1,3-Dipolar cycloaddition of diazomethane and diazocyclopropane to 2-fluoro-3-methylbutadiene and thermal transformations of fluorine-containing vinylpyrazolines and vinylcyclopropanes

Article abstract of DOI:10.1023/B:RUCB.0000042293.15892.9a

Reactions of 2-fluoro-3-methylbuta-1,3-diene with diazomethane in ether at 15°C and with diazocyclopropane generated in situ by decomposition of N-cyclopropyl-N-nitrosourea in the presence of K₂CO₃ in CH₂Cl₂ at -10°C selectively involve the double bond at the methyl group to give 3-(1-fluorovinyl)-3-methylpyrazolines. Thermal dediazotization of the latter at 250°C yields 1-(1-fluorovinyl)-1- methylcyclopropane and -spiropentane 5, which are capable of isomerizing, under more severe conditions (400 - 600°C), into 1-fluoro-2-methylcyclopent-1-ene and 5-fluoro-4-methylspiro[2.4]hept-4-ene (7), respectively. Spiropentane derivative 5 partially isomerizes into 1-fluoro-2-methyl-3-methylidenecyclohex- 1-ene. In a similar way, thermolysis of 6-(2,3,3-trifluorocyclobut-1-enyl)-4,5- diazaspiro[2.4]hept-4-ene at 400°C gives a mixture of 1-(spiropentyl)-2,3,3- trifluorocyclobut-1-ene and 2,3,3-trifluoro-1-(2-methylidenecyclobutyl)cyclobut- 1-ene. Thermolysis of 1-cyclopropyl-2,3,3-trifluorocyclobut-1-ene at 550 - 620°C affords a mixture of 1-(trifluorovinyl)cyclopentene and 2,3-difluorotoluene.

Full text of DOI:10.1023/B:RUCB.0000042293.15892.9a

1
318
Russian Chemical Bulletin, International Edition, Vol. 53, No. 6, pp. 1318—1322, June, 2004
1
,3ꢀDipolar cycloaddition of diazomethane and diazocyclopropane
to 2ꢀfluoroꢀ3ꢀmethylbutadiene and thermal transformations
of fluorineꢀcontaining vinylpyrazolines and vinylcyclopropanes
✾
E. V. Guseva, N. V. Volchkov, E. V. Shulishov, Yu. V. Tomilov,ꢀ and O. M. Nefedov
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
4
7 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (095) 135 6390. Eꢀmail: tom@ioc.ac.ru
Reactions of 2ꢀfluoroꢀ3ꢀmethylbutaꢀ1,3ꢀdiene with diazomethane in ether at 15 °C and
with diazocyclopropane generated in situ by decomposition of NꢀcyclopropylꢀNꢀnitrosourea in
the presence of K CO in CH Cl at –10 °C selectively involve the double bond at the methyl
2
3
2
2
group to give 3ꢀ(1ꢀfluorovinyl)ꢀ3ꢀmethylpyrazolines. Thermal dediazotization of the latter at
50 °C yields 1ꢀ(1ꢀfluorovinyl)ꢀ1ꢀmethylcyclopropane and ꢀspiropentane 5, which are capable
of isomerizing, under more severe conditions (400—600 °C), into 1ꢀfluoroꢀ2ꢀmethylcyclopentꢀ
ꢀene and 5ꢀfluoroꢀ4ꢀmethylspiro[2.4]heptꢀ4ꢀene (7), respectively. Spiropentane derivative 5
2
1
partially isomerizes into 1ꢀfluoroꢀ2ꢀmethylꢀ3ꢀmethylidenecyclohexꢀ1ꢀene. In a similar way,
thermolysis of 6ꢀ(2,3,3ꢀtrifluorocyclobutꢀ1ꢀenyl)ꢀ4,5ꢀdiazaspiro[2.4]heptꢀ4ꢀene at 400 °C gives
a mixture of 1ꢀ(spiropentyl)ꢀ2,3,3ꢀtrifluorocyclobutꢀ1ꢀene and 2,3,3ꢀtrifluoroꢀ1ꢀ(2ꢀmethylꢀ
idenecyclobutyl)cyclobutꢀ1ꢀene. Thermolysis of 1ꢀcyclopropylꢀ2,3,3ꢀtrifluorocyclobutꢀ1ꢀene
at 550—620 °C affords a mixture of 1ꢀ(trifluorovinyl)cyclopentene and 2,3ꢀdifluorotoluene.
Key words: fluorovinylcyclopropanes, fluorovinylpyrazolines, trifluorocyclobutenes,
1
13
fluorocycloalkenes, spiropentanes, dediazotization, thermolysis, rearrangements; H, C, and
19
F NMR spectra.
Fluorinated vinylcyclopropanes,1—4 which can isomerꢀ
tic spinꢀspin coupling constants (JH,Fꢀcis = 17.7 and
JH,Fꢀtrans = 49.9 Hz). The N atom is attached to the meꢀ
thylated carbon atom, which follows from the H NMR
ize into fluorineꢀcontaining cyclopentenes, are of certain
interest as fluorineꢀcontaining starting material. The presꢀ
ence of fluorine atoms in the cyclopropane fragment can
reduce the energy of activation of the vinylcyclopropꢀ
1
signals for the CH —CH fragment included in the fiveꢀ
2
2
3
membered ring of the resulting pyrazoline ( J = 7.7 Hz).
