Synthesis of Spiro[2.2]pentanes and Spiro[2.3]hexanes Employing the Me3Al/CH2I2 Reagent

Article abstract of DOI:10.1002/ejoc.201700991

Substituted alkylidenecyclopropanes reacted with 5 equivalents each of Me₃Al and CH₂I₂ at room temperature in hexane to give 1-mono- and 1,1-disubstituted spiro[2.2]pentanes in high yields. Surprisingly, the same reaction

Full text of DOI:10.1002/ejoc.201700991

A Journal of
Accepted Article
Title: Synthesis of Spiro[2.2]pentanes and Spiro[2.3]hexanes
Employing the Me3Al/CH2I2 Reagent
Authors: Ilfir R Ramazanov, Rita N Kadikova, Tat’yana P Zosim, Usein
M Dzhemilev, and Armin de Meijere
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To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201700991
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10.1002/ejoc.201700991
European Journal of Organic Chemistry
FULL PAPER
Synthesis of Spiro[2.2]pentanes and Spiro[2.3]hexanes
Employing the Me3Al/CH2I2 Reagent
Ilfir R. Ramazanov,*[a] Rita N. Kadikova,[a] Tat’yana P. Zosim,[a] Usein M. Dzhemilev[a] and Armin de
Meijere [b]
Abstract: Substituted alkylidenecyclopropanes reacted with
5
spiropentane-annelated cyclononane in 95% yield in one step
with the Et3Al/CH2I2 reagent. In contrast, the cyclopropanation of
1,2-cyclononadiene with CH2N2 in the presence of a palladium
catalyst involved only one double bond to give bicyclo[7.1.0]dec-
1-ene in 70% yield.[27,28] Repeated treatment of the latter with
CH2N2/[Pd(acac)2] gave the tricyclic spiropentane derivative in a
yield of only 15%. The reaction of phenylallene with
CH2N2/[Pd(OAc)2] gave only benzylidenecyclopropane in a yield
of 50%.[28] The use of Et3Al/CH2I2 allows one to prepare 1-
phenylspiro[2.2]pentane in quantitative yield. Accordingly,
aluminum carbenoids can be assumed to be active enough to
react with intermediately formed cyclopropylidene derivatives. It
is known that the relatively bulky zinc carbenoid impedes the
equivalents each of Me3Al and CH2I2 at room temperature in hexane
to give 1-mono- and 1,1-disubstituted spiro[2.2]pentanes in high
yields. Surprisingly, the same reaction with substituted
alkylidenecyclopropanes in CH2Cl2 afforded exclusively 1,1-
disubstituted spiro[2.3]hexanes. The transformation of 1,1-
diphenylspiro[2.2]pentane into 1,1-diphenylspiro[2.3]hexane was
studied with the use of CD2I2 and a plausible mechanism was
suggested. The reaction of substituted alkylidenecyclobutanes with
the Me3Al/CH2I2 reagent in CH2Cl2 gave only 1,1-disubstituted
spiro[2.3]hexanes.
cyclopropanation
of
sterically
hindered
alkenes.
Introduction
Bicyclopropylidenes and bicyclobutylidenes showed low
reactivity towards zinc carbenoids.[29,30] [3]Triangulane was
obtained in 5-15% yield using Zn/Cu and Zn/Ag couple from
vinylidenecyclopropane.[31] Thus, the cyclopropanation of
sterically congested alkenes with zinc carbenoids appears to be
problematic. Therefore it was of interest to examine aluminum
carbenoids in the reaction with alkylidenecyclopropanes and -
cyclobutanes.
The pioneering works of Simmons and Smith have revealed the
rich potential of zinc carbenoids in the synthesis of cyclopropane
compounds and gave a powerful impetus to the development of
new cyclopropanating agents.[1–11] Due to the use of readily
available precursors and reagents as well as the simplicity of the
procedure, the so-called Simmons-Smith reaction and its
analogues became extremely popular. However, it turned out
that carbenoids of other metals can also be useful.
Samarium(III) carbenoids can react with α-haloketones and 1,4-
diketones,[12–14] enolates,[15] esters[14,16] to give cyclopropanols.
The reaction of carbonyl compounds with Sm/CH2I2 gave
iodohydrins in good yields.[12,13,17] Samarium(III) carbenoids are
effective agents for the cyclopropanation of substituted allyl and
allenyl alcohols which proceed under mild conditions with high
diastereoselectivities.[18–21] Indium can insert into a carbon-
halogen bond of dibromosubstituted carbonyl compounds or
nitriles to give indium carbenoids that react with alkenes to
afford substituted cyclopropanes.[22,23] Aluminum carbenoids can
transform alkynes into substituted cyclopropanes in one
step.[24,25] As can be seen, each metal offers unique synthetic
possibilities. Previously we have noticed that aluminum
carbenoids can easily form spiropentanes from substituted
allenes with high steric demand.[26] Thus the twofold
Results and Discussion
The
experimental
tests
showed
that
substituted
alkylidenecyclopropanes 1a-i upon treatment with 5 equivalents
each of Me3Al and CH2I2 in hexane at room temperature for 18 h
furnish the corresponding spiropentanes 2a-i with high
selectivities in yields ranging from 62 to 82% (Scheme 1).
With smaller amounts of Me3Al and CH2I2 the conversion of the
alkylidenecyclopropanes
(diphenylmethylene)cyclopropane (1a) with 2 equivalents each
of Me3Al and CH2I2 within 18 gave 1,1-
decreases,
e.g.
h
diphenylspiro[2.2]pentane (2a) in 48% yield. This indicates a
lower reactivity of alkylidenecyclopropanes compared to less
substituted ethylenes.[32] According to RHF/6-31G(d,p)
calculations, the global index of nucleophilicity decreases in the
series: 2,3-dimethylbut-2-ene (10.2) > 2-methylprop-1-ene (6.9)
> propan-2-ylidenecyclopropane (6.8) > 1-octene (5.9) > propan-
2-ylidenecyclobutane (5.5) > 1,1'-bi(cyclopropylidene) (4.9) >
styrene (4.3). The global index of nucleophilicity was calculated
as 1/(the global index of electrophilicity).[33] The given order of
alkenes correctly reflects our understanding of the electronic
effects of substituents. However, according to B3LYP/6-31G(d)
computations, the calculated free activation energy for the
cyclopropanation with Me2AlCH2I increased in the order: 2-
cyclopropanation
of
1,2-cyclononadiene
afforded
the
[a]
[b]
Laboratory of Catalytic Synthesis, Institute of Petrochemistry and
Catalysis of RAS (IPC RAS), Prospect Oktyabrya, 141, 450075, Ufa,
Russian Federation.
E-mail: mailto:ilfir.ramazanov@gmail.com
Institut für Organische und Biomolekulare Chemie der Georg-
August-Universität Göttingen, Tammannstrasse 2, 37077 Göttingen,
Germany.
Supporting information for this article is given via a link at the end of
the document.
