Yolantinine, a New Dimeric Phenethylisoquinoline Alkaloid

As mentioned above, the only known naturally occurring monomeric phenethylisoquinoline alkaloid is autumnaline. There is also one fully characterized, naturally occurring bisphenylisoquinoline, namely, (—)-melanthioidine. Very recently, the new alkaloid yolantinine (jolantinine) was obtained from Merendera yolantae E. Czerniak (Liliaceae), and was assigned the structure shown below.  

The PMR spectrum of yolantinine exhibits 12 aromatic protons (86.38-6.75), two 0-methyl singlets (83.72 and 3.74), and two A-methyl singlets (82.22 and 2.33). The most significant feature of the CMR spectrum is the presence of 12 substituted aromatic carbons, and 12 unsubstituted aromatic carbons. The mass spectrum shows fragmentation peaks at mje 296, 192, and 121, which were assumed to possess the structures indicated.  

The structural assignment for yolantinine is not totally convincing since (a) The structure appears to violate the simple rules for biogenetic biaryl ether formation, and (b) the mje 296 ion substituted at C-6 and C-8 cannot arise from the expression ascribed to yolantinine, which incorporates a 6,7-disubstituted tetrahydroisoquinoline moiety. 

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