First allylboration of organic compounds with the N{double bond, long}N double bond. Synthesis of N-allylpyrazolidines and allyl-1,2-diphenylhydrazine

Article abstract of DOI:10.1016/j.jorganchem.2009.02.012

Triallylborane adds to the N{double bond, long}N double bond of pyrazolines 1 and 2 at 0 °C giving after deboronation the corresponding N-allylpyrazolidines 4 and 5. Further transformations of allylpyrazolidine 4 including the cyclopropane ring opening we

Full text of DOI:10.1016/j.jorganchem.2009.02.012

Journal of Organometallic Chemistry 694 (2009) 2106–2109
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Journal of Organometallic Chemistry
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First allylboration of organic compounds with the N@N double bond.
Synthesis of N-allylpyrazolidines and allyl-1,2-diphenylhydrazine
Ivan P. Klimenko a, Andrey F. Medvedev a, Victor A. Korolev a, G.D. Kolomnikova b
Yury V. Tomilov a, Yuri N. Bubnov b,
*
a N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky Pr., 119991 Moscow, Russian Federation
b A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 Vavilov Str., 119991 Moscow, Russian Federation
a r t i c l e i n f o
a b s t r a c t
Article history:
Triallylborane adds to the N@N double bond of pyrazolines 1 and 2 at 0 °C giving after deboronation the
corresponding N-allylpyrazolidines 4 and 5. Further transformations of allylpyrazolidine 4 including the
cyclopropane ring opening were studied. Allylboration of azobenzene with triallylborane gives rise to 1-
allyl-1,2-diphenylhydrazine.
Received 18 September 2008
Received in revised form 9 February 2009
Accepted 13 February 2009
Available online 26 February 2009
Ó 2009 Elsevier B.V. All rights reserved.
Keywords:
Triallylborane
Allylboration
Azocompounds
Pyrazolines
N-Allylpyrazolidine
1-Allyl-1,2-diphenylhydrazine
1. Introduction
dimethylcyclopropene [4] was carried out at ꢀ5 to 0 °C in THF un-
der dry argon. The reaction was completed in 0.5 h to furnish the
The ability of b,
c
-unsaturated (allylic) organoboron derivatives
product 3, that was observed by 11B NMR spectroscopy of reaction
mixture, with only the Alk2B–N fragment signal (broad singlet at
42.7 ppm) observed [5]. Subsequent deboration with MeOH (cleav-
age of B–N-bond) gave rise to allylpyrazolidine 4 in 76% yield
(Scheme 1).
to add to organic compounds containing C@O, C@S, C@N, C@C,
C„C and N@O fragments is a unique property of this class of
organoboranes [1]. These addition reactions proceed with allylic
rearrangement via six-membered cyclic transition state
(2
p
+ 2
p
+ 2
r
type) and present a novel and facile carbon–car-
1H NMR spectra of compound 4 shows signals at d 5.99 ppm
(1H), 5.11–5.17 (2H), and 3.22–3.39 (2H) which are characteristic
for the allyl group, broad signal of NH-group at 3.83 ppm, two dou-
blets at d 2.90 and 1.69 ppm corresponding to H(1) and H(5),
respectively, and signals of two methyl groups and 4 protons of
spiro-fused cyclopropane ring at high field. A location of allyl group
in the pyrazolidine 4 was assumed on the basis of 2D NOESY spec-
tra where interaction of methylene protons of the allyl group at
3.22 ppm with one of the protons of spiro-fused cyclopropane ring
at 0.74 ppm was observed. This data and an absence of NOE cross-
peaks in pyrazolidine 4 between doublet signal corresponding to
H(1) and any signals of CH2CH@CH2 fragment confirms that allyl
group is attached to N atom adjacent to spirocyclopropane ring.
Pyrazolidine 4 is readily oxidized by air giving a mixture of
unidentified products that is typical for pyrazolidines with unsub-
stituted NH-fragment [6].
bon/carbon–heteroatom bond formation pathway. These reactions
proceed as easily as polarisation or strain of double bond increase
[2]. Allylboration of carbonyl compounds, imines and acetylenes is
widely explored in organic synthesis as a key step in synthesis of
nature products and their analogues [3].
