REACTION OF TRIFLUOROMETHANESULFONYL CHLORIDE WITH CH ACIDS
1413
data on the chemical shifts of compounds III and IV
[5, 6] showed the presence of ~60% of monochloro
derivative III, ~30% of acetylacetone, and ~10% of
dichloride IV.
boiling at 92°C (25 mm) being collected. The product
(10 g) contained 59% of dichloride II, 25% of com-
pound I, and 21% of initial diethyl malonate.
The reaction of 16.7 g of trifluoromethanesulfonyl
chloride with 10 g of acetylacetone in the presence of
20 ml of triethylamine was carried out in a similar
way. The mixture was treated as described above, and
the residue was distilled first under reduced pressure
(bp 50°C at 25 mm) and then under atmospheric pres-
sure (bp 120°C). The product contained 9.2 g (~75%)
of compound III and ~20% of unreacted acetyl-
acetone.
Thus the chlorination of CH acids like XCH2Y with
trifluoromethanesulfonyl chloride could produce both
mono- and dichloro derivatives, depending on the re-
actant ratio, reaction conditions, and substrate activa-
tion mode; in addition, possible chlorination of the
initial CH acid to XCHClY with dichloride XCCl2Y
must be taken into account
Reaction of trifluoromethanesulfonyl chloride
with diethyl malonate sodium salt. Diethyl malonate,
15.3 g, was dissolved in 50 ml of anhydrous methanol,
a solution of an equimolar amount of sodium methox-
ide in 50 ml of anhydrous methanol was added, the
mixture was stirred, and a solution of 10.2 ml of tri-
fluoromethanesulfonyl chloride in 20 ml of anhydrous
methanol was added dropwise. The mixture was then
stirred for 2 h at 50°C, cooled, poured into water
acidified with hydrochloric acid, and extracted with
diethyl ether. The extract was dried over magnesium
sulfate and evaporated, and the residue was distilled
under reduced pressure. Yield of dichloride II 15.4 g
(75%), bp 120°C (20 mm). 1H NMR spectrum, δ, ppm:
1.33 t (6H, CH3, J = 7.2 Hz), 4.36 q (4H, CH2). 13C
NMR spectrum, δC, ppm: 13.59 (CH3), 62.92 (CH2),
164.28 (C=O). Mass spectrum, m/z (Irel, %): 133 (1.8)
[M – Cl]+, 126 (15) [M – CH2O]+, 105 (1.7) [M – Cl –
CO]+, 91 (3.5) [CH3COCHCl]+, 43 (100) [CH3CO]+.
Reaction of 3,3-dichloropentane-2,4-dione (IV)
with acetylacetone. 3,3-Dichloropentane-2,4-dione
(IV), 1.5 ml, was slowly added under stirring to a mix-
ture of 1.8 ml of acetylacetone, 2 ml of triethylamine,
and 5 ml of THF. The mixture was heated for 1 h at
50°C and treated as described above. According to the
1H NMR data, the residue (2.4 g) contained ~60% of
chloride III and ~10% of initial dichloride IV; it was
analyzed by GC–MS.
The NMR spectra were recorded from solutions in
CDCl3 on a Bruker DPX-400 spectrometer (400 MHz
1
13
for H and 100 MHz for C); the chemical shifts are
given relative to tetramethylsilane. Gas chromato-
graphic–mass spectrometric analysis was performed on
a Shimadzu QP2010 Plus instrument (electron impact,
70 eV; Equity 5 capillary column, 30 m×0.25 mm,
95% of dimethylpolysiloxane and 5% of diphenyl-
polysiloxane; oven temperature programming from 70
to 250°C; carrier gas helium; injector, interface, and
ion source temperature 250°C).
The reaction of trifluoromethanesulfonyl chloride
with diethyl malonate magnesium salt (prepared from
diethyl malonate and magnesium ethoxide) was per-
formed in a similar way. Yield of diethyl 2-chloro-
malonate (I) 13.2 g (85%), bp 90°C (20 mm). 1H NMR
spectrum, δ, ppm: 1.29 t (6H, CH3, J = 7.1 Hz), 4.21 q
(4H, CH2), 4.83 s (1H, CHCl). 13C NMR spectrum, δC,
ppm: 13.78 (CH3), 55.35 (CHCl), 63.11 (CH2), 164.44
(C=O). Mass spectrum, m/z (Irel, %): 134 (18) [M]+,
119 (30) [M – CH3]+, 92 (5) [M – CH2CO]+, 43 (100)
[CH3CO]+, 42 (8) [CH2CO]+.
This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 07-03-00425).
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 45 No. 9 2009