umpolung of alkynyl 1,2‐diketones via N‐heterocyclic carbene (NHC) catalysis was achieved for the first time, allowing the rapid access to a large variety of synthetically and pharmaceutically important α‐pyrones under very mild conditions. A completely new NHC‐catalyzed umpolung pattern involving an O‐acylated allenolate as the key intermediate was proposed. Moreover, an unprecedented reaction pathway
The activated alkynes have been used successfully for the first time as the dipolarophile in the palladium-catalyzed asymmetric (3 + 2) cycloaddition, affording highly functionalized cyclopentenes in good to high yields with high chemoselectivities and good to high enantioselectivities. The introduction of an additional carbonyl group at the α-position of the alkynyl esters is the key to activating
An efficient and mild one-pot approach for copper-catalyzed aerobic oxidative coupling of α-carbonyl aldehydes with terminal alkynes toward ynediones has been developed. Moreover, a variety of ynediones were constructed under the optimized reaction conditions, and a plausible mechanism was presented based on a series of control experiments.
Catalyst- and Additive-Free Annulation of Ynediones and (Iso)Quinoline <i>N</i>-Oxides: An Approach to Synthesis of Pyrrolo[2,1-<i>a</i>]Isoquinolines and Pyrrolo[1,2-<i>a</i>]Quinolines
作者:Wan-Wan Yang、Ya-Fang Ye、Lu-Lu Chen、Ji-Ya Fu、Jun-Yan Zhu、Yan-Bo Wang
DOI:10.1021/acs.joc.0c01932
日期:2021.1.1
A simple and effective annulation of ynediones and (iso)quinoline N-oxides was developed to afford various functionalized pyrrolo[2,1-a]isoquinolines and pyrrolo[1,2-a]quinolines in moderate to excellent yields. This protocol underwent a tandem [3 + 2] cycloaddition/ring-opening/N-nucleophilic addition, which exhibited high regioselectivity, broad substrate tolerance, and atom economy under catalyst-
开发了一种简单有效的炔和N-氧化物(异)喹啉环化反应,以中等到优异的产率提供了各种功能化的吡咯并[2,1- a ]异喹啉和吡咯并[1,2- a ]喹啉。该方案进行了串联[3 + 2]环加成/开环/ N-亲核加成,在无催化剂,无添加剂和空气条件下,具有较高的区域选择性,广泛的底物耐受性和原子经济性。此外,使用吡啶N-氧化物也成功地制备了吲哚利嗪。