See http://www.rsc.org/suppdata/dt/b5/b502892b/ for cry-
stallographic data in CIF or other electronic format.
147.0, 146.8, 133.3, 131.9, 129.1, 123.8, 102.7. Found: C, 66.4;
H, 5.3; N, 29.1. Required for C
8
H
7
N
3
: C, 66.2; H, 4.9; N, 29.0%.
K(Bp ). 3-(4-Pyridyl)pyrazole (1.44 g, 9.9 mmol) and
KBH (0.215 g, 4 mmol) were ground together thoroughly in a
4
py
Preparations
4
pestle and mortar and heated for 30 min in a Schlenk tube at 175–
3
-(4-Pyridyl)pyrazole. This was prepared in two steps from
◦
1
80 C under N
2
. The mixture was stirred throughout, although
4
-acetylpyridine as shown in Scheme 1. In the first step,
a mixture of 4-acetylpyridine (24.2 g, 0.2 mol) and N,N-
dimethylformamide–dimethyl acetal (40 cm ) was heated to re-
flux for 2 h. After concentration in vacuo, recrystallisation of the
orange residue from CHCl
powder (intermediate A) in 58% yield. Chemical ionization MS:
◦
this was hindered once melting occurred at 150 C. After cooling
to r.t., toluene (30 cm ) were added and the mixture was agitated
3
3
in an ultrasound cleaning bath for 20 min. The suspension was
filtered, and the solid was washed with hot toluene and hot
3
–hexane afforded an orange–yellow
hexane and then dried gave KBp as a white powder in 80%
4py
−
1
yield. Negative-ion electrospray MS: m/z 301 [C16 N
H
14
6
B] . H
+
1
m/z 177 (M + H) . H NMR (CDCl
3
): d 8.64 (2H, d, J 5.9;
2
6
NMR (MeOD): d 8.43 (4H, d, J 6.2; pyridyl H /H ), 7.82 (4H,
d, J 6.6; pyridyl H /H ), 7.61 (2H, d, J 2.2; pyrazolyl), 6.64
2H, d, J 1.9; pyrazolyl). C NMR (MeOD): d 150.5, 150.0,
2
6
pyridyl H /H ), 7.79 (1H, d, J 12.5; alkene CH), 7.63 (2H, d, J
3
5
3
5
5
(
.9; pyridyl H /H ), 5.60 (1H, d, J 12.5 Hz; alkene CH), 3.12
13
(
1
1
3
3H, s, Me), 2.89 (3H, s, Me). C NMR (CDCl
carbonyl), 155.09 (1C, alkene CH), 150.08 (2C, pyridyl CH),
47.07 (1C, pyridyl C), 121.07 (2C, pyridyl CH), 91.52 (1C,
alkene CH), 45.19 (1C, CH ), 37.30 (1C, CH ). Found: C, 64.5;
H, 6.8; N, 15.2. Required for C10 O: C, 64.8; H,
O·0.5H
.0; N, 15.1%. A mixture of A (20.3 g, 0.115 mmol), ethanol
3
): d 186.31 (1C,
11
44.9, 137.9, 121.6, 103.8. B NMR (MeOD): d −7.59. Found:
C, 53.9; H, 4.9; N, 23.7. Required for C16
H
14 6 2
N
BK·H
O: C,
1
−1
5
1
1
8
3.6; H, 4.5; N, 23.5%. IR (cm ): 2380m, 2263m, 1650w, 1604s,
3
3
555w, 1483m, 1457m, 1420m, 1357m, 1304w, 1247w, 1216w,
175s, 1142s, 1093m, 1105m, 1050s, 996s, 956w, 925w, 882w,
30s, 775s.
H
12
N
2
2
7
(
6
(
3
3
30 cm ) and hydrazine hydrate (30 cm ) was then heated to
3
py
◦
K(Bp ). A mixture of 3-(3-pyridyl)pyrazole (3.6 g,
0
C with stirring for 30 min. After addition to cold water
3
24.7 mmol) and dried, freshly ground KBH4 (554 mg,
130 cm ) and overnight refrigeration, the resulting off-white
◦
1
0.3 mmol) was heated in a Schlenk tube at 140 C for 2 h
precipitate was filtered off, washed with copious amounts of
water, and dried to give 3-(4-pyridyl)pyrazole in 77% yield.
