Laravel 4.2 Eloquent using lists() with a join query

I have a query that makes use of multiple joins:

public function scopePurchased($query, $userId)
{

    return $query
                ->join('products','characters.id','=','products.productable_id')
                ->join('bundle_product','bundle_product.product_id','=','products.id')
                ->join('bundles','bundles.id','=','bundle_product.bundle_id')
                ->join('purchases','purchases.bundle_id','=','bundles.id')
                ->join('users','purchases.user_id','=','users.id')
                ->whereNull('purchases.deleted_at')
                ->where('purchases.refunded', false)
                ->where('products.productable_type', '=', get_class($this))
                ->where('users.id','=',$userId)
                ->groupBy('characters.id')
                ->orderBy('characters.title', 'ASC');

}

And I want to retrieve an array of ID's from this query to use in another scope so:

$query->purchased($userID)->lists('id')

My initial thought was to use lists('id') which complained about an ambiguous query on the ID.

Column 'id' in field list is ambiguous 
(
SQL: select `id` from `characters` 
inner join `products` on `characters`.`id` = `products`.`productable_id` 
inner join `bundle_product` on `bundle_product`.`product_id` = `products`.`id` 
inner join `bundles` on `bundles`.`id` = `bundle_product`.`bundle_id` 
inner join `purchases` on `purchases`.`bundle_id` = `bundles`.`id` 
inner join `users` on `purchases`.`user_id` = `users`.`id` 
where `characters`.`deleted_at` is null 
and `purchases`.`deleted_at` is null 
and `purchases`.`refunded` = 0 
and `products`.`productable_type` = Character and `users`.`id` = 1 
group by `characters`.`id` 
order by `characters`.`title` asc
)

Makes sense, fair enough so I changed the lists to

$query->purchased($userID)->lists('characters.id')

Thinking that naming the table and column should fix it but finding that the lists function drops the 'character.' part and so having the same error.

It appear that lists may not use a dot notation, bring me to my question... Can I escape the dot notation or is there another way to get the list of ID's as an array?

Many thanks