According to the data on the highest reactivity of elecꢀ
tronꢀdeficient double bonds in 1,3ꢀdipolar cycloaddition,6
the observed regioselective addition of diazoalkanes sugꢀ
gests that the αꢀfluorovinyl group in diene 1 exhibit elecꢀ
tronꢀwithdrawing properties relative to the isopropenyl
fragment.
2
—4
ane→cyclopentene rearrangement (thus facilitating it)
or even change the direction of the reaction compared
4
to analogous nonfluorinated structures. The effect of
F atoms in the vinyl group of vinylcyclopropanes on their
thermal transformations has not been discussed to date.
In the present work, we studied 1,3ꢀdipolar cycloꢀ
addition of diazomethane and diazocyclopropane to
2
ꢀfluoroꢀ3ꢀmethylbutaꢀ1,3ꢀdiene, which affords the corꢀ
responding pyrazolines, and thermal dediazotization of
the pyrazolines obtained and previously synthesized 6ꢀ
(
4
2,3,3ꢀtrifluorocyclobutꢀ1ꢀenyl)ꢀ4,5ꢀdiazaspiro[2.4]heptꢀ
ꢀene. Deeper thermolysis of (fluorovinyl)cyclopropanes,
5
spiropentanes, and 1ꢀcyclopropylꢀ2,3,3ꢀtrifluorocyclobutꢀ
5
1
ꢀene were also investigated.
The reaction of 2ꢀfluoroꢀ3ꢀmethylbutaꢀ1,3ꢀdiene (1)
with diazomethane in ether (15 °C, 3 days) selectively
involves the methylated double bond to give 3ꢀ(1ꢀfluoroꢀ
vinyl)ꢀ3ꢀmethylpyrazoline (2) in ~95% yield. In the oleꢀ
1
fin range, its H NMR spectrum contains no signals other
The reaction of fluorobutadiene 1 with diazocycloꢀ
propane (generated in situ by decomposition of Nꢀcycloꢀ
than for protons of a fluorovinyl group with characterisꢀ
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1265—1269, June, 2004.
066ꢀ5285/04/5306ꢀ1318 © 2004 Plenum Publishing Corporation
1

1
,3ꢀDipolar cycloaddition of diazomethane
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 6, June, 2004
1319
propylꢀNꢀnitrosourea in the presence of an equimolar
mixture of KOH and K CO in CH Cl at –5 °C) also
characteristic highꢀfield signals for the spirocyclopropane
fragment, while the spectra of compound 8 show sigꢀ
nals for the methylidene fragment and three alicyclic
2
3
2
2
involves the methylated double bond to highly regioꢀ
selectively give 6ꢀ(1ꢀfluorovinyl)ꢀ6ꢀmethylꢀ4,5ꢀdiazaꢀ
spiro[2.4]heptꢀ4ꢀene (3) in ~40% yield. The presence of
the quaternary C atoms at the endocyclic azo group makes
this compound very stable and capable of being distilled
in vacuo (0.1 Torr). It should be noted that the reactions
CH ꢀgroup. The thermolysis of vinylspiropentane 5 at
2
430—440 °C gives a more complex mixture containing
oꢀxylene (~10%) and a number of unidentified comꢀ
pounds. The total yield of compounds 7 and 8 decreases
to ~50% and the ratio of 7 : 8 is ~2.6 : 1).
7
of 2ꢀmethylbutadiene with both diazomethane and
8
diazocyclopropane involve the nonsubstituted double
bond; in the latter case, the resulting 1ꢀpyrazoline is very
labile.
Because 1ꢀpyrazolines are known to easily undergo
thermal decomposition to give cyclopropanes and/or corꢀ
9
responding isomeric olefins, we studied the thermolysis
of pyrazolines 2 and 3 with the aim of obtaining fluoroꢀ
vinylcyclopropanes. Pyrolysis was carried out by passing
the vapor of pyrazoline with argon through a quartz tube
packed with quartz (atmospheric pressure, T > 250 °C).
It turned out that the thermolysis of pyrazoline 2 proꢀ
ceeds smoothly at 250—260 °C to give 1ꢀ(1ꢀfluorovinyl)ꢀ
1
ꢀmethylcyclopropane (4) in up to 85% yield, its isomeric
compounds being virtually absent. The spectroscopic charꢀ
acteristics of compound 4 fully agree with the sample
prepared by catalytic cyclopropanation of fluorobutadiene
1
0
1
with diazomethane in the presence of Pd(acac)2.
