2-Bromoethanol → 2-Bromoethyl 2,3,4,6-tetra-O-benzyl-alpha-D-galactopyranoside

HRID 653322

Reaktionsgleichung

Reaktionsgleichung von HRID 653322
C[Si](Br)(C)C.[CH2:6]([O:13][C@@H:14]1[C@@H:20]([O:21][CH2:22][C:23]2[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=2)[C@@H:19]([O:29][CH2:30][C:31]2[CH:36]=[CH:35][CH:34]=[CH:33][CH:32]=2)[C@@H:18]([CH2:37][O:38][CH2:39][C:40]2[CH:45]=[CH:44][CH:43]=[CH:42][CH:41]=2)[O:17][CH:15]1[OH:16])[C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1.[Br:46][CH2:47][CH2:48]O>[Br-].C([N+](CC)(CC)CC)C.C(Cl)Cl.[Co](Br)Br>[CH2:6]([O:13][C@@H:14]1[C@@H:20]([O:21][CH2:22][C:23]2[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=2)[C@@H:19]([O:29][CH2:30][C:31]2[CH:32]=[CH:33][CH:34]=[CH:35][CH:36]=2)[C@@H:18]([CH2:37][O:38][CH2:39][C:40]2[CH:41]=[CH:42][CH:43]=[CH:44][CH:45]=2)[O:17][C@@H:15]1[O:16][CH2:48][CH2:47][Br:46])[C:7]1[CH:8]=[CH:9][CH:10]=[CH:11][CH:12]=1

Komponenten

7

Edukt 3

HCID 108982-BromoethanolHCID 76113BromotrimethylsilaneHCID 27341542,3,4,6-Tetrakis-O-(phenylmethyl)-D-galactopyranose

Produkt 1

HCID 542531772-Bromoethyl 2,3,4,6-tetra-O-benzyl-alpha-D-galactopyranosideAusbeute 99,6 %

Reagenzien, Katalysatoren, Lösungsmittel 3

HCID 6285Tetraethylammonium BromideKatalysatorHCID 24610Cobalt dibromideKatalysatorHCID 6344DichloromethaneLösungsmittel

Versuchsvorschrift

Trimethylsilyl bromide (7.96 g, 6.78 ml. 52 mmol) was added with a syringe to a mixture of 2,3,4,6-tetra-O-benzyl-D-galactopyranose (28 g, 52 mmol), 2-bromoethanol (4.46 ml, 40.0 mmol), cobalt(II)bromide (11.4 g, 52.0 mmol), tetraethylammonium bromide (10.9 g, 52.0 mmol) and molecular sieves (4 Å, 41 g) in 138 ml of methylene chloride under nitrogen with protection from light. (The cobalt(II)chloride had been dried at 180°, 5×10-3 mm Hg over night. ) The reaction mixture was stirred at room temperature over night and filtered. The residue was washed with 100 ml of methylene chloride. The filtrate was evaporated at reduced pressure to give 25.8 g of the crude product, which was chromatographed (SiO2, isooctane:ethyl acetate 3:2) Fraction 1 was the pure title compound (6.0 g) and fraction 2 was a mixture of the anomers (α/β, 10.0 g) Total yield of glycosides 16 g (48 %) (This procedure is a slight modification of that of Koto et al.34.) [α]D23 =+30.5° (c 1.4, CHCl3). 1H-NMR (CDCl3, TMS) δ 7.30 (m, 20H, Ph), 4.97-4.42 (m, 9H), 4.0-3.8 (m, 6H), 3.52 (t, 4H, inter alia CH2Br). 13C-NMR (CDCl, TMS) δ 103.3 (d, Cl, JC--H =168 Hz), 84.2, 81.6, 80.2, 75.0 (C2-C5), 80.0, 78.7, 78.6, 78.5, 74.2, 73.5 (C6, benzylic CH2 and aglycon O--CH2), 35.5 (CH2Br)

Aufarbeitung

  1. dry with material(The cobalt(II)chloride had been dried at 180°
  2. wait5×10-3 mm Hg over night
  3. filtrationfiltered
  4. washThe residue was washed with 100 ml of methylene chloride
  5. customThe filtrate was evaporated at reduced pressure

Quellen und Nachweise

ORD-Eintrag
ord-30a077fbe7ab421e9c0b9fc6285935d0
Quelldatensatz
uspto-grants-1987_06
Patentnummer
US04675392

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