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L. QIN ET AL.
triethylamine in 8 ml tetrahydrofuran (THF) at a temperature of ꢁ15ꢀC. After
addition, the reaction mixture was kept at this temperature for 0.5 h. After that,
the precipitate triethylamine hydrochloride was filtered off, and the filtrate was
concentrated under vacuum to give crude products. The crude material was purified
by flash chromatography on silica gel.
Selected Data
O-p-Toluenesulfonyl benzyloxyhydroxamate (4a). Flash chromatography
gave white solid, mp 120–123ꢀC. Yield: 82.5%. IR (KBr) 3138, 2938, 1759, 1732,
1595, 1484, 1365, 1261, 1198, 1181, 1077 cmꢁ1 1H NMR (CDCl3, 400 MHz) d
.
2.431 (s, 3H), 5.035 (s, 2H), 7.190–7.213 (m, 2H), 7.260 (d, 2H), 7.335–7.357 (m,
3H), 7.754 (s, 1H), 7.830 (d, 2H). ESI-MS: 344 (M þ Na)þ.
O-Benzenesulfonyl benzyloxyhydroxamate (4b). Flash chromatography
gave pale yellow solid, mp 65–68ꢀC. Yield: 89.9%. IR (KBr) 3284, 1749, 1451,
1
1384, 1239, 1187, 1174, 1071 cmꢁ1. H NMR (CDCl3, 400 MHz) d 5.036 (s, 2H),
7.194–7.218 (m, 2H), 7.342–7.359 (m, 3H), 7.478–7.517 (m, 2H), 7.664–7.681 (m,
1H), 7.795 (s, 1H), 7.959–7.983 (m, 2H). ESI-MS: 330 (M þ Na)þ.
O-Methanesulfonyl benzyloxyhydroxamate (4c). Flash chromatography
gave white solid, mp 85–87ꢀC. Yield: 73.2%. IR (KBr) 3237, 2941, 1740, 1490,
1
1455, 1361, 1247, 1150, 1100 cmꢁ1. H NMR (CDCl3, 400 MHz) d 3.171 (s, 3H),
5.270 (s, 2H), 7.380–7.396 (m, 5H), 8.024 (s, 1H). ESI-MS: 268 (M þ Na)þ.
O-3,4-Difluorobenzenesulfonyl benzyloxyhydroxamate (4d). Flash chro-
matography gave pale yellow oil. Yield: 78.8%. IR (KBr) 3284, 1770, 1603, 1510,
1457, 1379, 1281, 1245, 1184, 1119, 1063 cmꢁ1 1H NMR (CDCl3, 400 MHz) d
.
5.043 (s, 2H), 7.170–7.210 (m, 3H), 7.335–7.362 (m, 3H), 7.770–7.773 (m, 1H),
7.752–7.797 (m, 1H), 8.329 (s, 1H). ESI-MS: 366 (M þ Na)þ.
O-p-Trifluoromethylbenzenesulfonyl benzyloxyhydroxamate (4e). Flash
chromatography gave pale yellow solid, mp 57–59ꢀC. Yield: 73.4%. IR (KBr) 3302,
1766, 1498, 1433, 1407, 1376, 1328, 1243, 1193, 1066, 1016 cmꢁ1. 1H NMR (CDCl3,
400 MHz) d 5.020 (s, 2H), 7.173–7.199 (m, 2H), 7.342–7.36 (m, 3H), 7.706 (d, 2H),
7.955 (s, 1H), 8.066 (d, 2H). ESI-MS: 398 (M þ Na)þ.
O-m-Fluorobenzenesulfonyl benzyloxyhydroxamate (4f). Flash chroma-
tography gave pale yellow solid, mp 76–77ꢀC. Yield: 84.2%. IR (KBr) 3285, 1774,
1
1594, 1478, 1459, 1430, 1378, 1309, 1244, 1223, 1186, 1083, 1059 cmꢁ1. H NMR
(CDCl3, 400 MHz) d 5.052 (s, 2H), 7.198–7.221 (m, 2H), 7.343–7.359 (m, 4H),
7.431–7.484 (m, 1H), 7.669 (d, 1H), 7.759 (d, 1H), 7.902 (s, 1H). ESI-MS: 348
(M þ Na)þ.
O-2,5-Difluorobenzenesulfonyl benzyloxyhydroxamate (4g). Flash chro-
matography gave pale yellow oil. Yield: 66.8%. IR (KBr) 3307, 1775, 1494, 1458,
1423, 1382, 1241, 1256, 1201, 1185, 1059 cmꢁ1 1H NMR (CDCl3, 400 MHz) d
.
5.073 (s, 2H), 7.018–7.072 (m, 1H). ESI-MS: 366 (M þ Na)þ.