Insect-melanin formation: in the insect cuticle, after dopamine formation from L-tyrosine (see Figure 6), this intermediate is acetylated to N-acetyl-dopamine (NADA). This is oxidized by an insect phenyl oxidase to N-acetyl-dopaminequinone (NADAQ), which is tautomerized to a quinone methide (NADAQM) form. This methide is dehydrated to dehydro-N-acetyl-dopamine (DeNADA) and further oxidized to a new quinone (DeNADAQ) in reactions also catalyzed by phenol oxidase. The last species can dimerize to a benzodioxan and subsequently to a polymer to harden and tan the insect exocuticle.