In this paper we describe the first allylboration of pyrazoline
derivatives 1 or 2 and azobenzene, the compounds containing both
cis and trans N@N double bonds. Further transformations of allylic
pyrazolidine derivative 4 are also presented.
2. Results and discussion
2.1. Reaction of pyrazolines 1 and 2 with triallylborane
Addition of triallylborane to pyrazoline 1 synthesized by the
interaction of in situ generated diazocyclopropane with 3,3-
Allylboration of pyrazoline 2 available by the cycloaddition of
diazocyclopropane to styrene [7] was performed in THF at 0 °C.
After the treatment with methanol, pyrazolidine 5 was isolated
in 45% yield as colorless oil (Scheme 2). This compound is also
* Corresponding author. Tel.: +7 499 1356166; fax: +7 499 1355085.
E-mail addresses: bubnov@ineos.ac.ru, bor@ioc.ac.ru (Y.N. Bubnov).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.02.012

I.P. Klimenko et al. / Journal of Organometallic Chemistry 694 (2009) 2106–2109
2107
propane ring at N atom remote from the ring [8]. In addition this
nitrogen atom is less sterically hindered, which may also play an
auxiliary role.
Me
Me
Me
6
Me
5
2'
3'
1
4
1. BAll3 / THF / 0 °C
2. MeOH / 60 °C
2
3
NH
N
N
2.2. Spontaneous isomerisation of allylpyrazolidine 4
N
1
Compound 4 was believed to be stable in the absence of oxygen,
however after 6 months the compound appeared to have decom-
posed, as proton signals associated with this compound were not
observed in solution. The main product was identified as substi-
tuted 4,5-diazaspiro[2.4]hept-5-ene 7, that formed in a ꢁ70% yield
by a cleavage of C–C bond of condensed cyclopropane ring follow-
ing by hydrogen shift:
4, 76%
– All-B(OMe)2
– C3H6
BAll3
MeOH / 60 °C
Me
H
Me
Me
Me
H
H
H
H
Me
6
Me
N
N
N
Me
N
Me
BAll2
H
7
BAll2
5
1
6
1
20 °C, N2
6 months
3
4
3
2N
5 N
3
4
2
N
N
H
Scheme 1. Reaction of pyrazoline 1 with triallylborane.
easily oxidized in air. Storing a solution of pyrazolidine 5 in CDCl3
(0 °C, 6 days) results in the formation of allylpyrazoline 6 which
was isolated in 35% yield by TLC on silica gel (Scheme 2). A small
amount of colorless precipitate was also formed, but it was not
identified.
4
7, 70%
Interestingly, in this case the cleavage of the C(1)–C(6) bond of
bicyclic system, but not the bridge the C(1)–C(5) bond takes place.
2.3. Isomerization of allylpyrazolidine 4 under the action of
The main differences in 1H NMR spectra of compounds 5 and 6
are in the observed chemical shifts of the protons for heterocyclic
fragments. Thus in pyrazolidine 5 the three-spin system of H(6)
and two H(7) protons is observed as three doublet of doublets at
d 4.64, 2.56 and 2.00 ppm, while in pyrazoline 6 two protons at
C(7) give the singlet at d 3.16 ppm. In 13C NMR spectra signals of
C(6) atoms of pyrazolidine 5 and pyrazoline 6 show at 62.9 and
148.4 ppm, respectively.
Hg(OCOCF3)2
The structure of pyrazolidine 4 having several chemically active
centers provides an interesting possibilities for its further transfor-
mations involving, for example, the opening of one or both cyclo-
propane fragments. In this connection,
a mercuration of
pyrazolidine 4 was studied to compare a reactivity of double bound
of the allyl group and cyclopropane rings [9]. Moreover, in the case
of anti-Markovnikov addition of Hg(OCOCF3)2 to double bond as it
was previously observed for some other systems [10] it could hope
to prepare a tricyclic molecule by a following interaction of NH-
fragment with organo-mercury intermediate formed.
