以L-薄荷醇、4-甲基-5-羟乙基噻唑、多聚甲醛、环氧乙烷等为原料,设计合成出一类新型的噻唑基温控手性离子液体催化剂,并将其用于催化反式肉桂醛和对甲酰基苯甲酸甲酯的反应,立体选择性地合成了含有两个手性中心的取代γ-丁内酯.利用催化剂的温控性能,使反应在温控溶剂中进行,可以达到温控相分离催化的效果,实现催化剂的循环使用.选择出最佳温控溶剂为 THF/正己烷(体积比为2.5∶2).以1,8-二氮杂双环[5,4,0]十一碳-7-烯(DBU)为碱试剂,在催化剂用量为反应原料的10 mol%,反应温度为35℃,反应时间为16 h的条件下,反式肉桂醛的转化率为95.4%,γ-丁内酯的选择性为80.4%,产物顺反比为3.3∶1,其ee值分别为21.3%和16.1%.考察了催化剂的循环使用性能,结果表明催化剂可循环使用4次,其催化活性基本保持不变.
From L-menthol, 5-(2-hydroxyethyl)-4-methylthiazole, paraformaldehyde and epoxyethane, a novel thermoregu-lated thiazolium chiral ionic liquid was synthesized and used for catalyzing the reaction of trans-cinnamaldehyde with methyl p-formylbenzoate to stereoselectively synthesize γ-butyrolactones with two chiral centres. By using the thermoregulation of the catalyst, the catalytic reaction in the thermoregulated solvent had the feature of“Thermoregulated Phase-separable Cataly-sis”, and the recycling of the ionic liquid catalyst was easily achieved. THF/n-hexane (V∶V=2.5∶2) mixed solvent was se-lected as the thermoregulated solvent. Under the conditions of 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) as the alkaline re-agent, the quantity of catalyst 10 mol%, the reaction temperature 35 ℃, and the reaction time 16 h, the conversion of trans-cinnamaldehyde could reach 95.4%, and the selectivity of γ-butyrolactones was 80.4%. The ratio of cis/trans product was 3.3, and the e
