1-hydroxy-3-(indol-3-ylmethyl)-6H,7H,8H-5lambda(5)-pyrrolo[1,2-a]pyrazine + dimethylallyl diphosphate = 1-hydroxy-3-{[2-(1,1-dimethylallyl)-indol-3-yl]methyl}-6H,7H,8H-5lambda(5)-pyrrolo[1,2-a]pyrazine + diphosphate — reaction