Reaction of pyrazolidine 4 with Hg(OCOCF3)2 was performed
under argon in dry acetonitrile at 0 °C for 2 h followed by treat-
ment with basic NaBH4 solution and organic compounds were ex-
tracted with Et2O. Spectral data of the reaction mixture show that
at least four products were formed in this reaction, but we were
able to isolate by column chromatography on silica gel and fully
identify only one of them, namely tetrahydropyridazine derivative
8 (21%, Scheme 3). According to 1H NMR spectra of 8, allyl group
was not involved in the reaction, while signals of both cyclopro-
pane rings disappeared.
A location of allyl group in the pyrazolidine 5 was also assumed
on the basis of 2D NOESY spectra where interaction of methylene
protons of the allyl groups at 3.33 ppm with one of the protons
of spiro-fused cyclopropyl ring at 0.98 ppm was observed. NOE
cross-peak was also observed in pyrazoline 6 between signal of al-
lyl CH2 group at 3.48 ppm and multiplet of cyclopropyl protons at
1.08 ppm.
Excellent regioselectivity of the triallylborane addition to pyraz-
olines 1 and 2 requires some comments. The most interesting is the
addition of All–B fragment to N@N bond of the compound 1, which
is substituted with cyclopropane rings of different nature – one
ring is spiro-fused, while another is presented as a part of bicyclic
system.
Regioselectivity of this reaction can be explained by the ability
of the electron density of spiro-fused cyclopropane ring, that is
perpendicular to the plane of pyrazoline ring to interact with
N@N double bond increasing electron density on nitrogen atom re-
mote from spiro-fused cyclopropane ring (i.e. on the N(2) atom in
the compound 1 or N(5) atom in the compound 2). This remote
nitrogen forms an initial complex with the boron atom of trially-
lborane molecule. It should be noted that other electrophiles also
attack pyrazoline 1 and other pyrazolines with spiro-fused cyclo-
The initial step of isomerisation of strained pyrazolidine 4 to
tetrahydropyridazine 8 is, probably, formation of complex of
Hg(OCOCF3)2 with less substituted nitrogen atom of pyrazolidine
followed by bonds reorganization and hydrogen migration
(Scheme 3).
1H NMR spectra of compound
8 shows narrow doublet
(J4,6 = 2.0 Hz) at 6.81 ppm relating to CH@N fragment and five
7
7
Ph
6
Ph
6
1
1
Ph
3
3
1. BAll3 / THF / 0 °C
O2 (air) / 0 °C
5
5 N
4
4
NH
2
2
N
N
N
2. MeOH / 60 °C
N
2
5, 45%
6, 35%
Scheme 2. Allylboration of pyrazoline 2.

2108
I.P. Klimenko et al. / Journal of Organometallic Chemistry 694 (2009) 2106–2109
eter (11B – 64.21 MHz, 13C – 50.32 MHz). The proton chemical
Me
N
Me
H
Me Me
shifts were referenced to Me4Si, which was added to solvent as
the internal standard. Carbon resonances were referenced to CDCl3
(d = 77.1 ppm) and the 11B NMR spectra to Et2O ꢂ BF3 (d = 0 ppm).
2D NMR spectra were obtained on a Bruker DRX-500 instrument.
The mass spectra were recorded on a Finnigan MAT INCOS-50
instrument (EI, 70 eV, direct inlet probe). Elemental analyses were
done with a Perkin–Elmer 2400 series II CHN analyzer. For chroma-
tography, silica gel 60 (0.040–0.063 mm; Merck) was used.
5
7
8
6
4
1. Hg(OCOCF3)2
2. NaBH4 / NaOH
N3
2
N
1
N
8, 21%
4
Me
Me
4.2. Synthesis of 3-allyl-6,6-dimethylspiro{2,3-
diazabicyclo[3.1.0]hexan-4,10-cyclopropane} (4)
.
Hg2+
Triallylborane (1.02 g, 7.6 mmol) was added dropwise at ꢀ5 to
0 °C over a period of 30 min to a stirred solution of 6,6-dimethyl-
.
