1.
2,2,2-Trifluoro-1-methoxyethanol was obtained from Avocado (trifluoroacetaldehyde methyl hemiacetal), tech. 90% and acetamide was obtained from Acros, 99%. The checkers used 2,2,2-trifluoro-1-methoxyethanol purchased from ABCR and acetamide purchased from Riedel de Haën.
2.
1,4-Dioxane was obtained from SDS Carlo Erba and used as received. All the solvents (petroleum ether, ethyl acetate, heptane, acetone, ethanol, methanol, tert-butyl methyl ether) were obtained from SDS Carlo Erba and used as received. The checkers used reagent-grade solvents purchased from Acros.
3.
(E. Merck, Darmstadt, 230–240 mesh) was used. The progress of the reaction was monitored by TLC on silica gel using hexanes/ethyl acetate (3:2) as eluent. The product has an Rf = 0.15 (stained with potassium permanganate solution [300 mL of water, 3 g of KMnO4, 20 g of K2CO3, 0.25 mL of acetic acid]).
4.
The submitters reported purification of the crude product by recrystallization: Dichloromethane (60 mL) is added to the crude product and the resulting mixture is vigorously stirred for 10 min. The resulting white precipitate is filtered, washed twice with 30 mL of dichloromethane and dried under vacuum (25 °C, 1 mmHg) for 1 h to give a crop of pure product. The corresponding filtrate is concentrated under reduced pressure, diluted in 80 mL of ethyl acetate and washed twice with 20 mL of a half-saturated aqueous sodium chloride solution. The organic solvent is then dried over anhydrous magnesium sulfate, filtered and evaporated to give a semi-solid residue. Dichloromethane (30 mL) is added and the mixture stirred vigorously for 10 min. The resulting white precipitate is filtered, washed twice with 10 mL of dichloromethane and dried under vacuum (25 °C, 1 mmHg) for 1 h to provide a second crop of pure product. The two crops are combined to give amide 1 (53% yield). The checkers obtained 41% of product using this purification method.
5.
The product exhibited the following properties: mp 117–119 °C; 1H NMR pdf (MeOD, 400 MHz) δ: 2.01 (s, 3 H), 4.83 (s, 2 H), 5.71 (m, 1 H).
6.
Thionyl chloride (99.5%) was obtained from Acros and used as received; the checkers used thionyl chloride (99%) purchased from Fluka.
7.
The product exhibited the following properties: mp 85–87 °C (heptane). 1H NMR pdf (CDCl3, 400 MHz) δ: 2.15 (s, 3 H), 6.33 (qd, J = 5.3, 11.0 Hz, 1 H), 7.31 (br. m, 1 H); 13C NMR pdf (CDCl3, 100 MHz) δ: 23.0, 60.7 (q, J = 38 Hz), 121.8 (q, J = 277 Hz), 170.4; IR (film): 3279, 3037, 1684, 1530, 1375, 1349, 1244, 1192, 1150, 1133, 857, 788, 690 cm−1; HRMS (EI): Calcd for C4H5NOF3Cl: 175.0011; Found: 175.0010.
8.
Potassium O-ethyl xanthate (99%) was obtained from Aldrich (listed under ethylxanthic acid potassium salt) and recrystallized from hot ethanol before use. The checkers used the commercial product as received.
9.
The progress of the reaction was monitored by TLC analysis on silica gel using hexanes/ethyl acetate (4:1) as eluent; the product had an Rf = 0.23 (stained with p-anisaldehyde solution [(950 mL of ethanol, 95%, 35 mL of concentrated sulfuric acid, 26 mL of p-anisaldehyde, 10.5 mL of acetic acid)].
10.