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700991
European Journal of Organic Chemistry
FULL PAPER
methylprop-1-ene (21.4 kcal/mol) < prop-1-ene (22.2 kcal/mol) <
compared to four in organoaluminum compounds. Moreover, the
Zn atom is coordinated by bulky ether molecules of the solvent.
It is known that the use of chlorinated solvents, e.g.
dichloromethane, increases the stability of intermediate
aluminum carbenoids[32] that might allow one to decrease the
amount of the organometallic reagent. Surprisingly, when
dichloromethane was used as a solvent instead of hexane,
2,3-dimethylbut-2-ene
(24.7
kcal/mol)
≈
propan-2-
ylidenecyclopropane (24.7 kcal/mol) < 1,1'-bi(cyclopropylidene)
(25.4 kcal/mol). Apparently, the reactivity of unsaturated
substrates in the reaction is largely determined by steric
constraints arising in the transition state. Indeed, the analysis of
the geometry of the transition state shows that the plane of the
π-bond and the plane passing through the Al-C(H2)-I atoms of
the aluminum carbenoid are not parallel in the case of
tetrasubstituted alkenes (Figure 1). This deviation results in an
increase of the activation energy of the cyclopropanation
reaction.
treatment of (diphenylmethylene)cyclopropane 1a with
5
equivalents each of Me3Al and CH2I2 within 8 h unexpectedly led
to 4,4-diphenylspiro[2.3]hexane (3a) in 78% yield (Scheme 2).
The conversion of the starting material 1a was more than 90%
after 3 h. According to GC analysis of the reaction mixture, the
yield of the products 2a and 3a was 82 and 11%, respectively.
However the content of the spiro[2.3]hexane 3a in the reaction
mixture after 8 h was 85% (by GC). The conversion of the
alkylidenecyclopropane 1b into the spiro[2.3]hexane 3b
proceeds much more slowly than that to the spiro[2.2]pentane
2b in hexane. The content of 3b reached 77% (by GC) only in 2
I
Al
5
CH2 2
equiv)
equiv)
(
R1
R2
Me
(5
3
R1
R2
rt,
18 h
hexane,
1a-i
2a-i
days. Cycloalkylidenecyclopropanes 1g-i showed
a similar
reactivity. However, alkylidenecyclopropane 1c was reactive
enough to afford spiro[2.3]hexane 3c in 79% isolated yield within
18 h. Contrary to our expectations, monosubstituted
alkylidenecyclopropanes 1d,e and 1,1'-bi(cyclopropylidene) 1f
gave only the spiro[2.2]pentanes 2d-f in 52-78% yield.
2
a
R1
R2
%
Ph
Ph
-Bu
Ph
80
75
81
73
67
62
77
82
76
n
n
b
c
-Bu
Me
H
n
d
e
-Hept
e u v
H I 5 q
C
i
)
)
-M
H
p
H
eOC6
4
(
e2 2
e u v
R1
R2
M A 5 q
l
i
(
-
3
f
-(CH2)2
-
-
g
h
i
-
,
,
(CH2)4
-
r
t
H
42
h
C
2Cl2
8
R1 R2
-
(CH2)5
1
3
2-adamantylidene
,
R1
R2
me
T
i
3
a
h
%
Scheme 1. Cyclopropanation of alkylidenecyclopropanes with Me3Al and
CH2I2 in hexane.
P
n
P
n
7
8
h
h
8
-
-
u
u
b
c
B
B
42
69
e
M
P
h
-
1
8
7
9
-
g
h
i
H
42
42
42
C
8
1
(
)
2 4
Al
H
I
I
-
-
H
C
68
83
(
)
2 5
2C
-
Al
a aman
ene
t
2
y
lid
d
Scheme 2. Cyclopropanation of alkylidenecyclopropanes with Me3Al and
CH2I2 in hexane.
Top
view
Figure 1. The transition state of the cyclopropanation reaction of
tetrasubstituted ethylenes.
Doering et al. have shown that methylene, generated by
irradiation of diazomethane, does not insert into the carbon-
carbon bonds of spiro[2.2]pentane, but only leads to 1-
methylspiro[2.2]pentane by carbon-hydrogen bond insertion.[36]
In order to learn more about the mechanism of the above
The Me3Al/CH2I2 reagent showed a higher reactivity than the
Simmons-Smith reagent Zn(Cu)/CH2I2 in the cyclopropanation of
1,1'-bi(cyclopropylidene). It can be linked to a lower activation
energy for the reaction of the alkene with an aluminum
carbenoid than with a zinc carbenoid. According to B3LYP/6-
311G(d,p) calculations, the activation energy of the reaction of
ethylene with Me2AlCH2I is 12.8 kcal/mol and that with IZnCH2I
is 21.2 kcal/mol.[34] In addition, the lower activity of zinc
carbenoids may be associated with its greater bulkiness since
the coordination number of Zn in RZnX structures reaches six[35]
reaction
leading
to
spiro[2.3]hexanes
we
used
dideuteriodiiodomethane in connection with trimethylaluminum
to react with 1,1-diphenylspiro[2.2]pentane 2a. Surprisingly, the
deuterium labels showed up on the cyclopropane ring of the
product 4,4-diphenylspiro[2.3]hexane-1,1-d2 (3a-D2) (Scheme 3).
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10.1002/ejoc.201700991
European Journal of Organic Chemistry
FULL PAPER
I
Al
5
CD2 2
equiv)
equiv)
(
AlMe2
D
Me
(5
3
H
D
H
H
H
H
H
Ph
Ph
AlMe2
H
H
H
H
H
H
AlMe2
rt,
CH Cl
24 h
H
,
5a
2
2
Ph
Ph
-D
H
Ph
Ph
77%
Ph
Ph
Ph
Ph
2a
3a
2
Ph
2a
4a
−
AlMe2
Scheme 3. Reaction of 1,1-diphenylspiro[2.2]pentane 2a with Me3Al/CD2I2
reagent.
D
Me
I
H
H
2AlCD2
D
−
Me
2AlI
Ph
6a
Ph
Ph
The observed dependence of the reaction rate on the character
of the substituents on the methylenecyclopropanes suggests an
ionic reaction mechanism. The carbon-carbon double bond
cyclopropanation is accompanied by the release of an equimolar
-D
3a
2
Scheme 4. Proposed mechanism for the transformation of spiro[2.2]pentanes
into spiro[2.3]hexanes.
