抄録
In an earlier work with Tomita, the absolute configuration of the coclaurine-type bases was established by derivation of D-(-)- and L-(+)-laudanosine, whose absolute configuration had been established by Corrodi and others, to D-(-)- or L-(+)-N, O, O-trimethylcoclaurine (IIa and IIb). As a result of these experiments, the absolute configuration of the two asymmetric centers was confirmed in majority of biscoclaurine-type bases which produce two kinds of optically active coclaurine-type bases by cleavage with metallic sodium in liquid ammonia. In continuation of this work, the absolute configuration of the two asymmetric centers in cepharanthine (IV), which has methylenedioxy group as the characteristic atom group in the molecule, was also established.
Cleavage reaction with sodium in liquid ammonia carried out on insularine (VIIa) and insulanoline (VIIb), having a depsidane ring as the characteristic atom group in the molecule, produces l-homoarmepavine (VIII), besides coclaurine-type base (IX) as the cleaved bases. One (in A) of the two asymmetric centers in insularine (VIIa) and insulanoline (VIIb) had not been established as yet.
In the present series work, in order to solve this problem, L-(+)-armepavine (X), whose absolute configuration had already been established, and dimethylamine were submitted to the Mannich reaction and its reaction product was reduced at a high pressure, affording L-(+)-homoarmepavine (VIIIa). Comparison of this product with l-homoarmepavine (VIII), obtained by the cleavage of insularine (VIIa) with metallic sodium in liquid ammonia, revealed that the absolute configuration of (VIII) was a D type. Consequently, the absolute configuration of the two asymmetric centers in insularine (VIIa) and insulanoline (VIIb) was completely established as (D, D).
