Thermal Decomposition of 4-Alkylidenepyrazolines
1-Met h oxyca r b on yl-1-(p -n it r ob en zyl)-3-p h en yla llen e
(12c). This was obtained in 62% yield from the reaction of the
phosphorane with phenylacetyl chloride: colorless oil; 1H NMR
(CDCl3) δ 8.12 (d, J ) 8.6 Hz, 2H), 7.43 (d, J ) 8.6 Hz, 2H),
7.35-7.20 (m, 5H), 6.56 (t, J ) 2.3 Hz, 1H), 3.82 and 3.76 (ABq
d, J ) 15.2, 2.3 Hz, 2H), 3.74 (s, 3H). IR (KBr) 1944, 1706,
1604, 1508, 1341 cm-1. Anal. Calcd for C18H15NO4: C, 69.89;
H, 4.89; N, 4.53. Found: C, 69.05; H, 4.94; N, 4.11.
(Z)-3-Meth oxycar bon yl-3-(p-n itr oben zyl)-4-ben zyliden e-
1-p yr a zolin e (14c). This was obtained quantitatively from
the reaction of 12c with diazomethane: colorless crystals; mp
89.2 °C dec; 1H NMR (CDCl3) δ 7.95 (d, J ) 8.6 Hz, 2H), 7.48-
7.34 (m, 3H), 7.20 (d, J ) 6.9 Hz, 2H), 6.89 (d, J ) 8.6 Hz,
2H), 6.64 (t, J ) 2.3 Hz, 1H), 5.33 and 4.77 (ABq d, J ) 22.8,
2.3 Hz, 2H), 4.08 and 3.53 (ABq, J ) 14.2 Hz, 2H), 3.77 (s,
3H); IR (KBr) 1736, 1603, 1595, 1514, 1345, 1245 cm-1. Anal.
Calcd for C19H17N33O4: C, 64.95; H, 4.88; N, 11.96. Found: C,
64.75; H, 4.88; N, 11.93.
1-Meth oxycar bon yl-3-(p-m eth oxyph en yl)-1-(p-n itr oben -
zyl)a llen e (12d ). This was obtained in 44% yield from the
reaction of the phosphorane with p-methoxyphenylacetyl
chloride: colorless needles; mp 111.5-112 °C; 1H NMR (CDCl3)
δ 8.12 (d, J ) 8.6 Hz, 2H), 7.43 (d, J ) 8.6 Hz, 2H), 7.14 (d, J
) 8.6 Hz, 2H), 6.86 (d, J ) 8.6 Hz, 2H), 6.52 (t, J ) 2.2 Hz,
1H), 3.82 (s, 3H), 3.85 and 3.70 (ABq d, J ) 14.6, 2.2 Hz, 2H),
(Z)-3-Met h oxyca r b on yl-4-(p -m et h oxyb en zylid en e)-3-
(p-n itr oben zyl)-1-pyr azolin e (14d). This was obtained quan-
titatively from the reaction of 12d with diazomethane: color-
1
less crystals; mp 69.7 °C dec; H NMR (CDCl3) δ 7.95 (d, J )
8.6 Hz, 2H), 7.16 (d, J ) 8.6 Hz, 2H), 6.97 (d, J ) 8.6 Hz, 2H),
6.89 (d, J ) 8.6 Hz, 2H), 6.56 (t, J ) 2.3 Hz, 1H), 5.30 and
4.75 (ABq d, J ) 23.1, 2.3 Hz, 2H), 4.08 and 3.59 (ABq, J )
14.2 Hz, 2H), 3.87 (s, 3H), 3.77 (s, 3H); IR (KBr) 1740, 1607,
1516, 1343, 1252 cm-1. Anal. Calcd for C20H19N3O5: C, 62.98;
H, 5.02; N, 11.02. Found: C, 62.87; H, 5.06; N, 10.95.
3.74 (s, 3H); IR (KBr) 1940, 1712, 1606, 1518, 1344, 1249 cm-1
.
Anal. Calcd for C19H17NO5: C, 67.25; H, 5.05; N, 4.13. Found:
C, 67.06; H, 5.05; N, 4.10.
