How to integrate Asp.Net 5.0 with Active Directory?

I'm building intranet application where I need to use Active Directory to authenticate users. In previous version I would use bearer tokens for that:

public static void ConfigureAuth(IAppBuilder app)
        {
            app.UseOAuthBearerTokens(OAuthOptions);
        }

But  IAppBuilder was replaced with IApplicationBuilder which doesn't contain UseOAuthBearerTokens.

Any help much appreciated, as I'm stuck with this for few days now.