5
24
J.Paleček, O. Paleta
PAPER
Yield: 1.17 g (76.1%); mp 61–63 °C (Lit.4,11 mp 61–63 °C).
The reaction was finished in several minutes (check by 19F NMR).
Further stirring for 1 h showed no changes in the reaction mixture
(following by F NMR). The solvent was then removed by rotary
evaporator and the crude aldol 10 was purified first by column chro-
matography (silica gel, 50 g) and finally by crystallization (hexane).
1
2
H NMR (CDCl ): d = 2.17 (s, 3 H, CH ), 3.11 (d, 1 H, J = 17.6
3
3
HH
19
2
Hz, CH ), 3.21 (d, 1 H, JHH = 17.6 Hz, CH ), 3.88 (s, 3 H,
2
2
COOCH ), 4.11 (s, 1 H, OH).
3
1
3
C NMR (CDCl ): d = 30.3 (CH ), 44.8 (CH ), 54.0 (COOCH ),
3
3
2
3
Yield: 0.69 g (64.2%); mp 61–63 °C (Lit.4,11 mp 61–63 °C).
2
1
7
1
8.9 (q, J = 30.3 Hz, CCF ), 122.9 (q, J = 285.5 Hz, CF ),
69.1 (COOCH ), 203.51 (C=O).
CF 3 CF 3
3
1
9
F NMR (CDCl ): d = –79.7 (s, CF ).
Acknowledgements
3
3
The research was supported by the Grant Agency of the Czech Re-
public (Project 203/02/0306) and partly by the Ministry of Educati-
on of the Czech Republic (Project MSM 223100001).
Methyl 2-(3,5-Dinitrobenzoyloxy)-2-(2-oxocyclopentyl)-3,3,3-
trifluoropropanoate (11)
1
9
A mixture of aldol 7 (0.38 g, 1.5 mmol, 90:10 diastereoisomeric ra-
tio), 3,5-dinitrobenzoyl chloride (1.04 g, 4.5 mmol), pyridine (0.35
g, 4.5 mmol), DMAP (0.18 g, 1.5 mmol) and 1,2-dichlorethane (50
References
1
9
mL) was refluxed overnight (check by F NMR). Column chroma-
tography of the crude product (silica gel, 50 g; CH Cl ) afforded a
2
2
(1) (a) Mustafa, M. E.; Takaoka, A.; Ishikawa, N. Bull. Soc.
Chim. Fr. 1986, 944. (b) Dyatchenko, V. I.; Galakhov, M.
V.; Fokin, A. V. Izv. Akad. Nauk SSSR, Ser. Khim. 1988,
1196. (c) Sewald, N.; Seymour, L. C.; Burger, K.
Tetrahedron: Asymmetry 1994, 5, 1051. (d) Dolenský, B.;
Kvíčala, J.; Paleta, O.; Čejka, J. Tetrahedron Lett. 1996, 37,
6939.
fraction of waxy pure major diastereoisomer 11a of the product 11
70 mg, 10.4%). Several attempts to obtain crystalline 11a using
(
various solvents were unsuccessful.
Diastereoisomer 11a
1
H NMR (CDCl ): d = 2.75 (m, 3 H, CH CH CH ), 3.04 (m, 3 H,
3
2
2
2
CH CH CH ), 3.57 (s, 3 H, COOCH ), 6.65 (m, 1 H, CH), 9.18 (d,
2
(2) Dolenský, B.; Kvíčala, J.; Paleček, J.; Paleta, O. J. Fluorine
Chem. 2002, 115, 67.
2
2
2
3
3
3
H, J = 2.2 Hz, Ph), 9.28 (d, 1 H, J = 2.2 Hz, Ph).
HN HN
1
3
(3) Paleček, J.; Dolenský, B.; Kvíčala, J.; Paleta, O. Abstracts of
C NMR (CDCl ): d = 27.6 (3 × CH ), 52.8 (COOCH ), 122.6 (q,
3
2
3
th
1J = 273.9 Hz, CF ), 123.1 (CH), 129.7 (Ph), 132.5 (Ph), 137.1
(
(
1
the 13 European Symposium on Fluorine Chemistry, Poster
CF
3
1; : Bordeaux France, 15-20 July 2001, 53.
Ph), 148.8 (Ph), 159.9 (OCOPh), 163.9 (COOCH ), 214.7 (C=O)
the signal of CCF was not observed in the spectrum).
3
(4) Golubiev, A. S.; Galakhov, M. V.; Kolomiets, A. F.; Fokin,
3
A. V. Izv. Akad Nauk SSSR, Ser. Khim. 1989, 9, 2127.
(5) Červinka, O. In The Chemistry of Enamines; Rappoport, Z.,
Ed.; Wiley: New York, 1994, 467.
9
F NMR (376.6 MHz, CDCl ): d = –60.0 (s, CF ).
3
3
+
MS (EI): m/z (%) = 416 (4) [M – 18], 385 (5), 359 (4), 281 (4), 235
(
(
9), 221 (23), 205 (32), 195 (100), 199 (25), 179 (9), 165 (62), 149
34), 133 (9), 103 (21), 91 (12), 75 (25), 63 (22).
