the present invention relates to a novel and efficient process for the preparation of 8 - hydroxybicyclotridec - 4 - ene - 2 , 6 - diyne ring system which is part of the aglycone of esperemicin and to novel cytotoxic antitumor agents having said bicyclic ring system . the present invention also provides a method for treating mammalian malignant tumors by administering to an animal in need of such treatment an antitumor effective amount of a compound of the present invention .