Acetylene cyclopropanation by CH2I2-Et3Al reagent

Article abstract of DOI:10.1016/S0022-328X(01)01167-6

The one-step method for a synthesis of 1,1,2-trialkyl- and 1,1,2,2-tetraalkylsubstituted cyclopropanes from mono- and dialkylsubstituted acetylenes, CH₂I₂ and Et₃Al was developed.

Full text of DOI:10.1016/S0022-328X(01)01167-6

Journal of Organometallic Chemistry 636 (2001) 91–95
www.elsevier.com/locate/jorganchem
Acetylene cyclopropanation by CH2I2–Et3Al reagent
Usein M. Dzhemilev a,*, Ilfir R. Ramazanov a, Askhat G. Ibragimov a,
Larisa I. Djyachenko a, Marina P. Lukjyanova a, Oleg M. Nefedov b,1
a Institute of Petrochemistry and Catalysis, Bashkortostan Republic Academy of Sciences,
and Ufa Scientific Centre of Russian Academy of Sciences, 450075 Ufa, Prospekt Oktyabrya 141, Russia
b N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow, Leninsky Prospect 47, Russia
Received 26 February 2001; accepted 28 July 2001
Abstract
The one-step method for a synthesis of 1,1,2-trialkyl- and 1,1,2,2-tetraalkylsubstituted cyclopropanes from mono- and
dialkylsubstituted acetylenes, CH2I2 and Et3Al was developed. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Acetylenes; Cyclopropanes; Cyclopropanation
1. Introduction
Et3Al under mild conditions (20–25 °C) to give 1,1,2-
trialkyl and 1,1,2,2-tetraalkylsubstituted cyclopropanes
(compound 1), respectively in average yields (Table 1;
Scheme 1).
The Simmons–Smith reaction is known to be suit-
able and widely used in laboratory practice method for
cyclopropanation of olefins and their derivatives [1].
However, with respect to acetylene compounds the
method was not developed properly, since terminal
acetylenes give products of CH2 group introduction on
terminal CꢀH bond [2], and disubstituted acetylenes
undergo rearrangements [3,4]. Later the modification of
the Simmons–Smith reaction with the use of organoa-
luminium reagents was developed [5], that was found to
be sufficiently efficient to olefins, but acetylene re-
actability was not studied. We have supposed the fail-
ures in acetylene cyclopropanation were caused by
metal nature, activating CH2I2, and thus we have stud-
ied the acetylene reactions with CH2I2 in the presence
of Et3Al.
Mass-spectrometry and element analysis show the
presence of cycle or double bond in compounds 1a–e.
However, signals of double bond were not observed by
NMR spectroscopy. At the same time there are signals
1
in strong field in H-NMR spectra (−0.01–0.7 ppm)
that evidences the presence of cyclopropane fragment in
1a–e. Moreover, in 13C-NMR spectra signals due to
cyclopropane ring carbons show coupling constants
1JCH ca. 155 Hz and those in alkyl groups ca. 125 Hz
[6]. The assignments in 13C-NMR spectra were based
on the additive scheme [7] and with the use of (Insensi-
tive Nuclei Enhanced by Polarization Transfer) INEPT
technique (Fig. 1).
Decyne-5 cyclopropanation proceeds not stereoselec-
tively to give two stereoisomers of 1a compound in 1:1
ratio. Octyne-4 cyclopropanation proceeds similarly. A
reaction of terminal acetylenes (heptyne-1, hexyne-1)
with CH2I2 and Et3Al leads to stereoselective formation
of trisubstituted cyclopropanes (1d,e). The above reac-
tion proceeds with octyne-2 to give one stereoisomer in
the same way, that evidences a steric control of the
reaction stereochemistry. The physical methods used by
us did not allow to determine a stereoconfiguration of
tri- and tetrasubstituted cyclopropanes.
2. Results and discussion
The preliminary experiments showed mono- and di-
alkylsubstituted acetylenes reacted with CH2I2, and
* Corresponding author. Fax: +7-3472-312750.
E-mail address: ink@anrb.ru (U.M. Dzhemilev).
