2874
V. M. Zakharova et al.
PAPER
and 19F nuclei. A clear interaction between fluorine atoms
of the RF-group and the hydrogen atom on the double
bond was established. Furthermore, a weak interaction of
the same F-atoms with hydrogens in the non-fluorinated
R1 group of F-vinyldiazoketones 4f,h was found. There-
fore, one can conclude that vinyldiazoketones 4 have the
expected E-configuration (Figure 2).
DBU (or another base) (4.5 mmol) was added dropwise to a mag-
netically stirred solution of 3-nitro-4-methyl-benzenesulfonyl azide
(20 mmol) and 1,3-diketone 3 (18 mmol) in CH2Cl2 (20 mL) under
cooling (0–5 °C) over 5–10 min. The reaction mixture was stirred
for 2–3 h, filtered through a short plug of silica gel (3 g), and washed
with CH2Cl2–hexane (2:1, 5 × 5 mL). Solvents from the combined
organic phases were removed in vacuo (or at atmospheric pressure
in the case of 1a), and the residue was purified by distillation under
vacuum (for 1i,j) or by column chromatography on silica gel (for
1a–h) to give diazodiketones 1.
Vinyldiazoketones 4a–h,k,l; General Procedure
F-Diazodiketone 1 (4 mmol) was added dropwise to a stirred sus-
pension of methylene triphenylphosphoranes 2a,b,d,e (4.8 mmol)
in Et2O (5 mL; toluene for 2c). After the complete disappearance of
1 from the reaction mixture (3–4 h, in the case of phosphoranes
2c,d,e starting diazo compounds 1a,c were still present even after
6–14 d), the solid matter was removed by filtration, the resultant fil-
trate was concentrated in vacuo, and the residue purified by column
chromatography to furnish F-vinyldiazoketones 4a–h,k,l as bright
yellow-orange oils. Vinyldiazoketones 4b,c,e were additionally pu-
rified by repeated column chromatography to give analytically pure
samples.
Figure 2
The considerable variation in the reactivity of fluorinated
1a–h and non-fluorinated 1i,j diazodiketones during the
Wittig reaction, as well as the discrepancy in the chemical
behavior of H- and F-acyl carbonyl, can be explained by
the enhanced electrophilic character of the carbonyl C-
atom in the perfluoroacyl substituent. This observation
has already been made for ordinary fluoroalkyl containing
ketones;15 it was determined for the first time in this series
of diazocarbonyl compounds with two electron-accepting
groups at the a,a¢-position to the C=O moiety. Moderate
yields obtained with (benzoyl)methylenephosphorane 2c,
and negative results with (formyl)- and (acetyl)methyl-
enephosphoranes 2d,e may be attributed to the weak reac-
tivity of these Wittig reagents bearing acyl groups.17 The
process is probably complicated by the easily occurring
consecutive reaction of the newly formed conjugated sys-
tem in vinyldiazoketone 4, which reacts with one more
molecule of phosporanes 2d,e to give polyolefinic struc-
tures.
References
(1) (a) Murphy, P. J.; Brennan, J. Chem. Soc. Rev. 1988, 17, 1.
(b) Murphy, P. J.; Lee, S. E. J. Chem. Soc., Perkin Trans. 1
1999, 3049.
(2) Maercker, A. Org. React. 1965, 14, 270.
(3) Guillaume, M.; Janousek, Z.; Viehe, H. G. Synthesis 1995,
920.
(4) Capuano, L.; Drescher, S.; Volker, H. Liebigs Ann. Chem.
1991, 331.
(5) Wang, Y.; Zhu, S.; Zhu, G.; Huang, Q. Tetrahedron 2001,
57, 7337.
(6) (a) Davies, H. M. L.; Clark, T.; Smith, H. D. J. Org. Chem.
1991, 56, 3817. (b) Davies, H. M. L.; Antoulinakis, E. G.
Org. React. 2001, 57, 326.