The formation of spiroheptene 7 is due to a vinylcycloꢀ
propane→cyclopentene rearrangement, which is analoꢀ
gous to the isomerization of isopropenylspiropentane into
1
1
5
ꢀmethylspiro[2.4]heptꢀ4ꢀene at 235—275 °C. The miꢀ
nor product 8 (~11%) seems to form as a result of the
rearrangement of the spiropentane fragment in compound
5 to the corresponding methylidenecyclobutane 9, which
is probably unstable at 380—400 °C and isomerizes into
the more stable cyclohexene 8. The thermolysis of the
latter at a higher temperature affords oꢀxylene via dehydroꢀ
fluorination. Indeed, thermal isomerization of spiroꢀ
pentanes usually leads to the corresponding methylideneꢀ
cyclobutanes, most probably through the initial cleavage
of the C(1)—C(2) bond rather than the C(1)—C(3)
Under analogous thermolysis conditions, the converꢀ
sion of spirocyclopropaneꢀcontaining pyrazoline 3 is also
fairly high; however, considerable resinification arises, in
contrast to pyrazoline 2. Nevertheless, the major volatile
product is 1ꢀ(1ꢀfluorovinyl)ꢀ1ꢀmethylspiropentane (5)
1
(
yield up to 51%), which was structurally identified by H
13
and C NMR spectroscopy (see Experimental).
Subsequent transformations of vinylcyclopropanes 4
and 5 require very drastic conditions, especially for
compound 4 (its high conversion was reached only at
1
1
bond. Thus, the presence of fluorine in the vinyl fragꢀ
ment of vinylspiropentanes radically does not affect the
direction of their isomerization.
5
80—600 °C). Under these conditions, the isomerization
of compound 4 mainly gives the expected volatile 1ꢀfluoroꢀ
In addition, we studied the thermolysis of 4,5ꢀdiazaꢀ
spiro[2.4]heptꢀ4ꢀene 10 obtained earlier from 2,3,3ꢀtriꢀ
fluoroꢀ1ꢀvinylcyclobutꢀ1ꢀene and the in situ generated
2
ꢀmethylcyclopentene (6); however, its yield is only 22%.
The isomerization of vinylspiropentane 5 proceeds virꢀ
5
tually completely at 390—400 °C; the major volatile prodꢀ
ucts are 5ꢀfluoroꢀ4ꢀmethylspiro[2.4]heptꢀ4ꢀene (7) and
diazocyclopropane. Compound 10 (~92% purity) is very
labile;5 however, its noticeable dediazotization occurs
only at T > 320 °C and is accompanied by intense
resinification. At 370 °C, the conversion of pyrazoline 10
is no higher than 60% and the volatile fraction of pyrolyzꢀ
ates mainly contains the expected 2,3,3ꢀtrifluoroꢀ1ꢀ
(spiropentꢀ1ꢀyl)cyclobutene (11); the yield of compound
11 from the starting pyrazoline is ~22%. At 400 °C, comꢀ
pound 10 converts virtually completely to give spiroꢀ
,12
1
ꢀfluoroꢀ2ꢀmethylꢀ3ꢀmethylidenecyclohexꢀ1ꢀene (8) (toꢀ
tal yield was 65—68%; 7 : 8 ≈ 5 : 1). Compound 7 was
isolated by preparative GLC (98% purity); compound 8
was enriched to ~85%. The structures of the fluoroꢀ
1
13
cycloalkenes obtained were determined from H, C,
and 1 F NMR spectra. Both compounds contain the
FC=CMe fragment; the spectra of compound 7 show
9

1320
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 6, June, 2004
Guseva et al.
pentane 11 and its isomer, namely, 2,3,3ꢀtrifluoroꢀ1ꢀ
2ꢀmethylidenecyclobutyl)cyclobutꢀ1ꢀene (12) in a total
of 2,3ꢀdifluorotoluene (17) (see Table 1), probably, as the
result of the opening of the cyclopropane ring in diene 16
followed by closing of a sixꢀmembered ring and its partial
dehydrofluorination.
(
yield of ~27% (11 : 12 ≈ 2.5 : 1). The structures of prodꢀ
ucts 11 and 12 containing the 2,3,3ꢀtrifluorocyclobutenyl
1
13
19
fragment were proved by H, C, and F NMR spectra.
The pyrolysis of pyrazoline 10 at 400 °C gives a number of
minor products; however, isomer 13 was not detected.
The structure of (trifluorovinyl)cyclopentene 15 was
1
13
19
confirmed by H, C, and F NMR spectra. In particuꢀ
lar, the trifluorovinyl fragment is manifested in the
19
F NMR spectrum by signals with characteristic spinꢀ
2
3
Unlike spiropentane 11, 1ꢀcyclopropylꢀ2,3,3ꢀtriꢀ
fluorocyclobutꢀ1ꢀene (14) is resistant to pyrolysis up
to 530 °C. Its conversion at 550 °C was ~20%, mainly
giving 1ꢀ(trifluorovinyl)cyclopentꢀ1ꢀene (15) (Table 1).
Apparently, the cyclobutene ring of compound 14 underꢀ
goes opening to give diene 16, which then isomerizes into
vinylcyclopentene 15. It should be noted that the nonꢀ
fluorinated hydrocarbon analog of compound 14, namely,
spin coupling constants ( J
= 71.0 Hz, J
=
F,F
F,Fꢀtrans
3
13
102.5 Hz, and J
= 27.5 Hz). The C NMR data for
F,Fꢀcis
2,3ꢀdifluorotoluene 17 agree with those for an authentic
sample prepared according to a known procedure.
1
4
Hence, the αꢀfluorovinyl fragment in vinylcycloꢀ
propanes and vinylspiropentanes does not impede the
vinylcyclopropane→cyclopentene rearrangement; howꢀ
ever, this process requires sufficiently drastic conditions
(490—600 °C). Spiropentane derivatives undergo parallel
isomerization into methylidenecyclobutanes, while for
trifluorocyclobutenylcyclopropanes, which contain the
"vinylic" fragment in the fourꢀmembered carbocycle, the
primary reaction is cyclobutene→butadiene isomerization.
