防已科植物アルカロイド研究 (第158報)

Isotetrandrineの液体アンモニア中に於ける金属リチウムによる開裂反応 (1)

抄録

Cleavage reaction of isotetrandrine (I) with metallic lithium in liquid ammonia, with benzene or toluene as a solvent, proceeds as with metallic sodium or potassium and l-O, O, N-trimethylcoclaurine (III) and d-N-methylcoclaurine (IV) are formed almost quantitatively as the bisected bases. However, the same reaction of (I) with dioxane as a solvent, affords, besides the foregoing (III) and (IV), two kinds of a phenolic base with a composition of C₁₉H₂₃O₃N. The amount of the nonphenolic portion formed in this case is extremely small. The two kinds of phenolic base melted at 132° and 162°, and identified as polymorphs. Oxidation of its ethyl ether with cold potassium permanganate afforded 1-oxo-2-methyl-6-ethoxy-7-methoxy-1, 2, 3, 4-tetrahydroisoquinoline (XIII), m. p. 97°, from which the structure of the phenol base was proved to be l-1-(4-methoxybenzyl)-2-methyl-6-hydroxy-7-methoxy-1, 2, 3, 4-tetrahydroisoquinoline (XI), formed by the secondary demethylation of (III) produced by the cleavage.