N
N
H
spiro{2,3-diazabicyclo[3.1.0]hex-2-en-4,10-cyclopropane}
(1)
(1.04 g, 7.6 mmol) in 5 mL of THF. Then reaction mixture was al-
lowed to warm up to room temperature and aliquote for 11B
NMR spectra was taken. The only signal of 11B at 42.7 ppm was ob-
served indicating the formation of the compound 3 with B–N-bond
[5]. Then 2 mL of MeOH was added at 0 °C and a mixture was re-
Scheme 3. Isomerization of allylpyrazolidine 4 under the action of Hg(OCOCF3)2.
well-resolved signals of allyl group. Deshielding influence of nitro-
gen atom leads to down-field shift of the multiplet of H(1) at
3.52 ppm. Other multipletes of cyclobutane system occupy a re-
gion from 1.50 to 2.28 ppm. Using a C6D6 instead of CDCl3 as a sol-
vent for NMR spectroscopy provides to avoid overlapping of
multipletes of cyclobutane protons and effectively employ 2D
NMR experiments – NOESY, COSY and {C,H}-correlation – for anal-
ysis of spectral data. Structure of compound 8 is also confirmed by
13C NMR spectra in which 10 signals are observed.
fluxed for 1 h. Pyrazolidine
4 was isolated as colorless oil
(1.030 g, 76% yield), b.p. 33–34 °C/0.01 Torr.
Elemental Anal. Calc. for C11H18N2: C, 74.11; H, 10.18; N, 15.71.
Found: C, 73.81; H, 10.07; N, 15.63%. The partial mass spectrum, m/
z (Irel (%)): 177 [MꢀH]+ (46), 163 [MꢀNH]+ (27), 41 [C3H5] (100). 1H
NMR (CDCl3, d, ppm, J/Hz): 0.55 (d.d.d, 2J = 4.3, 3J = 6.7, 3J = 10.0, 1H,
H(3’)), 0.74 (d.d.d, 2J = 5.7, 3J = 6.7, 3J = 10.7, 1H, H(2’)), 0.84 (d.d.d,
2J = 5.7, 3J = 6.6, 3J = 10.0, 1H, H(7)), 0.94 (m, 4H, H(8) + CH3), 1.31
(s, 3H, CH3), 1.69 (d, 3J = 7.3, 1H, H(5)), 2.90 (d, 3J = 7.3, 1H, H(1)),
3.22 (d.d.t, 4J ꢃ 1.5, 3J = 5.7, 2J = 13.7, 1H, one of NCH2), 3.39
(d.d.t, 4J ꢃ 1.5, 3J = 6.9, 2J = 13.7, 1H, one of NCH2), 3.83 (br.s, 1H,
NH), 5.11 (br.d, 3J = 10.2, 1H, one of @CH2), 5.17 (br.d, 3J = 17.2,
1H, one of @CH2), 5.99 (d.d.d.d, 3J = 5.7, 3J = 6.9, 3J = 10.2, 3J = 17.2,
1H, @CH). 13C NMR (CDCl3, d, ppm): 8.10 (C(2’)), 14.50 (CH3),
14.63 (C(3’)), 25.17 (CH3), 31.12 (C(6)), 39.39 (C(5)), 49.62 (C(4)),
51.50 (C(1)), 59.16 (NCH2), 116.27 (@CH2), 136.82 (@CH).
2.4. Reaction of triallylborane with azobenzene
Contrary to pyrazolines 1 and 2, azobenzene exists predomi-
nantly in trans-configuration. Its reaction with triallylborane pro-
ceeds at 0 °C. Further deboronation with aqueous NaOH and
distillation in vacuo gives rise to 1-allyl-1,2-diphenylhydrazine
(9) [11] in 65% yield.