amount of dimethylaluminum iodide which can trigger
a
subsequent transformation of the initially formed
The newly discovered virtual ring expansion of one of the
cyclopropane rings in spiro[2.2]pentanes in situ formed from
alkylidenecyclopropanes prompted us to subject the
homologous disubstituted methylenecyclobutanes 7 to the same
conditions. Yet, treatment of 1’,1’-diphenylmethylenecyclobutane
(7a) with 5 equivalents each of Me3Al and CH2I2 in CH2Cl2 for 18
h cleanly led to 1,1-diphenylspiro[2.3]hexane (8a) in 79% yield
(Scheme 5). It is remarkable that according to a qualitative
kinetic study, the alkylidenecyclobutane 7a is ~6 times less
reactive than the corresponding alkylidenecyclopropane 1a. No
traces of byproducts could be detected in the reaction mixture of
7a. Although the strain energy of 8a is not much lower than that
of 2a and the nucleophilicities of the diphenylcyclopropyl groups
in 8a and in 2a should also be very similar, the reactivity of 8a
towards the Me3Al/CH2I2 reagent apparently is much lower. This
cannot be due to steric effects, as the Me3Al/CH2I2 reagent is
effective for the cyclopropanation of even sterically congested
alkylidenecyclobutanes, such as the adamantylidene derivative
7i. This is understandable, because a cyclobutyl instead of a
cyclopropyl group in a carbocationic intermediate of type 4a
does far less efficiently delocalize the adjacent charge.[42]
Therefore, such a cyclobutylcarbinyl intermediate would not be
as easily formed from the spiro[2.3]hexane 8a as 4a is formed
from the spiro[2.2]pentane 2a. This prevents the substituted
spiro[2.2]pentanes 2. Dimethylaluminum iodide can also be
formed by a thermal decomposition of the aluminum carbenoid.
The degree of dissociation of the aluminum iodide should be
higher in a more polar solvent. Fukui indices were used to
estimate
local
nucleophilicities
in
1,1-
dimethylspiro[2.2]pentane.[37] According to B3LYP/6-31G(d,p)
computations there are two potential sites for electrophilic attack
located at the dimethyl-substituted cyclopropane ring. We
supposed that the electrophilic attack of the Me2Al+ species will
preferably occur at the methylene carbon atom of the diphenyl-
substituted cyclopropane ring in 2a to give an intermediate
carbocation 4a stabilized by a cyclopropyl and two phenyl
groups (Scheme 4). It is well known that a cyclopropyl group
significantly stabilizes a carbenium ion and in this respect is
even more efficient than a phenyl substituent.[38] Subsequent
ring-enlarging rearrangement gives the trisubstituted cyclobutyl
cation 5a which can cleave off the Me2Al+ cation with the aid of a
nucleophilic
iodide
ion
to
yield
2,2-
diphenylmethylenecyclobutane 6a. Reaction of the latter with the
aluminum carbenoid then affords the product 3a-D2. It should be
noted that the ring-enlarging rearrangement of (1-
methylcyclopropyl)carbinyl to 1-methylcyclobutyl cation is well
documented.[39] Moreover, the mechanism proposed in Scheme
4 is in accord with a study on the gas-phase protonation of
spiropentane which leads to the formation of (1-
methylcyclopropyl)carbinyl cation and its rearrangement into 1-
methylcyclobutyl cation.[40] Thus, the factors contributing to the
stabilization of the carbocation center in the intermediate 4a
accelerate the transformation of spiro[2.2]pentanes into
spiro[2.3]hexanes. It also explains the lack of reactivity of the
spiro[2.2]pentanes 2d-f because the attack of the
dimethylaluminum cation would lead to the secondary cations in
the case of 2d,e as well as a cyclopropyl cation from 2f, and all
these would be less stable than the tertiary cations formed from
2a-c and 2g-i. In fact, the activation energy for the formation of
an intermediate secondary cyclopropyl cation is the highest of all
spiro[2.3]hexane 8a from undergoing
a
ring enlargement
reaction.
I
Al
5
CH2 2
equiv)
equiv)
(
R1
R2
Me
(5
3
R1
rt,
18 h
hexane,
R2
8
7
8
a
R1
R2
Ph
Ph
-
%
79
67
76
82
86
Ph
c
Me
h
i
-(CH2)5
2-adamantylidene
for
cycloalkyl
cations
from
the
corresponding
p-
toluenesulfonates in SN1 solvolysis reaction.[41]
-
j
-(CH2)3
Scheme 5. Cyclopropanation of alkylidenecyclobutanes with Me3Al and CH2I2.
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10.1002/ejoc.201700991
European Journal of Organic Chemistry
FULL PAPER
8
9
7
2
9
2
7
The observed formal homologation of spiro[2.2]pentanes into
3
8
4
6
spiro[2.3]hexanes represents the first example of
a non-
1
3
4
1
10
6
11
17
transition metal-catalyzed cleavage of a carbon-carbon bond in
spiropentanes. To recognize distinctive features of aluminum
salts, we computed the cationic complexes Me2Al(+)*ClCH2Cl,
MeMg(+)*Me2O and MeZn(+)*Me2O at the RHF/6-31G(d,p) level
of theory. The NBO charge of the metal atom decreased in the
following order: Me2Al(+)*ClCH2Cl (+1.91 au) > MeMg(+)*Me2O
(+1.57 au) > MeZn(+)*Me2O (+1.43 au). It is possible that a
higher charge on the aluminum atom promotes the cleavage of
the carbon-carbon bond. The main factors contributing to the
transformation of spiro[2.2]pentanes into spiro[2.3]hexanes are:
i) the reaction between the Me2Al(+) cation and
spiro[2.2]pentane is facilitated by favorable charge stabilizations;
ii) the (1-methylcyclopropyl)carbinyl to 1-methylcyclobutyl cation
rearrangement has a low activation barrier.
12
5
10
5
16
13
12
2b
11
a
2
15
14
13
8
7
2
3
2
9
1
11
9
7
3
4
6
12
10
8
6
1
10
4
11
5
12
5
2d
c
2
2
4
7
2
6
3
1
1
3
8
6
4
5
5
1
7
3
6
9
7
6
5
2
4
8
11
2f
e
2
2g
9
10
O
2
Conclusions
4
3
7
9
12
8
1
8
12
5
7
6
5
13
Thus, we report an efficient method for the preparation of
substituted spiro[2.2]pentanes and spiro[2.3]hexanes from
10
1
3
2i
11
14
4
substituted
alkylidene-cyclopropanes
and
9
10
2
2h
alkylidenecyclobutanes under the action of CH2I2 and Me3Al.
Figure 2. Numbering of atoms in the reported 13С- and 1H-NMR spectral
data of the compounds 2a-2i.
1,1-Diphenylspiro[2.2]pentane (2a).[46] To a solution of 0.413 g (2 mmol)
of (diphenylmethylene)cyclopropane and 0.80 mL (10 mmol) of CH2I2 in
hexane (8 mL), was added 1 mL (10 mmol) of Me3Al (caution:
organoaluminums are pyrophoric and can ignite on contact with air, water
or any oxidizer) at 0 oC under an argon atmosphere. The mixture was
stirred at room temperature for 18 hours. Then, the reaction mixture was
diluted with 5 mL of CH2Cl2, and 3 mL of water was added dropwise
while cooling the flask in an ice bath. The precipitate was collected on a
filter paper. The aqueous layer was extracted with diethyl ether (3×5 mL).
