Not familiar with scala project structure but looks similar to maven one.
Two points,
edu/knowitall/openie/openIECli, I see the class name is wrong should be edu/knowitall/openie/OpenIECli (case-sensitivity) . Although it should be a typo error, but better to check this one too.
which class are you trying to execute.
Also, you can refer to this link: How to solve java.lang.NoClassDefFoundError?
I suspect some problem with the build path, but need more details to look into.