The product exhibited the following properties: mp 84–86 °C; 1H NMR pdf (CDCl3, 400 MHz) δ: 1.45 (t, J = 7.0 Hz, 3 H), 2.11 (s, 3 H), 4.70 (q, J = 7.0 Hz, 2 H), 6.61 (qd, J = 7.6, 9.7 Hz, 1 H), 7.43 (d, J = 9.7 Hz, 1 H); 13C NMR pdf (CDCl3, 100 MHz) δ: 13.6, 22.8, 57.9 (q, J = 38 Hz), 71.4, 123.5 (q, J = 279 Hz), 170.9, 207.1; IR (film): 3278, 2990, 2933, 1667, 1514, 1370, 1334, 1289, 1246, 1210, 1186, 1127, 1115, 1102, 1049, 857, 819, 684 cm−1. The product obtained following the procedure was pure enough for use in the next step. However, it could be recrystallized by dissolving 1 g of the compound in a hot mixture of 1 mL of ethyl acetate and 10 mL of heptane and allowing the solution to cool to room temperature whereupon the product crystallized (yield of crystallization > 85%). Anal. Calcd for C7H10F3NO2S2: C, 32.18; H, 3.86. Found: C, 32.57; H, 3.91.
11.
Vinyl acetate (99+%) and lauroyl peroxide (DLP, 97%) were obtained from Aldrich, and used as received. 1,2-Dichloroethane (99+%) was purchased from SDS Carlo Erba and used as received. The checkers used 1,2-dichloroethane (99%) purchased from KMF.
12.
When performed on a smaller scale (4.28 g of xanthate 3) complete conversion was reached with only 3 portions of lauroyl peroxide with a reaction time of only 4.5 h.
13.
The progress of the reaction was followed by TLC analysis on silica gel using hexanes/ethyl acetate (4:1) as eluent and visualization was performed with p-anisaldehyde solution. The product had an Rf = 0.075.
14.
The product exhibited the following properties: 1H NMR pdf (CDCl3, 400 MHz, mixture of diastereomers) δ: 1.30 (br. t, 3 H), 1.41 (t, J = 7.0 Hz, 3 H), 2.02 (s, 6 H), 2.07 (s, 6 H), 2.10–2.27 (m, 2 H), 2.44–2.51 (m, 2 H), 4.61–4.67 (m, 4 H), 4.79–4.85 (m, 2 H), 6.54 (dd, J = 3.0, 9.7 Hz, 2 H), 6.65 (m, 2 H); IR (CCl4): 3429, 2982, 1767, 1706, 1503, 1369, 1235, 1188, 1137, 1049 cm−1. MS (ESI): 370 ([M+Na]+).
15.
(±)-10-Camphorsulfonic acid was purchased from Acros, 98%, and used as received.
16.
Approximately 150 g of silica (E. Merck, Darmstadt, 230–240 mesh) was used with hexanes/ethyl acetate (2:3) as the eluent, Rf = 0.16 (stained with potassium permanganate solution).
17.
The submitters reported that the crude product could be purified by crystallization by cooling a solution in Et2O (20 mL) to −78 °C (52% yield). The checkers, however, experienced problems caused by gelation of the mixture and therefore utilized chromatographic purification.
18.
The product exhibited the following properties: mp 61–63 °C (ether). 1H NMR pdf (CDCl3, 400 MHz) δ: 1.83 (ddd, J = 3.9, 9.8, 14.2 Hz, 1 H), 2.03 (s, 3 H), 2.04 (ddd, J = 3.3, 7.6, 14.2 Hz, 1 H), 3.34 (s, 3 H), 3.36 (s, 3 H), 4.46 (dd, J = 7.6, 3.9 Hz, 1 H), 4.75 (m, 1 H), 6.89 (d, J = 9.6 Hz, 1 H); 13C NMR pdf (CDCl3, 100 MHz) δ: 22.9, 31.7, 47.6 (q, J = 32 Hz), 53.1, 53.9, 101.6, 125.2 (q, J = 280 Hz), 170.6; IR (CCl4): 3285, 3072, 2939, 2834, 1665, 1551, 1437, 1375, 1299, 1265, 1181, 1135, 1064 cm−1. MS (EI) m/z (rel. intensity): 198 (45), 139 (58), 124 (56), 75 (100); HRMS (ESI): 252 ([M+Na]+). Anal. Calcd for C8H14F3NO3: C, 41.92; H, 6.16. Found: C, 41.84; H, 6.09.