Redirect domains to single domain

I have recenty moved my website to a single wordpress install. When it was in Multisite we were using WPMU domian mapping, which automacially redirected requests made to and to

But sadly, domain mapping doesn't work on a single site install and now I can't seem to find a good way to forward my domain.

I've tried adding the following to my .htaccess:
RewriteEngine On
RewriteCond %{HTTP_HOST} ^cuartetotanguero\.com$ [OR]
RewriteCond %{HTTP_HOST} ^www\.cuartetotanguero\.com$
RewriteRule ^(.*)$ [R=301,L]

But that gives me a "too many redirects" error which seems to indicate the conditions are matching the new site.... I don't know why.

I've tried using the Redirection plugin, but can seem to get it to match domains, just paths.

Can you recommend the best way to acomplish this. It seem to recall wordpress having an option to force a specific domain but maybe that isn't accurate.

Thank you for your help.