Ergoline derivatives—XIV : Synthesis of clavine alkaloids

The treatment of methyl lysergate with mercuric acetate in methanol yields, instead of the expected 10 - methoxy - 6 - methyl - ergoline - 8 β - carboxylic acid methyl ester (2), 10 - methoxy - 8,9 - didehydro - 6 - methyl - ergoline - 8 - carboxylic acid methyl ester (3), whose structure is demonstrated. From 3, penniclavine (14) and isosetoclavine (15) were prepared according to Scheme 1.