Synthesis and Conformation of (5R,8R,10R)‐8‐(Methylthiomethyl)ergoline‐6‐carboxamidine

The title compound 7 and two related novel ergolines have been synthesised from (5R,8R,10R)-8-(methyl-thiomethyl)ergoline-6-carbonitrile (4). The guanidine function of 7 induces a boat conformation of ergoline-ring D, as demonstrated by a careful NMR spectroscopic analysis of 7 and its N-hydroxy congener 6. Diphenylphosphinodithioic acid has been used to convert the cyanamide function of 4 into the thiourea function at (5R,8R,10R)-8-(methylthiomethyl)ergoline-6-thiocarboxamide (5).