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Catalytic Transformations of Alkynes into either α‐Alkoxy or α‐Aryl Enolates: Mannich Reactions by Cooperative Catalysis and Evidence for Nucleophile‐Directed Chemoselectivity
Author(s) -
Sahani Rajkumar Lalji,
Patil Manoj D.,
Wagh Sachin Bhausaheb,
Liu RaiShung
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201806883
Subject(s) - chemoselectivity , nucleophile , chemistry , catalysis , nitrone , mannich reaction , combinatorial chemistry , selectivity , aryl , medicinal chemistry , nucleophilic addition , alkoxy group , organic chemistry , cycloaddition , alkyl
The catalytic formation of gold enolates from 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(2 H )‐ones with syn selectivity. The mechanism involves the Mannich reactions of gold enolates with imines through an O‐H‐N hydrogen‐bonding motif. For aryloxyethynes, their gold enolates react selectively with nitrones to deliver 3‐alkylidenebenzofuran‐2‐ones, as controlled by a C‐H‐O hydrogen‐bonding motif.