Selective O-demethylation of isoquinoline alkaloids: Preparation of hydrocotarnoline from hydrocotarnine and conversion of S-(+)-laureline into S-(+)-roemerine via S-(+)-mecambroline

Abstract

The methoxy group in the simple isoquinoline alkaloid hydrocotarnine and in the aporphine alkaloid S-(+)-laureline can be cleaved selectively with trimethylsilyl iodide in boiling o-dichlorobenzene in the presence of 1,4-diazabicyclo[2.2.2]octane, affording hydrocotarnoline and S-(+)-mecambroline, respectively. Deoxygenation of S-(+)-mecambroline afforded S-(+)-roemerine.