Hydroheteroarylation of Alkynes under Mild Nickel Catalysis
作者:Yoshiaki Nakao、Kyalo Stephen Kanyiva、Shinichi Oda、Tamejiro Hiyama
DOI:10.1021/ja0623459
日期:2006.6.1
Nickel complexes having a bulky tri(sec-alkyl)phosphine ligand catalyze hydroheteroarylation of alkynes at 35 degrees C. Selective activation of an Ar-H bond over an Ar-CN bond of N-protected 3-cyanoindoles is achieved by a proper choice of ligand and/or an N-protecting group. The catalysis is applicable to a diverse range of heteroarenes to afford cis-hydroheteroarylation products in highly chemo- and stereoselective manners. Excellent regioselectivity is observed with unsymmetrical alkynes to give the corresponding heteroaryl-substituted ethenes having a larger substituent trans to an aryl group.
Cobalt-Catalyzed Addition of Azoles to Alkynes
作者:Zhenhua Ding、Naohiko Yoshikai
DOI:10.1021/ol101777x
日期:2010.9.17
A ternary catalytic system consisting of a cobalt salt, a diphosphine ligand, and a Grignard reagent promotes syn-addition of an azole C(2)-H bond across an unactivated internal alkyne with high chemo-, regio-, and stereoselectivities under mild conditions. Mechanistic experiments suggest that the reaction involves oxidative addition of the oxazolyl C-H bond to the cobalt center, alkyne insertion into the Co-H bond, and reductive elimination of the resulting diorganocobalt species.
Practical Approach for Hydroheteroarylation of Alkynes Using Bench-Stable Catalyst
作者:Yoshiaki Nakao、Kyalo Stephen Kanyiva、Tamejiro Hiyama