1
ꢀcyclopropylcyclobutꢀ1ꢀene, is capable of selectively
1
3a
isomerizing into 2ꢀcyclopropylbutaꢀ1,3ꢀdiene
during
lowꢀtemperature pyrolysis (143—193 °C, static conditions)
and photolysis.1 The observed enhanced thermal stabilꢀ
ity and high isomerization temperature of cyclopropylꢀ
cyclobutene 14 compared to its nonfluorinated analog
correlates with the known fact1 that introduction of fluoꢀ
rine atoms into a cyclobutene ring significantly increases
the energy of activation of thermal cyclobutene→butaꢀ
diene isomerization.
3b
3c
Experimental
1H and 13C NMR spectra were recorded on Bruker ACꢀ200
(
200 and 50.3 MHz), Bruker AMꢀ300 (300 and 75.5 MHz), and
The thermolytic conversion of cyclobutene 14 subꢀ
stantially increases at 600—620 °C; however, the process
is complicated by intense resinification and the formation
Bruker DRXꢀ500 spectrometers (500 MHz) in CDCl with
3
19
0
.05% Me Si as the internal standard. F NMR spectra were
4
recorded on a Bruker ACꢀ200 spectrometer (188.3 MHz); chemiꢀ
cal shifts were referenced to CCl F as the external standard.
3
Table 1. Conversion of 1ꢀcyclopropylꢀ2,3,3ꢀtrifluorocyclobutꢀ
Mass spectra were recorded on a Finnigan MAT INCOSꢀ50
instrument (EI, 70 eV, RSLꢀ200 capillary column (30 m) or
direct inlet probe). Preparative separation was carried out
in a column (180×0.6 cm) with 5% SEꢀ30 on Chromaton
NꢀAWꢀHMDS (argon as a carrier gas, 80 mL min–1, column
temperature 45—90 °C). The starting 2ꢀfluoroꢀ3ꢀmethylbutaꢀ
1
ꢀene (14) and the yields of the products of its thermolysis at
different temperatures*
T/°C
Conversion
%)
Yield (%)
Ratio of
(
1
5
17
15 : 17
1
0
1
,3ꢀdiene (1), 6ꢀ(2,3,3ꢀtrifluorocyclobutꢀ1ꢀenyl)ꢀ4,5ꢀdiazaꢀ
5
spiro[2.4]heptꢀ4ꢀene (10), and 1ꢀcyclopropylꢀ2,3,3ꢀtrifluoroꢀ
cyclobutꢀ1ꢀene (14) were prepared according to known proceꢀ
5
6
6
50
00
20
19
95
100
18
32
6
—
17
38
—
1.9 : 1
1 : 6.4
5
dures.
3
ꢀ(1ꢀFluorovinyl)ꢀ3ꢀmethylꢀ4,5ꢀdihydroꢀ3Hꢀpyrazole (2).
*
For the thermolysis conditions, see Experimental.
A solution of 2ꢀfluoroꢀ3ꢀmethylbutaꢀ1,3ꢀdiene (1) (0.52 g,

1
6
,3ꢀDipolar cycloaddition of diazomethane
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 6, June, 2004
1321
mmol) and diazomethane (~23 mmol) in 10 mL of ether was
110—112 °C. Found (%): C, 76.01; H, 8.74. C H F. Calcuꢀ
8 11
1
kept at 15 °C for 3 days and then passed through a layer of Al O3
lated (%): C, 75.85; H, 8.52. H NMR (CDCl ), δ: 0.71 (ddd,
2
3
2
(
0.5 cm). The solvent and the unconsumed reagents were reꢀ
1 H, H(4), J = 4.1 Hz, J
= 5.3 Hz, Jcis = 8.8 Hz); 0.78 (m,
trans
moved at 20 Torr to give pyrazoline 2 (0.71 g, ~93%) as a
yellowish liquid. Found (%): C, 56.17; H, 7.04; N, 21.86.
