Reaktion #61227

Reaktionsgleichung

carbon tetrabromide

7-Hydroxy-6-(4-hydroxy-3-methyl-but-2-enyl)-5-methoxy-4-methyl-3H-isobenzofuran-1-one

7-hydroxy-6-(4-hydroxy-3-methyl-but-2-enyl)-5-methoxy-4-methyl-3H-isobenzofuran-1-one

carbon tetrabromide

triphenylphosphine

→

6-(4-bromo-3-methyl-but-2-enyl)-7-hydroxy-5-methoxy-4-methyl-3H-isobenzofuran-1-one

Ausbeute 42.3%

Lösungsmittel

dichloromethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGthe mixture was shaken further for 1 hour
2. 2
   FiltrationThe mixture was filtered
3. 3
   Einengenthe filtrate was concentrated
4. 4
   SonstigeThe residue was chromatographed on silica gel (0% to 60% ethyl acetate/hexanes)

Vorschrift

Polymer-supported triphenylphosphine (3 mmol/g, 0.5 g) was soaked in dichloromethane (10 mL) for 1 hour 7-Hydroxy-6-(4-hydroxy-3-methyl-but-2-enyl)-5-methoxy-4-methyl-3H-isobenzofuran-1-one 1A (100 mg, 0.36 mmol) and carbon tetrabromide (143 mg, 0.43 mmol) were sequentially added and the mixture was shaken for 1 hour at room temperature. More carbon tetrabromide (143 mg, 0.43 mmol) was added and the mixture was shaken further for 1 hour. The mixture was filtered and the filtrate was concentrated. The residue was chromatographed on silica gel (0% to 60% ethyl acetate/hexanes) to afford 6-(4-bromo-3-methyl-but-2-enyl)-7-hydroxy-5-methoxy-4-methyl-3H-isobenzofuran-1-one 3B as an oil (52 mg, 42%); 1H NMR (300 MHz, CDCl3) δ 1.95 (s, 3H), 2.16 (s, 3H), 3.44 (d, J=7.2 Hz, 2H), 3.78 (s, 3H), 3.98 (s, 2H), 5.21 (s, 2H), 5.68 (t, J=7.2 Hz, 1H), 7.71 (brs, 1H) ppm.

Quelle