Ghulam A. Miana

The quettamines: a new class of isoquinoline alkaloids

Three quettamine type alkaloids, which incorporate either a benzofuran or a dihydrobenzofuran moiety within the molecular framework, have been obtained from Berberis baluchistanica. These are dihydrosecoquettamine (1), secoquettamine (2), and quettamine chloride (3). Alkaloids 1 and 3 are racemates. Hofmann degradation of quettamine (3) provides secoquettamine (2) and the styrene 4 which has a trans relationship between the hydrogens at C-1 and C-α, thus indicating the identical stereochemistry in quettamine. Emde reduction of quettamine leads to dihydrosecoquettamine (1) and the stilbene 5. Two other polar alkaloids in the plant are (+)-armepavine methochloride (6) and oblongine chloride (7). An oblongine type alkaloid must be the biogenetic precursor for the quettamines. Arguments are presented favoring direct oxidative coupling in the biogenesis of the cularine alkaloids.

Three new alkaloids from Buxus papillosa

Abstract Three new steroidal alkaloids have been obtained from Buxus papillosa Schneider. These are (−)-cyclobuxupaline- C (IV)(+)-cyclopapilosine- D (VII) and (+)-buxamine- C (IX). A known alkaloid also present is desoxy-16-buxidienine (X).