Ethyl isobutyrate → ethyl (E) 6-(4-methoxyethoxymethoxy-1,3-dihydro-6-methoxy-7-methyl-3-oxoisobenzofuran-5-yl)-2,2,4-trimethyl-4-hexenoate

Participants

Reaction Conditions

Reaction Steps

A freshly prepared solution of lithium diisopropylamide (2.8 mmol/10 ml THF) was cooled to -78° C. and ethyl isobutyrate (0.75 ml) was added slowly. The solution was stirred at -78° C. for 40 minutes and then a solution of (E)-4-(1,3-dihydro-6-methoxy-4-methoxyethoxymethoxy-7-methyl -3-oxoisobenzofuran-5-yl)-2-methylbut-2-enyl bromide (0.6 g) in THF (2 ml) and HMPA (1.5 ml) was added via syringe at such rate that the temperature was maintained below -60° C. After stirring for 30 minutes at -78° C., the mixture was poured onto 100 ml of a concentrated solution of NH4Cl. The organic and aqueous phases were separated and the aqueous phase was extracted with ethyl acetate (2×50 ml). The combined organic layers were dried over Na2SO4 and evaporated to give a residue which was passed through a column (silica gel, CH2Cl2 -EtOAc 95:5) to afford 480 mg (74%) of ethyl (E)-6-(4-methoxyethoxymethoxy-1,3-dihydro-6-methoxy-7-methyl-3-oxoisobenzofuran -5-yl)-2,2,4-trimethyl-4-hexenoate as a colorless oil.

Provenance & Evidence