Guys, good night. It's OK?

I have a question that is difficult to solve.

How would I make this query using Laravel 5 Repositories?

$ Result = DB :: select ('select * from user or where not exists (select 1 from challenges c where u.id = c.user_id limit 1)')

The query is bringing the result perfectly, but not in the format to use in the angular.

This point I'm not understanding how to return the same query:

$ Result = $ this-> challengeRepository-> skipPresenter () -> with ($ this-> with) -> findWhere ([
// Default Condition =
?????
]) -> first ();

Remember that if I use a simple query the result is shown normally.

$ Result = $ this-> repository-> skipPresenter () -> with ($ this-> with) -> first ();

Does anyone have a tip?

Thank you.