Â
B. Dolensky et al. / Journal of Fluorine Chemistry 115 (2002) 67±74
73
(t, 3H, CH3, 3JHH 7:4 Hz), 1.62 (sex, 2H, 3JHH 7:1 Hz),
3.31 (td, 1H, CH2, 2JHH 8:8 Hz, 3JHH 6:6 Hz), 3.65 (td,
4.5.2. Preparation of the dimer 7
Round-bottom ¯ask (25 ml) equipped with a re¯ux con-
denser connected with a drying tube (CaCl2) was charged
with MTFP (3) (3.75 g, 24 mmol) and 96% H2SO4 (1.71 g,
16.7 mmol 100% H2SO4) and the mixture was heated at
100 8C on an oil bath for 24 h while stirring (magnetic
spinbar). After cooling to room temperature, the mixture
was extracted with CFC-113 (5 ml  10 ml, check by GCb)
and the combined extracts were dried (MgSO4). The solvent
was then removed from the ®ltrate on rotary evaporator
(44 8C/39.6 kPa) and the residue was distilled to afford
dimer 7, yield 0.95 g (23%), purity 90% (GC) identi®ed
as a mixture of diastereoisomers A and B.
2
3
1H, CH2, JHH 8:8 Hz, JHH 6:6 Hz), 3.95 (s, 3H,
COOCH3), 4.58 (bs, 1H) ppm.
19F NMR (75.4 MHz, CDCl3): d À81.7 (s, CF3) ppm.
13C NMR(75.46 MHz,CDCl3):d9.93(CH2), 25.30(CH2),
2
54.43 (CH3), 65.83 (COOCH3), 93.72 (q, JCF 33:8 Hz),
120.89 (q, 1JCF 287:5 Hz), 167.82 (COOCH3) ppm.
MS (Mr 216), m/z (% relative intensity): EI: 157/9
(M À 59), 129/2, 115/1, 109/3, 105/3, 97/2, 95/1, 87/1,
81/1, 78/2, 69/17, 67/3, 60/2, 59/20, 51/2, 50/2, 45/5, 43/
100, 41/25, 33/4, 32/1, 31/15.
4.4.2.4. Methyl 2-butoxy-3,3,3-trifluoro-2-hydroxy-
1
1H NMR (300.07 MHz, CDCl3): d 3.97 (s, 3H), 3.98 (s,
3H), 4.07 (s, 6H), 5.01 (bs, 2H) ppm.
propanoate (14c). H NMR (300.07 MHz, CDCl3): d 0.90
3
3
(t, 3H, CH3, JHH 7:2 Hz), 1.37 (sex, 2H, CH2, JHH
IR (KBr): n 3700±2400, 1752, 1630, 1248, 1197, 1095,
7:1 Hz), 1.59 (kv, 2H, CH2, JHH 6:6 Hz), 3.36 (td, 1H,
991, 706 cmÀ1
.
3
2
3
CH2, JHH 8:8 Hz, JHH 6:6 Hz), 3.70 (td, 1H, CH2,
2JHH 8:8 Hz, JHH 6:6 Hz), 3.68 (s, 3H, COOCH3),
4.5.3. Diastereoisomer A
19F NMR (75.4 MHz, CDCl3): d À81.9 (s, CF3), À82.6 (s,
3
4.42 (bs, 1H) ppm.
19F NMR (75.4 MHz, CDCl3): d À81.8 (s, CF3) ppm.
13C NMR (75.46 MHz, CDCl3): d 13.54 (CH2), 18.92
(CH2), 31.29 (CH2), 54.62 (COOCH3), 64.12 (CH3), 93.69
CF3) ppm.
13C NMR (75.46 MHz, CDCl3): d 56.52, 93±99 (2q),
1
1
119.91 (q, JCF 286:9 Hz), 120.02 (q, JCF 286:9 Hz),
2
1
(q, JCF 33:8 Hz), 120.83 (q, JCF 287:5 Hz), 168.02
160.59, 160.84 ppm.
