2'-Nitropapaveraldine Methohalide の還元成績体について : 複素環式化合物の合成研究 第234報

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Catalytic reduction of 2'-nitropapaveraldine methochloride (IX) in dehyd. ethanol, in the presence of a small amount of potassium hydroxide, over Raney nickel catalyst, resulted unexpectedly in abnormal fission of the carbon-carbon bond to produce the ester compound (X), isocarbostril compound (XI), and tetrahydroisoquinoline compound (XIIa). On the other hand, reduction of IX in a mixed solvent of methanol and ethanol (3 : 1), in the presence of a small amount of water and an excess of sodium borohydride, followed by immediate catalytic reduction of its product over Raney nickel catalyst afforded XIIa from the hexane-soluble portion. Treatment of the hexane-insoluble portion with acetic anhydride gave the diacetyl compound (XVII). This abnormal reaction mechanism was considered to be as depicted in Chart 4.