1 H, H(5)); 0.89 (m, 3 H, H(4), H(5) and H (2)); 1.23 (s, 3 Н,
a
2
Me); 1.40 (d, 1 Н, Н (2), J = 4.2 Hz); 4.23 (dd, 1 Н,
b
1
3
2
C H FN . Calculated (%): C, 56.35; H, 7.13; N, 21.67. H NMR
FC=CH(trans), J
= 50.0 Hz, J = 3.0 Hz); 4.52 (dd,
H,Fꢀtrans
= 17.3 Hz, J = 3.0 Hz). C NMR
H,Fꢀcis
6
9
2
2
3
2
13
(
CDCl ), δ: 1.47, 1.91 (both br.dt, 1 Н each, CН , J = 12.6 Hz,
J = 7.7 Hz); 1.52 (s, Me); 4.62 (t, 2 Н, NCН , J ≈ 7.7 Hz); 4.67
1 Н, FC=CH(cis), J
3
2
3
3
(CDCl ), δ: 4.1, 5.8 (both s, C(4), C(5)); 19.2 (d, C(2), J
=
=
2
2
3
C,F
3
2
(
(
(
dd, 1 H, =CH(trans), JH,Fꢀtrans = 49.8 Hz, J = 3.5 Hz); 4.76
3.7 Hz); 19.3 (d, Me, J
= 4.2 Hz); 21.3 (d, C(1), J
C,F
C,F
2
13
2
dd, 1 H, =CH(cis), J
= 17.9 Hz, J = 3.5 Hz). C NMR
≈ 3.0 Hz); 27.3 (s, C(4)); 77.0 (s,
27.2 Hz); 29.1 (s, C(3)); 87.2 (d, =CH , J
= 22.8 Hz); 168.8
H,Fꢀcis
2
C,F
3
1
19
CDCl ), δ: 21.2 (d, Me, J
(d, =CF, J
= 255 Hz). F NMR (CDCl ), δ: –103.9 (dd,
C,F 3
3
C,F
2
2
C(5)); 90.4 (d, =CH , J
2
= 19.4 Hz); 91.4 (d, C(3); J
≈ 258 Hz). F NMR (CDCl ), δ:
=
JH,Fꢀtrans = 50.0 Hz, J
m/z (Irel (%)): 125 [M – H] (8), 111 [M – Me] (43), 91 (29),
77 (19), 68 (28), 55 (27), 41 (100).
= 17.3 Hz). Partial MS,
H,Fꢀcis
2
C,F
C,F
1
19
+
+
5.6 Hz); 164.9 (d, CF, J
C,F
3
–
106.5 (dd, J
= 49.8 Hz, J
= 17.9 Hz). MS,
H,Fꢀcis
H,Fꢀtrans
m/z (Irel (%)): 127 [M – H]+ (5), 113 [M – Me]+ (7), 99 (30),
1ꢀFluoroꢀ2ꢀmethylcyclopentene (6). A pyrolyzate (0.76 g)
obtained from 1ꢀ(1ꢀfluorovinyl)ꢀ1ꢀmethylcyclopropane (4)
(3.00 g, 30 mmol) at 600 °C was distilled at an atmospheric
pressure to give fluorocyclopentene 6 (0.66 g, 22%) as a colorꢀ
8
5 (63), 79 (39), 65 (30), 58 (57), 39 (100).
ꢀ(1ꢀFluorovinyl)ꢀ6ꢀmethylꢀ4,5ꢀdiazaspiro[2.4]heptꢀ4ꢀene
3). NꢀCyclopropylꢀNꢀnitrosourea (2.71 g, 21 mmol) was added
at –10 °C for 30 min to a vigorously stirred solution of 2ꢀfluoroꢀ
6
(
1
less liquid, b.p. 72—74 °C (≥98% purity). H NMR (CDCl ), δ:
3
3
2
ꢀmethylbutaꢀ1,3ꢀdiene (1) (3.60 g, 42 mmol), K CO (3.48 g,
1.59 (br.s, 3 Н, Me); 1.86 (m, 2 Н, H(4)); 2.20 (m, 2 Н, H(3));
2
3
13
5 mmol), and KOH (1.41 g, 25 mmol) in 15 mL of CН Cl .
2.40 (m, 2 Н, H(5)). C NMR (CDCl ), δ: 10.6 (s, Me); 18.7
2
2
3
3
2
Then, the reaction mixture was stirred at 0 °C for 1 h and
filtered. The filtrate was concentrated and distilled in vacuo
(d, C(4), J
= 9.3 Hz); 29.2 (d, C(5), J
= 8.1 Hz); 128.7 (d, C(2), 2JC,F = 40.7 Hz);
≈ 269 Hz). F NMR (CDCl ), δ: –131.4
(br.s.). Partial MS, m/z (Irel (%)): 99 [M – H] (38), 84 (48),
67 (20), 55 (32), 43 (100).
= 21.7 Hz); 32.1
C,F
C,F
3
(d, C(3), J
C,F
1
19
(
Tbath 70—75 °C, 0.1 Torr) to give pyrazoline 3 (1.30 g, 40%) as
155.3 (d, C(1), J
C,F
3
+
a slightly yellow oily liquid. Found (%): C, 62.23; H, 7.13;
N, 18.20. C H FN . Calculated (%): C, 62.38; H, 7.24;
N, 18.08. H NMR (CDCl ), δ: 1.11 (m, 2 Н, Н(1) and Н(2)
oriented from the N atom of the heterocycle); 1.55 (s, 3 Н, Me);
1
Н(1) and Н(2) oriented toward the N atom of the heterocycle);
2
JH,Fꢀtrans = 49.1 Hz, J = 3.4 Hz); 4.76 (dd, 1 Н, =CH(cis),
JH,Fꢀcis = 17.8 Hz, J = 3.4 Hz). C NMR (CDCl ), δ: 13.6,
8
11
2
1
Thermolysis of 1ꢀ(1ꢀfluorovinyl)ꢀ1ꢀmethylspiropentane (5)
(0.12 g, 0.9 mmol) at 390 °C gave a mixture (0.081 g) of 5ꢀfluoroꢀ
4ꢀmethylspiro[2.4]heptꢀ4ꢀene (7) (~80%) and 1ꢀfluoroꢀ2ꢀ
methylꢀ3ꢀmethylidenecyclohexꢀ1ꢀene (8) (16%). The total yield
of these products was ~65%. Compound 7 was isolated by preꢀ
parative GLC (~98% purity), while compound 8 was enriched
to ~85%. Analogously, the thermolysis of spiropentane 5 (0.12 g,
0.9 mmol) at 440 °C gave a mixture (0.074 g, ~62%) containing
spiroheptene 7 (56—58%), fluorocyclohexene 8 (~22%), oꢀxyꢀ
lene (~13%), and some amounts of minor products.
