Visual Studio For Mac 1.0
So I've installed Visual Studio for Mac and running Sierra 10.12.1. There is an issue with installing certain Nugets and whilst resolving Microsoft.AspNet.Core.Mvc issue (which was due to TargetFramework in project file wasn't 1.1.0) I'm struggling with Microsoft.Extensions.Configuration.Json.
Here is the error message

If you try Xamarin, you know VISUAL STUDIO ON Mac is a tools to build application for mac, so do not think you can grab a c# web appication and build and running on mac. That should be a dream. But for a.net core application. It should work. Visual Studio Mac 7.6.11 build 9 resx file no output visual studio for mac Alexander Bisset reported Nov 08 at 12:22 AM. Visual Studio is a new member of the Visual Studio family, enabling developers on macOS to build apps for mobile, Web, and cloud with Xamarin and.NET Core, as well as games with Unity. Use Visual Studio to develop apps for Android, macOS, iOS, tvOS, watchOS, Web, and cloud.
If someone at Microsoft sees this here are some other concerns :)
Overall experience with searching after Nuget packages is horrible. One would like to be able to search using wildcards or, at least, expect it to find related packages if just entering Json (Microsoft.Extensions.Configuration.Json is not found...).
Also reporting a problem from VS isn't working, it complains over internet connection which I have since I'm posting this question from the same computer.
2 Answers
Visual Studio For Mac Tutorial

Visual Studio For Mac 1.0.2
Installing the dependency Microsoft.Extensions.Configuration.FileExtensions first and then adding Microsoft.Extensions.Configuration.Json resulted in a successful install!
Edit: The happy times was unfortunately over sooner then i'd hoped. Exact same issue when trying to install EntityFrameworkCore and the list of transient dependencies are hopeless to follow bortom up
I had similar problem and I just went to manage NuGet Packages and Update the packages to the latest. That works for me.