The combined organic layers were washed with brine (10 mL), dried over
anhydrous CaCl2 and concentrated in vacuo to give the crude product as
a colorless oil. The residue was distilled through a micro column at a
pressure of 1 mm Hg to give 2a (0.35 g, 80%) as a colorless oil. b.p. 121-
122 oC (1 mm Hg). 1H NMR (δ, ppm): 1.00-1.08 (m, 2 Н, C(4)HA,C(5)HA),
1.08-1.15 (m, 2 Н, C(4)HB, C(5)HB), 1.78 (s, 2 Н, C(2)H2), 7.00-7.53 (m,
10 Н, Ph). 13C NMR (δ, ppm): 7.0 (2 С, C(4,5)), 24.8 (C(3)), 25.0 (C(2)),
33.1 (C(1)), 125.8 (2 C, C(9,15)), 128.1 and 128.5 (4 C and 4 C,
C(7,11,13,17) and C(8,10,14,16)), 144.7 (2 C, C(6,12)). Mass m/z (%):
220 (20) [M]+, 205 (87), 191 (100), 165 (53), 142 (19), 129 (74), 115 (45),
91 (6).
Experimental Section
General remarks
The reagents were purchased from Sigma-Aldrich or Acros.
Dichloromethane and hexane were distilled over P2O5.
Cyclopropylidenealkanes 1a-i were prepared by Wittig olefination
reactions of the corresponding aldehydes and ketones upon treatment
with 3-bromopropyltriphenylphosphonium bromide and t-BuOK.[43]
Cyclobutylidenealkanes 7a, 7c, 7h, 7i were prepared in an analogous
manner
bromobutyltriphenylphosphonium
Bi(cyclobutylidene) 7j
from
the
corresponding
bromide and
was prepared
ketones,
t-BuOK.
from
4-
1,1'-
3-
bromopropyltriphenylphosphonium bromide and t-BuOK in 50% yield.[44]
Nuclear Magnetic Resonance spectroscopy was performed on a Bruker
Avance 400 instrument. The 1H NMR spectra were recorded at 400 MHz
and 13C NMR spectra at 100 MHz in CDCl3. The chemical shifts are
reported in parts per million relative to tetramethylsilane (TMS) as the
internal standard. The numbering of atoms in the 13С- and 1H-NMR
spectra of the compounds 2a-2i, 3a-3c, 3g-3i, 8a, 8c and 8h-8j. are
shown in Figures 2, 3 and 4. Elemental analyses were performed using a
Carlo-Erba CHN 1106 elemental analyser. Mass spectra were recorded
on a Finnigan 4021 instrument. The yields were calculated from the
isolated amount of substituted spiro[2.2]pentanes and spiro[2.3]hexanes
obtained from starting substituted alkylidenecyclopropanes and
alkylidenecyclobutanes. All quantum chemical calculations were
performed using the B3LYP/6-31G(d) basis set as implemented in the
Gaussian 09 software.[45]
1,1-Dibutylspiro[2.2]pentane (2b). Using the procedure described above,
0.332 g (2 mmol) of nonan-5-ylidenecyclopropane gave a crude product
that was distilled through a micro column at 5 mm Hg to afford 2b (0.27 g,
75%) as a colorless oil. b.p. 80-83 oC (5 mm Hg). 1H NMR (δ, ppm, J/Hz):
0.55 (br.s., 2 Н, C(2)H2), 0.60-0.67 (m, 2 Н, C(4)HA, C(5)HA), 0.67-0.75
(m, 2 Н, C(4)HB, C(5)HB), 0.91 (t, J = 6.7, 6 H, C(9,13)H3), 1.05-1.55 (m,
12 Н, C(6-8,10-12)H2). 13C NMR (δ, ppm): 4.3 (2 С, C(4,5)), 14.2 (2 C,
C(9,13)), 18.6 (C(2)), 23.2 (2 C, C(8,12)), 28.6 (2 C, C(7,11)), 34.5 (2 С,
C(6,10)), 20.9 (C(3)), 23.1 (C(1)). Mass m/z (%): 180 (<1) [M]+, 165 (1),
151 (13), 137 (6), 123 (35), 109 (36), 95 (100), 81 (96), 67 (68), 55 (52).
Anal. calcd for C13H24, %: C, 86.6; H, 13.4. Found, %: C, 86.5; H, 13.2.
Synthesis of substituted spiro[2.2]pentanes
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10.1002/ejoc.201700991
European Journal of Organic Chemistry
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(1-Methylspiro[2.2]pentan-1-yl)benzene (2c).[47] Using the procedure
described above, 0.29 g (2 mmol) of (1-cyclopropylideneethyl)benzene
gave a crude product that was distilled through a micro column at 5 mm
Hg to afford 2c (0.26 g, 81%) as a colorless oil. b.p. 86-88 oC (5 mm Hg).
1H NMR (δ, ppm, J/Hz): 0.78-0.87 (m, 2 Н, C(4)HA, C(5)HA), 0.90-0.98 (m,
2 Н, C(4)HB, C(5)HB), 1.19 (d, J = 4.0, 1 H, C(2)HA), 1.30 (d, J = 4.0, 1 H,
C(2)HB), 1.51 (s, 3 Н, C(12)H3), 7.14-7.39 (m, 5 Н, Ph). 13C NMR (δ,
ppm): 5.4 and 6.4 (C(4) and (5)), 22.4 (C(2)), 22.9 (C(3)), 23.0 (C(12)),
24.4 (C(1)), 125.0 (C(9)), 126.0 (2 C, C(8,10)), 128.0 (2 C, C(7,11)),
146.1 (C(6)). Mass m/z (%): 158 (3) [M]+, 143 (100), 129 (79), 115 (72),
103 (20), 91 (18), 77 (28), 63 (10).
19.0 (C(2)), 20.7 (C(3)), 22.4 (C(1)), 25.8 (2 C, C(6,10)), 26.3 (C(8)), 34.5
(2 C, C(7,9)). Mass m/z (%): 136 (2) [M]+, 121 (16), 107 (84), 93 (59), 79
(100), 67 (36). Anal. calcd for C10H16, %: C, 88.2; H, 11.8. Found, %: C,
87.9; H, 11.9.
1-Adamantylidenespiro[2.2]pentane (2i). Using the procedure described
above, 0.24 g (2 mmol) of cyclopropylidenecyclohexane gave a crude
product that was distilled through a micro column at 10 mm Hg to afford
2i (0.20 g, 76%) as a colorless oil. b.p. 75-76 oC (10 mm Hg). 1H NMR (δ,
ppm): 0.56 (s, 2 Н, C(2)H2), 0.61-0.64 (m, 2 Н, C(4,5)HA), 0.83-0.86 (m, 2
Н, C(4,5)HB), 1.29 (br.s., 2 H, C(6)H), 1.50-1.60 (m, 1 Н, C(7)HA), 1.68-
1.80 (m, 6 Н, C(8,11)H2), 1.80-1.90 (m, 1 Н, C(9)H), 1.90-2.00 (m, 2 Н,
C(7)HB, C(10)H). 13C NMR (δ, ppm): 2.8 (2 С, C(4,5)), 19.0 (C(2)), 20.8
(C(3)), 27.5 (C(9)), 28.3 (C(10)), 30.2 (C(1)), 36.4 (2 C, C(8,14)), 36.4 (2
C, C(6,13)), 36.4 (2 C, C(7,12)). Mass m/z (%): 188 (23) [M]+, 173 (19),
159 (72), 145 (73), 117 (68), 91 (100), 79 (55). Anal. calcd for C14H20, %:
C, 89.3; H, 10.7. Found, %: C, 89.3; H, 10.6.