3-(p-Ch lor op h en yl)-1-m eth oxyca r bon yl-1-(p-n itr oben -
zyl)a llen e (12e). This was obtained in 56% yield from the
reaction of the phosphorane with p-chlorophenylacetyl chlo-
(Z)-4-(p-Ch lor oben zylid en e)-3-m eth oxyca r bon yl-3-(p-
n itr oben zyl)-1-p yr a zolin e (14e). This was obtained quan-
titatively from the reaction of 7e with diazomethane: colorless
1
ride: colorless needles; mp 97.0-97.6 °C; H NMR (CDCl3) δ
8.13 (d, J ) 8.6 Hz, 2H), 7.41 (d, J ) 8.6 Hz, 2H), 7.29 (d, J )
8.6 Hz, 2H), 7.13 (d, J ) 8.6 Hz, 2H), 6.51 (t, J ) 2.5 Hz, 1H),
3.78 (br s, 2H), 3.75 (s, 3H); 13C NMR (CDCl3) δ 213.0 (s), 166.1
(s), 146.8 (s), 146.4 (s), 129.8 (s), 129.7 (d), 129.1 (d), 128.8 (s),
128.4 (d), 123.6 (d) 103.2 (s), 98.4 (d), 52.6 (q), 35.4 (t); IR (KBr)
1940, 1714, 1595, 1517, 1345, 1273 cm-1. Anal. Calcd for
1
crystals; mp 89.2 °C dec; H NMR (CDCl3) δ 7.97 (d, J ) 8.6
Hz, 2H), 7.43 (d, J ) 8.6 Hz, 2H), 7.15 (d, J ) 8.6 Hz, 2H),
6.91 (d, J ) 8.6 Hz, 2H), 6.59 (t, J ) 2.3 Hz, 1H), 5.32 and
4.75 (ABq d, J ) 23.1, 2.3 Hz, 2H), 4.08 and 3.49 (ABq, J )
14.5 Hz, 2H), 3.77 (s, 3H); IR (KBr) 1743, 1604, 1516, 1348,
1236 cm-1. Anal. Calcd for C19H16N3O4Cl: C, 59.15; H, 4.18;
N, 10.89. Found: C, 59.22; H, 4.28; N, 10.80.
C
18H14NO4Cl: C, 62.88; H, 4.11; N, 4.07. Found: C, 62.73; H,
4.17; N, 4.00.
1-Meth oxycar bon yl-1-(p-n itr oben zyl)-3-(p-n itr oph en yl)-
a llen e (12f). This was obtained in 41% yield from the reaction
of the phosphorane with p-nitrophenylacetyl chloride: colorless
(Z)-3-Meth oxycar bon yl-3-(p-n itr oben zyl)-4-(p-n itr oben -
zylid en e)-1-p yr a zolin e (14f). This was obtained in 55% yield
from the reaction of 12f with 0.9 M amount of diazomethane:
1
1
needles; mp 133.5-134.0 °C; H NMR (CDCl3) δ 8.19 (d, J )
yellowish crystals; mp 100.5 °C dec; H NMR (CDCl3) δ 8.32
8.6 Hz, 2H), 8.14 (d, J ) 8.6 Hz, 2H), 7.42 (d, J ) 8.6 Hz, 2H),
7.35 (d, J ) 8.6 Hz, 2H), 6.61 (t, J ) 2.3 Hz, 1H), 3.82 (d, J )
2.3 Hz, 2H), 3.77 (s, 3H); IR (KBr) 1944, 1704, 1594, 1516,
1348, 1275 cm-1. Anal. Calcd for C18H14N2O6: C, 61.02; H, 3.98;
N, 7.91. Found: C, 60.89; H, 3.93; N, 7.88.
1-Met h oxyca r b on yl-1-(p -n it r ob en zyl)-3,3-d ip h en yla l-
len e (12g). This was prepared in 58% yield by refluxing
diphenyl ketene with an equimolar of the phosphorane in dry
benzene for 4 h: colorless plates; mp 132.5-133.2 °C; 1H NMR
(CDCl3) δ 8.06 (d, J ) 8.6 Hz, 2H), 7.17-7.36 (m, 12H), 3.85
(s, 2H), 3.78 (s, 3H); IR (KBr) 1942, 1711, 1606, 1598, 1522,
1348, 1255 cm-1. Anal. Calcd for C24H19NO4: C, 74.79; H, 4.97;
N, 3.63. Found: C, 75.18; H, 5.11; N, 3.65.
Gen er al P r ocedu r e for P r epar ation of Alkyliden epyr a-
zolin es 14. An ethereal solution containing 3 mmol of diazo
compound was added to the solution of allenes 12 (2 mmol) in
dichloromethane at 0 °C. After standing at 0 °C overnight, the
solvent was removed, and the product was recrystallized from
dichloromethane/ether.
(d, J ) 8.6 Hz, 2H), 7.99 (d, J ) 8.2 Hz, 2H), 7.41 (d, J ) 8.6
Hz, 2H), 6.92 (d, J ) 8.2 Hz, 2H), 6.72 (br s, 1H), 5.39 (dd, J
) 23.1, 2.3 Hz, 2H), 4.80 (dd, J ) 23.1, 2.0 Hz, 2H), 4.11 and
3.44 (ABq, J ) 14.5 Hz, 2H), 3.79 (s, 3H); IR (KBr) 1743, 1595,
1516, 1347, 1247 cm-1. Anal. Calcd for C19H16N4O6: C, 57.57;
H, 4.07; N, 14.14. Found: C, 57.22; H, 4.04; N, 13.88.
3-Meth oxyca r bon yl-3-(p-n itr oben zyl)-4-d ip h en ylm eth -
ylen e-1-p yr a zolin e (14g). This was obtained quantitatively
from the reaction of 12g with diazomethane; colorless crystals;
mp 125.5 °C dec; 1H NMR (CDCl3) δ 8.13 (d, J ) 8.6 Hz, 2H),
7.44-7.25 (m, 8H), 7.17-7.13 (m, 2H), 6.94-6.70 (m, 2H), 5.05
and 4.53 (ABq, J ) 23.4 Hz, 2H), 3.86 and 3.07 (ABq, J )
14.2 Hz, 2H), 3.78 (s, 3H); IR (KBr) 1741, 1605, 1520, 1491,
1351, 1252 cm-1. Anal. Calcd for C25H21N3O4: C, 70.25; H, 4.95;
N, 9.83. Found: C, 69.87; H, 5.01; N, 9.71.
