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.
AND POLYMERIC MATERIALS
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.
Reaction of olefins with formaldehyde in the pres-
ence of acid catalysts (Prins reaction) is the main
route to substituted 1,3-dioxanes [13 4]. This process
is widely used in commercial synthesis of 4,4-dimeth-
yl-1,3-dioxane whose cleavage yields isoprene .
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. .
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
in organic solvents (1,2-dichloroethane, chloroben-
zene, 1,4-dioxane, diisopropyl ether) in the presence
of catalytic amounds of H
. 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 .
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: