Preparation of an ecteinascidin product with a spiroamine-1,4-bridge involves forming a 1,4 bridge using a 1-labile, 10- hydroxy, 18-protected hydroxy, di-6,8-en-5-one fused ring compound. The C-18 protection is removed before spiroamine (preferably spiroquinoline) introduction. An independent claim is included for the manufacture of the ecteinascidin compound involving removing both protecting groups in a single step, according to the scheme. [Image] T : amino protecting group; and T' : hydroxy protecting group. ACTIVITY : Cytostatic. MECHANISM OF ACTION : None given.