Structure elucidation and 1H/13C NMR spectral assignments of four trabectedin related compounds

Structurally, trabectedin is composed of three tetrahydro-isoquinoline subunits. Two of them form an annulated ring systemcomprising five six-membered rings, including a piperazine moi-ety.Linkedtothissystemisalactonebridgecontainingathio-etherfunction. The third tetrahydro-isoquinoline subunit is attached tothe lactone bridge at the alpha position of the carbonyl (Fig. 1).AsbecameevidentfromNMRandMSanalysis,theecteinascidinsdescribed in this work feature an additional double bond in thecentral fused ring system (Fig. 1). UV data support these findings.Furthermore, three of these trabectedin analogs lack the thirdtetrahydro-isoquinoline subunit. In the following text, the