(7) Doyle, M. P.; Yan, M.; Hu, W.; Gronenberg, L. S. J. Am.
Chem. Soc. 2003, 125, 4692.
(8) (a) Regitz, M.; Maas, G. Diazo Compounds. Properties and
Synthesis; Academic Press: New York, 1986, 326.
(b) Doyle, M. P.; McKervey, M. A.; Ye, T. Modern
Catalytic Methods for Organic Synthesis with Diazo
Compounds; Wiley: New York, 1998, 9.
(9) (a) Doyle, M. P.; Dorrow, R. L.; Terpstra, J. W.;
Rodenhouse, R. A. J. Org. Chem. 1985, 50, 1663.
(b) Nikolaev, V. A.; Utkin, P. Yu.; Korobitsyna, I. K. Zh.
Org. Khim. 1989, 25, 1176.
In summary, the reaction of fluoroalkyl-containing diazo-
diketones with (alkyloxycarbonyl)- and (benzoyl)methyl-
ene triphenylphosphoranes proceeds chemoselectively at
the perfluoroacyl carbonyl group furnishing the corre-
sponding fluorinated vinyldiazoketones with E configura-
tion at the carbon–carbon double bond, in moderate to
good yields.
1H, 13C, and 19F NMR spectra were recorded on a Varian Gemini-
300 and Bruker DRX-600 NMR spectrometers at an operating fre-
quency of 300 or 600 MHz (1H), 75 or 150 MHz (13C) and at 282
MHz (19F) in CDCl3 using TMS and CFCl3 as internal standards. IR
spectra were recorded on a spectrophotometer Specord 75IR with
KBr pellets. Microanalysis was performed on a Heraeus CHNS
Rapid Analyzer. All reactions were carried out in carefully purified
and dried solvents, and were monitored by TLC on Silufol UV/VIS
254 nm plates (KAVALIER) using UV light and iodine as visualiz-
ing agents. Preparative column chromatography was carried out on
neutral silica gel (CHEMAPOL L 40/100 or MERCK 70–230
mesh) with petroleum ether (40–70 °C) and Et2O as eluents.
(10) Nikolaev, V. A.; Kantin, G. P.; Utkin, P. Yu. Zh. Org. Khim.
1994, 30, 1292.
(11) (a) Alloum, A. B.; Villemin, D. Synth. Commun. 1989, 19,
2567. (b) Popik, V. V.; Korneev, S. M.; Nikolaev, V. A.;
Korobitsyna, I. K. Synthesis 1991, 195.
(12) Galiullina, S. V.; Zakharova, V. M.; Kantin, G. P.; Nikolaev,
V. A. Zh. Org. Khim. 2005, in press.
(13) (a) Kaplan, F.; Meloy, G. K. J. Am. Chem. Soc. 1966, 88,
950. (b) Lauer, W.; Krause, V.; Wengenroth, H.; Meier, H.
Chem. Ber. 1988, 121, 465. (c) Nikolaev, V. A.; Popik, V.
V.; Korobitsyna, I. K. Zh. Org. Khim. 1991, 27, 505.
(14) Davies, H. M. L.; Clark, D. M.; Smith, T. K. Tetrahedron
Lett. 1988, 26, 5659.
(15) Eguchi, T.; Aoyama, T.; Kakinuma, K. Tetrahedron Lett.
1992, 33, 5545.
(16) Nägele, U.; Hanack, M. Liebigs Ann. Chem. 1989, 847.
(17) Johnson, A. Ylid Chemistry; Academic Press: New York,
1966, 400.
2-Diazo-1,3-diketones 1a–j; General Procedure
The diazo transfer reaction to prepare F-diazodiketones 1a–h was
performed in carefully dried equipment, with moisture excluded at
all stages of the process.10 Reaction with non-fluorinated 1,3-dike-
tones was carried out in the usual manner.8
Synthesis 2005, No. 17, 2871–2874 © Thieme Stuttgart · New York
Zakharova, Valerija M.
