Heterocarpine, a novel alkaloid from Ceratocapnos heterocarpa, has been characterised as (+/-)-1-hydroxymethyl-2-(3-hydroxy-4-methoxybenzyl)-7-hydroxy-6-methoxy-1,2,3,4-tetrahydroisoquinoline. The alkaloid was synthesized from the corresponding 3,4-dihydro isoquinoliniun salt. A key step in the process is the acid resin catalysed methanolysis of the l-carbamoyl isoquinoline. The structural correlation of the hydroxymethylated alkaloids heterocarpine and malacitanine with their unsubstituted counterparts capnosine and caseamine, also present in the plant, might be of biosynthetic significance. (C) 1998 Elsevier Science Ltd. All rights reserved.