Ph
H
Ph
1. All3B /THF / 0 °C
2. MeOH / 30 °C
3. NaOH
4.3. Synthesis of 4-allyl-6-phenyl-4,5-diazaspiroheptane (5)
N
N
N
N
_
Ph
Ph
N-Allylpyrazolidine 5 was synthesized and isolated in the same
manner as described above for compound 4 starting from pyrazo-
line 2 (0.41 g, 2.4 mmol) and triallylborane (0.32 g, 2.4 mmol). For
initial adduct with B–N-bond a broad singlet at 43.3 ppm was ob-
served in 11B NMR spectra. Pyrazolidine 5 was obtained by distilla-
tion as colorless oil (0.23 g, 45% yield), b.p. 61–63 °C/0.01 Torr.
1H NMR (CDCl3, d, ppm, J/Hz): 0.64 (m, 1H, H(1)), 0.77 (m, 1H,
H(2)), 0.98 (m, 2H, H(1) + H(2)), 2.00 (d.d, 3J = 6.2, 2J = 12.7, 1H,
H(7)), 2.56 (d.d, 3J = 9.4, 2J = 12.7, 1H, H(7)), 3.29 (d.d.t, 4J ꢃ 1.5,
3J = 6.1, 2J = 13.8, 1H, one of NCH2), 3.33 (d.d.t, 4J ꢃ 1.4, 3J = 6.3,
2J = 13.8, 1H, one of NCH2), 4.12 (br.s, 1H, NH), 4.64 (d.d, 3J = 6.2,
3J = 9.4, 1H, H(6)), 5.11 (br.d, 3J = 10.2, 1H, one of @CH2), 5.19
9, 65%
3. Conclusion
Triallylborane allyborates the N@N double bond of pyrazolines
and azobenzene under mild conditions (ꢀ5 to 0 °C) to give after
deboronation N-allylpyrazolidines and allylhydrazine, respectively.
Rearrangement of allylpyrazolidine 4 into tetrahydropyridazine
derivative 8 in the presence of Hg(OCOCF3)2 proceeding via cleav-
age of both cyclopropane rings was observed. Compounds 4 and 5
are transformed spontaneously or under the action of O2 to 4,5-
diazaspiro[2.4]hept-5-enes (7) and (6), respectively.
4
(d.q, 2J ꢃ J ꢃ 1.7, 3J = 17.2, 1H, one of @CH2), 5.99 (d.d.t, 3J = 6.2,
3J = 10.2, 3J = 17.2, 1H, @CH), 7.27 (m, 3H, Ph), 7.41 (m, 2H, Ph).
13C NMR (CDCl3, d, ppm): 10.28 (C(2)), 13.96 (C(1)), 41.57 (C(7)),
50.76 (C(3)), 57.60 (NCH2), 62.94 (C(6)), 116.29 (@CH2), 126.98
(2 ꢄ C-ortho), 127.11 (C-para), 128.52 (2 ꢄ C-metha), 136.59
(@CH), 143.46 (C-ipso).
4. Experimental
4.1. Materials and instrumentation
All reactions were carried out under argon atmosphere. All the
reagents used were chemically pure and are of analytical reagent
grade. Triallylborane [3a] and pyrazolines 1 [4] and 2 [7] were pre-
pared as described previously. All solvents used in the reactions
were dried and freshly distilled. The 1H NMR spectra were re-
corded on a Bruker AM-300 spectrometer (1H – 300.13 MHz), 11B
and 13C NMR spectra were recorded on a Bruker AC-200 spectrom-
4.4. Isolation of 4-allyl-6-phenyl-4,5-diazospirohept-5-ene (6)
Solution of N-allylpyrazolidine 5 (43 mg, 0.2 mmol) in 0.4 ml of
CDCl3 was stored at 0 °C. Monitoring with 1H NMR spectroscopy
indicated gradual disappearance of compound 5 and growing of
signals of pyrazoline 6. The reaction was complete after 6 days.
Small amount of colorless precipitate was also formed, but its

I.P. Klimenko et al. / Journal of Organometallic Chemistry 694 (2009) 2106–2109
2109
structure was not determined. Reaction mixture was filtered, solu-
tion concentrated in vacuo and the residue was purified by pre-
parative TLC on silica gel using toluene–MeOH (30:1) as eluent
to give compound 6 (15 mg, 35% yield) as pale yellow oil.
