Yao, Hongliang Song, Liyan Liu, Yuan Tong, Rongbiao Cascade Michael Addition/Cycloketalization of Cyclic 1,3-Dicarbonyl Compounds: Important Role of the Tethered Alcohol of α,β-Unsaturated Carbonyl Compounds on Reaction Rate and Regioselectivity Reactions of α,β-unsaturated aldehydes and cyclic 1,3-dicarbonyl compounds proceed primarily by cascade Knoevenagel condensation/six-π-electron electrocyclization (K6EC, formal [3 + 3] cycloaddition), while α,β-unsaturated ketones usually react with cyclic 1,3-dicarbonyl compounds in a 1,4-addition manner. This paper discloses our findings that under acidic conditions, α,β-unsaturated carbonyl compounds (ketones and aldehydes) with a tethered alcohol react with cyclic 1,3-dicarbonyl compounds in a highly regioselective 1,4-addition fashion via in situ generation of a hypothetical α-methylene cyclic oxonium ion as the reactive Michael acceptor. Our studies uncovered the important effect of the tethered alcohol on the reaction rate and/or efficiency and some new mechanistic aspects of the cascade Michael addition/cycloketalization. Finally, the substrate scope was examined, and 43 analogues of penicipyrone and tenuipyrone were prepared in good to excellent yields. Important Role;substrate scope;acidic conditions;K 6EC;43 analogues;Reaction Rate;Compound;reactive Michael acceptor;Tethered Alcohol;cyclic;reaction rate;ketone;dicarbonyl;aldehyde;carbonyl compounds;cascade 2014-09-19
    https://acs.figshare.com/articles/dataset/Cascade_Michael_Addition_Cycloketalization_of_Cyclic_1_3_Dicarbonyl_Compounds_Important_Role_of_the_Tethered_Alcohol_of_Unsaturated_Carbonyl_Compounds_on_Reaction_Rate_and_Regioselectivity/2253538
10.1021/jo501604e.s005