Although characterisation data were satisfactory at this stage,
the material could be further purified by vigorous washing with
toluene (ultrasound cleaning bath) followed by recrystallisation
from water. X-Ray quality crystals were grown by diffusion of
pentane into a concentrated DCM solution of the sample. EI-
under N
2
. The mixture was stirred throughout, although this
was hindered once melting had occurred. After cooling to r.t.,
3
3
toluene (30 cm ) and chloroform (25 cm ) were added and the
mixture was agitated in an ultrasound cleaning bath for 20 min.
Eventually a white suspension was produced. The mixture was
filtered and the white solid was washed with warm toluene. The
white powder was then washed with several portions of hexane
+
1
MS: 145 (M ). H NMR (CDCl ): d 11.68 (1H, br s, NH), 8.65
3 5
3
3
2
6
(total 50 cm ) before final washing with ether and overnight
(
2H, d, J 6.2, pyridyl H /H ), 7.72 (2H, d, J 5.9, pyridyl H /H ),
.68 (1H, d, J 2.6; pyrazolyl), 6.76 (1H, d, J 2.2 Hz; pyrazolyl).
3
py
drying. This gave KBp in 52% yield. Negative-ion electrospray
7
−
1
1
3
MS: m/z 301 [C H N B] . H NMR (MeOD): d 8.94 (2H, d, J
C NMR (MeOD): d 150.5, 149.8, 143.4, 131.6, 121.6, 104.4.
Found: C, 66.3; H, 5.1; N, 29.2. Required for C
H, 4.9; N, 29.0%.
16
14
6
2
6
2
.4; pyridyl H ), 8.35 (2H, dd, J 1.2, 4.8; pyridyl H ), 8.21 (2H,
8
H
7
3
N : C, 66.2;
4
ddd, J 8.1, 3.4, 1.8; pyridyl H ), 7.61 (2H, d, J 2.1; pyrazolyl),
.40 (2H, dd, J 4.9, 7.9; pyridyl H ), 6.53 (2H, d, J 1.8; pyrazolyl).
5
7
1
3
3
-(3-Pyridyl)pyrazole. This was prepared in a similar manner
C NMR (MeOD): d 149.1, 147.6, 147.3, 137.8, 134.8, 133.1,
11
to 3-(4-pyridyl)pyrazole (above), except using 3-acetylpyridine
as starting material. A mixture of 3-acetylpyridine (24.2 g,
.20 mol) and N,N-dimethylformamide–dimethyl acetal
40 cm ) was heated to reflux for 2 h. Removal of the solvent in
vacuo delivered a brown sludgy residue, which was recrystallised,
from CH Cl/hexane to afford intermediate B as a yellow powder
125.2, 102.8. B NMR (MeOD): d −7.02. Found: C, 54.7; H,
4.4; N, 23.7. Required for C16 O: C, 55.0; H, 4.3;
H
14
N
6
BK·0.5H
2
−
1
0
(
N, 24.1%. IR (cm ): 2373m, 2340m, 2256m, 1599w, 1579w,
1486m, 1466w, 1424m, 1358m, 1309m, 1247w, 1174s, 1139s,
1094m, 1050s, 1028m, 1006m, 950m, 898m, 853w, 810m, 756s,
723s, 709s.
