A new efficient synthetic process for the construction of the pentacyclic core of marine alkaloid ecteinascidins

The pentacyclic core of ecteinascidins was constructed from two fundamental building blocks, the 1,2,3,4-tetrahydroisoquinoline derivative and the substituted phenylalanine derivative, via 8 steps using readily available L-Dopa as starting material. The key steps involve coupling of the two aforementioned building blocks, regioselective reduction of the 11-carbonyl group of the key intermediate piperazine-1,4-dione derivative, and intramolecular Pictet–Spengler cyclization.