3
2
.62 (dd, 1 Н, H (7), J = 12.5 Hz, J
≈ 1.0 Hz); 1.75 (m, 2 Н,
H,F
a
2
.10 (d, 1 Н, H (7), J = 12.5 Hz); 4.66 (dd, 1 Н, =CH(trans),
b
2
2
13
3
3
1
4.2 (both s, CH CH ); 22.2 (d, Me, JC,F ≈ 3.0 Hz); 35.3
2
2
2
(
s, C(7)); 69.3 (s, C(3)); 90.1 (d, C(6), J = 25.8 Hz); 90.5 (d,
C,F
2
1
19
=
CH , J = 19.0 Hz); 165.1 (d, CF, J ≈ 259 Hz). F NMR
2 C,F
C,F
= 49.1 Hz, J
+
(
CDCl ), δ: –105.8 (dd, J
= 17.8 Hz).
Compound 7. Found (%): C, 75.61; H, 8.59. C H F. Calcuꢀ
3
H,Fꢀtrans
H,Fꢀcis
8
11
1
MS, m/z (Irel (%)): 125 [M – H – N ] (4), 111 (33), 97 (15), 85
lated (%): C, 75.85; H, 8.52. H NMR (CDCl ), δ: 0.39, 0.62
2
3
(
22), 77 (15), 66 (12), 59 (11), 51 (27), 39 (100).
(both m, 2 H each, H(1), H(2)); 1.26 (q, 3 Н, Me, J = 2.3 Hz);
3
Thermal transformations of pyrazolines and vinylcycloꢀ
1.90 (br.dd, 2 Н, H(7), J ≈ 7.4 and 7.8 Hz); 2.52 (m, 2 Н,
13
propanes (general procedure). A quartz tube (inner diameter
.6 cm, length 18 cm, twoꢀthirds full of small quartz) purged
H(6)). C NMR (CDCl ), δ: 6.0 (s, Me); 9.7 (s, C(1), C(2));
3
0
26.4 (d, C(3), JC,F = 9.5 Hz); 28.0 (d, C(6), JC,F = 21.0 Hz);
–
1
with argon (~4 mL min ) was heated in a tube microfurnace
heating zone range ~12 cm). The heating temperature was set
30.3 (d, C(7), JC,F = 7.5 Hz); 113.0 (d, C(4), J
= 10.8 Hz);
C,F
19
(
153.9 (d, C(5), JC,F = 270 Hz). F NMR (CDCl ), δ: –126.3
3
+
+
and measured with an electronic thermometer, its sensor being
fixed in the central zone of the microfurnace. Test compounds
were injected with a syringe into the initial heating zone in
microportions (~1 g h–1) and thermolysis products were colꢀ
lected in a trap cooled to –40 °C. The compositions of the
reaction mixtures were determined from GCꢀMS and H NMR
data. Then the reaction mixtures were distilled or separated by
preparative GLC and identified by conventional methods.
(br.s). Partial MS, m/z (Irel (%)): 126 [M] (100), 111 [M – Me]
(70), 109 (48), 79 (20).
1
Compound 8. H NMR (CDCl ), δ: 1.76 (q, 3 Н, Me, J =
3
2.2 Hz); 1.79 (m, 2 Н, H(5)); 2.32 (m, 4 Н, H(4), H(6)); 4.77,
13
4.82 (both m, 1 Н each, =CH ). C NMR (CDCl ), δ: 9.2 (d,
2
3
1
Me, JC,F = 8.8 Hz); 22.4 (d, C(5), JC,F = 9.2 Hz); 26.6 (d, C(6),
JC,F = 27.2 Hz); 31.6 (s, C(4)); 107.1 (d, =CH , J =10.9 Hz);
2
C,F
C,F
116.2 (d, C(2), JC,F =17.5 Hz); 143.8 (d, C(3), J
159.1 (d, C(1), JC,F ≈ 262 Hz). F NMR (CDCl ), δ: –100.6
(br.s). Partial MS, m/z (Irel (%)): 126 [M] (100), 111 [M – Me]
= 8.2 Hz);
19
1
ꢀ(1ꢀFluorovinyl)ꢀ1ꢀmethylcyclopropane (4) was obtained
3
+
+
from pyrazoline 2 (0.51 g, 4 mmol) at 250 °C. The yield of
compound 4 was 0.34 g (85%). The product is identical in GLC
and H NMR data with a sample prepared earlier by catalytic
cyclopropanation of 2ꢀfluoroꢀ3ꢀmethylbutaꢀ1,3ꢀdiene (1).
ꢀ(1ꢀFluorovinyl)ꢀ1ꢀmethylspiro[2.2]pentane (5). A pyrolyzꢀ
ate (0.66 g) obtained from pyrazoline 3 (1.31 g, 8.5 mmol)
at 260 °C was distilled at an atmospheric pressure to give
vinylspiropentane 5 (0.54 g, 51%) as a colorless liquid, b.p.
