Asymmetric Michael Addition Reaction of 3-Hydroxychromone
3-Hydroxychromone skeleton exists in a large number of natural products,and most of its derivatives have important physiological activities and potential medicinal value.However,the asym-metric chiral catalytic reaction of 3-hydroxychromone has been studied less so far.The optimal reaction conditions were determined by screening the chiral cinchona base catalyst,solvent,temperature,ratio,concentration of substrate and catalyst dosage by controlled variable method.Taking the reaction of compounds 1a and 2a as an example,0.10 mmol of compound 1a and 0.12 mmol of compound 2a were reacted in 1.0 mL of MTBE at 0 ℃ for 24～48 h under the catalysis of Cat*5(10％).The sub-strate was studied for universality,and 2-aryl-3-hydroxychromone derivatives were obtained with medi-um to excellent yield(71％～99％)and good enantioselectivity(56％～89％).The product 3al with the highest enantioselectivity(89％)was subjected to a 30-fold amplification reaction to obtain the tar-get product in 99％yield and 76％enantioselectivity.The structures of all compounds were confirmed by 1H NMR,13C NMR,HPLC and HR-MS(ESI).
chiral cinchonaine3-hydroxychromone(E)-(2-nitrovinyl)benzeneasymmetric Michael addition reactioncontrolled variable method
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