How to use BOOST_THROW_EXCEPTION correctly?

I try to use boost exceptions and fall. There are the problem code:

struct exception_base : virtual std::exception, virtual boost::exception 
{
    exception_base(std::exception&& e)
        : std::exception(e)
    {}
};

int main()
{
    std::string exception_description;

    try
    {
        BOOST_THROW_EXCEPTION(exception_base(std::runtime_error("hello exception")));
    }
    catch (exception_base& ex)
    {
        exception_description = boost::diagnostic_information(ex);
    }

    return 0;
}

In this case the value of the exception_description have the last string - "std::exception::what: Unknown exception". It is unexpected value. If I change BOOST_THROW_EXCEPTION to usual throw - the last string of exception_description value looks expected - "std::exception::what: hello exception"

So how to use BOOST_THROW_EXCEPTION correctly?