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Selective Catalytic Hydration of Alkynes in the Presence of Au‐Cavitands: A Study in Structure–Activity Relationships
Author(s) -
Inoue Mami,
Ugawa Katto,
Maruyama Tomoyuki,
Iwasawa Tetsuo
Publication year - 2018
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201800948
Subject(s) - cavitand , chemistry , quinoxaline , moiety , methylene , alkyne , cationic polymerization , catalysis , stereochemistry , polymer chemistry , medicinal chemistry , organic chemistry , supramolecular chemistry , molecule
The effects of the catalytic cavities in gold‐functionalized cavitands in the hydration of internal alkynes have been studied. Variations on cavitand structures revealed the importance of two features that were studied: (1) flanking aromatic rings, and (2) an adjacent P=O moiety. The di‐quinoxaline‐spanned resorcin[4]arene system provides a well‐defined compartment, in which a cationic Au ion activates an internal alkyne for conversion into a ketone by delivery of water that has also been activated, this time by a P=O moiety. We synthesized four variations on our parent cavitand. Variations of the cavitand walls include replacement of quinoxaline components with pyrazine or methylene units. Variation of the P=O center was accomplished with methylene or quinoxaline moieties. All variants displayed lower catalytic activity or selectivity, allowing us to confirm the significance both of an internal cavity and of an activation site for water.