1 Fax: +095-1355320
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01167-6

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U.M. Dzhemile6 et al. / Journal of Organometallic Chemistry 636 (2001) 91–95
Table 1
Acetylene cyclopropanation by CH2I2–Et3Al reagent
Entry
Acetylene
Solvent
Reagent ratio [Alkyne]–CH2I2–Et3Al
Reaction time, h
Product
Yield, %
1
2
3
4
5
6
7
Decyne-5
Octyne-4
Octyne-2
Heptyne-1
Heptyne-1
Hexyne-1
Hexane
Hexane
Hexane
Hexane
Dichloromethane
Hexane
Dichloromethane
1:2:4
1:2:4
1:2:4
1:2:3
1:1:1
1:2:3
1:1:1
18
18
18
8
18
8
1a
1b
1c
1d
2d
1e
2f
58
52
55
43
46
49
38
Phenylacetylene
18
A structure of the products was stated to depend on
a reagent ratio and a solvent nature. In a ratio of
heptyne-1–CH2I2–Et3Al=1:2:3 trisubstituted cyclo-
propane 1c is the main product of the reaction (Entry
4). In equimolar ratio of reagents heptyne-1 gives 1-
amyl-1-propylcyclopropane (2d) (Entry 5) together with
the compound 1d in sufficient amount (2d:1d=5:3 at
60% acetylene conversion degree). The analogous for-
mation of 1-alkyl(phenyl)-1-propylcyclopropanes is ob-
served for the other terminal acetylenes, in the case of
phenylacetylene 1-phenyl-1-propylcyclopropane (2f) is
the main reaction product (Entry 7).
On the basis of experimental data we have proposed
a scheme of the reaction course (Scheme 2). A genera-
tion of diethyl(iodomethyl)aluminium [8] is the initial
step of the reaction, the latter is able to carboaluminate
acetylene to give iodocontaining alkenylalane. A subse-
quent reaction way depends on reagents ratio and an
acetylene reactability. Scheme 2 demonstrates a stere-
oconfiguration of cyclopropane 1 is determinated at the
step of Et2AlI elimination from dialuminium com-
pound, and a formation of either one or two stereoiso-
mers may occur in dependence on a nature of
substitutents in initial acetylene.
3. Experimental
Commercial 95% Et3Al (Redkinskii pilot-production
plant), starting acetylenes and CH2I2 were used.
All reactions were carried out under dry argon atmo-
sphere. Solvents were dried and freshly distilled before
use. The reaction products were analyzed using chro-
matograph ‘Carlo Erba’ (glass capillary column ‘Ultra-
1’ (Hewlett-Packard), 25 m×0.2 mm, flame-ionization
detector, working temperature 50–170 °C, gas-carrier–
helium). Mass spectral measurements were performed
on Finnigan 4021 gas chromatograph–mass spectrome-
1
ter at 70 eV and mass data were tabulated as m/z. H
and 13C spectra were recorded as CDCl3 solutions on
spectrometers ‘JEOL FX-90Q’ (22.5 MHz for 13C and
90 MHz for 1H) and ‘Bruker AM-300’ (75 MHz for 13
C
1
and 300 MHz for H). TMS, C6D6 and CDCl3 were
used as internal standard. 13C-NMR spectra were
recorded on ‘JEOL FX-90Q’ using complete proton-de-
coupled mode and with the use of INEPT technique.
Partially proton-decoupled mode was used on ‘Bruker
AM-300’ for 13C-NMR. Quoted yields were obtained
after distillation.