CH3), 0.98 (s, 3H, CH3), 1.50 (m, 1H, H(7)), 1.65 (m, 1H, H(7)),
1.72 (m, 1H, H(8)), 1.87 (m, 1H, H(8)), 2.28 (m, 1H, H(6)), 3.44
(d.d.t, 4J ꢃ 1.1, 3J = 7.2, 2J = 14.3, 1H, one of NCH2), 3.52 (m, 1H,
H(1)), 3.98 (d.d.t, 4J ꢃ 1.7, 3J = 5.1, 2J = 14.3, 1H, one of NCH2),
5.09 (br.d, 3J = 10.2, 1H, one of @CH2), 5.17 (br.d, 3J = 17.2, 1H,
one of @CH2), 6.06 (d.d.d.d, 3J = 5.1, 3J = 7.2, 3J = 10.2, 3J = 17.2, 1H,
@CH), 6.81 (d, 4J = 2.0, H(4)). 13C NMR (CDCl3, d, ppm): 21.24
(C(7)), 22.09 (C(8)), 23.25 (2ꢄCH3), 31.67 (C(5)), 45.70 (C(6)),
53.94 (C(1)), 57.36 (NCH2), 116.74 (@CH2), 135.57 (@CH), 149.81
(C(4)).
Elemental Anal. Calc. for C14H16N2: C, 79.21; H, 7.60; N, 13.20.
Found: C, 79.36; H, 7.75; N, 12.94%. The partial mass spectrum,
m/z (Irel (%)): 212 [M]+ (14), 211 [MꢀH]+ (13), 197 [MꢀNH]+ (15),
183 [MꢀHꢀN2]+, 157 [MꢀC3H5N]+ (20), 51 (63), 41 [C3H5] (92),
39 (100). 1H NMR (CDCl3, d, ppm, J/Hz): 0.62 (m, 2H, H(1) + H(2)),
1.08 (m, 2H, H(1) + H(2)), 3.16 (s, 2H, H(7)), 3.48 (d.t, 4J ꢃ 1.5,
4
3J = 6.1, 2H, NCH2), 5.14 (d.q, 2J ꢃ J ꢃ 1.5, 3J = 10.3, 1H, one of
4
@CH2), 5.24 (d.q, 2J ꢃ J ꢃ 1.6, 3J = 17.3, 1H, one of @CH2), 6.05
4.7. Synthesis of 4-allyl-1,2-diphenylhydrazine (9)
(d.d.t, 3J = 6.1, 3J = 10.3, 3J = 17.3, 1H, @CH), 7.32 (m, 3H, Ph), 7.61
(m, 2H, Ph). 13C NMR (CDCl3, d, ppm): 8.65 (C(1) + C(2)), 41.91
(C(7)), 47.91 (C(3)), 52.13 (NCH2), 116.62 (@CH2), 125.52 (2 ꢄ C-
ortho), 128.31 (2 ꢄ C-metha), 128.46 (C-para), 133.16 (C-ipso),
135.59 (@CH), 148.43 (C(6)).
Triallylborane (2.42 g, 18 mmol) was added to azobenzene
(3.28 g, 18 mmol) at 0 °C and the reaction was warmed to room
temperature; a clean solution was formed in several minutes.
Methanol (3 ml) was added dropwise at 30 °C. Further treatment
with aqueous NaOH (10%, 7 ml), extraction with ether, drying
and distillation gave rise to 1-allyl-1,2-diphenylhydrazine (9) in
65% yield, b.p. 98–100 °C/0.03 Torr. 1H NMR (CDCl3, d, ppm, J/
4.5. Isolation of 4-allyl-7-iso-propyl-4,5-diazospirohept-5-ene (7)
4
Hz): 4.10 (br.s, 2H, NCH2), 5.20 (d.q, 2J ꢃ J ꢃ 1.5, 3J = 17.0, 1H,
Pyrazolidine 4 (287 mg, 1.6 mmol) was kept under Ar at room
temperature for 6 months; 1H NMR spectra showed that it had
decomposed almost completely with formation of several prod-
ucts. The yield of main product – pyrazoline 7 – was estimated
as 60–70% based on data of 1H NMR spectra. It was isolated as pale
yellow oil (111 mg, 39% yield) by column chromatography on silica
gel using petrol ether–AcOEt (10:1) as eluent.
