Russian Journal of Organic Chemistry, Vol. 39, No. 8, 2003, pp. 1204 1205. Translated from Zhurnal Organicheskoi Khimii, Vol. 39, No. 8, 2003,
p. 1275.
Original Russian Text Copyright
2003 by Gevorkyan, Arakelyan, Barsegyan, Petrosyan, Panosyan.
SHORT
COMMUNICATIONS
Dimerization of Sodium Enolates of Malonic Ester
and Acetylacetone Effected by the Action
of 4-Methyl-3,4-dibromotetrahydropyran
A. A. Gevorkyan, A. S. Arakelyan, S. V. Barsegyan, K. A. Petrosyan,
and G. A. Panosyan
Institute of Organic Chemistry, Armenian National Academy of Sciences, Yerevan, 375095 Armenia
Received September 29, 2002
It was shown formerly that 4-methyl-3,4-dibromo-
tetrahydropyran (I) in reactions with a number of
nucleophiles formed in succession products of de-
hydrobromination and substitution, dihydropyrans
III [1 3]. In performing similar reactions with
enolates of -dicarbonyl compounds we revealed an
unusual process: formation of dehydrodimers V of
the initial dicarbonyl compounds. For instance, from
malonic ester malonylmalonic ester (Va) was obtain-
ed [4], and acetylacetone gave rise to 3,4-diacetyl-
hexane-2,5-dione (Vb) [5].
Dimeric compounds V are known to be prepared
by oxidizing the corresponding sodium enolates with
various oxidants: iodine, silver oxide, copper(II) tri-
flate etc. [6]. In our case the reaction occurred under
the effect of only dibromide I which evidently plays
the role of an oxidant being converted into 4-methyl-
2H-dihydropyran (VI).
By this procedure under standard conditions of
dicarbonyl compounds alkylation [7] [at reagents ratio
(I) RCOCH COR 1: 2] we obtained diethyl 2,3-di-
2
ethoxycarbonylsuccinate (Va, R = OEt), yield 63%
R = OEt (a), Me (b); Y = N(Alkyl) ; NHAr, NHAlkyl, OCOMe; OAr.
2
(
[
with respect to the initial dibromide), mp 74 75 C
13C NMR spectrum, , ppm: 2.81 (Me), 191.66
(C=O).
1
4], H NMR spectrum, , ppm: 1.27 t (12H, J 7.1),
3
.93 s (2H), 4.17 q (4H); 13C NMR spectrum, ,
REFERENCES
ppm: 13.42 (Me), 50.56 (CH), 60.95 (CH ), 165.78
2
(
C=O), and 3,4-diacetylhexane-2,5-dione (Vb,
1. Gevorkyan, A.A., Kazaryan, P.I., Khizantsyan, N.M.,
and Panosyan, G.A., Khim. Geterotsikl. Soed. , 1981,
p. 1025.
1
R=Me): yield 18%, mp 192 193 C [5], H NMR
spectrum, , ppm: 1.99 s (12H), 12.74 s (2H);
1
070-4280/03/3908-1204$25.00 2003 MAIK Nauka/Interperiodica