Synthesis of cyclopropane-containing organoaluminum compounds by the reaction of acetylenes with CH2I2 and Et3Al

Article abstract of DOI:10.1007/s11172-009-0180-6

Reactions of disubstituted and terminal acetylenes with CH ₂I₂ and Et₃Al in the molar ratio 1 : 4 : 6 lead to the selective formation of organoaluminum compounds containing di-, tri-, or tetrasubstituted cyclopropane fragments depending on the nature of acetylene and reaction conditions.

Full text of DOI:10.1007/s11172-009-0180-6

Russian Chemical Bulletin, International Edition, Vol. 58, No. 7, pp. 1349—1352, July, 2009
1349
Synthesis of cyclopropaneꢀcontaining organoaluminum compounds
by the reaction of acetylenes with CH2I2 and Et3Al
I. R. Ramazanov,a L. K. Dil'mukhametova,a U. M. Dzhemilev,a and O. M. Nefedovb
aInstitute of Petrochemistry and Catalysis, Russian Academy of Sciences,
141 prosp. Oktyabrya, 450054 Ufa, Russian Federation.
Fax: +7 (347) 284 2750. Eꢀmail: ink@anrb.ru
bN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5328
Reactions of disubstituted and terminal acetylenes with CH2I2 and Et3Al in the molar ratio
1 : 4 : 6 lead to the selective formation of organoaluminum compounds containing diꢀ, triꢀ, or
tetrasubstituted cyclopropane fragments depending on the nature of acetylene and reaction
conditions.
Key words: triethylaluminum, organoaluminum compounds, diiodomethane, cyclopropanes,
alkynes.
Earlier,1,2 we have found that the reaction of monoꢀ
and disubstituted acetylenes with CH2I2 and Et3Al taken
in excess leads to the selective enough formation of triꢀ
and tetrasubstituted cyclopropanes, respectively, in up to
80% yields.
The purpose of the present work is to evaluate the scope
of this reaction, as well as to identify the intermediate
organoaluminum compounds (OAC).
It was found that the reaction of dialkylꢀsubstituted
acetylenes (octꢀ4ꢀyne, decꢀ5ꢀyne) with CH2I2 and Et3Al
in the molar ratio of the reactants 1 : 4 : 6 and the reaction
time of 1 h leads to the formation of organoalumiꢀ
num compounds 1a,b in 51 and 58% yields, respectively
(Scheme 1). When the reaction time was increased to 8 h,
the cyclopropaneꢀcontaining OAC 1a,b were transformed
to 2a,b in 78 and 83% yields, respectively. The best results
Scheme 1
a
b
c
Ph
Me
d
e
R1
R2
R
Prn
Prn
Bun
Bun
nꢀC5H11 nꢀC10H21
H
H
3 = H, (3, 5), D (4, 6)
Reagents and conditions: i. CH2I2 (4 equiv.), Et3Al (6 equiv.), CH2Cl2, 22 °C; ii. 22 °C, 7 h.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1311—1314, July, 2009.
1066ꢀ5285/09/5807ꢀ1349 © 2009 Springer Science+Business Media, Inc.

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Ramazanov et al.
were achieved when the reaction was performed in haloꢀ
genꢀcontaining solvents (dichloromethane, dichloroethꢀ
ane). In hydrocarbon solvents (hexane, benzene), the
formation of the cyclopropane occurs at lower rate and in
lower yields. For instance, the reaction of octꢀ4ꢀyne with
CH2I2 and Et3Al in hexane for 8 h gives compound 2a in
41% yield. The use of ether solvents (diethyl ether, THF)
inhibits the reaction.
tuted cyclopropane 1c to tetrasubstituted cyclopropane 2
under the reaction conditions occurs.
Terminal acetylenes (heptꢀ1ꢀyne, dodecꢀ1ꢀyne)
react with CH2I2 and Et3Al (the molar ratio acetyꢀ
lene : CH2I2 : Et3Al = 1 : 4 : 6) to form OAC 2d,e in 79 and
87% yields, respectively. The structures of trisubstituted
cyclopropanes 5d,e were established by spectroscopic
methods.1 The 13C NMR spectra of 6d,e exhibit one set of
signals, which indicates the formation of one stereoisoꢀ
mer, the configuration of which can not be established
by NMR.
