Nice answers. merlyn's in particular.

I was definitely overthinking or underthinking the problem. Here is my take for the record.

    sub find_quote {

        my $str = $_[0];

        my $c;

        $str =~ s/(
                    (?{$c = 1})
                    ".*?"
                    (?{$c++})
                    (?(?{$c % 2 == 0})(?!")|^)
                  )
                 /<$1>/xg;

        return $str;
    }
[download]

--
John.