New route of reaction between acyl isothiocyanates and cyclic β-diketones

Full text of DOI:10.1023/B:RUJO.0000034955.48174.8f

Russian Journal of Organic Chemistry, Vol. 40, No. 2, 2004, pp. 280-281. Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 2, 2004,
pp. 308-309.
Original Russian Text Copyright Ó 2004 by Vovk, Chubaruk, Bol’but.
SHORT
COMMUNICATIONS
New Route of Reaction between Acyl Isothiocyanates and Cyclic
b-Diketones
M. V. Vovk, N. G. Chubaruk, andA. V. Bol’but
Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev, 02094 Ukraine
e-mail: mvovk@i.com.ua
Received July 15, 2002
The reaction of acyl isothiocyanates with b-dicarbonyl
compounds is thoroughly studied nowadays [1-10]. In a
wide range of reaction conditions the process proceeds
as C-thiocarbamoylation of the dicarbonyl component.
For instance, C-thiocarbamoylated derivatives of
1,3-cyclohexanedione [7] or dimedone [8, 9] formed in
good yields at boiling reagents in dioxane or acetone.
(alcohol solution of KOH) acts as pseudohaloid. We
believe that conversion of C-carbamoylated products into
O-acylated derivatives under the action of alkali is less
probable. The latter is confirmed by formation of
derivatives of S,N-ketene acetal type in reaction between
benzoyl isothiocyanate with b-dicarbonyl compounds in
DMF in the presence of KOH [3].
Compounds IIIa–IIIf are viscous oily fluids. Their
We found reaction conditions where the character of
the process crucially changed: the acyl isothiocyanates
operated not as thiocarbamoylating but as acylating
agents. It was demonstrated that reaction of benzoyl
isothiocyanates Ia-Id with cyclic diketones IIa, IIb in
the presence of equimolar amount of KOH at room
temperature furnished O-acylation products IIIa-IIIf.
We assume as more probable a direct O-acylation of
b-diketones of II type with compounds I whose
isothiocyanate group under the reaction conditions
struc-ture was confirmed by IR spectra containing
–1
characteristic absorption bands of keto (1665–1675 cm )
–1
and ester (1725–1740 cm ) carbonyl groups, and by 1H
NMR spectra where appeared a signal from proton CH=
at 5.94–6.06 ppm
3-Acyloxy-2-cyclohexen-1-ones (IIIa–IIIf). To a
solution of 0.006 mol of b-diketone IIa, IIb and 0.337 g
(0.006 mol) of KOH in 30 ml of ethanol was added at
stirring in one portion 0.006 mol of benzoyl isothiocyanate
Ia–d. After stirring for 15 min the reaction mixture was
poured into water (50 ml), the organic products were
extracted into dichloromethane (2´25 ml), the extract was
dried on Na2SO4, and the solvent was evaporated. Then
the residue was extracted with boiling hexane (100 ml),
and on evaporating the solvent the substance was
subjected to chromatography (eluent ethylacetate–
hexane, 1:2).
2
2
ꢁ
5
ꢀ
1 & 6
5
ꢁ
5
2
,,DꢂꢁE
B
,DꢁꢁꢁG
2
ꢁ
5
.2+ꢀ HWKDQRO
3-Benzoyloxy-2-cyclohexen-1-one (IIIa). Yield
B
–1
1
76%, Rf 0.82. IR spectrum, cm : 1675, 1730 (C=O). H
NMR spectrum, d, ppm: 2.07–2.11m (2H, H5), 2.38–
2.41m (2H, H6), 2.70–74m (2H, H4), 5.91s (1H, CH= ),
7.59–7.73m (3H, H3', H4', H5'), 8.09d (2H, H2', H6',
J 7.8 Hz). Found, %: C 71.83; H 5.72. C13H12O3.
Calculated, %: C 72.21; H 5.59.
.6&1
2
5ꢁ
2
,,, ꢁꢁꢁI
5
B
I, R = Ph (a), 4-ClC6H4 (b), 4-BrC6H4 (c), 4-MeOC6H4
(d); II, R' = H (a), Me (b); III, R' = H, R = Ph (a), 4-ClC6H4
(b), R' = Me, R = Ph (c), 4-ClC6H4 (d), 4-BrC6H4 (e),
4-MeOC6H4 (f).
3-(4-Chlorobenzoyloxy)-2-cyclohexen-1-one
–1
(IIIb). Yield 61%, Rf 0.60. IR spectrum, cm : 1675, 1735
1070-4280/04/4002-0280Ó2004 MAIK “Nauka/Interperiodica”