(COOCH3) ppm.
MS (Mr 330), m/z (% relative intensity): EI: 282/0.5,
225/7, 197/7, 171/4, 157/1, 143/9, 129/1, 109/10, 97/11, 81/
17, 69/100, 65/5, 59/56, 50/4, 45/2, 43/3, 31/3.
MS (Mr 230), m/z (% relative intensity): EI: 171/2
(M À 59), 157/4 (M À 73), 129/1, 115/1, 109/3, 105/4,
97/2, 95/1, 88/2, 81/1, 78/2, 69/20, 67/3, 60/1, 59/19, 57/
100, 51/2, 50/3, 45/5, 43/6, 41/46, 39/7, 33/3, 31/10.
4.5.4. Diastereoisomer B
19F NMR (75.4 MHz, CDCl3): d À81.2 (q, CF3, JHF
4.5. Dimer of methyl 3,3,3-trifluoropyruvate hydrate (7)
and its reactions with alkanols
2:9 Hz), À82.3 (q, CF3, JHF 2:9 Hz) ppm.
C13C NMR (75.46 MHz, CDCl3): d 55.51, 56.52, 93±99
1
1
(2q), 119.33 (q, JCF 285:2 Hz), 119.73 (q, JCF
4.5.1. Attempts to prepare dimer 13 as a reference
compound
286:9 Hz), 160.90, 165.26 ppm.
MS (Mr 330), m/z (% relative intensity): EI: 312/0.01,
282/1, 225/5, 197/7, 171/8, 143/8, 109/10, 97/10, 81/11, 69/
100, 65/5, 59/70, 50/4, 45/2, 43/5, 31/2.
(A) A round-bottomed flask (10 ml) equipped with a reflux
condenser connected to a drying tube (CaCl2) was
charged with MTFP (3) (0.54 g, 3.5 mmol), K2CO3
(0.48 g, 3.5 mmol) and dichloromethane (2.6 ml) and
the mixture was refluxed on a oil bath for 24 h while
stirring (magnetic spinbar). After the reaction, the
mixture contained only hemiacetal 6 as the product
(analysis by 19F NMR) [25].
(B) In the apparatus as earlier, hemiacetal 6 (0.57 g,
3.01 mmol) and K2CO3 (0.2 g, 1.47 mmol) were heated
to 90 8C for 1 h while stirring. A sample of the mixture
contained 6 and a small amount of a volatile compound
as the only product, whose 19F NMR signal corre-
sponded to that of fluoroform. After additional 1 h
heating of the mixture the 19F NMR analysis showed no
presence of any fluorinated compound in the mixture.
4.5.5. Decomposition of dimer 7 by the reaction with
alcohols
Dimer 7 (0.4 g) was dissolved in dry Et2O (8 ml) and the
solution divided in four portions of 2 ml each. Alcohols
(methanol, ethanol, propanol and butanol) were added to
each portion and after standing for 24 h at room temperature
the solutions were analyzed (GC±MS, 19F NMR). Product
mixtures were obtained by evaporation of volatile compo-
nents and analyzed by 1H and 13C NMR. In all the reactions,
1:1 mixtures of products 6, 14a±14c and 15a±d were
obtained. GC±MS analysis of the products failed owing
to decomposition of free acids in heated inlet.
For the spectra of compounds 6, 14a±14c see Section 4.3.2.
4.5.5.1. 3,3,3-Trifluoro-2-hydroxy-2-methoxypropanoic
acid (15a). 1H NMR (300.07 MHz, CDCl3): d 3.45 (m, 3H,
OCH3), 6.53 (bs, 2H) ppm.
19F NMR (75.4 MHz, CDCl3): d À81.9 (s, CF3) ppm.
4.5.1.1. Fluoroform. 19F NMR (75.4 MHz, CDCl3): d
2
À78.5 (d, CHF3, JHF 78:9 Hz) ppm; [32]: À78.3 (d,
2JHF 79:1 Hz) ppm.