Described herein is the first total synthesis of ecteinascidin 743 (1), 1 an exceedingly potent and rare marine-derived antitumor agent which is slated for clinical trials when adequate quantities become available. 2, 3 The synthesis is enantio-and stereocontrolled, convergent and short (Scheme 1). The R, β-unsaturated malonic ester 2, prepared as a mixture of E and Z isomers from 2-(benzyloxy)-3-methyl-4, 5-(methylenedioxy) benzaldehyde4a and allyl 2, ...