Acid-catalyzed condensation of vinyl-gem-dichlorocyclopropanes with formaldehyde in nonaqueous solutions

Article abstract of DOI:10.1134/S1070427208030269

Condensation of vinyl-and vinylmethyl-1,1-dichlorocyclopropanes with formaldehyde in organic solvents of various polarities was studied.

Full text of DOI:10.1134/S1070427208030269

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 3, pp. 475 477. Pleiades Publishing, Ltd., 2008.
Original Russian Text S.V. Kopsov, S.S. Zlotskii, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 3, pp. 490 492.
MACROMOLECULAR CHEMISTRY
AND POLYMERIC MATERIALS
Acid-Catalyzed Condensation
of Vinyl-gem-dichlorocyclopropanes with Formaldehyde
in Nonaqueous Solutions
S. V. Kopsov and S. S. Zlotskii
Ufa State Petroleum Technical University, Ufa, Bashkortostan, Russia
Received January 16, 2007
Abstract Condensation of vinyl- and vinylmethyl-1,1-dichlorocyclopropanes with formaldehyde in organic
solvents of various polarities was studied.
DOI: 10.1134/S1070427208030269
Reaction of olefins with formaldehyde in the pres-
ence of acid catalysts (Prins reaction) is the main
route to substituted 1,3-dioxanes [1 4]. This process
is widely used in commercial synthesis of 4,4-dimeth-
yl-1,3-dioxane whose cleavage yields isoprene [3].
The condensation is performed most frequently in an
aqueous solution, but in this case it is accompanied
by formation of hydroxyl-containing by-products:
unsaturated alcohols, diols, hydroxyfurans, etc. [4].
in organic solvents (1,2-dichloroethane, chloroben-
zene, 1,4-dioxane, diisopropyl ether) in the presence
of catalytic amounds of H SO . The starting vinyl-
gem-dichlorocyclopropanes are formed in virtually
quantitative yield by the addition of dichlorocarbene
to the corresponding dienes in a two-phase system [5].
2
4
We found that the reaction of Ia and Ib with form-
aldehyde yielded the coresponding 1,3-dioxanes (IIa,
IIb) and 1,3-dioxolanes (IIIa, IIIb) in comparable
amounts. Apparently, the highly reactive intermediate
unsaturated alcohol reacts with formaldehyde to form
a hemiacetal whose hydroxy group undergoes intra-
molecular adition to the double bond to form hetero-
cycles IIa, IIb, IIIa, and IIIb:
To prepare dioxanes containing a gem-dichloro-
cyclopropane fragment, which can be of interest as
biologically active compounds and intermediates for
organic synthesis, we used the reaction of vinyl-gem-
dichlorocyclopropanes Ia and Ib with formaldehyde
Ia, Ib
A
IIa, IIb
IIIa, IIIb
475

476
KOPSOV, ZLOTSKII
Table 1. Reaction of vinyl-gem-dichlorocyclopropanes Ia and Ib with formaldehyde. Molar ratio of Ia or Ib to CH2O and
H2SO4 1 : 2.5 : 0.5, 55 C, 3 h
Conversion, %
Selectivity, %
Ib
Solvent
Ia
Ib
Ia
Ia
Ib
1,2-Dichloroethane
Chlorobenzene
1,4-Dioxane
95
85*
60
40**
90
40
45
70
75
50
45
50
60
35
45
40
35
35
40
20
20
65
50
95
Diisopropyl ether
* More than 20% high-boiling unidentified products.
** About 5% low-boiling components.
where R = H (a), CH (b).
formals and formation of noticeable amounts of poly-
formals. The condensation with Ia in 1,4-dioxane
yields an impurity of low-boiling substances. The
mass spectrum of one of them contains peaks of ions
B and C with m/z 179 and 85, respectively. We be-
lieve that this minor component (1 1.5%) is spirocy-
clic compound IV formed by 1,2-migration of the
methyl group and closure of the pyran ring in interme-
diate carbocation A:
3
It is interesting that, in polar solvents (1,4-dioxane,
diisopropyl ether), the selectivity with respect to
1,3-dioxanes IIa and IIb is somewhat higher than in
chlorinated hydrocarbons (Table 1). Apparently, the
ratio of the six- (IIa, IIb) and five-membered (IIIa,
IIIb) products is determined by the rate of proton
addition to carbon atoms of the double bond of the
intermediate hemiacetal. In the isoprene derivative,
the methyl group facilitates the formation of carbo-
cations in which the positive charge is conjugated
with the quasiaromatic orbitals of the three-membered
carbocycle, which may be responsible for the ob-
served prevalence the reaction pathway leading to the
six-membered heterocycle.
B, m/z = 179
The reaction with Ia in 1,2-dichloroethane yields
more than 20% high-boiling unidentified products,
which may be due to hindered cyclization of oligo-
C, m/z = 85
A+
Table 2. Relative activity of olefins in the Prins reaction.
Olefin : CH2O : H2SO4 molar ratio 1 : 2.5 : 0.5, 55 C,
30 min, solvent (i-Pr)2O
IV
Compound
CH3
Relative activity
Sigmatropic shifts in the course of the Prins reac-
tion were observed previously [6].
The activity of olefins Ia and Ib was compared
with that of 1-heptene and styrene in competitive reac-
tions. The relative activity of these unsaturated com-
pounds was judged from the rates of formation of 1,3-
dioxacyclanes IIa, IIb, IIIa, and IIIb and of 4-amyl-
and 4-methyl-4-phenyl-1,3-dioxanes which are selec-
tively formed from 1-heptene and -methylstyrene,
respectively [1]. The activity of the aromatic olefin
exceeds that of Ia by more than an order of magni-
tude, and compound IIa, in turn, is two times more
active than the terminal linear unsaturated hydrocar-
bon (Table 2).
1
Cl
Cl
Cl
Cl
2.5
0.5
15
CH3
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 81 No. 3 2008

