t, 1H, p-HPh(2), J 7.6 Hz), 7.39 (d, 2H, o-HPh(2), J 7.0 Hz), 7.29 (t,
2H, m-HPh(1), J 7.8 Hz), 7.17 (dd, 1H, β-HPy, J1 7.2 Hz, J2 6.3 Hz), 7.13
(d, 2H, o-HPh(1), J 7.7 Hz), 6.91 (t, 1H, p-HPh(1), J 7.3 Hz).
3b R = 4-MeC6H4
3c R = 3,5-Me2C6H3
Scheme 3
†
1H NMR spectra (400 MHz) were recorded on a Bruker-Avance spec-
1
trometer in CDCl3.
(E)-phenylhydrazone of 2-pyridyl 4-methylphenyl ketone 3b: H NMR,
Phenylhydrazones 1a–c were obtained previously.17–19 1d was syn-
thesised similarly to 1a–c. 1H NMR data for 1a and 1d are described for
the first time in this paper.
d: 8.70 (s, 1H, NH), 8.37 (ddd, 1H, α-HPy, J1 4.9 Hz, J2 1.7 Hz, J3 1.0 Hz),
8.25 (dt, 1H, β'-HPy, J1 8.0 Hz, J2 1.0 Hz), 7.81 (td, 1H, γ-HPy, J1 8.3 Hz,
J1 1.8 Hz), 7.36 (d, 2H, o-HPh(2), J 7.1 Hz), 7.28–7.20 (m, 7H, m-HPh(2)
,
1a: 1H NMR, d: 8.57 (ddd, 1H, α-HPy, J1 5.0 Hz, J2 1.8 Hz, J3 1.1 Hz),
8.36 (s, 1H, NH), 8.03 (d, 1H, β'-HPy, J 8.0 Hz), 7.83 (s, 1H, CH=), 7.72
(dt, 1H, γ-HPy, J1 7.5 Hz, J2 1.2 Hz), 7.32 (t, 2H, m-HPh, J 7.8 Hz), 7.23–
7.15 (m, 3H, o-HPh, β-HPy), 6.94 (t, 1H, p-HPh).
o-HPh(1), m-HPh(1), β-HPy), 6.83 (tt, 1H, p-HPh(1), J1 6.6 Hz, J2 1.8 Hz),
2.43 (s, 3H, Me).
(E)-phenylhydrazone of 2-pyridyl 3,5-dimethylphenyl ketone 3c:
1H NMR, d: 8.51 (d, 1H, α-HPy, J 3.0 Hz), 8.20 (d, 1H, β'-HPy, J 8.0 Hz),
7.78 (s, 1H, NH), 7.71 (td, 1H, γ-HPy, J1 7.6 Hz, J 1.6 Hz), 7.61 (m, 2H,
m-HPh(1), J 8.3 Hz), 7.19–7.09 (m, 4H, β-HPy, p-HPh(2), o-HPh(1)), 6.97 (s,
2H, o-HPh(2)), 6.88 (t, 1H, p-HPh(1), J 7.3 Hz), 2.44 (s, 6H, Me).
1d: 1H NMR, d: 7.87 (s, 1H, CH=), 7.35–7.20 (m, 4H, o-HPh, α-HThienyl
,
,
NH), 7.12–7.06 (m, 3H, m-HPh, β'-HThienyl), 7.03 (dd, 1H, β-HThienyl
J1 4.9 Hz, J2 3.5 Hz), 6.89 (t, 1H, p-HPh, J 7.3 Hz).
252 Mendeleev Commun. 2006

Mendeleev Commun., 2006, 16(5), 251–254
Table 1 Characterization of 1a, 1d, 2a–k, 3a–c.
