Morphinan-3-ol,7,8-didehydro-4,5-epoxy-6-methoxy-17-methyl-, (5a,6a)-

Heterocodeine (6-methoxymorphine) is an opiate derivative, the 6-methyl ether of morphine, and a structural isomer of codeine; it is called \"hetero-\" because it is the reverse isomer of codeine. Heterocodeine was first synthesised in 1932 and first patented in 1935. It can be made from morphine by selective methylation. Codeine is the natural mono-methyl ether, but must be metabolized for activity (that is, it is a prodrug). In contrast the semi-synthetic mono-methyl ether, heterocodeine is a direct agonist. The 3,6 methyl di-ether of morphine is thebaine.