Reaktion #3996

Reaktionsgleichung

NaHCO3

2,5,9-trimethyl-11-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2,4,6,8,10-undecapentaene-1-ol

trimethyl orthoformate

methanol

trifluoroacetic acid

→

1-methoxy-2,5,9-trimethyl-11-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2,4,6,8,10-undecapentaene

Lösungsmittel

THF

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   Extraktionextracted with chloroform three times
2. 2
   ExtraktionThe combined organic extract
3. 3
   Waschenis washed with water
4. 4
   Trocknendried over Na2SO4
5. 5
   Sonstigeevaporated in vacuo
6. 6
   Sonstigeto give a residue, which
7. 7
   Sonstigeis purified by HPLC (4% ether in hexane, silica gel column)

Vorschrift

To a solution of 2,5,9-trimethyl-11-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2,4,6,8,10-undecapentaene-1-ol (1.6 g, 5 mmol), 106 g (10 mmol) of trimethyl orthoformate and 160 mg (5 mmol) of dry methanol in 5 ml of dry THF is added dropwise a solution of 40 μL of trifluoroacetic acid in 1 ml of dry THF over a 1 minute period at room temperature. After overnight standing, the reaction mixture is poured into cold aqueous 5% NaHCO3 and extracted with chloroform three times. The combined organic extract is washed with water, dried over Na2SO4 and evaporated in vacuo to give a residue, which is purified by HPLC (4% ether in hexane, silica gel column) to afford of 1-methoxy-2,5,9-trimethyl-11-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2,4,6,8,10-undecapentaene as an oil.

Quelle