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Solvent‐Free Ruthenium(II)‐Catalyzed C–H Activation: Synthesis of Alkenylarylpyrazole Derivatives
Author(s) -
Shome Sanchari,
Singh Surya Prakash
Publication year - 2015
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.201500634
Subject(s) - chemistry , chemoselectivity , catalysis , ruthenium , substrate (aquarium) , solvent , carboxylate , alkyl , environmentally friendly , combinatorial chemistry , organic chemistry , surface modification , medicinal chemistry , polymer chemistry , ecology , oceanography , biology , geology
The Ru II carboxylate complex Ru(MesCO 2 ) 2 ( p ‐cymene) (Mes = mesityl) was found to be an efficient catalyst for the direct dehydrogenative alkenylation of N ‐arylpyrazoles by using styrenes and acrylates in the presence of Cu(OAc) 2 · H 2 O in open air. The highly step‐economical C–H bond functionalization process is characterized by a wide substrate scope and significant chemoselectivity, which allowed direct alkenylation to be performed either under solvent‐free reaction conditions or by using a user‐friendly solvent system in which water was present as the major component. With less‐reactive styrenes, monoalkenylation took place, whereas with alkyl acrylates ortho ‐dialkenylation occurred. This approach may provide new insight into the design of an environmentally benign method for the oxidative heterocoupling of N ‐phenylpyrazole.