General synthesis of phenanthroindolizidine, phenanthroquinolizidine, and related alkaloids: preparation of (.+-.)-tylophorine, (.+-.)-cryptopleurine, (.+-.)-septicine, and (.+-.)-julandine
General synthesis of phenanthroindolizidine, phenanthroquinolizidine, and related alkaloids: preparation of (.+-.)-tylophorine, (.+-.)-cryptopleurine, (.+-.)-septicine, and (.+-.)-julandine