(3R,4R)-4-Benzyloxycarbonyloxy-2-[1-methoxy-meth-(E)-ylidene]-3-[(S)-1-(2,3,4,9-tetrahydro-1H-β-carbolin-1-yl)methyl]-hexanoic acid methyl ester

(3R,4R)-4-Benzyloxycarbonyloxy-3-((R)-2-formyl-2,3,4,9-tetrahydro-1H-β-carbolin-1-ylmethyl)-2-[1-methoxy-meth-(E)-ylidene]-hexanoic acid methyl ester

(3R,4R)-4-Benzyloxycarbonyloxy-3-((S)-2-formyl-2,3,4,9-tetrahydro-1H-β-carbolin-1-ylmethyl)-2-[1-methoxy-meth-(E)-ylidene]-hexanoic acid methyl ester