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Catalytic Electrophilic Halogenation of Silyl‐Protected and Terminal Alkynes: Trapping Gold(I) Acetylides vs . a Brønsted Acid‐Promoted Reaction
Author(s) -
Starkov Pavel,
Rota Filippo,
D'Oyley Jarryl M.,
Sheppard Tom D.
Publication year - 2012
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.201200491
Subject(s) - chemistry , halogenation , electrophile , cationic polymerization , catalysis , silylation , acetylide , electrophilic addition , medicinal chemistry , brønsted–lowry acid–base theory , alkyne , trimethylsilyl , annulation , organic chemistry , halide
In the presence of a cationic gold(I) catalyst and N ‐halosuccinimide, both trimethylsilyl‐protected and terminal alkynes are converted into alkynyl halides. Further experiments showed that silyl‐protected alkynes undergo electrophilic iodination and bromination under Brønsted acid catalysis, whilst terminal alkynes require a cationic gold catalyst. The former reactions probably proceed via activation of the electrophile, whilst the latter reactions proceed via a gold(I) acetylide intermediate. Gold‐catalysed halogenation was further combined with gold‐catalysed hydration and subsequent annulation to provide convenient routes to iodomethyl ketones and five‐membered aromatic heterocycles.