Check if current page is wp-admin

I have created a common custom dashboard for my users located at “http://website.com/login/dashboard/”

I’m trying to redirect users to that custom dashboard only if they are NOT admins & if the page IS http://www.website.com/login/wp-admin/

The redirection function I have is:

add_action( 'admin_init', 'redirect_so_15396771' );

function redirect_so_15396771()
{   
    if ( defined( 'DOING_AJAX' ) && DOING_AJAX )  
        return;

    if ( current_page('is_admin()') & !current_user_can('delete_users') ) {
            wp_redirect( site_url( '/login/dashboard/' ) );
            exit();
    }
}

You can test for roles with current_user_can():

if ( is_admin() && !current_user_can('administrator') ) {
    // redirect
}