C(15)
C(18)
C(3)
Elemental analysis (%),
calculated (found)
C(16)
C(17)
C(14)
C(13)
C(4)
Com- Empirical
pound formula
Yield
C(2)
C(1)
Mp/°C
(%)
C(5)
N(2)
C(6)
C(7)
C(8)
C(9)
C
H
N
N(3)
N(1)
1a
1d
2a
2b
C12H11N3
C11H10N2S
C17H14N4S
C17H14N6
73.03
5.62
21.30
176
70
77
70
65
(73.46) (5.32)
65.32 4.98
(65.12) (5.00)
66.64 4.61
(66.70) (4.16)
67.54 4.67
(67.50) (4.56)
(21.62) (EtOH)a
13.85
(13.78) (EtOH)
18.29 138
(18.35) (Et2O)
27.80 178–181
138–139
C(12)
C(11)
C(10)
(27.55) (Et2O–CHCl3,
3:1)
2c
2d
2e
2f
C18H14BrN5 56.86
(56.68) (3.60)
72.36 5.43
(72.09) (5.57)
72.93 5.81
(72.90) (5.78)
C18H14N6O2 62.42 4.07
(62.35) (3.89)
3.71
18.42
(17.96) (Et2O)
22.21 149
(22.38) (Et2O)
21.26 148–149
(21.39) (Et2O)
24.26 205–208
128
40
40
32
63
Figure 3 Difference in twisting of phenyl rings [C(7) to C(12)] in 3a'
and 3a''.
C19H17N5
C20H19N5
dominates in the mixture. The single-crystal X-ray diffraction
study†† of these two forms showed that the isolated crystals
are polymorph modifications of 3a. The molecular structures of
polymorphs are shown in Figures 1 and 2. Structures of mole-
cules of 3a'‡‡ and 3a'' are very close to each other. Both
contain an almost planar backbone, which includes a pyridine
ring, a phenyl group [atoms C(13) to C(18)] and hydrazone C(7),
N(2) and N(3) atoms. The structures differ in the degree of
tilting of phenyl ring [containing atoms C(7) to C(12)] around
the C(6)–C(7) single bond. The respective twisting angles are
73.8° for 3a' and 44.0° for 3a'' (Figure 3).
(24.20) (decomp.)
(Et2O)
2g
2h
2i
C17H14N6
67.54
(67.50) (4.72)
C18H14BrN5 56.86 3.71
(56.80) (3.44)
72.36 5.43
(72.45) (5.30)
72.93 5.81
(72.81) (5.77)
C18H14N6O2 62.42 4.07
(62.03) (4.15)
4.67
27.80
(27.62) (EtOAc)
18.42 159–160
(18.19) (Et2O)
22.21 176–177
(22.34) (Et2O)
21.26 181–182
(21.27) (acetonitrile)
24.26 232–235
209
46
23
67
30
25
C19H17N5
C20H19N5
2j
According to the above data, products 3 do not possess azo
fragments, which were expected for the products of aza-coupling
reactions. Compounds 3 are the products of a new C-arylation
reaction.
2k
(24.50) (decomp.)
(Et2O)
3a
C18H15N3
79.10
(79.12) (4.73)
5.53
15.37
148–150
33
(14.84) (hexane–
This work was supported by the Russian Foundation for
Basic Research (grant no. 06-03-33077).
EtOAc, 3:1)
3b
3c
C19H17N3
C20H19N3
79.41
(79.51) (6.10)
79.70 6.35
5.96
14.62
(14.89) (Et2O)
13.94 141–143
168–169
45
35
References
(79.59) (6.58)
(13.89) (Et2O)
1 O. M. Polumbrik, I. G. Ryabokon and L. N. Markovskii, Khim. Geterotsikl.
Soedin., 1978, 266 [Chem. Heterocycl. Compd. (Engl. Transl.), 1978, 14,
218].
aLit.,17 mp 175 °C.
