Organocatalytic Domino Michael-Heterocyclization Reaction of α,β-Unsaturated Aldehydes and α-Cyano Ketones: Synthesis of Enantioenriched 4,5,6-Trisubstituted 3,4-Dihydropyranones
作者:James O. Guevara-Pulido、José M. Andrés、Rafael Pedrosa
DOI:10.1002/ejoc.201402982
日期:2014.12
electron-poor aromatic, or electron-withdrawing substituents at the β position easily react with different ketones leading to enantioenriched hemiacetals, which were further oxidized to give 4,5,6-trisubstituted-3,4-dihydropyranones in good yields and with excellent enantioselectivities. The behavior of the ketones is dependent on the α substituent of the carbonyl group, and a fine-tuning of the pKa values is
在 β 位具有脂肪族、缺电子芳香族或吸电子取代基的 α,β-不饱和醛很容易与不同的酮反应,导致对映体富集的半缩醛,后者被进一步氧化得到 4,5,6-三取代-3,4 -二氢吡喃酮以良好的收率和优异的对映选择性。酮的行为取决于羰基的 α 取代基,需要微调 pKa 值才能获得良好的结果。