Reaktion #607397

Reaktionsgleichung

solution

(2Z,4E)-methyl 5-((S)-1-hydroxy-2,6,6-trimethyl-4-oxocyclohex-2-en-1-yl)-3-methylpenta-2,4-dienoate

methyl iodide

Lithium hexamethyl disilazane

→

title compound

(2Z,4E)-methyl 5-((S)-1-hydroxy-2,3,6,6-tetramethyl-4-oxocyclohex-2-en-1-yl)-3-methylpenta-2,4-dienoate

Lösungsmittel

tetrahydrofuran

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigethe ice bath was removed
2. 2
   workup.STIRRINGThe resulting solution was stirred at ambient temperature overnight
3. 3
   SonstigeThe reaction was quenched with saturated aqueous ammonium chloride solution (200 ml) and water (200 ml)
4. 4
   Extraktionextracted with ethyl acetate (3×150 ml)
5. 5
   TrocknenThe combined organic solution was dried (MgSO4)
6. 6
   Filtrationfiltered
7. 7
   Einengenconcentrated
8. 8
   SonstigeThe residue was purified on a silica gel column
9. 9
   Wascheneluted with ethyl acetate and hexane

Vorschrift

A solution of Example 1a (27.8 g, 0.1 mole) in anhydrous tetrahydrofuran (THF, 600 ml) was cooled to 0° C. with an ice bath under an atmosphere of nitrogen. Lithium hexamethyl disilazane (1.0 M solution in THF, 150 ml) was added dropwise via a syringe over about 30 minutes. The resulting solution was stirred at 0° C. for 30 minutes and the ice bath was removed. A solution of methyl iodide (8.09 ml, 18.4 g, 0.13 mole) in anhydrous THF (20 ml) was added via a syringe over 20 minutes. The resulting solution was stirred at ambient temperature overnight. The reaction was quenched with saturated aqueous ammonium chloride solution (200 ml) and water (200 ml) and extracted with ethyl acetate (3×150 ml). The combined organic solution was dried (MgSO4), filtered and concentrated. The residue was purified on a silica gel column eluted with ethyl acetate and hexane. The title compound was obtained as a white solid (17.1 g). 1HNMR (CDCl3): δ7.84 (d, 1H), 6.16 (d, 1H), 5.75 (s, 1H), 3.70 (s, 3H), 2.44 (d, 1H), 2.34 (d, 1H), 2.00 (s, 3H), 1.88 (s, 3H), 1.83 (s, 3H), 1.07 (s, 3H), 1.00 (s, 3H). MS (ESI—): m/e=291.

Quelle