1-Heptylspiro[2.2]pentane (2d). Using the procedure described above,
0.304 g (2 mmol) of octylidenecyclopropane gave a crude product that
was distilled through a micro column at 5 mm Hg to afford 2d (0.24 g,
73%) as a colorless oil. b.p. 73-75 oC (5 mm Hg). 1H NMR (δ, ppm, J/Hz):
0.40-0.44 (m, 1 Н, C(2)HA), 0.85-0.90 (m, 1 Н, C(2)HB), 0.60-0.68 and
0.70-0.78 ((m, 1 Н, C(4)HA) and (m, 1 Н, C(5)HA)), 0.70-0.78 and 0.95-
1.00 ((m, 1 Н, C(4)HB) and (m, 1 Н, C(5)HB)), 0.91 (t, J = 5.6, 3 H,
Synthesis of substituted spiro[2.3]hexanes
C(12)H3), 1.00-1.05 (m, 1 Н, C(1)H), 1.20-1.45 (m, 12 Н, C(6-11)H2). 13
C
NMR (δ, ppm): 3.5 and 6.2 (2 С, C(4,5)), 12.4 (C(2)), 14.1 (C(12)), 14.5
(C(3)), 17.6 (C(1)), 22.7 (C(11)), 29.3 and 29.4 and 29.6 and 31.9 (C(7-
10)), 32.8 (C(6)). Mass m/z (%): 152 (<1), 137 (2), 123 (3), 109 (17), 95
(55), 81 (100), 67 (96), 55 (62), 41 (82). Anal. calcd for C12H22, %: C,
86.7; H, 13.3. Found, %: C, 86.5; H, 13.3.
10
9
11
10
12
9
8
5
3
9
12
14
10
5
7
11
8
1
6
3
1
4
6
7
5
8
4
15
16
7
13
4
1
12
2
6
1-Methoxy-4-(spiro[2.2]pentan-1-yl)benzene (2e). Using the procedure
described above, 0.32 g (2 mmol) of 1-(cyclopropylidenemethyl)-4-
methoxybenzene gave a crude product that was distilled through a micro
column at 2 mm Hg to afford 2e (0.23 g, 67%) as a colorless oil. b.p. 92-
93 oC (2 mm Hg). 1H NMR (δ, ppm): 0.77-0.78 (m, 1 H, C(5)HA), 0.78-
0.80 (m, 1 H, C(4)HA), 0.93-0.96 (m, 1 H, C(5)HB), 0.97-1.01 (m, 2 Н,
C(2)HA, C(4)HB), 1.46-1.50 (m, 1 H, C(2)HB), 2.21-2.26 (m, 1 H, C(1)H),
3.82 (s, 3 H, C(12)H3), 6.85-7.10 (m, 4 Н, Ph). 13C NMR (δ, ppm): 4.8
(C(5)), 7.3 (C(4)), 17.1 (C(2)), 18.1 (C(3)), 21.8 (C(1)), 55.3 (C(12)),
113.7 (2 C, C(8,10)), 127.0 (2 C, C(7,11)), 135.2 (C(6)), 157.5 (C(9)).
Mass m/z (%): 174 (35), 159 (100), 146 (34), 134 (39), 131 (55), 119 (32),
115 (38), 103 (79), 91 (52). Anal. calcd for C12H14O, %: C, 82.7; H, 8.1.
Found, %: C, 82.8; H, 8.2.
18
14
11
2
13
17
13
3
2
a
3
c
3
3b
6
5
4
3
7
5
6
8
7
5
3
8
7
1
4
9
8
9
2
9
4
6
1
10
1
3
14
3
1
10
11
11
2
12
15
10
2
h
i
3g
3
3
Figure 3. The numbering of atoms in the reported 13С- and 1H-NMR
spectral data of the compounds 3a-3c, 3g-3i.
4,4-Diphenylspiro[2.3]hexane (3a). To a solution of 0.413 g (2 mmol) of
(cyclopropylidenemethylene)dibenzene and 0.80 mL of CH2I2 (10 mmol)
in CH2Cl2 (8 mL), 1 mL of Me3Al (10 mmol) (caution: organoaluminums
are pyrophoric and can ignite on contact with air, water or any oxidizer)
Dispiro[2.0.24.13]heptane (2f).[48] Using the procedure described above,
0.16 g (2 mmol) of 1,1'-bi(cyclopropylidene) gave a crude product that
was distilled through a micro column at 750 mm Hg to afford 2f (0.12 g,
62%) as a colorless oil. The spectral properties (1H NMR, 13C NMR) were
in good agreement with those reported in the literature. b.p. 126-130 C
(750 mm Hg).
o
was added at 0 C under an argon atmosphere. The mixture was stirred
o
at room temperature for 8 h. Then, the reaction mixture was diluted with
5 mL of CH2Cl2, and 3 mL of water was added dropwise while cooling the
flask in an ice bath. The precipitate was collected on a filter paper. The
aqueous layer was extracted with diethyl ether (3×5 mL). The combined
organic layers were washed with brine (10 mL), dried over anhydrous
CaCl2 and concentrated in vacuo to give the crude product as a colorless
oil. The residue was distilled through a micro column at 1 mm Hg to give
Dispiro[2.0.4.1]nonane (2g). Using the procedure described above, 0.22
g (2 mmol) of cyclopropylidenecyclopentane gave a crude product that
was distilled through a micro column at 20 mm Hg to afford 2g (0.19 g,
77%) as a colorless oil. b.p. 78-81 oC (20 mm Hg). 1H NMR (δ, ppm):
0.69 (br.s., 4 H, C(4,5)H2), 0.82 (br.s., 2 H, C(2)H2), 1.40-1.75 (m, 8 H,
C(6-9)H2). 13C NMR (δ, ppm): 5.4 (2 С, C(4,5)), 19.1 (C(2)), 20.6 (C(3)),
26.6 (2 C, C(7,8)), 26.7 (C(1)), 33.9 (2 C, C(6,7)). Mass m/z (%): 122 (2)
[M]+, 107 (82), 93 (57), 79 (100), 67 (33). Anal. calcd for C9H14, %: C,
88.5; H, 11.6. Found, %: C, 88.2 H, 11.4.
