Epipodophyllotoxin derivitive Furo[3',4':6,7]naphtho[2,3-d]-1,3-dioxol-6(5aH)-one, 9-[(4,6-O-ethylidene-.beta.-D-glucopyranosyl)oxy]- 5,8,8a,9-tetrahydro-5-(3,4,5-trimethoxyphenyl)- NSC363606