Hexafluoroisopropanol Promoted Ring‐Opening‐Cyclization of Donor–Acceptor Cyclopropanes with Primary Amines
摘要:
We reveal here a catalyst‐free, ring‐opening‐cyclization of donor‐acceptor cyclopropanes with primary amines to synthesize functionalized dihydropyrroles. This protocol avoids inert conditions and solvents promoted by hexafluoroisopropanol (HFIP). The reaction is quite general with aryl, alkyl, and alicyclic amines. A good number of cyclopropanes bearing keto groups reacted excellently to produce the desired products. Further, we complemented this method with Meldrum's acid‐derived cyclopropanes for synthesizing γ‐lactams. We have demonstrated the post‐synthetic applications of the products and gram‐scale synthesis to highlight the adaptability of this synthetic protocol.
Reductive Amination/Cyclization of Keto Acids Using a Hydrosilane for Selective Production of Lactams versus Cyclic Amines by Switching of the Indium Catalyst
作者:Yohei Ogiwara、Takuya Uchiyama、Norio Sakai
DOI:10.1002/anie.201509465
日期:2016.1.26
amines by reductive amination, using an indium/silane combination. This relatively benign and safe catalyst/reductant system tolerates the use of a variety of functional groups, especially ones that are reduction‐sensitive. A direct switch from synthesizing lactams to synthesizing cyclic amines is achieved by changing the catalyst from In(OAc)3 to InI3. This conversion occurs by further reduction of the
The Catalyst-Controlled Divergent Cascade Reactions of Homo-Propargylic Amines and Nitrones: Synthesis of Pyrrolo-Isoxazolidines and γ-Lactams
作者:Yuanfang Kong、Yingze Liu、Boyi Wang、Shengli Li、Lingyan Liu、Weixing Chang、Jing Li
DOI:10.1002/adsc.201701476
日期:2018.3.20
Two controllable one‐pot cascade cyclization reactions of homopropargylic amines and nitrones were developed by using different metal Cu and Ag salts. The pyrroloisoxazolidines and γ‐lactams were obtained in good to high yields, respectively. Herein, nitrones played dual roles, both as 1,3‐dipoles and oxidants, and four stereocenters were simultaneously formed in the hydroamination cyclization‐1,3‐dipolar