General procedure for synthesis of 1,2-dialkyl-1,2-di-
ethylcyclopropanes:
a
100 ml three-necked-flask
CH2I2+Et3Al“Et2AlCH2I+EtI
equipped with magnetic stirrer was charged with
CH2Cl2 (50 ml) and Et3Al (40 mmol) at 0 °C under dry
argon atmosphere. Disubstituted acetylene (10 mmol)
and CH2I2 (20 mmol) consequentially were dropwise
added and the reaction mixture was stirred for 15 min
at 0 °C. The reaction mixture was allowed to warm to
room temperature (r.t.) and was stirred for 18 h. Then
the reaction was quenched with 10% water solution of
HCl. The layers were separated and the (aq.) layer was
extracted with diethyl ether. The combined organic
According to Scheme 2, the acetylene carboalumina-
tion by diethyl(iodomethyl)aluminium is one of the key
steps of the reaction. Cp2ZrCl2 is known to be effective
acetylene carboalumination catalyst [9]. Under the reac-
tion conditions in the presence of catalytic amounts of
Cp2ZrCl2 phenyl- and allylcontaining acetylenes react
with Et3Al to give 2,3-disubstituted aluminacyclopent-
2-enes, that shows a proceeding of the reaction of
acetylene cycloalumination found by us previously
[10,11]. However, a reaction of mono- and dialkylsub-
stituted acetylenes with Et3Al and CH2I2 is not effected
by the presence of a catalyst.
Thus, we have studied for the first time a reaction of
cyclopropanation of mono- and disubstituted acetyle-
nes by CH2I2–Et3Al reagent. The effective one-step
method for cyclopropanation of mono- and dialkylsub-
stituted acetylenes to tri- and tetraalkylsubstituted cy-
clopropanes was developed.
Scheme 1.

U.M. Dzhemile6 et al. / Journal of Organometallic Chemistry 636 (2001) 91–95
93
Fig. 1. Indexing of atoms in 13C and 1H-NMR spectral data of 1a–e and 2d,f.
extracts were washed with water (50 ml), sat. aq. NaCl
(20 ml), dried over CaCl2 and filtered. After evapora-
tion of solvents the crude product was purified by
vacuum distillation.
sity): 182 (M+, 5), 153 (M+-C2H5, 41), 139(M+-C3H7,
45), 97 (10), 83 (28).
1-(n-Amyl)-2-methyl-1,2-diethylcyclopropane
(1c).
bp. 86 °C/12 Torr. Anal. Found: C, 85.47; H, 14.39.
C13H26 Calc.: C, 85.63; H, 14.37%. 13C-NMR (CDCl3,
22.5 MHz): l 29.56 (s, C(1)), 25.73 (s, C(2)), 25.08 (t,
C(3)), 29.04 (t, C(4)), 26.90 (t, C(5)), 32.68 (t, C(6)),
22.93 (t, C(7)), 14.22 (q, C(8)), 30.80 (t, C(9)), 11.49 (q,
C(10)), 34.38 (t, C(11)), 11.36 (q, C(12)), 18.96 (q,
1,2-Di(n-butyl)-1,2-diethylcyclopropane (1a). bp.
102 °C/5 Torr. Anal. Found: C, 85.31; H, 14.56.
C15H30 Calc.: C, 85.63; H, 14.37%. 13C-NMR (CDCl3,
1
75 MHz): l 30.04 (s, C(1)), 24.27 (t, JCH=155.6 Hz,
C(2)), 30.72 C 30.77 (t, 1JCH=124.1 Hz, C(3)), 29.24 (t,
1JCH=125.4 Hz, C(4)), 23.30 (t, 1JCH=125.4 Hz,
1
C(13)). H-NMR (CDCl3/C6D6, 90 MHz): l −0.07–
C(5)), 14.22 (q, 1JCH=124.4 Hz, C(6)), 24.27 (t, 1JCH
=
0.06 (m, 2H, C(3)H2), 0.61–0.98 (m, 9H, C(8,10,12)H3),
1.02 (s, 3H, C(13)H3), 1.06–1.47 (m, 12H, C(4–
7,9,11)H2). EIMS m/z (relative intensity): 182 (M+, 5),
153 (M+-C2H5, 23), 111 (M+-C5H11, 33), 97 (24), 83
(62), 69 (95), 55 (100).
1
1
126.1 Hz, C(7)), 11.18 (q, JCH=125.0 Hz, C(8)). H-
NMR (CDCl3/C6D6, 300 MHz): l 0.68–1.10 (m, 14H,
C(2)H2, C(6,8)H3), 1.17–1.53 (m, 16H, C(3–5,7)H2).
