酰氯在BaSO4,喹啉-S或硫脲鈍化的Pd催化劑的催化下氫化還原得到醛的反應。如果不進行鈍化,生成的醛會繼續還原成醇,因此可能的副產物有醇,酯和烷烴等。反應常用的溶劑有甲苯、二甲苯、THF等等,通常要求嚴格無水條件下進行,否則會有酸酐類副產物生成。硝基,鹵素,酯基等基團在此反應條件下不會被還原。
反應機理
反應實例
【Synthesis 1976, 767–768】
【Org. Process Res. Dev. 2012, 16, 1607-1617】
A pressure vessel is charged in order with 600 mL of dry toluene,25 g. (0.30 mole) of anhydrous sodium acetate,3 g. of dry, 10% palladium-on-carboncatalyst,23 g. (0.10 mole) of 3,4,5-trimethoxybenzoyl chloride, and 1 mL of Quinoline S. The pressure vessel is flushed with nitrogen, sealed, evacuated briefly, and pressured to 50 p.s.i. with hydrogen. The mixture is shaken with 50 p.s.i. of hydrogen for 1 hour at room temperature, then heated at 35–40° for 2 hours. Agitation is continued overnight while the reaction mixture cools to room temperature. The pressure on the vessel is released, the vessel is opened, and the mixture is filtered through10 gof Celite filter aid, and the insoluble material is washed with 25 mL of toluene. The combined filtrates are washed successively with 25 mL of 5% sodium carbonate solution and 25 mL of water. The toluene solution is dried over5 gof anhydrous sodium sulfateand filtered. The filtrate is concentrated by distillation at reduced pressure using a water aspirator. The residue is distilledthrough a 10-cm. Vigreux column with warm watercirculating through the condenser, to preventcrystallization of the distillate, yielding 12.5–16.2 g (64–83%) of 3,4,5-trimethoxybenzaldehyde, b.p. 158–161°C(7–8 mmHg.), m.p. 74–75°C.
【Organic Syntheses, Coll. 1988,6,1007】
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