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Gold‐Catalyzed Synthesis of 2,5‐Disubstituted Oxazoles from Carboxamides and Propynals
Author(s) -
Xu Yun,
Wang Qian,
Wu Yufeng,
Zeng Zhongyi,
Rudolph Matthias,
Hashmi A. Stephen K.
Publication year - 2019
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201801386
Subject(s) - chemistry , moiety , oxazole , electrophile , substituent , nucleophile , carbenoid , aldehyde , ketone , combinatorial chemistry , catalysis , selectivity , cyanation , stereochemistry , organic chemistry , rhodium
2,5‐Disubstituted oxazoles are synthesized by oxidative gold catalysis. In contrast to a reported procedure that delivers 2,4‐disubstituted oxazoles starting from terminal alkynes, a switch in selectivity towards a 2,5‐disubstitution is achieved by the use of propynals as starting materials. In the new reaction, the key intermediate is formed by the nucleophilic attack of the carboxamide onto a gold carbenoid, and then condensates with the more electrophilic aldehyde moiety already present in the substrate and not with the ketone that is derived from the oxygen donor. This new cyclization mode introduces a new carbonyl moiety as substituent at the 2,5‐disubstituted oxazole, an attractive motive that can be found in bioactive compounds or be used for further derivatizations.