(85), 109 (50), 79 (43), 51 (20), 39 (50).
1
Thermolysis of 6ꢀ(2,3,3ꢀtrifluorocyclobutꢀ1ꢀenyl)ꢀ4,5ꢀdiazaꢀ
spiro[2.4]heptꢀ4ꢀene (10). A. A pyrolyzate (0.24 g) obtained
from pyrazoline 10 (0.41 g, 2 mmol) at 370 °C was distilled in
vacuo (Tbath 60—65 °C, 6 Torr) to give 2,3,3ꢀtrifluoroꢀ1ꢀ
(spiropentꢀ1ꢀyl)cyclobutene (11) (72 mg, 22%; ~96% purity).
A pyrolyzate (0.11 g) obtained from compound 10 at 400 °C
1
0
1

1322
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 6, June, 2004
Guseva et al.
(
(
virtually complete conversion) contained spiropentane 11
~73%) and 2,3,3ꢀtrifluoroꢀ1ꢀ(2ꢀmethylidenecyclobutyl)cycloꢀ
JC,F = 12.5 Hz); 149.4, 150.9 (both dd, C(2), C(3), 1JC,F
=
246.5 Hz, 2JC,F = 12.8 Hz). F NMR (CDCl ), δ: –139.2,
19
3
3
butꢀ1ꢀene (12) (18%). The total yield of these compounds was
27%. Compounds 11 and 12 were isolated by preparative GLC
at 90 °C.
Compound 11. Found (%): C, 61.79; H, 5.04. C H F . Calꢀ
–142.7 (both br.d, J = 24.5 Hz).
~
We are grateful to A. S. Shashkov (Institute of Organic
Chemistry of the Russian Academy of Sciences) for his
9
9 3
1
1
13
culated (%): C, 62.07; H, 5.21. H NMR (CDCl ), δ: 0.88 (m,
4
(
methodical assistance in recording H and C NMR specꢀ
tra on a Bruker DRXꢀ500 spectrometer.
3
2
3
Н, CH CH ); 1.17 (t, 1 Н, H (2´), J ≈ J
= 4.2 Hz); 1.38
2
2
a
trans
2
3
dd, 1 Н, H (2´), J = 4.2 Hz, J = 7.7 Hz); 2.01 (dd, 1 Н,
b cis
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 02ꢀ03ꢀ33365)
and the President of the Russian Federation (State Proꢀ
gram for Support of Leading Scientific Schools, Grant
NShꢀ1987.2003.3).
H(1´), J
= 4.2 Hz, Jcis = 7.7 Hz); 2.46 (m, 2 Н, Н(4)).
trans
13
C NMR (CDCl ), δ: 4.9, 5.5 (both s, C(4´), C(5´)); 13.3 (q,
3
C(2´), JC,F = 1.8 Hz); 14.0 (q, C(1´), JC,F = 4.0 Hz); 15.8 (q,
C(3´), JC,F = 2.0 Hz); 37.0 (dt, C(4), J = 19.1 and 22.5 Hz);
1
C(1), J
2
C,F
1
2
18.1 (td, CF , J
= 275 Hz, J
= 26.0 Hz); 128.9 (td,
C,F
≈ 17.0 and 6.0 Hz); 138.3 (dt, =CF, J
2
C,F
1
= 337 Hz,
C,F
C,F
19
JC,F = 25.0 Hz). F NMR (CDCl ), δ: –111.0, –111.7
3
References
(
both br.d, CF2, 2JF,F ≈ 203 Hz), –119.8 (br.s, =CF). MS,
m/z (Irel (%)): 173 [M – H]+ (1), 153 (4), 145 (25), 133 (26),
1
. T. Hudlicky, T. M. Kutchan, and S. M. Naqvi, in Organic
Reactions, Ed. A. S. Kende, Wiley, 1985, 33, 247.
1
(
23 (23), 109 (80), 91 (35), 84 (48), 77 (20), 63 (18), 51 (35), 44
+
38), 39 [C H ] (100).
3 3
1
2. Z. Goldshmidt and B. Crammer, Chem. Soc. Rev., 1988,
7, 229.
3. W. R. Dolbier, Jr. and S. F. Sellers, J. Org. Chem., 1982, 47, 1.
Compound 12. H NMR (CDCl ), δ: 2.06, 2.25 (both m,
3
1
1
(
Н each, H(4´)); 2.64 (m, 5 Н, H(4), H(1´), H(3´)); 4.82, 4.88
13
both br.q, 1 Н each, =CH ). C NMR (CDCl ), δ: 21.5 (q,
2
3
4
. S. F. Sellers, W. R. Dolbier, Jr., H. Koroniak, and D. M.
C(4´), JC,F = 1.7 Hz); 29.8 (s, C(3´)); 36.7 (dt, C(4), JC,F ≈ 19.0
and 22.0 Hz); 39.6 (q, C(1´), J = 3.8 Hz); 107.2 (s, =CH );
1
C(1), JC,F ≈ 17.0 and 6.0 Hz); 136.0 (q, C(2´), J = 4.0 Hz);
1
AlꢀFekri, J. Org. Chem., 1984, 49, 1033.