3
3
+
in 94% yield. Chemical ionization MS: m/z 177 (M + H) , 159
4
py
K(Tp ). 3-(4-Pyridyl)pyrazole (0.96 g, 6.6 mmol) and
KBH (0.108 g, 2 mmol) were ground together thoroughly in a
+
1
2
(
(
(
M − H
2
O). H NMR (CDCl
3
): d 8.95 (1H, s; pyridyl H ), 8.52
6
4
4
1H, d, J 4.8; pyridyl H ), 8.05 (1H, d, J 8.1; pyridyl H ), 7.70
pestle and mortar, and heated under N
2
in a Schlenk tube, with
5
1H, d, J 12.5; alkene CH), 7.22 (1H, dd, J 4.8, 8.1; pyridyl H ),
.54 (1H, d, J 12.5; alkene CH), 3.02 (3H, s; Me), 2.82 (3H, s;
◦
3
stirring, at 230 C for 3.5 h. After cooling to r.t., 30 cm of toluene
were added and the mixture was agitated in an ultrasound
cleaning bath for 20 min. The suspension was filtered, and the
solid was washed with hot toluene and hot hexane and then
5
13
Me). C NMR (CDCl
alkene, CH), 151.31 (1C, pyridyl, CH), 148.79 (1C, pyridyl, CH),
35.57 (1C, pyridyl, C), 134.98 (1C, pyridyl, CH), 123.22 (1C,
alkene, CH), 45.16 (1C, CH ), 37.32 (1C, CH ). Found: C, 68.6;
H, 7.2; N, 16.0. Required for C10 O: C, 68.2; H, 6.9; N,
5.9%. Compound B (33.5 g, 0.19 mol), ethanol (60 cm ) and
hydrazine hydrate (60 cm ) was then heated to 65 C with stirring
for 40 min. Removal of the solvent in vacuo afforded a dark
orange oil. This was heated overnight whilst under vacuum and
upon cooling formed a beige hard solid of 3-(3-pyridyl)pyrazole
in 85% yield. X-Ray quality crystals of polymorph II were grown
by diffusion of pentane into a concentrated DCM solution of
the sample; crystals of polymorph I grew spontaneously from
the orange oil over a period of 2 months. Characterisation data
were satisfactory at this stage, although the material could be
3
): d 186.21 (1C, carbonyl), 154.68 (1C,
1
4
py
dried gave KTp as a white powder in 25% yield. Negative-ion
3
3
−
1
ES MS: m/z 444 [C24
H
19
N B] . H NMR (MeOD): d 8.50 (6H,
9
H
12
N
2
2
6
3 5
d, J 6.2, pyridyl H /H ), 7.88 (6H, d, J 6.2, pyridyl H /H ), 7.41
3
1
1
3
3
◦
(
3H, d, J 2.2, pyrazolyl), 6.80 (3H, d, J 2.4 Hz, pyrazolyl).
C
B
1
1
NMR (MeOD): d 151.0, 150.1, 144.5, 136.7, 121.7, 104.3.
NMR (MeOD): 0.37. Found: C, 57.8; H, 4.0; N, 25.0. Required
−
1
for C24
2
1
H
19
N
9
BK·H
418m, 1606s, 1487m, 1455m, 1420m, 1357m, 1306w, 1252w,
200s, 1175s, 1127w, 1107w, 1081s, 1053s, 996s, 958w, 831s, 763s.
2
O: C, 57.5; H, 4.2; N, 25.1%. IR (cm ):
3
py
K(Tp ). 3-(3-Pyridyl)pyrazole (12.68 g, 87 mmol) and
dried, freshly ground KBH
a Schlenk tube at 215 C for 2 h under N
4
(1.27 g, 24 mmol) were heated in
. The mixture was
◦
2
purified further by recrystallisation from CH
2
Cl
2
–hexane. EI-
stirred throughout, although this became more difficult once
+
1
2
3
MS: 145 (M ). H NMR (CDCl
3
): d 9.06 (1H, s; pyridyl H ),
melting had occurred. After cooling to r.t., toluene (40 cm ) and
6
4
3
8
7
.54 (1H, d, J 4.7; pyridyl H ), 8.08 (1H, d, J 8.1; pyridyl H ),
.61 (1H, d, J 2.3; pyrazolyl), 7.30 (1H, dd, J 5.0, 7.9; pyridyl
chloroform (40 cm ) were added and the mixture was agitated
in an ultrasound cleaning bath for 20 min. The mixture was
periodically agitated with a glass rod, and sonicated for a further
5
13
H ), 6.62 (1H, d, J 2.0; pyrazolyl). C NMR (CDCl ): d 148.3,
3
D a l t o n T r a n s . , 2 0 0 5 , 1 9 1 0 – 1 9 2 3
1 9 2 1