o
3a (0.37 g, 78%) as a colorless oil. b.p. 147-148 C (1 mm Hg).1H NMR
(δ, ppm): 0.53-0.57 (m, 2 Н, C(5)HA, C(6)HA), 0.57-0.63 (m, 2 Н, C(5)HB,
C(6)HB), 2.15 (t, J = 7.4, 2 Н, C(3)H2), 2.67 (t, J = 7.4, 2 Н, C(2)H2), 7.00-
7.47 (m, 10 Н, Ph). 13C NMR (δ, ppm): 9.8 (2 С, C(5,6)), 27.3 (C(3)), 29.0
(C(4)), 31.6 (C(2)), 55.1 (C(1)), 125.6 (2 C, C(10,16)), 127.5 (4 C,
C(9,11,15,17)), 128.0 (4 C, C(8,12,14,18)), 147.5 (2 C, C(7,13)). Mass
m/z (%): 234 (49) [M]+, 219 (24), 205 (68), 180 (47), 165 (48), 128 (55),
115 (47), 91 (100), 77 (25), 51 (15), 41 (3). Anal. calcd for C18H18, %: C,
92.3; H, 7.7. Found, %: C, 92.2; H, 7.6.
Dispiro[2.0.5.1]decane (2h). Using the procedure described above, 0.24
g (2 mmol) of cyclopropylidenecyclohexane gave a crude product that
was distilled through a micro column at 10 mm Hg to afford 2h (0.22 g,
82%) as a colorless oil. b.p. 76-78 oC (10 mm Hg). 1H NMR (δ, ppm):
0.56 (br.s., 2 H, C(2)H2), 0.60-0.65 (m, 2 H, C(4)HA, C(5)HA), 0.72-0.77
(m, 2 H, C(4)HB, C(5)HB), 1.25-0.37 (m, 4 H, C(6,7,9,10)HA), 1.37-1.47
(m, 6 H, C(6,7,9,10)HB, C(8)H2). 13C NMR (δ, ppm): 3.6 (2 C, C(4,5)),
5,5-Dibutylspiro[2.3]hexane (3b). Using the procedure described above
with an increase of the reaction time to 48 hours, 0.332 g (2 mmol) of
nonan-5-ylidenecyclopropane gave a crude product that was distilled
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700991
European Journal of Organic Chemistry
FULL PAPER
through a micro column at 4 mm Hg to give 3b (0.27 g, 69%) as a
colorless oil. b.p. 92-93 oC (4 mm Hg). 1H NMR (δ, ppm, J/Hz ): 0.15-0.25
(m, 2 Н, C(6)HA, C(5)HA), 0.45-0.57 (m, 2 Н, C(5)HB, C(6)HB), 0.93 (t, J =
7.2, 6 H, C(10,14)H3), 1.00-1.15 (m, 4 Н, C(8,12)H2), 1.15-1.40 (m, 8 Н,
C(7,9,11,13)H2), 1.75-1.85 (m, 2 Н, C(2,3)HA), 1.85-1.95 (m, 2 Н,
C(2,3)HB). 13C NMR (δ, ppm): 8.7 (2 С, C(5,6)), 14.2 (2 C, C(10,14)),
23.7 (2 C, C(9,13)), 26.3 (2 C, C(8,12)), 28.1 (C(4)), 26.8 and 28.4 (C(2)
and C(3)), 38.8 (2 C, C(7,11)), 42.5 (C(1)). Mass m/z (%): 194 (<1) [M]+,
165 (11), 152 (9), 151 (72), 137 (10), 123 (17), 109 (62), 95 (100), 81
(88), 67 (68). Anal. calcd for C14H26, %: C, 86.5; H, 13.5. Found, %: C,
86.5; H, 13.3.
34.3 (2 C, C(9,15)), 35.9 (2 C, C(8,13)), 38.0 (C(12)). Mass m/z (%): [M]+,
202 (26), 187 (27), 173 (57), 159 (25), 145 (44), 131 (42), 105 (50), 91
(100), 79 (70). Anal. calcd for C15H22, %: C, 89.0; H, 11.0. Found, %: C,
89.9; H, 10.9.
Synthesis of substituted spirohexanes by the reaction of
alkylidenecyclobutanes with Me3Al and CH2I2
6
3
6
4
3
2
5
2
8
5
9
13
1
1
8
4
7
7
7
9
13
12
4
6
14
10
4-Methyl-4-phenylspiro[2.3]hexane (3c). Using the procedure described
above with an increase of the reaction time to 18 hours, 0.29 g (2 mmol)
of (1-cyclopropylideneethyl)benzene gave a crude product that was
distilled through a micro column at 1 mm Hg to afford 2c (0.27 g, 79%) as
a colorless oil. b.p. 77-78 oC (1 mm Hg). 1H NMR (δ, ppm): 0.30-0.35 (m,
2 Н, C(5)H2), 0.35-0.41 (m, 1 H, C(6)HA), 0.52-0.58 (m, 1 H, C(6)HB),
1.49 (s, 3 H, C(13)H3), 1.95-2.00 (m, 1 H, C(2)HA), 2.30-2.40 (m, 1 H,
C(3)HA), 2.05-2.10 (m, 1 H, C(2)HB), 2.57-2.65 (m, 1 H, C(3)HB), 7.15-
7.35 (m, 5 Н, Ph). 13C NMR (δ, ppm): 8.7 (C(6)), 11.6 (C(5)), 26.1 (C(13)),
26.8 and 31.6 (C(2) and C(3)), 30.1 (C(4)), 44.5 (C(1)), 125.4 (C(10)),
125.9 (2 C, C(9,11)), 128.0 (2 C, C(8,12)), 147.8 (C(7)). Mass m/z (%):
172 (3) [M]+, 157 (34), 143 (52), 129 (100), 118 (51), 103 (21), 91 (31),
77 (27). Anal. calcd for C13H16, %: C, 90.6; H, 9.4. Found, %: C, 90.4; H,
9.3.
8
12
2
1
5
11
18
15
10
11
11
9
17
16
10
3
8a
8c
8h
5
6
4
7
9
4
6
2
7
1
2
5
8
8
3
1
9
10
3
11
12
8i
8j
Figure 4. The numbering of atoms in the reported 13С- and 1H-NMR
spectral data of the compounds 8a, 8c, 8h-8j.
Dispiro[2.0.4.2]decane (3g). Using the procedure described above with
an increase of the reaction time to 48 hours, 0.29 g (2 mmol) of
cyclopropylidenecyclopentane gave a crude product that was distilled
through a micro column at 10 mm Hg to afford 3g (0.22 g, 81%) as a
colorless oil. b.p. 78-81 oC (10 mm Hg). 1H NMR (δ, ppm): 0.18-0.33 (m,
2 Н, C(5)HA, C(6)HA), 0.39-0.51 (m, 2 Н, C(5)HB, C(6)HB), 1.21-1.66 (m,
8 Н, C(7-10)H2), 1.96-1.89 (m, 2 Н, C(3)H2), 1.96-2.02 (m, 2 Н, C(2)H2).
