p-Toluenesulfonic acid → (2R,4aR,10bR)-6-(2,6-Dimethoxy-pyridin-3-yl)-9-ethoxy-8-methoxy-1,2,3,4,4a,10b-hexahydro-phenanthridin-2-ol tosylate

Participants

Reaction Conditions

Reaction Steps

(2R,4aR,10bR)-6-(2,6-Dimethoxy-pyridin-3-yl)-9-eth oxy-8-methoxy-1,2,3,4,4a,10b-hexahydro-phenanthridin-2-ol (1.5 g; 3.6 mmol) is dissolved in 9 ml of 2-propanol. The solution is heated up to 60° C. 723 mg (3.8 mmol) of p-toluenesulfonic acid are added. The solution is cooled down to room temperature and stirred over night. From a part of the solution seed crystals are produced and added to the remaining solution. The crystals are filtered off and dried to obtain 1.98 g (94%) of the title compound (m.p.: 218° C.).

Provenance & Evidence