4
one of @CH2), 5.24 (d.q, 2J ꢃ J ꢃ 1.4, 3J = 10.4, 1H, one of @CH2),
3
5.65 (br.s, 1H, NH), 5.87 (d.d.t, 3J ꢃ 5.9, 3J = 10.4, J = 17.0, 1H,
@CH), 6.80 (m, 4H, Ph), 6.97 (m, 2H, Ph), 7.20 (m, 4H, Ph). 13C
NMR (CDCl3, d, ppm): 53.46 (NCH2), 112.82 and 113.15 (4C-ortho),
118.87 and 119.91 (2C-para), 118.91 (@CH2), 129.24 and 129.42
(4C-metha), 131.89 (@CH), 147.43 and 149.77 (2C-ipso). Lit. [11].
Elemental Anal. Calc. for C11H18N2: C, 74.11; H, 10.18; N, 15.71.
Found: C, 73.96; H, 10.11; N, 15.58%. The partial mass spectrum, m/
z (Irel (%)): 177 [MꢀH]+ (16), 135 [MꢀC3H7]+ (22), 41 [C3H5] (100).
1H NMR (CDCl3, d, ppm, J/Hz): 0.24 (d.d.d, 2J = 5.5, 3J = 7.3, 3J = 10.0,
1H, H(1)), 0.86 (m, 2H, H(2) + H(2)), 0.95 (d, 3J = 6.9, 3H, CH3), 0.97
(d, 3J = 6.9, 3H, CH3), 1.07 (d.d.d, 2J = 5.5, 3J = 6.7, 3J = 10.5, 1H, H(1)),
1.67 (d.sept, 3J = 4.1, 3J = 6.9, 1H, CH), 2.77 (d.d, 3J = 1.7, 3J = 4.1, 1H,
H(7)), 3.29 (d.d.t, 4J ꢃ 1.6, 3J = 5.9, 2J = 14.4, 1H, one of NCH2), 3.33
(d.d.t, 4J ꢃ 1.6, 3J = 6.1, 2J = 14.4, 1H, one of NCH2), 5.12 (d.q,
Acknowledgements
This work was supported by the President of Russian Federation
(Sci. School No. 3834.2008.3), Russian Foundation for Basic Re-
search (grant No 08-03-00790), and Presidium of RAS (No. 18,
coordinator – V.A. Tartakovsky).
References
4
4
2J ꢃ J ꢃ 1.6, 3J = 10.2, 1H, one of @CH2), 5.22 (d.q, 2J ꢃ J ꢃ 1.6,
3J = 17.2, 1H, one of @CH2), 5.96 (d.d.t, 3J ꢃ 6.0, 3J = 10.2, 3J = 17.2,
1H, @CH), 6.71 (d, 3J = 1.7, 1H, (H(6)). 13C NMR (CDCl3, d, ppm):
3.80 (C(2)), 9.62 (C(1)), 17.93 (CH3), 21.10 (CH3), 28.89 (CH),
49.02 (C(3)), 51.95 (NCH2), 58.57 (C(7)), 116.41 (@CH2), 135.73
(@CH), 141.65 (C(6)).
[1] Yu.N. Bubnov, Pure Appl. Chem. 59 (1987) 895.
[2] Yu.N. Bubnov, in: D. Kaufmann, D.S. Matteson (Eds.), Science of Synthesis,
Houben–Weyl Methods of Molecular Transformations. Organometallics: Boron
Compounds, vol. 1, Georg Thieme, Stuttgart, 2004, pp. 945–1072 (Chapter 35).