ACID-CATALYZED CONDENSATION
477
Table 3. Constants and spectral characteristics of the products obtained
Tb, C/P,
Mass spectrum, m/z
(Irel, %)
Compound
Rf
1H NMR spectrum, , ppm
mm Hg
4-(2,2-Dichlorocyclopropyl)-
1,3-dioxane IIa
111/5
0.35 1.4 1.5 (m, 1H, CHCCl2); 1.6 1.8 198, 200 (0.7) [M+]; 109,
(m, 2H, CH2CCl2); 1.85 2.1 (m, 2H, 111 (5); 87 (100); 57 (60)
CH2); 3.6 3.8 (m, 2H, CH2O); 4.0
4.15 (m, 1H, CHO); 4.6 5.0 (d.d, 2H,
OCH2O)
4-(2,2-Dichloro-1-methylcyclo-
propyl)-1,3-dioxane IIb
115/5
105/5
108/5
0.37 1.35 (s, 3H, CH3); 1.4 1.6 (d.d, 2H, 212, 214 (1) [M+]; 123,
CH2CCl2); 2.4 2.6 (m, 2H, CH2); 3.6 125 (3); 87 (100); 57
3.8 (m, 2H, CH2O); 3.95 4.15 (m, 1H, (51); 45 (81)
CHO); 4.65 5.0 (d.d, 2H, OCH2O)
0.27 1.4 1.5 (m, 1H, CHCCl2); 1.6 1.8 (m, 198, 200 (0.1) [M+]; 100
2H, CH2CCl2); 1.6 2.1 (m, 2H, CH2); (45); 84 (50); 73 (100)
3.5 3.8 (m, 2H, CH2O); 4.1 4.25 (m,
4-(2,2-Dichlorocyclopropyl-
methyl)-1,3-dioxolane IIIa
1H, CHO); 4.6 5.0 (d.d, 2H, OCH2O)
4-(2,2-Dichloro-1-methylcyclo-
propylmethyl)-1,3-dioxolane
IIIb
0.30 1.4 (s, 3H, CH3); 1.4 1.6 (d.d, 2H, 212, 214 (0.1) [M+]; 114
CH2CCl2); 1.6 2.2 (m, 2H, CH2); 3.4 (37); 84 (40); 73 (100)
3.7 (m, 2H, CH2O); 4.05 4.2 (m, 1H,
CHO); 4.6 5.1 (d.d, 2H, OCH2O)
EXPERIMENTAL
CONCLUSION
1
Condensation of vinyl- and vinylmethyl-gem-di-
chlorocyclopropanes with formaldehyde in organic
solvents of various polarities was performed. The
reaction occurs along two parallel pathways, yielding
the corresponding 4-gem-dichlorocyclopropyl-1,3-di-
oxolanes and -1,3-dioxanes via the intermediate un-
saturated alcohol.
The H NMR spectra were recorded on a Bruker
AM-300 spectrometer (300 MHz) in acetone-d ,
CDCl , or C D + CCl . GLC analyses were per-
formed on a Tsvet-500M device (flame ionization
detector, 5 1000-mm metal column, stationary phase
5% SE-30 on Chromaton N-AW, programmed heating
6
3
6
6
4
1
from 50 to 220 C at a rate of 6 deg min , carrier gas
helium).
REFERENCES
Vinyl-gem-dichlorocyclopropanes Ia and Ib were
prepared by the published procedure [5]. The unsatu-
rated compounds used in the study were no less than
99% pure.
1. Shepelevich, I.S., Talipova, G.R., and Talipov, R.F., in
Novye napravleniya v khimii tsiklicheskikh atsetalei
(New Lines in Chemistry of Cyclic Acetals), Ufa: Re-
aktiv, 2002, p. 36.
Acid-catalyzed reaction of olefins with formalde-
hyde (general procedure). A solution of 0.1 mol of
appropriate olefin in 10 ml of appropriate solvent was
added with vigorous stirring to a mixture of 7.7 g
(0.26 mol) of paraform, 3.1 ml of concentrated
H SO , and 5 ml of the solvent. The mixture was
2. Talipov, R.F. and Safarov, M.G., Bashkir. Khim. Zh.,
1997, vol. 4, no. 3, p. 10.
3. Rakhmankulov, D.L., Zlotskii, S.S., Kantor, E.A.,
et al., Mekhanizmy reaktsii atsetalei (Mechanisms of
Reactions of Acetals), Moscow: Khimiya, 1987.
4. Talipov, R.F., Mustafin, A.M., Talipova, G.R., and
Safarov, M.G., Zh. Obshch. Khim., 1996, vol. 66, no. 8,
p. 1382.
5. Arbuzova, T.V., Zlotskii, S.S., and Rakhmanku-
lov, D.L., Bashkir. Khim. Zh., 2005, vol. 12, no. 2,
p. 19.
6. Talipov, R.F., New Approaches to Synthesis of -Sub-
stituted Hydrogenated Furans and Role of Formalde-
hyde Oligomers in the Pattern of Product Formation in
the Prins Reaction, Doctoral Dissertation, Ufa, 1998.
2
4
heated to 50 60 C, with the stirring continued, until
the paraform dissolved completely. After cooling, the
mixture was neutralized with aqueous ammonia, the
organic layer was separated and dried over CaCl , and
2
the solvent was evaporated. The products were iso-
lated by column chromatography on silica gel (eluent
hexane ethyl acetate, 6 : 1).
Some characteristics of the synthesized compounds
are given in Table 3.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 81 No. 3 2008