EIMS m/z (relative intensity): 210 (M+, 5), 181 (M+-
C2H5, 39), 153 (M+-C4H9, 39), 125 (12), 111 (21), 97
(60), 83 (54), 69 (100).
General procedure for synthesis of 1-alkyl-1,2-di-
ethylcyclopropanes:
a
100 ml three-necked-flask
1,2-Di(n-propyl)-1,2-diethylcyclopropane (1b). bp.
83 °C/10 Torr. Anal. Found: C, 85.79; H, 14.25.
C13H26 Calc.: C, 85.63; H, 14.37%. 13C-NMR (CDCl3,
22.5 MHz): l 30.02 (s, C(1)), 24.43 (t, C(2)), 33.47 C
33.60 (t, C(3)), 20.20 (t, C(4)), 14.74 (t, C(5)), 24.43 (t,
C(6)), 11.29 (q, C(7)). 1H-NMR (CDCl3/C6D6, 90
MHz): l 0.73–1.00 (m, 14H, C(2)H2, C(5,7)H3), 1.05–
1.48 (m, 12H, C(3,4,6)H2). EIMS m/z (relative inten-
equipped with magnetic stirrer was charged with
CH2Cl2 (50 ml) and Et3Al (30 mmol) at 0 °C under dry
argon atmosphere. Terminal acetylene (10 mmol) and
CH2I2 (20 mmol) consequentially were dropwise added
and the reaction mixture was stirred for 15 min at 0 °C.
The reaction mixture was allowed to warm to r.t. and
was stirred for 8 h. Then the reaction was quenched
with 10% water solution of HCl. The layers were

94
U.M. Dzhemile6 et al. / Journal of Organometallic Chemistry 636 (2001) 91–95
tensity): 168 (M+, 4), 139 (M+-C2H5, 3), 126 (3), 112
(11), 97 (M+-C5H11, 41), 83 (39), 70 (52), 69 (67), 55
(100).
separated and the (aq.) layer was extracted with diethyl
ether. The combined organic extracts were washed with
water (50 ml), sat. aq. NaCl (20 ml), dried over CaCl2
and filtered. After evaporation of solvents the crude
product was purified by vacuum distillation.
1-(n-Butyl)-1,2-diethylcyclopropane (1e). bp. 79 °C/
25 Torr. Anal. Found: C, 85.51; H, 14.40. C11H22 Calc.:
C, 85.63; H, 14.37%. 13C-NMR (CDCl3, 22.5 MHz): l
26.14 (s, C(1)), 29.13 (d, C(2)), 18.27 (t, C(3)), 29.46 (t,
C(4)), 26.79 (t, C(5)), 23.28 (t, C(6)), 14.18 (q, C(7)),
30.37 (t, C(8)), 10.60 (q, C(9)), 22.44 (t, C(10)), 14.50
1-(n-Amyl)-1,2-diethylcyclopropane (1d). bp. 75 °C/
10 Torr. Anal. Found: C, 85.42; H, 14.23. C12H24 Calc.:
C, 85.63; H, 14.37%. 13C-NMR (CDCl3, 75 MHz): l
1
24.82 (s, C(1)), 26.25 (d, JCH=154.8 Hz, C(2)), 18.31
1
1
(t, JCH=156.3 Hz, C(3)), 30.47 (t, JCH=125.0 Hz,
(q, C(11)). 1H-NMR (CDCl3/C6D6, 90 MHz):
l
1
1
C(4)), 26.64 (t, JCH=126.5 Hz, C(5)), 32.55 (t, JCH
=
−0.16–0.35 (m, 3H, C(2)H, C(3)H2), 0.68–1.02 (m,
9H, C(7,9,11)H3), 1.14–1.49 (m, 10H, C(4–6,8,10)H2).
EIMS m/z (relative intensity): 154 (M+, 6), 125 (M+-
C2H5, 3), 112 (14), 97 (M+-C4H9, 17), 83 (24), 70 (36),
69 (79), 55 (100).
