Catalytic Transformations of Alkynes into either α-Alkoxy or α-Aryl Enolates: Mannich Reactions by Cooperative Catalysis and Evidence for Nucleophile-Directed Chemoselectivity
作者:Rajkumar Lalji Sahani、Manoj D. Patil、Sachin Bhausaheb Wagh、Rai-Shung Liu
DOI:10.1002/anie.201806883
日期:2018.11.5
The catalytic formation of gold enolatesfrom alkynes, nitrones, and nucleophiles is described, and their Mannich reactions result in nucleophile‐directed chemoselectivity through cooperative catalysis. For 1‐alkyn‐4‐ols and 2‐ethynylphenols, their gold‐catalyzed nitrone oxidations afforded N‐containing dihydrofuran‐3(2H)‐ones with syn selectivity. The mechanism involves the Mannich reactions of gold
With the aim to develop new potent antitubercular agents, a series of novel dispirooxindolopyrrolidines and dispirooxindolopyrrolothiazoles have been synthesized via a three-component 1,3-dipolar cycloaddition of (Z)-3-arylidenebenzofuran-2-ones, substituted isatin derivatives and alpha-aminoacids. The stereochemistry of the spiroadducts has been confirmed by an X-ray diffraction analysis. All the target heterocycles were evaluated for in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv strain and the most active compounds were subjected to cytotoxicity studies against (RAW 264.7) cell lines. Among them, twelve compounds showed potent anti-tubercular activity with MIC ranging from 1.56 to 6.25 mu g/mL. In particular dispirooxindolopyrrolothiazole derivatives 5c and 5f were found to be the most active (MIC of 1.56 mu g/mL) with a good safety profile (27.53% and 20.74% at 50 mu M, respectively). This is the first report demonstrating the benzofuranone oxindole hybrids as potential antimycobacterial agents. (C) 2015 Elsevier Ltd. All rights reserved.
Enantioselective construction of spiro-tetrahydroquinoline scaffolds through asymmetric catalytic cascade reactions
作者:Jia-Lu Zhang、Rui Ma、Huan-Huan Zhao、Peng-Fei Xu
DOI:10.1039/d2cc00502f
日期:——
asymmetric catalytic cascade reactions catalyzed by quinine-derived chiral bifunctionalsquaramideorganocatalysts. In this approach, differently substituted spiro-tetrahydroquinoline derivatives were smoothly obtained with high yields, and excellent diastereoselectivities and enantioselectivities (up to 99% yield, up to >20 : 1 dr, up to >99% ee, 40 examples) under mild reaction conditions.