C,F
2
1
2
5. Yu. V. Tomilov, E. V. Guseva, N. V. Volchkov, E. V.
Shulishov, and O. M. Nefedov, Izv. Akad. Nauk, Ser. Khim.,
2001, 2119 [Russ. Chem. Bull., Int. Ed., 2001, 50, 2113].
18.0 (td, CF2, JC,F = 275 Hz, JC,F ≈ 25.0 Hz); 128.7 (td,
C,F
39.1 (dt, =CF, 1JC,F = 338 Hz, J
2
= 25.0 Hz). F NMR
C,F
19
6
7
8
. M. Regitz and H. Heydt, 1,3ꢀDipolar Cycloaddition Chemisꢀ
try, Ed. A. Padwa, Wiley Interscience, New York, 1984,
V. 1, p. 393.
. I. S. Lishanskii, V. I. Pomerantsev, and L. D. Turkova,
Zh. Org. Khim., 1972, 264 [J. Org. Chem. USSR, 1972 (Engl.
Transl.)].
(
CDCl ), δ: –112.0 (CF ); –115.7 (=CF).
3 2
Thermolysis of 1ꢀcyclopropylꢀ2,3,3ꢀtrifluorocyclobutꢀ1ꢀene
14) (1.67 g, 11 mmol) at 600 °C gave a mixture (0.90 g) of
(
1
ꢀ(trifluorovinyl)cyclopentꢀ1ꢀene (15) (~60%) and 2,3ꢀdiꢀ
1
fluorotoluene (17) (32%) (GLC and H NMR data). The data
on the thermolysis of cyclobutene 14 at 550, 600, and 620 °C are
summarized in Table 1. The spectroscopic data for 1ꢀ(triꢀ
fluorovinyl)cyclopentene (15) were obtained by subtracting the
signals for 2,3ꢀdifluorotoluene synthesized according to a known
procedure.14
. Yu. V. Tomilov, E. V. Shulishov, G. P. Okonnishnikova,
and O. M. Nefedov, Izv. Akad. Nauk, Ser. Khim., 1995, 2199
[
Russ. Chem. Bull., 1995, 44, 2105 (Engl. Transl.)].
9. P. S. Engel, Chem. Rev., 1980, 80, 99.
10. E. V. Guseva, N. V. Volchkov, E. V. Shulishov, Yu. V.
Tomilov, and O. M. Nefedov, Eur. J. Org. Chem., 2004 (in
press).
1
Compound 15. H NMR (CDCl ), δ: 1.99 (m, 2 H, H(4));
3
13
2
(
3
.51 (m, 4 Н, H(3), Н(5)); 6.02 (m, 1 H, =CH). C NMR
CDCl ), δ: 23.3 (s, C(4)); 31.6 (dd, C(5), J = 5.6 and 3.2 Hz);
3
C,F
1
2
11. J. J. Gajewski, J. Am. Chem. Soc., 1970, 92, 3688.
2.6 (s, C(3)); 128.0 (ddd, =CF, J
= 233 Hz, J
= 49.5
C,F
C,F
1
2. E. V. Guseva, N. V. Volchkov, Yu. V. Tomilov, B. B.
and 18.0 Hz); 129.5 (dd, C(2), JC,F = 11.8 and 4.4 Hz); 136.5
(
2
2
1
Averkiev, and O. M. Nefedov, Eur. J. Org. Chem., 2003, 492.
q, C(1), J
≈ 20.0 Hz); 153.3 (ddd, =CF , J
= 242 and
C,F
2
C,F
2
19
13. (a) D. Dickens, H. M. Frey, and R. F. Skinner, Trans.
Faraday Soc., 1969, 65, 453; (b) J. M. Jasinskl, J. K. Frisoll,
and C. B. Moore, J. Phys. Chem., 1983, 87, 3826; (c) W. R.
Dolbier, Jr., T. A. Gray, J. J. Keaffaber, L. Celewicz, and
H. Koroniak, J. Am. Chem. Soc., 1990, 112, 363.
35 Hz, J
= 49.0 Hz). F NMR (CDCl ), δ: –102.5 (dd,
J = 71.0 Hz, Jcis = 27.5 Hz) and –116.4 (dd, =CF , J =
C,F
3
3
2
2
3
3
7
3
1.0 Hz, J
= 102.5 Hz); –173.8 (dd, =CF, J
= 102.5 Hz,
trans
trans
Jcis = 27.5 Hz). MS, m/z (Irel (%)): 148 [M]+ (100), 127 (30),
9
7 (31), 79 (46), 67 (17), 39 (35).
1
14. US Pat. 6 008 407; Chem. Abstr., 2000, 132, P51451z.
Compound 17. H NMR (CDCl ), δ: 2.31 (m, 3 H, Me);
3
6
2
6
.91 (m, 3 Н, Ar). 13C NMR (CDCl ), δ: 14.3 (t, Me, J
.9 Hz); 114.5 (d, C(4), JC,F = 17.3 Hz); 123.6 (dd, C(6), JC,F
=
=
3
C,F
.6 and 5.1 Hz); 126.1 (t, C(5), JC,F = 3.5 Hz); 127.3 (d, C(1),
Received April 15, 2004