General procedure for synthesis of 1-alkyl(phenyl)-1-
propylcyclopropanes: a 100 ml three-necked-flask
equipped with magnetic stirrer was charged with
1
123.7 Hz, C(6)), 22.54 (t, JCH=125.0 Hz, C(7)), 14.22
1
1
(q, JCH=123.8 Hz, C(8)), 29.82 (t, JCH=125.4 Hz,
C(9)), 10.71 (t, 1JCH=124.6 Hz, C(10)), 22.87 (t,
1JCH=125.7 Hz, C(11)), 14.67 (q, 1JCH=124.3 Hz,
C(12)). 1H-NMR (CDCl3/C6D6, 300 MHz): l 0.18–0.42
3
(m, 3H, C(2)H, C(3)H2), 0.85 (t, JCH=4.9 Hz, 6H,
C(10,12)H3), 0.97 (t, JCH=6.8 Hz, 3H, C(8)H3), 1.07–
3
1.50 (m, 12H, C(4–7,9,11)H2). EIMS m/z (relative in-
CH2Cl2 (50 ml) and Et3Al (10 mmol) at 0 °C under dry
Scheme 2.

U.M. Dzhemile6 et al. / Journal of Organometallic Chemistry 636 (2001) 91–95
95
argon atmosphere. Terminal acetylene (10 mmol) and
CH2I2 (10 mmol) consequentially were dropwise added
and the reaction mixture was stirred for 15 min at 0 °C.
The reaction mixture was allowed to warm to r.t. and
was stirred for 18 h. Then the reaction was quenched
with 10% water solution of HCl. The layers were
separated and the (aq.) layer was extracted with diethyl
ether. The combined organic extracts were washed with
water (50 ml), sat. aq. NaCl (20 ml), dried over CaCl2
and filtered. After evaporation of solvents the crude
product was purified by vacuum distillation.
TMS, 90 MHz): l 0.60–1.04 (m, 7H, C(2)H2, C(9)H3),
1.07–1.66 (m, 4H, C(7,8)H2), 7.02–7.49 (m, 5H, Ph).
EIMS m/z (relative intensity): 160 (M+, 17), 132 (10),
131 (21), 117 (100), 115 (29), 91 (31).
Acknowledgements
We are grateful to the Russian Foundation of Basic
Research (Project Nos. 00-15-97312 and 00-03-32736)
for financial support.
1-(n-Amyl)-1-propylcyclopropane (2d). Bp. 68 °C/17
Torr. Anal. Found: C, 85.57; H, 14.21. C11H22 Calc.: C,
85.63; H, 14.37%. 13C-NMR (CDCl3, 22.5 MHz): l
19.29 (s, C(1)), 12.01 (t, C(2)), 36.13 (t, C(3)), 26.38 (t,
C(4)), 32.36 (t, C(5)), 22.87 (t, C(6)), 14.22 (q, C(7)),
38.41 (t, C(8)), 19.87 (t, C(9)), 14.61 (q, C(10)). 1H-
NMR (CDCl3/C6D6, 90 MHz): l 0.13 (s, 4H, C(2)H2),
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3
0.83 (t, JCH=6.2 Hz, 6H, C(7,10)H3), 1.02–1.39 (m,
12H, C(3–6,8,9)H2). EIMS m/z (relative intensity): 154
(M+, 1), 126 (2), 125 (2), 112 (6), 98 (19), 84 (24), 70
(67), 69 (68), 55 (100).
1-Phenyl-1-propylcyclopropane (2f). Bp. 83 °C/5
Torr. Anal. Found: C, 89.61; H, 9.92. C12H16 Calc.: C,
89.94; H, 10.06%. 13C-NMR (CDCl3, 22.5 MHz): l
25.79 (s, C(1)), 13.05 (t, C(2)), 145.64 (t, C(3)), 128.08
(t, C(4)), 129.06 (t, C(5)), 125.81 (t, C(6)), 42.83 (t,
C(7)), 20.46 (t, C(8)), 14.35 (q, C(9)). 1H-NMR (CDCl3/
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