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Synthesis of 2‐Haloalkylpyridines via Cp*RuCl‐Catalyzed Cycloaddition of 1,6‐Diynes with α‐Halonitriles. Unusual Halide Effect in Catalytic Cyclocotrimerization
Author(s) -
Yamamoto Yoshihiko,
Kinpara Keisuke,
Nishiyama Hisao,
Itoh Kenji
Publication year - 2005
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.200505193
Subject(s) - cycloaddition , chemistry , nitrile , substituent , catalysis , acetonitrile , alkyne , medicinal chemistry , halide , halogen , substrate (aquarium) , photochemistry , organic chemistry , alkyl , oceanography , geology
In the presence of 2–5 mol % Cp*RuCl (cod), various 1,6‐diynes reacted with α‐monohalo‐ and α,α‐dihalonitriles at ambient temperature to afford 2‐haloalkylpyridines in 42–93% isolated yields. The failure of acetonitrile, N , N ‐dimethylaminoacetonitrile, phenylthioacetonitrile, and methyl cyanoacetate as nitrile substrate clearly showed that the α halogen substitution is essential for the present cycloaddition under mild conditions. The cycloaddition of unsymmetrical diynes bearing a substituent on one alkyne terminal gave 2,3,4,6‐substituted pyridines exclusively.