反应详情

A solution of methyl 3,7-dimethyl-4-nitro-6-octenoate (24.55 g, 0.107 m) in methanol (10 ml) is added dropwise to a solution of sodium methoxide (6.37 g, 0.118 m) in methanol (250 ml) at room temperature under nitrogen. The mixture is stirred for 1 hour, added to a mixture of 20% titanous chloride (170 ml, 0.267 m) and pH 7 buffer (potassium phosphate monobasicsodium hydroxide buffer) solution (340 ml). The resulting mixture is stirred for 30 minutes after which it is treated with ether (1 l). The organic phase is separated, dried (Na2SO4) and evaporated in vacuo to give the crude product (15.4 g). This material is purified by column chromatography on silica gel (300 g, 2% ethyl acetate in hexane) to give methyl 3,7-dimethyl-4-oxo-6-octenoate as a colorless liquid (6.8 g, 35%). ir (neat) 1705 and 1735 cm-1 ; nmr (CDCl3) δ: ##STR9##

1. stirringThe resulting mixture is stirred for 30 minutes after which it
2. customThe organic phase is separated
3. dry with materialdried (Na2SO4)
4. customevaporated in vacuo
5. customto give the crude product (15.4 g)
6. customThis material is purified by column chromatography on silica gel (300 g, 2% ethyl acetate in hexane)