Based on the literature data and our experimental reꢀ
sults, we suggested the following pathway for the reaction
(Scheme 2). The reaction starts from the generation of
diethyl(iodoomethyl)aluminum.5 The latter is capable of
carboalumination of acetylene to form iodineꢀcontaining
alkenylalane,6 the subsequent reaction of which with Et3Al
leads to the formation of unsaturated OAC. Further cycꢀ
lopropanation of the double bond7 and insertion of the
CH2 group at the Al—C bond lead to OAC 1, which then
rearranges to 2. According to the mechanism suggested,
three molecules of CH2I2 and four molecules of Et3Al are
involved into formation of one molecule of cyclopropane,
which agrees with the optimum molar proportion of reacꢀ
tants found experimentally.
As it has been already noted, terminal acetylenes in the
reactions with Et3Al and CH2I2 form only one stereoisoꢀ
mer, whereas the reaction with octꢀ4ꢀyne gives rise to
a mixture of stereoisomers 2a in the ratio 1 : 1 (see Scheme 1).
According to the mechanism suggested (see Scheme 2),
the stereoconfiguration of final product 2 is determined in
the rearrangement stage of OAC 1 to 2 and in first approxiꢀ
mation depends on the relative stability of eclipsed conꢀ
formations I and II (Scheme 3). For instance, in the case
of octꢀ4ꢀyne (R1 = R2 = Prn) the difference between poꢀ
tential energy of conformations I and II will be minimum
The structures of compounds 1a,b and 2a,b were esꢀ
tablished based on the analysis of their hydrolysis and
deuterolysis products. The presence in the 13C NMR
spectrum of compound 4b of intensive signal for the CH2
group at 6.05 and 6.15 ppm with the spinꢀspin couꢀ
1
pling constant JCH = 155.65 Hz is characteristic of cycꢀ
lopropane systems and the presence in the 1H NMR
spectrum of a multiplet in the region 0.05—0.40 ppm inꢀ
dicates the presence of the cyclopropane fragment in
the molecule of compound 4b. In addition, in the mass
spectrum of compound 4b, there is no signal of the molecꢀ
ular ion, rather the signal for the fragment [M – 28]+
formed by elimination of ethylene from the molecular
ion is present, which is characteristic of 1,1ꢀdisubstitutꢀ
ed cyclopropanes with αꢀsubstituted alkyl substituents.3
The nonequivalence of the CH2 protons of the cycloꢀ
propane fragment apparently is due to the presence of
the diastereotopic carbon atom in the ring. Assignment
of the signals in the 13C NMR spectra of compounds
4a,b were made according to the known spectral paraꢀ
meters of analogous cyclopropane compounds3 and the
Lindeman—Adams additive scheme.4 The structures of
tetrasubstituted cyclopropanes 5a,b and equal proportion
of cisꢀ and transꢀisomers in them have been established
by us earlier1.
Phenylmethylacetylene under conditions chosen and
the reaction time of 8 h is transformed to the only product
1c in 62% yield. No subsequent rearrangement of disubstiꢀ
Scheme 2
R1, R2 = alkyl, alkyl; Ph, H; alkyl, H

Organoaluminium cyclopropanes
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 7, July, 2009
1351
Scheme 3
The product yields were determined by GC of the hydroꢀ
lysis products of the corresponding OAC using an internal
standard.aa
due to the small difference in the bulkiness of ethyl and
propyl groups, which leads to the realization of both stereꢀ
oconfigurations of compound 2a. In the case of heptꢀ1ꢀ
yne (R1 = nꢀC5H11, R2 = H), conformation I will be
energetically more favorable, which provides formation of
only one stereoisomer of compound 2 with the cisꢀarꢀ
ranged substituents R1 and R2. However, a strict descripꢀ
tion of the rearrangement process suggests calculation of
its activation barrier, which was made using the PM3
semiempirical method (see Ref. 8). The calculated values
of the formation enthalpy of transition states III and IV
confirmed conclusions made by qualitative consideration
of eclipsed conformers I and II. For instance, in the case
of octꢀ4ꢀyne, the potential energy difference of transition
states III and IV was only 0.7 kcal mol–1, whereas for
heptꢀ1ꢀyne transition state III has proved energetically
more favorable by 7.1 kcal mol–1. In conclusion, terminal
acetylenes R—C≡C—H under the reaction conditions apꢀ
parently are transformed to trisubstituted cyclopropanes
with cisꢀarrangement of substituents R and H.