(6) (a) Hayakawa, K.; Takewaki, M.; Fujimoto, I.; Kanematsu,
K. J. Org. Chem. 1986, 51, 5100. (b) Rejzek, M.; Wimmer,
Z.; Šaman, D.; Řičánková, M. Helv. Chim. Acta 1984, 77,
Anal. Calcd for C H F N O : C, 44.25; H, 3.02; N, 6.45. Found:
C, 44.89; H, 3.12; N, 6.97.
1
6
13
3
2
9
1
241. (c) Wang, C.; Kohn, H. Org. Lett. 2000, 2, 1773.
7) (a) White, W. A.; Weingarten, H. J. Org. Chem. 1967, 32,
13. (b) Knüpel, S.; Fröhlich, R.; Erker, G. J. Organomet.
(
2
Minor Diastereoisomer 11b
Chem. 2000, 595, 308.
1
9
F NMR (376.6 MHz, CDCl ): d = –59.5 (s, CF ).
3
3
(
8) (a) Ahmed, M. G.; Moeiz, S. M. I.; Ahmed, S. A.; Kiuchi, F.;
Tsuda, Y. Tetrahedron 2001, 57, 3143. (b) Pal, S.;
Mukhopadhyaya, J. K.; Ghatak, U. R. J. Org. Chem. 1994,
Methyl 3,3,3-Trifluoro-2,2-dihydroxypropanoate (12)
Under argon, a dry flask (100 mL) equipped with septum and mag-
netic spinbar was charged with CH Cl (50 mL), MeTFP (1) (0.78
g, 5.01 mmol) and subsequently a solution of H O (0.09 g, 5.01
mmol) in CH Cl (10 mL) at r.t. while stirring. The reaction was
finished immediately after the addition of H O (check by F NMR).
The solvent was removed on a rotary evaporator to afford product
1
59, 2687.
2
2
(
9) (a) Stanley, J. W.; Beasley, J. G.; Mathison, I. W. J. Org.
Chem. 1972, 37, 3746. (b) Sansoulet, J.; Tackx, C. C. R.
Acad. Sci., Ser. IIc: Chim. 1960, 250, 4370. (c) Ahlbrecht,
H.; Raab, W. Synthesis 1980, 4, 320.
2
2
2
1
9
2
(
10) Hickmott, P. W. In The Chemistry of Enamines; Rappoport,
Z., Ed.; Wiley: New York, 1994, 727.
(11) Paleta, O.; Paleček, J.; Dolenský, B. J. Fluorine Chem. 2001,
111, 175.
12) Parcell, R. F.; Hauck, F. P. Jr. J. Org. Chem. 1963, 28, 3468.
13) Procházka, M.; Křestanová, V.; Paleček, M.; Pecka, K.
Collect. Czech. Chem. Commun. 1970, 35, 3813.
14) Eckstein, Z.; Grochowski, E.; Urbanski, T. Bull. Acad. Pol.
Sci. Ser. Sci. Chim. 1959, 7, 289.
2.
Yield 0.86 g (99%) (Lit.18 yield 99%).
1
H NMR (DMSO-d ): d = 3.74 (s, 3 H, COOCH ), 8.05 (br s, 2 H,
6
3
(
(
OH).
1
3
3
C NMR (DMSO-d ): d = 52.4 (COOCH ), 90.3 (q, J = 32.1
6
2
3
CF
Hz, CCF ), 121.7 (q, J = 288.6 Hz, CF ), 166.6 (COOCH ).
1
3
CF
3
3
(
9
F NMR (CDCl ): d = –83.7 (s, CF ).
3
3
+
(15) Ibaceta-Lizana, J. S. L.; Iyer, R.; Jackson, A. H.; Shannon,
MS (EI): m/z (%) = 157 (M – 17, 0.5), 146 (1), 129 (1), 126 (1),
1
6
+
P. V. R. J. Chem. Soc., Perkin Trans.1 1978, 2, 733.
15 (M – 59, 78), 97 (5), 95 (61), 81 (4), 78 (11), 69 (100), 67 (8),
0 (45), 59 (91), 51 (77), 50 (18), 45 (79), 33 (23), 32 (29), 31 (50).
(
(
16) Munk, M. E.; Kim, Y. K. J. Am. Chem. Soc. 1964, 86, 2213.
17) Safina, Y. G.; Malkova, G. S.; Cherkasov, R. A. Zh. Obshch.
Khim. 1991, 61, 620.
18) Saloutin, V. I.; Piterskikh, I. A.; Pashkevich, K. I. Izv. Akad.
Nauk SSSR, Ser. Chim. 1986, 625.
Reaction of Hydrate 12 with Enamine 6
(
Under argon, a dry flask (100 mL) equipped with septum and mag-
netic spinbar was charged with a solution of hydrate 12 (0.86 g, 4.94
mmol) in CH Cl (30 mL) and a solution of enamine 6 (0.62 g, 4.95
(
19) Paleta, O.; Volkov, A.; Hetflejš, J. J. Fluorine Chem. 1999,
2
2
102, 147.
mmol) in CH Cl (30 mL) was added dropwise at r.t. while stirring.
2
2
Synthesis 2004, No. 4, 521–524 © Thieme Stuttgart · New York