Currently the .NET Core 1.0.0-preview2-1-003177 tooling does not have support for compilation to native binaries. The "dotnet build --native" command did exist in early versions of the tooling but that was just a proof of concept and could only compile simple "Hello World" programs.
The version of .NET Core optimized for creating native binaries is still under active development and is yet to be released, it's called CoreRT.
If you'd still like to distribute applications that don't require .NET Core to be pre-installed on the user's computer, you can take a look at Self Contained Deployment, this model packages up the .NET Core runtime and dependencies which must be distributed with the generated native binary.
If you want truly native compilation that produces a SINGLE BINARY, then you'll have to wait for CoreRT to at least get into preview, which should happen sometime in 2017