5-ter t-Bu tyl-4-(p-ch lor oben zyliden e)-3-m eth oxycar bon -
yl-3-(p-n itr oben zyl)-1-p yr a zolin e (14h ). The 1:2 mixture of
14h (Z) and 14h (E) was obtained quantitatively from the
reaction of 12e with diazoneopentane and separated by
fractional recrystallization.
3-Met h oxyca r b on yl-4-m et h ylen e-3-(p -n it r ob en zyl)-1-
p yr a zolin e (14a ). This was obtained quantitatively from the
reaction of 12a with diazomethane: colorless crystals; mp
125.0 °C dec; 1H NMR (CDCl3) δ 8.08 (d, J ) 8.6 Hz, 2H), 7.31
(d, J ) 8.6 Hz, 2H), 5.42 (t, J ) 2.6 Hz, 1H), 5.37 (t, J ) 2.3
Hz, 1H), 5.02 and 4.56 (ABq d, J ) 23.1, 2.5 Hz, 2H), 3.90 and
3.33 (ABq, J ) 13.9 Hz, 2H), 3.75 (s, 3H); IR (KBr) 1734, 1604,
1516, 1349, 1251 cm-1. Anal. Calcd for C13H13N3O4: C, 56.72;
H, 4.76; N, 15.27. Found: C, 56.67; H, 4.77; N, 15.12.
(Z)-4-Eth yliden e-3-m eth oxycar bon yl-3-(p-n itr oben zyl)-
1-p yr a zolin e (14b). This was obtained quantitatively from
the reaction of 12b with diazomethane: colorless crystals; mp
97.0 °C dec; 1H NMR (CDCl3) δ 8.06 (d, J ) 8.6 Hz, 2H), 7.20
(d, J ) 8.6 Hz, 2H), 5.69 (qt, J ) 7.2, 2.2 Hz, 1H), 5.01 (d quint,
J ) 22.8, 2.2 Hz, 1H), 4.26 (d quint, J ) 22.8, 2.2 Hz, 1H),
3.93 (d, J ) 13.9 Hz, 1H), 3.57 (d, J ) 13.9 Hz, 1H), 3.78 (s,
3H), 1.80 (dt, J ) 7.2, 2.2 Hz, 3H); IR (KBr) 1729, 1606, 1520,
1346, 1253 cm-1. Anal. Calcd for C14H15N3O4: C, 58.12; H, 5.23;
N, 14.53. Found: C, 58.26; H, 5.26; N, 14.42.
(Z)-5-ter t-Bu t yl-4-(p -ch lor ob en zylid en e)-3-m et h oxy-
ca r bon yl-3-(p-n itr oben zyl)-1-p yr a zolin e (14h (Z)): color-
less crystals; mp 139.5 °C dec; 1H NMR (CDCl3) δ 7.99 (d, J )
8.6 Hz, 2H), 7.42 (d, J ) 8.6 Hz, 2H), 7.23 (d, J ) 8.6 Hz, 2H),
6.90 (d, J ) 8.6 Hz, 2H), 6.71 (d, J ) 2.3 Hz, 1H), 4.22 (d, J )
2.3 Hz, 1H), 3.96 and 3.19 (ABq, J ) 13.9 Hz, 2H), 3.85 (s,
3H), 1.12 (s, 9H); IR (KBr) 1740, 1672, 1603, 1518, 1348, 1251
cm-1. Anal. Calcd for C23H24N3O4Cl: C, 62.62; H, 5.47; N, 9.51.
Found: C, 62.57; H, 5.43; N, 9.50.
(Z)-5-ter t-Bu t yl-4-(p -ch lor ob en zylid en e)-3-m et h oxy-
ca r bon yl-3-(p-n itr oben zyl)-1-p yr a zolin e (14h (E)): color-
less crystals; mp 120.3 °C dec; 1H NMR (CDCl3) δ 7.98 (d, J )
8.6 Hz, 2H), 7.41 (d, J ) 8.6 Hz, 2H), 7.10 (d, J ) 8.6 Hz, 2H),
7.09 (d, J ) 8.6 Hz, 2H), 6.87 (d, J ) 2.3 Hz, 1H), 5.09 (d, J )
2.3 Hz, 1H), 4.09 and 3.21 (ABq, J ) 14.2 Hz, 2H), 3.73 (s,
3H), 0.99 (s, 9H); IR (KBr) 1734, 1604, 1517, 1346, 1236 cm-1
.
Anal. Calcd for C23H24N3O4Cl: C, 62.62; H, 5.47; N, 9.51.
Found: C, 62.42; H, 5.53; N, 9.38.
J . Org. Chem, Vol. 68, No. 25, 2003 9719