7, 8-Di-substituted isoquinoline derivatives, which possess oxygen linkage at the 7- and 8-position, being considered to have a very close relation to the cularine alkaloids from the biogenetic point of view, can not be, according to the Bischler-Napieralski reaction, obtained from the amide which is derived from 3, 4-dialkyloxyphenethylamine by usual method. Therefore, carbamate (XIV) is subjected to the bromination to give XV, which is then cyclized by polyphosphoric acid, affording XVI, and it is further led to XVII. When XVII is treated with LiAlH4, both 7, 8-di-substituted isoquinoline derivative (XVIII) and XIX are obtained. XVIII is led to XX, which is reacted with 6-bromopiperonal (XXV) by means of the Ullmann reaction, to give 2-(5-bromo-1, 2, 3, 4-tetrahydro-2-methyl-7-methoxy-8-isoquinolinoxy)-4, 5-methylenedioxybenzaldehyde, and it is reduced further to alcohol derivative (XXVII) by NaBH4. It affords alcohol derivative (XXVIII), which is led to methochloride (XXXI) through XXIX and XXX, XXXI is also prepared from XXXII, derived from XXVIII, by treating with thionyl chloride. XXXI thus obtained is treated with magnesium with an aim to synthesize O-methylcularicine (XXXIII), however, such an attempt was found to be unsuccessful.