14
Experimental
Commercially available reactants were used in this work.
Dichloromethane was distilled over P2O5 before use. The reacꢀ
tion products were analyzed on a Carlo Erba chromatograph (an
Ultraꢀ1 glass capillary column (Hewlett Packard) 25 m × 0.2 mm,
a flame ionization detector, thermostate temperature was
50—170 °C, carrier gas was helium). Mass spectra were meaꢀ
sured on a Finnigan 4021 instrument with the ionization potenꢀ
tial of 70 eV and the temperature of ionizing chamber of 200 °C.
1H and 13C NMR spectra were recorded on a JEOL FXꢀ90Q
(22.5 MHz for 13C and 90 MHz for 1H) and Bruker AMꢀ300
(75.46 MHz for 13C and 300 MHz for 1H) spectrometers using
SiMe4 (1H) and CDCl3 13C) as internal standards. 13C NMR
(
spectra were recorded in the modes with the full proton couꢀ
pling, as well as using the INEPT (Insensitive Nuclei Enhanced
by Polarization Transfer) procedure. The atoms numeration is
given in Fig. 1.
Fig. 1. The carbon atoms numeration in the 13C and 1H NMR
spectra of compounds 4a—c, 6a,b,d,e.

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Ramazanov et al.
Quantum chemical calculations were performed with full
optimization of geometry by the restricted Hartree—Fock method
in the PM3 semiempirical basis using the GAMESS program.8
Synthesis of substituted cyclopropanes (general procedure).
Dichloromethane (30 mL), alkyne (10 mmol), CH2I2 (3.2 mL,
40 mmol), and Et3Al (60 mmol) were sequentially placed under
an inert gas into a 50ꢀmL glass reaction flask equipped with
a magnetic stirring bar and cooled with an ice bath, the mixture
was stirred for a required time at 20—25 °C. Then the reaction
mixture was hydrolyzed with 10% aqueous HCl or 15% DCl in
D2O, the water layer was extracted with diethyl ether. The exꢀ
tract was combined with the organic layer, kept over anhydrous
CaCl2, and concentrated in vacuo. Individual products were isoꢀ
lated by distillation in vacuo.
3ꢀDeuteromethylꢀ3ꢀ(1ꢀpropylcyclopropyl)hexane (4a), b.p.
96 °C (15 Torr). Found (%): C, 84.91; (H+D), 15.09. C13H25D.
Calculated (%): C, 85.16; H, 13.74; D, 1.10. The yield was 51%.
13C NMR, δ: 6.06 (t, C(9)); 6.17 (t, C(10)); 8.95 (q, C(12));
15.01 (q, C(1)); 15.26 (q, C(8)); 17.79 (t, C(2)); 19.85 (C(13),
1JCD = 19.05 Hz); 20.13 (t, C(7)); 22.71 (s, C(4)); 31.65
(t, C(11)); 35.42 (t, C(6)); 37.36 (s, C(5)); 43.48 (t, C(3)). 1H NMR,
δ: 0.06—0.42 (m, 4 H, C(9)H2, C(10)H2); 0.73 (s, 2 H, C(13)H2D);
0.83—0.88 (m, 9 H, C(1)H3, C(8)H3, C(12)H3); 1.01—1.52
(m, 10 H, C(2)H2, C(3)H2, C(6)H2, C(7)H2, C(11)H2). MS, m/z:
155 [M – C2H4]+.
C
15H29D. Calculated (%): C, 85.22; H, 13.83; D, 0.95. The
yield was 83%. 13C NMR, δ: 11.15 (C(12), JCD = 19.03 Hz);
11.18 (q, C(14)); 14.22 (q, C(1,10)); 23.30 (t, C(2), C(9)); 24.27
(t, C(11), C(13)); 24.27 (t, C(15)); 29.24 (t, C(3), C(8)); 30.04
(s, C(5)); 30.72, 30.77 (both t, C(4), C(7)). 1H NMR, δ:
0.68—1.10 (m, 13 H, C(15)H2, C(1)H3, C(10)H3, C(14)H3,
C(12)H2D); 1.17—1.53 (m, 16 H, C(2)H2, C(3)H2, C(4)H2,
C(7)H2, C(8)H2, C(9)H2, C(11)H2, C(13)H2). MS, m/z: 211
[M]+ (4), 182 [M+ – Et] (26), 154 [M+ – Bu] (25).