[3] (a) B.M. Mikhailov, Yu.N. Bubnov, Organoboron Compounds in Organic
Synthesis, Harwood Acad. Sci. Publ., London, 1984;
(b) Y. Yamamoto, N. Asao, Chem. Rev. 93 (1993) 2207;
(c) D.S. Matteson, Stereodirected Synthesis with Organoboranes, Springer,
Berlin, 1995;
4.6. Isomerization of pyrazolidine 4 into 8 with Hg(OCOCF3)2
(d) P.V. Ramachandran, M.V.R. Reddy, H.C. Brown, in: Boron Chemistry at the
Beginning of the 21st Century, Editorial URSS, Sci. Publ., Moscow, 2002.
[4] Yu.V. Tomilov, E.V. Shulishov, O.M. Nefedov, Izv. AN SSSR, Ser. Khim. (1991)
1057 [Bull. Acad. Sci. USSR. Div. Chem. Sci., Int. Ed. 40 (1991) 939 (Engl.
Transl.)].
To a stirred solution of pyrazolidine 4 (178 mg, 1.0 mmol) in
20 mL of dry CH3CN at ꢀ5 °C was added dropwise solution of
Hg(OCOCF3)2 (640 mg, 1.5 mmol) in 4 mL of dry CH3CN and stirring
was continued for 2 h at 0 °C, then a solution of NaBH4 (76 mg,
2 mmol) in 2 mL of 3 N aqueous NaOH was added. After 40 min
at 0 °C, 50 ml of saturated aqueous NaHCO3 was added and prod-
ucts was extracted with Et2O (4 ꢄ 20 mL). Organic layers was com-
bined, dried over Na2SO4, then Et2O was evaporated in vacuo and
residue was separated by column chromatography on silica gel
using gradient elution with petrol ether–EtOAc (40:1 to 5:1).
2-Allyl-5,5-dimethyl-2,3-diaza-bicyclo[4.2.0]oct-3-ene (8) was
isolated as colorless oil (36 mg, 21%).
[5] H. Nöth, B. Wrackmeyer, Nuclear Magnetic Resonance Spectroscopy of Boron
Compounds, Springer-Verlag, Berlin-Heidelberg, NY, 1978.
[6] C.H. Jarboe, in: R.H. Wiley (Ed.), The Chemistry of Heterocyclic Compounds,
vol. 22, Interscience Publishers, New York – London – Sydney, 1967, p. 284.
[7] Yu.V. Tomilov, I.V. Kostyuchenko, E.V. Shulishov, B.B. Averkiev, M.Yu. Antipin,
O.M. Nefedov, Izv. AN. Ser. Khim. (1999) 1328 [Russ. Chem. Bull., Int. Ed. 48
(1999) 1316].
[8] (a) Yu.V. Tomilov, G.P. Okonnishnikova, E.V. Shulishov, O.M. Nefedov, Izv. AN.
Ser. Khim. (1994) 1993 [Russ. Chem. Bull., Int. Ed. 43 (1994) 1880];
(b) Yu.V. Tomilov, G.P. Okonnishnikova, E.V. Shulishov, O.M. Nefedov,
Mendeleev Commun. (1994) 119.
[9] S. von Angerer, in: A. De Meijere (Ed.), Houben–Weyl Methods of Organic
Chemistry, vol. E17c, George Thieme Verlag, Stuttgart, 1997, pp. 1972–1977
(Chapter 2.1.1).
[10] S. Deloise, H. Tietgen, H. Kunz, Collect. Czech. Chem. Commun. 65 (2000) 816.
[11] K. Berg-Nielsen, E. Bernatek, Acta Chem. Scand. 26 (1972) 4130.
Elemental Anal. Calc. for C11H18N2: C, 74.11; H, 10.18; N, 15.71.
Found: C, 73.96; H, 10.38; N, 15.60%. The partial mass spectrum, m/
z (Irel (%)): 178 [M]+ (11), 149 [MꢀC2H5]+ (13), 135 [MꢀC3H7]+
(100), 41 [C3H5] (84). 1H NMR (C6D6, d, ppm, J/Hz): 0.73 (s, 3H,