The development of highly efficient methods for the selective formation of carbon-heteroatom bond catalyzed by transition-metal complexes is a central and challenging subject of modern organic synthesis. These new processes enable us to realize the lower energy and resources consumption. We have recently focused our attention on novel catalytic performance of ruthenium complexes, since ruthenium complexes often show interesting catalytic activity and product selectivity by controlling their electronic and steric conditions, which are quite different from those with other transition-metal complexes. The objective of this research is to develop and establish the methods for catalytic activation of small polar molecules such as alcohols, amines, and thiols by use of environmentally benign ruthenium complexes, leading to highly efficient and novel methods for catalytic heterofunctionalization of C-C unsaturated compounds without the formation of any byproducts. In view of the ecological catalysts, the following reactions were developed in this study. They involve (1) intramolecular oxidative amination of aminoalkenes, (2) S-propargylation of thiols by propargylic carbonates, (3) cross-bennzannulation of electron-defficient alkynes with allylic compounds, and (4) oxidative cyclization of 4-penten-1-ols, which are all characteristic of the ecological ruthenium catalyst.