Alkenes ruthenium-catalyzed heterocycles synthesi

A similar type of cascade reaction has been carried out with cyclic alkenes bearing only one olefinic side chain to obtain substituted heterocycles via ruthenium-catalyzed ring closing-ring opening metathesis (RCM-ROM) reactions. The preparation of enantiomerically pure cis- or trans-a,a -disubstituted piperidines has been achieved in the same yield for the two diastereoisomers [35] (Scheme 17). This reaction has also been used as a key step for the synthesis of natural products [36-39]. 

Direct C-H bond functionalization via ruthenium complexes catalysis has been well explored [5]. However, the rapid progress for heterocycle synthesis via ruthenium-catalyzed C-H activation has been only achieved since 2011. By utilizing the less expensive and stable ruthenium(II) complex [RuCl2(/ -cymene)]2, the oxidative cyclization reactions with a series of unsaturated small molecules like alkenes and alkynes proved to be a fast access to heterocycles. Herein, this chapter is intended to provide an overview of reported examples for ruthenium-catalyzed C-H bond activation and cyclization for heterocycle synthesis till the end of 2014, including mechanism presentations... 

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