反应详情

A solution of 1,4-dioxaspiro[4.5]decane-7-carboxylic acid (Step A) (99.3 g) and triethylamine (80.8 g) in 1000 mL of dichloromethane is cooled in an ice bath, and treated dropwise with isobutyl chloroformate (80.1 g), dropwise, under nitrogen. After 30 minutes, a solution of 4-phenyl-1,2,3,6-tetrahydropyridine (84.7 g) in 500 mL of dichloromethane is added dropwise over a 2-hour period. The mixture is stirred at room temperature for 2 additional hours. The solvent is removed in vacuo. The residue is suspended in 1000 mL of ethyl acetate, cooled to 0° C., and sequentially washed with ice-cold 1N aqueous hydrochloric acid solution and brine, dried over magnesium sulfate, and evaporated in vacuo. The crude product is purified by flash chromatography (silica; hexane:ethyl acetate, 3:1) to give 107.1 g of the title compound as a yellow oil (silica; Rf =0.4; 1% methanol, 99% chloroform); Mass Spectrum (Electron Ionization) (MS (EI)) 327 (M, 26.1%), 141 (100%).

1. customThe solvent is removed in vacuo
2. temperaturecooled to 0° C.
3. washsequentially washed with ice-cold 1N aqueous hydrochloric acid solution and brine
4. dry with materialdried over magnesium sulfate
5. customevaporated in vacuo
6. customThe crude product is purified by flash chromatography (silica; hexane:ethyl acetate, 3:1)