Try this one after removing all the carriage returns in the HTML file. Assuming that all the contents are stored in $file,

$file =~ s/<blockquote><DIV ([^>]+)><DIV ([^>]+)><font ([^>]+)>code<\/font><\/DIV><font ([^>]+)>(.+)<\/font><\/DIV><\/blockquote>/<BLOCKQUOTE><p class="style2">$5<\/p><\/BLOCKQUOTE>/g;

Sriram