Department of Chemistry, National Taiwan Normal University , Taipei 11677, Taiwan R.O.C.
Org Lett. 2016 Jul 1;18(13):3098-101. doi: 10.1021/acs.orglett.6b01265. Epub 2016 Jun 21.
An efficient organocatalytic reaction using 1,3-nitro enynes with 4-hydroxycoumarin and 4-hydroxy-6-methyl-2-pyrone to afford pyrano-annulated scaffolds in high yield (up to 88% yield) and excellent stereoselectivities (up to >20:1 dr and >99% ee) is described. The reaction proceeded through sequential conjugate addition, allene formation, intramolecular oxa-Michael 6-endo-dig cyclization and DABCO-catalyzed olefin isomerization. A kinetic profile for isomerization was established. The mechanism for the organocascade reaction was proposed according to requisite computational and mechanistic experimental studies.
本文描述了一种使用 1,3-硝基烯炔与 4-羟基香豆素和 4-羟基-6-甲基-2-吡喃酮的高效有机催化反应，以高产率（高达 88%的产率）和优异的立体选择性（高达>20:1 的 dr 和>99%的 ee）得到吡喃并[2,3-c]吡喃骨架。该反应通过顺序共轭加成、烯丙基形成、分子内氧杂-Michael 6-endo-dig 环化和 DABCO 催化的烯烃异构化进行。建立了异构化的动力学曲线。根据必要的计算和机理实验研究，提出了有机级联反应的机理。
