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0 °C

Freshly distilled diisopropylamine (0.435 ml) was dissolved in THF (10 ml). The solution was cooled to 0° C. and n-BuLi (1.3 ml, 2.38M) was added. The mixture was stirred at 0° C. for 20 minutes. The ice-bath was replaced by a dry ice-acetone bath and a solution of ethyl benzylidine glycinate (0.445 g) in THF (2 ml) was added slowly at -78°. The resulting red solution was stirred at -78° C. for 40 minutes. This solution was then transferred via cannula to a solution of (E)-4-(1,3-dihydro-6-methoxy -4-methoxyethoxymethoxy-7-methyl-3-oxoisobenzofuran-5-yl)-2-methylbut2-enyl bromide (0.667 g) dissolved in THF (20 ml) and HMPA (2 ml). After stirring the mixture at -78° C. for 90 minutes, the reaction mixture was poured into a concentrated solution of NH4Cl, extracted with ethyl acetate (3×30 ml), and the combined organic layers were dried over Na2SO4 and evaporated to give a dark oil, which was passed through a column (silica gel, ethyl acetate) giving 0.443 g (63%) of ethyl (E)-6-(4-methoxyethoxymethoxy -1,3-dihydro-6-methoxy-7-methyl-3-oxoisobenzofuran-5-yl)-2-amino-4-methyl -4-hexenoate the product as a light yellow oil.

1. stirringThe resulting red solution was stirred at -78° C. for 40 minutes
2. stirringAfter stirring the mixture at -78° C. for 90 minutes
3. extractionextracted with ethyl acetate (3×30 ml)
4. dry with materialthe combined organic layers were dried over Na2SO4
5. customevaporated
6. customto give a dark oil, which