First of all sorry for my bad english. I\'m a german guy.
The code given below is working fine in PHP:
$string = preg_replace(\'/href=\"(.*?)(\\.|\\,)\"/
You need a backslash in front of the parentheses you want to reference, thus
sed 's/href="\(.*?\)(.|\,)"/href="{$\1}"/g' test.htm