1
1ꢀ[1ꢀ(2ꢀDeuteroethyl)ꢀ2ꢀethylcyclopropyl]pentane (6d), b.p.
87 °C (20 Torr). Found (%): C, 84.42; (H+D), 15.58. C15H29D.
Calculated (%): C, 85.12; H, 13.69; D, 1.19%. The yield was
79%. 13C NMR, δ: 10.66 (C(10), JCD = 19.01 Hz); 14.22
1
(q, C(8)); 14.67 (q, C(12)); 18.31 (t, C(3)); 22.54 (t, C(7)); 22.87
(t, C(11)); 24.82 (s, C(1)); 26.25 (d, C(2)); 26.64 (t, C(5)); 29.82
(t, C(9)); 30.47 (t, C(4)); 32.55 (t, C(6)). 1H NMR, δ: 0.18—0.42
(m, 3 H, C(2)H, C(3)H2); 0.85 (t, 6 H, C(10)H3, C(12)H3,
3JCH = 4.9 Hz); 0.97 (t, 3 H, C(8)H3, 3JCH = 6.8 Hz); 1.07—1.50
(m, 12 H, C(4)H2, C(5)H2, C(6)H2, C(7)H2, C(9)H2, C(11)H2).
MS, m/z: 169 [M]+ (4), 140 [M+ – Et] (3), 98 [M+ – C5H11] (41).
1ꢀ[1ꢀ(2ꢀDeuteroethyl)ꢀ2ꢀethylcyclopropyl]decane (6e), b.p.
121 °C (3 Torr). Found (%): C, 85.30; (H+D), 14.70. C17H23D.
Calculated (%): C, 85.27; H, 13.89; D, 0.84%. The yield was
87%. 13C NMR, δ: 10.71 (C(15), JCD = 19.07 Hz); 14.28
1
(q, C(17)); 14.67 (t, C(13)); 18.38 (t, C(3)); 22.61 (t, C(14));
22.87 (t, C(12)); 24.88 (s, C(1)); 27.03 (s, C(2)); 26.31 (t, C(5));
29.56 (t, C(10)); 29.95 (t, C(6), C(7), C(8), C(9)); 30.41
(t, C(4)); 30.54 (t, C(16)); 32.10 (t, C(11)). 1H NMR, δ: 0.15—0.35
(m, 3 H, C(2)H, C(3)H2); 0.65—1.00 (m, 11 H, C(13)H3,
C(17)H3, C(15)H2D); 1.05—1.55 (m, 22 H, C(4)H2, C(5)H2,
C(6)H2, C(7)H2, C(8)H2, C(9)H2, C(10)H2, C(11)H2, C(12)H2,
C(14)H2, C(16)H2). MS, m/z: 239 [M]+ (3).
3ꢀ(1ꢀButylcyclopropyl)ꢀ3ꢀdeuteromethylheptane (4b), b.p.
91 °C (3 Torr). Found (%): C, 85.01; (H+D), 14.99. C15H29D.
Calculated (%): C, 85.22; H, 13.83; D, 0.95. The yield was 58%.
13C NMR, δ: 6.05 (t, C(11)); 6.15 (t, C(12)); 8.82 (q, C(14));
1
14.28 (q, C(1), C(10)); 19.87 (C(15), JCD = 19.07 Hz); 22.67
(s, C(5)); 23.65 (s, C(9)); 23.91 (t, C(2)); 26.44 (t, C(8)); 28.78
(t, C(3)); 31.38 (t, C(7)); 31.77 (t, C(13)); 37.30 (s, C(6)); 38.73
(t, C(4)). 1H NMR, δ: 0.05—0.40 (m, 4 H, C(11)H2, C(12)H2);
0.56 (s, 2 H, C(15)H2D); 0.75—0.80 (m, 9 H, C(1)H3, C(10)H3,
C(14)H3); 1.00—1.45 (m, 14 H, C(2)H2, C(2)H2, C(3)H2,
C(4)H2, C(7)H2, C(8)H2, C(9)H2, C(11)H2). MS, m/z: 183
[M – C2H4]+.