2 R. Kuhn and H. Trischmanm, Monatsh. Chem., 1964, 95, 457.
3 F. A. Neugebauer and R. Bernhardt, Chem. Ber., 1974, 107, 529.
4 F. A. Neugebauer, Monatsh. Chem., 1966, 97, 846.
C(3)
C(15)
†† Crystallographic data for 3a': C18H15N3, yellow prisms, M = 273.34,
crystals are monoclinic, space group P21/c, a = 10.796(2), b = 9.326(2)
C(4)
C(5)
C(2)
C(14)
C(16)
C(17)
N(2)
C(1)
C(13)
N(3)
and c = 14.941(3) Å, b = 106.25(3)°, V = 1444.2(5) Å3, Z = 4, dcalc
=
= 1.257 g cm–3. Reflections were collected on an Enraf Nonius CAD4
diffractometer at 293 K [q/2q, l(MoKα) = 0.71073 Å, β-filter]. The structure
was solved by a direct method (SHELXS-97) and refined by the full-matrix
least-square technique against F2 for all non-hydrogen atoms (SHELXL-97),
GOF = 0.976, F(000) = 576. Limiting indices –12 £ h £ 12, 0 £ k £ 11,
0 £ l £ 17. Reflections collected/unique, 2721/2611 (Rint = 0.0179), R1 =
= 0.0317, wR2 = 0.0909 [for 3283 reflections with I > 2s(I)], R1 = 0.0841,
wR2 = 0.0953 (for all data). Largest difference peak and hole, 0.132 and
–0.129 eÅ–3.
C(18)
C(6)
N(1)
C(7)
C(8)
C(9)
C(12)
C(11)
C(10)
Figure 1 Molecular structure of 3a'. Projection on the N(2)–N(3)–Ph
[C(13) to C(18)] mean plane.
Crystallographic data for 3a'': C18H15N3, red prisms, M = 273.34,
crystals are monoclinic, space group P21/n; a = 12.204(2), b = 8.149(2)
and c = 14.766(3) Å, b = 99.84(3)°, V = 1446.9(5) Å3, Z = 4, dcalc
=
= 1.255 g cm–3. Reflections were collected on an Enraf Nonius CAD4
diffractometer at 293 K [q/2q, l(MoKα) = 0.71073 Å, β-filter]. The structure
was solved by a direct method (SHELXS-97) and refined by the full-matrix
least-square technique against F2 for all non-hydrogen atoms (SHELXL-97),
GOF = 1.007, F(000) = 576. Limiting indices –0 £ h £ 14, 0 £ k £ 9,
–17 £ l £ 17. Reflections collected/unique, 2818/2687 (Rint = 0.0233),
R1 = 0.0293, wR2 = 0.0882 [for 3283 reflections with I > 2s(I)], R1 = 0.0671,
wR2 = 0.0930 (for all data). Largest difference peak and hole, 0.125 and
–0.123 eÅ–3.
C(15)
C(3)
C(16)
C(14)
C(13)
C(4)
C(5)
C(2)
C(1)
C(17)
C(18)
N(2)
C(6)
C(7)
C(8)
C(9)
N(3)
N(1)
C(12)
C(11)
C(10)
Atomic coordinates, bond lengths, bond angles and thermal param-
eters have been deposited at the Cambridge Crystallographic Data Centre
(CCDC). These data can be obtained free of charge via www.ccdc.cam.uk/
conts/retrieving.html (or from the CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK; fax: +44 1223 336 033; or deposit@ccdc.cam.ac.uk). Any
request to the CCDC for data should quote the full literature citation and
CCDC reference numbers 610460 and 610461 for 3a' and 3a'', respectively.
For details, see ‘Notice to Authors’, Mendeleev Commun., Issue 1, 2006.
‡‡ 3a' was obtained earlier20 by a different method.
Figure 2 Molecular structure of 3a''. Projection on the N(2)–N(3)–Ph
[C(13) to C(18)] mean plane.
¶
Column chromatography of 3a–c was carried out on Silica gel (35/70)
with a hexane–ethyl acetate (3:1) eluent.
Mendeleev Commun. 2006 253

Mendeleev Commun., 2006, 16(5), 251–254
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Received: 16th June 2006; Com. 06/2742
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254 Mendeleev Commun. 2006