Figure 3. Retrosynthetic analysis shows different ways leading to the same molecule. Overview about different strategies: C) Extraction and distillation from natural sources (vegetables, nuts and beans) with focus on the biosynthesis of 3-isobutyl-2-methoxypyrazine in grapes from amino acids leucine and glycine and D) Biobased syntheses by in vivo biotransformation starting from amino acids and sugars.