1ꢀ(2ꢀDeuteromethylbutꢀ2ꢀyl)ꢀ1ꢀphenylcyclopropane (4c), b.p.
109 °C (10 Torr). Found (%): C, 88.34; (H+D), 11.66. C14H19D.
Calculated (%): C, 88.82; H, 10.12; D, 1.06. The yield was 62%.
13C NMR, δ: 8.76 (t, C(9), C(10)); 9.09 (q, C(8)); 23.84 (C(12),
1JCD = 19.01 Hz); 24.17 (q, C(11)); 32.88 (t, C(7)); 33.60
(s, C(5)); 34.96 (s, C(6)); 126.00 (d, C(1)); 127.17 (d, C(3)); 132.38
(d, C(2)); 145.77 (s, C(4)). 1H NMR, δ: 0.50—0.75 (m, 4 H,
C(9)H2, C(10)H2); 0.82 (s, 5 H, C(11)H3, C(12)H2D); 0.90
(t, C(8)H3, J = 7.33 Hz); 1.28 (q, J = 6.96 Hz); 7.10—7.35 (m, Ph).
References
1. I. R. Ramazanov, M. P. Luk´yanova, A. Z. Sharipova, A. G.
Ibragimov, U. M. Dzhemilev, O. M. Nefedov, Izv. Akad.
Nauk, Ser. Khim., 2001, 1338 [Russ. Chem. Bull., Int. Ed.,
2001, 50, 1406].
2. U. M. Dzhemilev, I. R. Ramazanov, A. G. Ibragimov, L. I.
Dyachenko, M. P. Lukjyanova, O. M. Nefedov, J. Organoꢀ
metal. Chem., 2001, 636, 91.
3. U. M. Dzhemilev, A. G. Ibragimov, I. R. Ramazanov, M. P.
Luk´yanova, A. Z. Sharipova, L. M. Khalilov, Izv. Akad. Nauk,
Ser. Khim., 2000, 1092 [Russ. Chem. Bull., Int. Ed., 2000,
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4. L. P. Lindeman, J. Q. Adams, Anal. Chem., 1971, 43, 1245.
5. D. B. Miller, Tetrahedron Lett., 1964, 17, 989.
6. H. Hoberg, Lieb. Ann., 1962, 656, 1.
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50, 4412.
8. M. W. Schmidt, K. K. Baldridge, J. A. Boatz, S. T. Elbert,
M. S. Gordon, J. J. Jensen, S. Koseki, N. Matsunaga, K. A.
Nguyen, S. Su, T. L. Windus, M. Dupuis, J. A. Montgomery,
J. Comput. Chem., 1993, 14, 1347.
MS, m/z: 189 [M]+ (10), 161 [M+ – C2H4] (36), 159 [M+
–
– C2H4D] (45); 145 [M+ – C3H6D] (55); 117 [M+ – C5H10D]
(69); 72 [C5H10D] (90).
1ꢀ(2ꢀDeuteroethyl)ꢀ2ꢀethylꢀ1,2ꢀdipropylcyclopropane (6a),
b.p. 105 °C (20 Torr). Found (%): C, 84.79; (H+D), 15.21.
C13H25D. Calculated (%): C, 85.16; H, 13.74; D, 1.10. The
1
yield was 78%. 13C NMR, δ: 11.25 (C(10), JCD = 19.05 Hz);
11.29 (q, C(12)); 14.74 (t, C(1,8)); 20.20 (t, C(2,7)); 24.43
(t, C(9), C(11)); 24.43 (t, C(13)); 30.02 (s, C(4)); 33.47, 33.60
(both t, C(3), C(6)). 1H NMR, δ: 0.73—1.00 (m, 13 H, C(13)H2,
C(1)H3, C(8)H3, C(12)H3, C(10)H2D); 1.05—1.48 (m, 12 H,
C(2)H2, C(3)H2, C(6)H2, C(7)H2, C(9)H2, C(11)H2). MS, m/z:
183 [M]+ (3), 154 [M+ – Et] (23), 140 [M+ – Pr] (25).
1,2ꢀDibutylꢀ1ꢀ(2ꢀdeuteroethyl)ꢀ2ꢀethylcyclopropane (6b),
b.p. 65 °C (1 Torr). Found (%): C, 84.66; (H+D), 15.34.
Received September 2, 2008;
in revised form March 27, 2009