Nickel-Catalyzed Cross-Coupling of Chromene Acetals and Boronic Acids
作者:Thomas J. A. Graham、Abigail G. Doyle
DOI:10.1021/ol300364s
日期:2012.3.16
nes is described. Under base-free conditions, readily accessible 2-ethoxy-2H-chromenes undergo Csp3–O activation and Csp3–C bond formation in the presence of an inexpensive nickel catalyst and boronicacids. This new strategy enables broad access to 2-substituted-2H-chromenes and has been applied to the late-stage incorporation of complex molecules, including the pharmaceuticals loratidine and indomethacin
描述了一种用于合成 2-芳基-和杂芳基-2 H-色烯的模块化和高效方案。在无碱条件下,容易获得的 2-乙氧基-2 H-色烯在廉价的镍催化剂和硼酸存在下经历 C sp 3 -O 活化和 C sp 3 -C 键形成。这种新策略可以广泛使用 2-取代-2 H-色烯,并已应用于复杂分子的后期掺入,包括药物氯雷他定和吲哚美辛甲酯。
Copper-catalyzed oxidative cross-dehydrogenative coupling of 2<i>H</i>-chromenes and terminal alkynes
作者:Fei Yang、Yangshan Li、Paul E. Floreancig、Xiaoyan Li、Lei Liu
DOI:10.1039/c8ob00949j
日期:——
An efficient copper-catalyzedcross-dehydrogenativecoupling of 2H-chromenes and terminal alkynes mediated by DDQ has been established. A protic additive, EtOH, proved to be crucial for harmonizing the oxidation with a subsequent alkynylation step by retaining the oxidation state of an oxocarbenium ion in the form of acetal. The CDC reaction exhibits a good substrate scope, with a range of terminal
Catalyst‐Free Synthesis of α‐Functionalized 2
<i>H</i>
‐Chromenes in Water: A Tandem Self‐Promoted
<i>pseudo</i>
‐Substitution and Decarboxylation Process
作者:Chunhui Jiang、Yayun Chen、Hongkui Zhang、Jian‐Ping Tan、Tianli Wang
DOI:10.1002/asia.201900641
日期:2019.9.2
protocol was also demonstrated by the scale-up synthesis and versatile conversions of the title product into other useful compounds. In addition, control experiments indicated that water was essential for the reactivity. Mechanistic studies further revealed that the reaction proceeded through a self-promoted tandem pseudo-substitution and decarboxylation process.
Catalytic Asymmetric Addition of Aldehydes to Oxocarbenium Ions: A Dual Catalytic System for the Synthesis of Chromenes
作者:Magnus Rueping、Chandra M. R. Volla、Iuliana Atodiresei
DOI:10.1021/ol302084q
日期:2012.9.7
A synergistic catalytic system for the first asymmetric addition of aldehydes to in situ generated prochiral oxocarbenium ions has been developed. The dual catalytic protocol allows the simultaneous activation of both electrophile and nucleophile and provides access to a variety of valuable chiral 2H-chromenes with excellent enantioselectivities.