Divergent NHC-Catalyzed Oxidative Transformations of 3-Bromoenal: Selective Synthesis of 2<i>H</i>-Pyran-2-ones and Chiral Dihydropyranones
作者:Gang Wang、Xia Chen、Gaohan Miao、Weijun Yao、Cheng Ma
DOI:10.1021/jo400950j
日期:2013.6.21
A selectivesynthesis of either 2H-pyran-2-ones (4) or chiral dihydropyranones (6) from the same substrates of 3-bromoenals and 1,3-dicarbonyl compounds upon oxidative N-heterocyclic carbene catalysis is presented. It is shown that the oxidative transformation of 3-bromoenals under NHC catalyst can be well controlled to proceed through two pathways, i.e., elimination of reducible β-bromide or by an
Oxidant free synthesis of α-pyrones <i>via</i> an NHC-catalyzed [3 + 3] annulation of bromoenals with 2-chloro-1,3-diketones
作者:Cong Luo、Xinyi Xu、Jianfeng Xu、Xingkuan Chen
DOI:10.1039/d2ob01859d
日期:——
An NHC-catalyzed [3 + 3] annulation reaction between α-bromo enals and 2-chlorocyclohexane-1,3-diones was developed for the rapid and efficient synthesis of various 4,5,6-trisubstituted α-pyrones, which are core structures in numerous natural products and synthetic bioactive molecules, in generally good to excellent yields.
Construction of Functionalized 2<i>H</i>-Pyran-2-ones via N-Heterocyclic Carbene-Catalyzed [3 + 3] Annulation of Alkynyl Esters with Enolizable Ketones
作者:Zheng Liang、Jibin Li、Lei Wang、Zexuan Wei、Jiahui Huang、Xinrui Wang、Ding Du
DOI:10.1021/acs.joc.2c02392
日期:2023.2.3
A new synthesis of functionalized 2H-pyran-2-ones has been developed through N-heterocyclic carbene-catalyzed formal [3 + 3] annulation of alkynyl esters with enolizable ketones. The key to the success of this protocol relies on the use of an NHC instead of a tertiaryamine as the catalyst. This protocol also features a broad substrate scope and mildmetal-free conditions, offering simple and rapid
ReBr(CO)5-catalyzed sequential addition–cyclization of 1,3-dicarbonyl compounds with electron-deficient internal alkynes affording trisubstituted 2H-pyran-2-ones
作者:Wen-Guo Zhao、Ruimao Hua
DOI:10.1016/j.tet.2007.09.038
日期:2007.11
The reaction of 1,3-dicarbonyl compounds such as acetoacetate, acetylacetone, dibenzoylmethane, and benzoylacetate with electron-deficient internal alkynes in the presence of catalytic amount of ReBr( CO) 5 in toluene under neutral conditions resulted in the formation of 4,5,6-trisubstituted 2H-pyran-2-ones in moderate to high yield. The reaction took place via a two-step sequence including the rhenium(I)-catalyzed addition of the activated methylenes to alkynes to give enolic 2-alkenyl derivatives, and subsequently dealcoholic cyclization to form 2H-pyran-2-one derivatives. (c) 2007 Elsevier Ltd. All rights reserved.
Ruhemann, Journal of the Chemical Society, 1899, vol. 75, p. 253