反应详情

温度

40 °C

1.4 g of sodium hydride, 50% in mineral oil, were suspended in 50 ml of abs. dimethyl sulphoxide and treated dropwise while cooling with ice with 8.5 g of 2-bromo-3-hydroxy-5,5,8,8-tetra-methyl-5,6,7,8-tetrahydro-naphthalene dissolved in 60 ml of abs. dimethylformamide. The reaction mixture was stirred at 40° C. for ½ hour and subsequently a solution of 4.4 g of propyl bromide in 20 ml of dimethylformamide was added while cooling with ice. After stirring at room temperature for 20 hours the mixture was poured into ice-water, extracted with ethyl acetate and the crude product obtained after drying and evaporation of the solvent was filtered over a silica gel column (eluent hexane/ethyl acetate=9:1). 9.5 g of 2-bromo-3-propoxy-5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-naphthalene were obtained as a brownish oil. This oil was dissolved in 100 ml of abs. tetrahydrofuran and treated dropwise at −78° C. with 40 ml of tert.butyllithium, 1.4 molar in pentane. After stirring at −78° C. for ½ hour 75 ml of abs. dimethylformamide were added dropwise and the mixture was stirred at room temperature for 1 hour. The pale beige suspension was poured into ice-water and extracted with ethyl acetate. After drying and evaporation of the organic phase the crude product was filtered over a silica gel column (eluent hexane/5% ether). There were obtained 6.6 g of 2-formyl-3-propoxy-5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-naphthalene as a pale yellow oil which solidified upon cooling, melting point 51-52° C.

1. dissolutiondissolved in 60 ml of abs
2. temperaturewhile cooling with ice
3. stirringAfter stirring at room temperature for 20 hours the mixture
4. extractionextracted with ethyl acetate
5. customthe crude product obtained
6. customafter drying
7. customevaporation of the solvent
8. filtrationwas filtered over a silica gel column (eluent hexane/ethyl acetate=9:1)