NEW ROUTE OF REACTION BETWEEN ACYL ISOTHIOCYANATES
281
1
(C=O). H NMR spectrum, d, ppm: 2.10–2.14 m (2H,
d, ppm: 1.15 s (6H, 2Me), 2.33 s (2H, H6), 2.53 s (2H,
H4), 6.04 s (1H, CH=), 6.97 d (2H, H3', H5', J 8.0 Hz),
H5), 2.46 t (2H, H6, J 5.8 Hz), 2.67 t (2H, H4, J 5.8 Hz),
6.04 ñ (1H, CH=), 7.47 d (2H, H3', H5', J 8.0 Hz), 8.02 d 8.03 d (2H, H2', H6', J 8.0 Hz) Found, %: C 69.73;
(2H, H2', H6', J 8.0 Hz). Found, %: C 62.59; H 4.30.
H 6.47. C16H18O4. Calculated, %: C 70.06; H 6.61.
C13H11ClO3. Calculated, %: C 62.29; H 4.42.
IR spectra were recorded on spectrophotometer UR-
20 from solutions in CH2Cl2. H NMR spectra were
registered on spectrometer Varian-Gemini (300.0 MHz)
in CDCl3, internal reference TMS.
1
3-Benzoyloxy-5,5-dimethyl-2-cyclohexen-1-one
–1
(IIIc). Yield 72%. Rf 0.71. IR spectrum, cm : 1670,
1
1725 (C=O). H NMR spectrum, d, ppm: 1.16 s (6H,
2Me), 2.33 s (2H, H6), 2.56 s (2H, H4), 6.06 s (1H, CH= ),
REFERENCES
7.50–7.53 m (2H, H3', H5'), 7.65 t (1H, H4', J 7.8 Hz),
8.08 d (2H, H2' H6', J 7.7 Hz). Found, %: C 74.07; H
1. Dehne, H. and Krey, H., J. Pract. Chem., 1982, vol. 324,
p. 915.
2. Mohareb, R.M., Habashi,A., Ibrahim, N.S., and Sherif, S.M.
Synthesis, 1987, p. 228.
3. Mohareb, R.F., Shams, H.H., andAzis, S.I., J. Chem. Res.,
1992, vol. 5, p. 1132.
4. Mohareb, R.F., Azis, S.I., Abdel-Sayed, N.I., and El-Ab-
lack, F.Z., Collect. Cheh. Chem. Commun., 1993, vol. 58,
p. 947.
5. Assy, M.G. and Moustafa, H.Y., Phosphorus, Sulfur,
Silicon,1995, vol. 105, p. 213.
6. Hetaba,A.A.,Assy, M.G., and Fikry, R.M., Ind. J. Chem. B,
1996, vol. 35, p. 144.
7. Assy, M.G..,Phosphorus, Sulfur, Silicon, 1996, vol. 108,
p. 15.
8. Assy, M.G. and Motti, F.M., Egypt. J. Chem., 1996, vol. 39,
581.
,
6.77. C15H16O3. Calculated, %: C 73.75; H 6.60.
3-(4-Chlorobenzoyloxy)-5,5-dimethylcyclo-
hexen-1-one (IIId). Yield 63%, Rf 0.74. IR spectrum,
–1
1
cm : 1665, 1730 (C=O). H NMR spectrum, d, ppm:
1.16 s (6H, 2Me), 2.33 s (2H, 4-CH2), 2.55 s (2H, H4),
6.05 s (1H, CH=), 7.47 d (2H, H3', H5', J 8.0 Hz), 8.02 d
(2H, H2', H6', J 8.0 Hz) Found, %: C 64.52; H 5.60.
C15H15ClO3. Calculated, %: C 64.64; H 5.42.
3-(4-Bromobenzoyloxy)-5,5-dimethyl-2-cyclo-
hexen-1-one (IIIe). Yield 60%, Rf 0.8. IR spectrum,
–1
1
cm : 1670, 1725 (C=O). H NMR spectrum, d, ppm:
1.16 s (6H, 2Me), 2.34 s (2H, H6), 2.55 s (2H, H4), 6.05
s (1H, CH=), 7.64 d (2H, H3', H5', J 7.8 Hz), 7.93 d (2H,
H2', H6', J 7.8 Hz) Found, %: C 55.98; H 4.86.
C15H15BrO3. Calculated, %: C 55.75; H 4.68.
9. Assy, M.G. and Hetaba, A.A., J. Ind. Chem. Soc., 1997,
vol. 74, p. 239.
10. Amine M.S. and Arief M.M.H., Ind. J. Chem. B, 1998,
vol. 37, p. 135.
3-(4-Methoxybenzoyloxy)-5,5-dimethyl-2-
cyclohexen-1-one (IIIf). Yield 65%, Rf 0.70. IR
–1
1
spectrum, cm : 1665, 1740 (C=O). H NMR spectrum
,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 40 No. 2 2004