Synthesis of optically active aporphine and morphinandienone alkaloids via p-quinol esters

Article abstract of DOI:10.1016/0957-4166(95)00213-9

Lead tetraacetate oxidation of N-trifluoroacetylnorcodamine (5) in (S)-(+)-2-phenylpropionic acid gave a diastereomeric mixture of two p-quinol acylates, which were easily separated to enantiomerically pure 6a and 6b. Treatment of the chiral quinol acylates (6a) and (6b) with trifluoroacetic acid in CH₂Cl₂ at room temperature afforded (1R)-(-)-6-trifluoroacetylwilsonirine (7a) and (1S)-(+)-(7b), respectively. Saponification of 7a and 7b gave rise to (-)-wilsonirine (8a) and its enantiomer (8b), respectively. Similarly, (-)-nordomesticine (12a) and (+)-(12b) were synthesized in enantiomerically pure form from 10a and 10b. On the other hand, acid treatment of 6a and 6b in CH₃CN at lower temperature (-30°C) llowed by N-deprotection gave the corresponding normorphinandienones (15a and 15b) as major products, which were transformed to enantiomerically pure (-)-16a and (+)-sebiferine (16b). In a similar sequence of reactions, (+)-amurine (19a) and its enantiomer (19b) were synthesized.