13C NMR (δ, ppm): 8.9 (2 C, C(5,6)), 24.0 (2 C, C(8,9)), 27.1 and 32.5
(C(2) and C(3)), 27.2 (C(4)), 36.7 (2 C, C(7,10)), 48.9 (C(1)). Mass m/z
(%): 136 (<1) [M]+, 121 (12), 107 (96), 93 (57), 79 (100), 67 (55), 53 (18).
Anal. calcd for C10H16, %: C, 88.2; H, 11.8. Found, %: C, 88.1; H, 11.7.
1,1-Diphenylspiro[2.3]hexane (8a). To a solution of 0.442 g (2 mmol) of
(cyclobutylidenemethylene)dibenzene and 0.80 mL (10 mmol) of CH2I2
in CH2Cl2 (8 mL) was added 1 mL of Me3Al (10 mmol) (caution:
organoaluminums are pyrophoric and can ignite on contact with air, water
or any oxidizer) at 0 oC under an argon atmosphere. The mixture was
stirred at room temperature for 18 h. Then, the reaction mixture was
diluted with 5 mL of CH2Cl2, and 3 mL of water was added dropwise
while cooling the flask in an ice bath. The precipitate was collected on a
filter paper. The aqueous layer was extracted with diethyl ether (3×5 mL).
The combined organic layers were washed with brine (10 mL), dried over
anhydrous CaCl2 and concentrated in vacuo to give the crude product as
a colorless oil. The residue was distilled through a micro column at 1 mm
Hg to give 8a (0.37 g, 79%) as a colorless oil. b.p. 147-148 oC (1 mm Hg).
1H NMR (δ, ppm): 1.48 (s, 2 H, C(3)H2), 1.90-2.03 (m, 3 Н, С(4,6)HA,
C(5)A), 2.07-2.21 (m, 1 Н, С(5)HB), 2.27-2.37 (m, 2 Н, С(4,6)HB), 7.15-
7.35 (m, 10 Н, Ph). 13C NMR (δ, ppm): 16.1 (C(5)), 28.3 (C(3)), 29.2 (2 C,
C(4,6)), 33.5 (C(2)), 37.5 (C(1)), 125.8 (2 C, C(10,16)), 128.1 (4 C
(9,11,15,17), 129.2 (4 C, C(8,12,14,18)), 143.3 (2 C, C(7,13)). Mass m/z
(%): 234 (26) [M]+, 219 (6), 206 (100), 178 (18), 165 (27), 128 (47), 115
(28), 91 (77), 77 (15), 51 (8). Anal. calcd for C18H18, %: C, 92.3; H, 7.7.
Found, %: C, 92.1; H, 7.7.
Dispiro[2.0.5.2]undecane (3h). Using the procedure described above with
an increase of the reaction time to 48 hours, 0.24 g (2 mmol) of
cyclopropylidenecyclohexane gave a crude product that was distilled
through a micro column at 10 mm Hg to afford 3h (0.20 g, 68%) as a
o
1
colorless oil. b.p. 94-96 C (10 mm Hg). H NMR (δ, ppm, J/Hz): : 0.15-
0.21 (m, 2 H, C(5)HA, C(6)HA), 0.45-0.51 (m, 2 Н, C(5)HB, C(6)HB), 0.77-
1.16 (m, 2 Н, C(7,11)HA), 1.21-1.40 (m, 2 Н, C(8,10)HA), 1.39-1.58 (m, 4
Н, C(8,10)HB, C(9)H2), 1.58-1.75 (m, 2 Н, C(7,11)HB), 1.81-1.88 (m, 2 Н,
C(2)H2), 1.93-2.02 (m, 2 Н, C(3)H2). 13C NMR (δ, ppm): 7.3 (2 С, C(5,6)),
22.7 (2 C, C(8,10)), 26.2 (C(3)), 26.2 (C(9)), 28.3 (C(4)), 29.5 (C(2)), 35.5
(2 С, C(7,11)), 40.6 (C(1)). Mass m/z (%): 150 (<1) [M]+, 136 (2), 121
(16), 107 (82), 93 (57), 79 (100), 67 (33). Anal. calcd for C11H18, %: C,
87.9; H, 12.1. Found, %: C, 87.9; H, 12.1.
(1-Methylspiro[2.3]hexan-1-yl)benzene (8c). Using the procedure
described above, 0.316 g (2 mmol) of (1-cyclobutylideneethyl)benzene
gave a crude product that was distilled through a micro column at 4 mm
1-Adamantylidenespiro[2.3]hexane (3i). Using the procedure described
above with an increase of the reaction time to 48 hours, 0.35 g (2 mmol)
of 2-cyclopropylideneadamantane gave a crude product that was distilled
through a micro column at 1 mm Hg to afford 3h (0.34 g, 83%) as a
colorless oil. b.p. 109-110 oC (1 mm Hg). 1H NMR (δ, ppm): 0.20-0.27 (m,
2 Н, C(5)HA, C(6)HA), 0.78-0.87 (m, 2 Н, C(5)HB, C(6)HB), 1.55 (br.s., 2 H,
C(7)H), 1.64-1.68 (m, 2 Н, C(12)H2), 1.70-1.80 (m, 2 H, C(10,11)H), 1.78-
1.85 (m, 1 Н, C(2)HA), 1.82-1.88 (m, 4 Н, C(9)H2), 1.85-1.90 (m, 1 Н,
C(2)HB), 1.87-1.93 (m, 1 Н, C(3)HA), 1.88-1.92 (m, 4 Н, C(8)H2), 1.93-
1.97 (m, 1 Н, C(3)HB). 13C NMR (δ, ppm): 7.8 (2 С, C(5,6)), 27.2 and
27.6 (2 C, C(10,11)), 27.8 and 30.8 (C(2) and C(3)), 33.6 (2C, C(7,14)),
o
Hg to afford 8c (0.23 g, 67%) as a colorless oil. b.p. 101-103 C (4 mm
1
Hg). H NMR (δ, ppm): 0.71 (d, J = 4.8, 1 H, C(3)HA), 1.13 (d, J = 4.7, 1
H, C(3)HB), 1.35 (s, 3 Н, С(13)H3), 1.80-1.88 (m, 1 Н, С(4)HA), 1.88-1.99
(m, 2 Н, С(4)HB, С(5)HA), 1.99-2.06 (m, 1 Н, С(6)HA), 2.06-2.20 (m, 1 Н,
С(5)HB), 2.39-2.49 (m, 1 Н, С(6)HB), 7.15-7.40 (m, 5 Н, Ph). 13C NMR (δ,
ppm): 15.9 (C(5)), 22.2 (C(13)), 26.2 (C(3)), 27.0 (C(2)), 27.4 and 28.0
(C(4) and C(6)), 31.7 (C(1)), 125.2 (C(10)), 127.5 (2 C, C(9,11), 128.0 (2
C, C(8,12)), 144.6 (C(7)). Mass m/z (%): 172 (4) [M]+, 157 (8), 144 (49),
129 (100), 115 (18), 105 (11), 91 (16), 77 (14), 65 (4), 51 (7). Anal. calcd
for C13H16, %: C, 90.6; H, 9.4. Found, %: C, 90.5; H, 9.4.
