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研究了手性磷酸催化下邻羟基苄醇和邻羟基苯乙烯的不对称[4+2]环加成反应,立体选择性地一步构建了手性2,4-二取代四氢色满骨架,该反应具有较高的收率、中等到较高的对映选择性和很好的非对映选择性(最高产率为78%,最高ee值为72%,dr值基本都大于95∶5).带有不同取代基的多种邻羟基苄醇和邻羟基苯乙烯均适用于该反应,电子效应对于该反应的对映选择性有一定影响,其中连有供电子基的底物具有更高的反应活性和对映选择性.由邻羟基苄醇原位生成的邻亚甲基苯醌中间体和邻羟基苯乙烯可以同时与催化剂手性磷酸形成双重氢键,对于促进反应的进行和控制该反应的对映选择性起着至关重要的作用.
The asymmetric [4 + 2] cycloaddition reaction of o-hydroxybenzyl alcohol and o-hydroxystyrene with chiral phosphate was studied, and the chiral 2,4-disubstituted tetrachromatic full-size skeleton was stereoselectively established The reaction has higher yield, moderate to high enantioselectivity and good diastereoselectivity (the highest yield is 78%, the highest ee is 72%, and the values of dr are basically greater than 95: 5) Various orthohydroxybenzyl alcohols with different substituents and ortho-hydroxystyrene are suitable for this reaction, and the electronic effect has some influence on the enantioselectivity of the reaction, in which the electron-donating substrate has a higher Reactivity and enantioselectivity. O-Methylbenzoquinone intermediate formed from o-hydroxybenzyl alcohol in situ and o-hydroxystyrene can form double hydrogen bonds with the catalyst chiral phosphate simultaneously to promote the progress of the reaction and control the The enantioselectivity of the reaction plays a crucial role.