I am implementing Asp.Net core Web API , entity framework core, database first approach using Visual Studio 2017. I have managed to generate the context and class files base
The solution Rohith / Harold Javier / Sami provided works. I would like to add that you can create a separate EF6 project to generate the C# classes for resultsets and then copy the files to your EFCore project. If you change a stored proc, you can update the result file using the methods discussed here: Stored Procedures and updating EDMX
If you need corresponding typescript interfaces, you can install this VS2017 extension typescript definition generator: https://marketplace.visualstudio.com/items?itemName=MadsKristensen.TypeScriptDefinitionGenerator
There are still be a couple of copying, but it is less tedious than creating the classes manually.
Edit: there is a VS2017 extension for generating the dbconext https://marketplace.visualstudio.com/items?itemName=ErikEJ.EFCorePowerTools. It does not do stored procedures, but it provides a right click menu item from VS project instead of the command line Scaffold-DbContext.