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700991
European Journal of Organic Chemistry
FULL PAPER
Dispiro[3.0.5.1]undecane (8h). Using the procedure described above,
0.27 g (2 mmol) of cyclobutylidenecyclohexane gave a crude product that
was distilled through a micro column at 5 mm Hg to afford 8h (0.23 g,
76%) as a colorless oil. b.p. 85-88 oC (5 mm Hg). 1H NMR (δ, ppm): 0.17
(s, 2 Н, C(3)H2), 1.10-1.30 (m, 4 Н, C(7,11)H2), 1.40-1.70 (m, 6 Н, C(8-
10)H2), 1.80-2.00 (m, 3 Н, С(4)HA, С(5)HA, С(6)HA), 2.00-2.15 (m, 1 H,
С(5)HB), 2.15-2.25 (m, 2 Н, С(4)HB, С(6)HB). 13C NMR (δ, ppm): 16.7
(C(5)), 22.6 (C(2)), 25.1 (C(3)), 25.8 (2 C, C(8,10)), 26.4 (C(9)), 27.1 (2 C,
C(4,6)), 32.1 (2 C, C(7,11)), 35.7 (C(1)). Mass m/z (%): 150 (4) [M]+, 135
(17), 122 (84), 107 (52), 93 (59), 79 (100), 67 (72), 53 (27), 41 (54). Anal.
calcd for C11H18, %: C, 87.9; H, 12.1. Found, %: C, 88.7; H, 11.9.
was distilled through a micro column at 750 mm Hg to afford 2f (0.15 g,
78%) as a colorless oil. The spectral properties (1H NMR, 13C NMR) were
in good agreement with those obtained in the previous run for the
synthesis of 2f.
Acknowledgements
The authors are indebted to Dr. Sergei I. Kozhushkov (Institut für
Organische und Biomolekulare Chemie, Georg-August-
Universität Göttingen) for useful discussions especially
concerning the mechanism of the unusual transformation of
spiro[2.2]pentanes into spiro[2.3]hexanes and kindly providing
the sample of bicyclopropylidene. This work was supported by
the Department of Chemistry and Material Sciences of the
Russian Academy of Sciences (program No. 1-OKhNM), the
Russian Foundation for Basic Research (grant no. 16-03-00935
and no. 16-33-60167) and by the Grant of the RF President (Sci.
Sh.–6651.2016.3) which are gratefully acknowledged. We also
acknowledge the Center of collective use of the unique
equipment «Agidel» at the Institute of Petrochemistry and
Catalysis of the Russian Academy of Sciences.
1-Adamantylidenespiro[2.3]hexane (8i). Using the procedure described
above, 0.38 g (2 mmol) of 2-cyclobutylideneadamantane gave a crude
product that was distilled through a micro column at 1 mm Hg to afford 8i
(0.33 g, 82%) as a colorless oil. b.p. 112-113 oC (1 mm Hg). 1H NMR (δ,
ppm): 0.18 (s, 2 Н, C(3)H2), 1.05 (br.s, 2 H, C(7)H), 1.68-1.92 (m, 8 Н,
C(8,9)H2), 1.75-1.82 (m, 2 Н, C(12)H2), 1.92-2.00 (m, 4 Н, C(10,11)H,
C(4)A, C(6)A), 1.98-2.05 (m, 1 H, C(5)HA), 2.05-2.15 (m, 1 H, C(5)HB),
2.18-2.25 (m, 2 H, C(4)B, C(6)B). 13C NMR (δ, ppm): 17.4 (C(5)), 25.0
(C(3)), 26.8 (2 C, C(4,6)), 27.7 and 28.1 (C(10) and C(11)), 29.6 (C(2)),
32.0 (C(1)), 33.6 (2 C, C(7)), 36.3 (2 C, C(9)), 36.4 (2 C, C(8)), 37.4
(C(12)). Mass m/z (%): [M]+, 202 (31), 187 (34), 174 (63), 159 (23), 145
(24), 131 (43), 117 (43), 105 (37), 91 (100), 79 (90). Anal. calcd for
C15H22, %: C, 89.0; H, 11.0. Found, %: C, 88.9; H, 11.0.
Keywords: alkylidenecyclopropanes • spiro[2.2]pentanes •
Dispiro[3.0.35.14]nonane (8j).[49] Using the procedure described above,
0.22 g (2 mmol) of 1,1'-bi(cyclobutylidene) gave a crude product that was
distilled through a micro column at 20 mm Hg to afford 8j (0.21 g, 86%)
as a colorless oil. b.p. 75-78 oC (20 mm Hg). 1H NMR (δ, ppm): 0.33 (s, 2
H, C(3)H2), 1.80-2.20 (m, 12 Н, C(4-9)H2). 13C NMR (δ, ppm): 16.2 (2 C,
C(5,8)), 24.0 (C(3)), 26.7 (4 C, C(4,6,7,9)), 27.7 (2 C, C(1,2)). Mass m/z
(%): 122 (2) [M]+, 107 (2), 94 (45), 79 (100).
spiro[2.3]hexanes • cyclopropanation • aluminum carbenoid
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10.1002/ejoc.201700991
European Journal of Organic Chemistry
FULL PAPER
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10.1002/ejoc.201700991
European Journal of Organic Chemistry
FULL PAPER
Entry for the Table of Contents
Layout 2:
FULL PAPER
n =
n=
1
1,2
equiv)
Spiro[2.2]pentanes and
spiro[2.3]hexanes synthesis
I
5
(5
CH2 2
equiv)
equiv)
I
5
CH2 2
(
(
R1
R2
Me Al
Me Al
3
n
( )
69-83%
62-86%
examples
14
n
(5
3
( )
R1
equiv)
examples
Ilfir R. Ramazanov,* Rita N. Kadikova,
Tat’yana P. Zosim, Usein M. Dzhemilev
and Armin de Meijere
6
rt, 1-2
CH2Cl2
d
,
rt,
h
hexane, 18
R2
R1 R2
H
R=Ar,Alk,
cycloalkyl,
Page No. – Page No.
Alkylidenecyclopropanes and alkylidenecyclobutanes with Me3Al/CH2I2 reagent in
hexane gave substituted spiro[2.2]pentanes and spiro[2.3]hexanes in high yields.
The same reaction with alkylidenecyclopropanes in CH2Cl2 afforded exclusively 1,1-
disubstituted spiro[2.3]hexanes. The transformation of 1,1-
Synthesis of Spiro[2.2]pentanes and
Spiro[2.3]hexanes Employing the
Me3Al/CH2I2 Reagent
diphenylspiro[2.2]pentane into 1,1-diphenylspiro[2.3]hexane was studied with the
use of CD2I2 and a plausible mechanism was suggested.
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