Ru3(CO)12-Catalyzed Coupling Reaction of sp3C−H Bonds Adjacent to a Nitrogen Atom in Alkylamines with Alkenes

Abstract

Catalytic reactions which involve the cleavage of an sp³ C−H bond adjacent to a nitrogen atom in N-2-pyridynyl alkylamines are described. The use of Ru₃(CO)₁₂ as the catalyst results in the addition of the sp³ C−H bond across the alkene bond to give the coupling products. A variety of alkenes, including terminal, internal, and cyclic alkenes, can be used for the coupling reaction. The presence of directing groups, such as pyridine, pyrimidine, and an oxazoline ring, on the nitrogen of the amine is critical for a successful reaction. This result indicates the importance of the coordination of the nitrogen atom to the ruthenium catalyst. In addition, the nature of the substituents on the pyridine ring has a significant effect on the efficiency of the reaction. Thus, the substitution of an electron-withdrawing group on the pyridine ring as well as a substitution adjacent to the sp² nitrogen in the pyridine ring dramatically retards the reaction. Cyclic amines are more reactive than acyclic ones. The choice of solvent is also very important. Of the solvents examined, 2-propanol is the solvent of choice.