Stereochemie der Umwandlung von Dihydrothebain in Thebain Synthese von markierten Thebainen

Abstract

Abstract The complete stereochemistry of the Δ 6 ‐dihydrothebaine → 7‐bromodihydrocodeinone dimethyl ketal → codeinone dimethyl ketal → thebaine sequence of transformations has been elucidated by NMR studies of the isotopically labeled compounds prepared using diimide‐d 2 , methyl hypobromite‐[ 14 C], and methyl hypobromite‐d 3 . Final elimination of methanol from codeinone dimethyl ketal proceeds in a stereospecific manner: cis under acid catalysis with POC1 3 , and trans under alkaline catalysis with EtO − . As a result of these reactions, variously isotopically labeled thebaines can be prepared.