Cesium carbonate → 2-(2-Methoxycarbonylethylthio)ethyl 2,3,6-tri-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl)-beta-D-galactopyranoside

HRID 653323Notes

Reaction equation

HRID 653323 reaction equation
[C:1]([O:4][C@@H:5]1[C@@H:14]([O:15][C:16](=[O:18])[CH3:17])[C@@H:13]([O:19][C@H:20]2[O:37][C@H:36]([CH2:38][O:39][C:40](=[O:42])[CH3:41])[C@H:31]([O:32][C:33](=[O:35])[CH3:34])[C@H:26]([O:27][C:28](=[O:30])[CH3:29])[C@H:21]2[O:22][C:23](=[O:25])[CH3:24])[C@@H:12]([CH2:43][O:44][C:45](=[O:47])[CH3:46])[O:11][C@H:6]1[O:7][CH2:8][CH2:9]Br)(=[O:3])[CH3:2].[SH:48][CH2:49][CH2:50][C:51]([O:53][CH3:54])=[O:52].C(=O)([O-])[O-].[Cs+].[Cs+].C(OCC)(=O)C.C(CC(C)(C)C)(C)C>[Cl-].C[N+](CCCCCCCC)(CCCCCCCC)CCCCCCCC.C1C=CC=CC=1.O>[C:1]([O:4][C@@H:5]1[C@@H:14]([O:15][C:16](=[O:18])[CH3:17])[C@@H:13]([O:19][C@H:20]2[O:37][C@H:36]([CH2:38][O:39][C:40](=[O:42])[CH3:41])[C@H:31]([O:32][C:33](=[O:35])[CH3:34])[C@H:26]([O:27][C:28](=[O:30])[CH3:29])[C@H:21]2[O:22][C:23](=[O:25])[CH3:24])[C@@H:12]([CH2:43][O:44][C:45](=[O:47])[CH3:46])[O:11][C@H:6]1[O:7][CH2:8][CH2:9][S:48][CH2:49][CH2:50][C:51]([O:53][CH3:54])=[O:52])(=[O:3])[CH3:2]

Participants

8

Reactant 4

HCID 10796Cesium carbonateHCID 18050Methyl 3-mercaptopropionate2×HCID 18516502EtOAc isooctaneHCID 228870902-Bromoethyl 2,3,6-tri-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl)-beta-D-galactopyranoside

Product 1

HCID 541726522-(2-Methoxycarbonylethylthio)ethyl 2,3,6-tri-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl)-beta-D-galactopyranoside

Reagents, catalysts & solvents 3

HCID 21218Trioctylmethylammonium chlorideCatalystHCID 241BenzeneSolventHCID 962WaterSolvent

Procedure

2-Bromoethyl 2,3,6-tri-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl)-β-D-galactopyranoside (15) (251 mg; 0.338 mmol), methyl 3-mercaptopropionate (38 μl; 0.35 mmol) methyltrioctylammonium chloride (ca 10 mg) and cesium carbonate (114 mg; 0.35 mmol) were dissolved in benzene (0.5 ml) and water (0.5 ml). The reaction mixture was stirred (magnet) over night and analyzed by TLC (SiO2, ethyl acetate:isooctane 4:1; reaction 2/3 completed). Methyl 3-mercaptopropionate (ca 20 μl) was added and the reaction mixture was stirred for 24 h (TLC showed complete reaction). The phases were separated, the water phase was extracted twice with methylene chloride and the combined organic phases were dried (sodium sulfate) which gave a yellow to green solution. Evaporation gave a syrup which was chromatographed (SiO2, ethyl acetate:isooctane 2:1) to give the title compound (22) as a syrup. Yield: 211 mg (80%). [α]D23 +70.0° (c 0.6; CHCl3); 1H-NMR (CDCl3, TMS) δ 5.57 (d, 1H, J3',4' =3.0 Hz, H4'), 5.39 (dd, 1H, J2',3' =11.0 Hz. H2'), 5.19 (dd, 1H, H3'), 5.17 (dd, 1H, J2,3 =11 Hz, H2), 5.00 (d, 1H, J1',2' =4.0 Hz, H1'), 4.80 (dd, 1H, J3,4 =3.0 Hz, H3), 4.51 (d, 1H, J1,2 =8.0 Hz, H1), 3.70 (s, 3H, CH3 --O), 2.82, 2.75, 2.63 (t, 2H each, J=7 Hz, CH2 --S, CH2 --CO), 2.13, 2.11, 2.08, 2.08, 2.06, 2.04, 1.98 (s, 3H each, CH3CO) ppm. 13C-NMR (CDCl3, TMS) δ 172.3 (COOCH3), 170.7, 170.6, 170.5, 170.4, 170.1, 169.8, 169.2 (CH3CO), 101.1 (Cl), 99.4 (Cl'), 77.1, 72.7, 72.0, 68.6, 68.5, 67.9, 67.4, 67.1 (C2-C5, C2'-C5'), 69.5 (OCH2), 62.0, 60.5 (C6, C6'), 51.8 (COOCH3), 34.7, 31.4, 27.4 (CH2S, CH2 --CO), 21.0, 20.7 (CH3CO) ppm.

Workup

  1. stirringthe reaction mixture was stirred for 24 h
  2. custom(TLC showed complete reaction)
  3. customThe phases were separated
  4. extractionthe water phase was extracted twice with methylene chloride
  5. dry with materialthe combined organic phases were dried (sodium sulfate) which
  6. customgave a yellow to green solution
  7. customEvaporation
  8. customgave a syrup which
  9. customwas chromatographed (SiO2, ethyl acetate:isooctane 2:1)

Sources & evidence

ORD record
ord-36df67bfbe55479ca97689c189ee47e3
Source dataset
uspto-grants-1987_06
Patent number
US04675392

Reaction notes

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