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A Copper‐ and Phosphine‐Free Nickel(II)‐Catalyzed Method for C−H Bond Alkynylation of Benzothiazoles and Related Azoles
Author(s) -
Patel Ulhas N.,
Punji Benudhar
Publication year - 2018
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.201800243
Subject(s) - chemistry , alkynylation , catalysis , phosphine , combinatorial chemistry , nickel , copper , homogeneous catalysis , medicinal chemistry , organic chemistry
A phosphine‐free nickel(II)‐catalyzed method for the C(2)−H bond alkynylation of (benzo)thiazoles, (benz)imidazoles, and oxazoles is described. Well‐defined and air‐stable (Phen)NiCl 2 catalyst efficiently catalyzes the coupling of diverse azoles with alkynyl bromides without the use of a copper co‐catalyst, and the method tolerates synthetically important functional groups. Preliminary mechanistic studies on this Ni II ‐catalyzed alkynylation emphasize the homogeneous nature of the catalyst, and rule out a radical manifold for the reaction. The synthetic utility of this Ni‐catalyzed method is demonstrated by further functionalizing the alkynylated benzothiazoles to 3‐methyl‐2‐(alkynyl)benzo[ d ]thiazolium salts that are known DNA cleaving agents.