Enantioselective Synthesis of Arene cis-Dihydrodiols from 2-Pyrones
An enantioselective chemical synthesis of arene cis-dihydrodiols has been realized from 2-pyrones through sequential ytterbium-catalyzed asymmetric inverse-electron-demand Diels–Alder (IEDDA) reaction of 2-pyrones and retro-Diels–Alder extrusion of CO2. By using this strategy, a series of substituted arene cis-dihydrodiols can be obtained efficiently with high enantioselectivity (>99 % ee in many cases). Based on this strategy, efficient and concise asymmetric total syntheses of (+)-MK7607 and 1-epi-(+)-MK7607 were accomplished.
Liang, Xiao-Wei,Zhao, Yunlong,Si, Xu-Ge,Xu, Meng-Meng,Tan, Jia-Hao,Zhang, Zhi-Mao,Zheng, Cheng-Gong,Zheng, Chao,Cai, Quan
supporting information
p. 14562 - 14567
(2019/09/06)
Inverse-electron-demand Diels-Alder reactions of α,β-unsaturated hydrazones with 3-methoxycarbonyl α-pyrones
Inverse-electron-demand Diels-Alder reactions of 3-electron-withdrawing group substituted α-pyrones with α,β-unsaturated hydrazones as electron-rich counterparts are catalyzed by Eu(hfc)3 to afford bicyclic lactone cycloadducts. This is an example of umpolung cycloaddition based on functional transformation of carbonyls to hydrazones. A subsequent dehydrazonation reaction enables indirect synthesis of carbonyl group-containing bicyclic lactones, which cannot be easily obtained by the cycloaddition of α-pyrones and enals.