Water → HCID 53633087, compound

Participants

Reaction Conditions

Reaction Steps

Under stirring at -78° C., a solution of ethyl 5-methoxycarbonyl-3-methyl-2-pentenoate (3.0 g) in ether (30 ml) is added to a solution of LiAlH4 (1.0 g) in ether (50 ml). The mixture is further, stirred for 30 minutes, after which cold water and a saturated aqueous solution of sodium hydrogen carbonate are added followed by extraction with ethyl acetate. The extract is worked up in the conventional manner and the residue is purified by column chromatography on silica gel (100 g) with CCl4 -ethyl acetate (10:1) as the eluent. The above procedure provides a colorless oil of ethyl 6-hydroxy-3-methyl-2-hexenoate. This product (2.6 g) is mixed with 3,4-dihydro-α-pyran (5.2 g) and under ice-cooling, concentrated hydrochloric acid (0.04 ml) is added. The mixture is stirred for 3 hours, after which a saturated aqueous solution of sodium hydrogen carbonate is added followed by extraction with ethyl acetate. The extract is worked up in the conventional manner and the residue is purified by column chromatography on silica gel (100 g) with CCl4 -ethyl acetate (10:1) as the eluent. This procedure provides a colorless oil of ethyl 3-methyl-6-(α-tetrahydropyranyloxy)-2-hexenoate. A solution of this product (3.5 g) in ether (50 ml) is added to a solution of LiAlH4 (1.0 g) in ether (100 ml) at -78° C. with constant stirring. The mixture is further stirred at -20° C. for an hour, at the end of which time the excess LiAlH4 is decomposed with cold water. To this reaction mixture is added a saturated aqueous solution of sodium hydrogen carbonate followed by extraction with ethyl acetate. The extract is worked up in the conventional manner and the residue is purified by column chromatography on silica gel (70 g) with CCl4 -ethyl acetate (3:1) as the eluent. The above procedure provides a colorless oil of VII (R4 =H, n=O, m=2, R5 =THP). This product (1.9 g) and VI (R=H3C, X=Y=OH) (2.0 g) are dissolved in dioxane (30 ml), followed by addition of a mixture of BF3 -ether (10 ml) and dioxane (20 ml) at room temperature with stirring. The mixture is kept stirred for 2 hours, at the end of which time it is diluted with cold water and extracted with ethyl acetate. The extract is worked up in the conventional manner to recover IIIb (R=H3C, X=Y=OH, n=O, m=3).

Provenance & Evidence