Bisphenethylisoquinolines

Structure 176 was suggested for jolantinine. No data bearing on the chirality of the alkaloid were presented. It is apparently the first singly bridged bisphenethylisoquinoline alkaloid (104). 

The NlVIR-spectrum was found to be similar to that of 1-phenethyl-isoquinolines. This fact, together with its simplicity and the foregoing information about the functional groups, suggested that the alkaloid has a symmetrical bisphenethylisoquinoline structure. 

Phenethylisoquinoline alkaloids are classified into seven major alkaloid groups based on structural differences simple 1-phenethylisoquinolines (1), homomorphinanedienones (2), bisphenethylisoquinolines (3), homoproaporphines (4), homoaporphines (5), homoerythrines (6), and dibenz[benzylisoquinoline alkaloids. Although tropolone and Cephalotaxus alkaloids also belong to the... 

The new bisphenethylisoquinoline alkaloid is jolantinine 22, which was isolated from Meredera jolantae (8). The structure of (22) was determined by IR, H-NMR, and mass spectroscopy. 

Phenethylisoquinoline alkaloids are classified into six major alkaloid groups based on structural differences, namely, simple 1-phenethyliso-quinoline (1), homomorphinandienone (2), bisphenethylisoquinoline (3), homoproaporphine (4), homoaporphine (5), and homoerythrina alkaloids (6). These alkaloids are related to the benzylisoquinoline alkaloids such as morphinandienone, bisbenzylisoquinoline, proaporphine, apor-phine, and erythrina alkaloids. Although colchicine and its derivatives also belong to the phenethylisoquinoline alkaloids group, these alkaloids are not included in this review as they have been reviewed earlier 1). 

The symmetry of the bisphenethylisoquinoline molecule is such that reductive cleavage of 0,0-dimethylmelanthioidine (17) with sodium in liquid ammonia afforded almost exclusively the one phenolic isoquinoline 18 (12, 13) which showed a negative first Cotton effect. Previous knowledge (14, 15) of ORD measurement on tetrahydroiso-quinoline chromophores established the illustrated R-configuration and indicated that the molecule is in a head-to-tail arrangement. 

The base (149) has been oxidized by electrochemical methods to the dibenzo-quinolizinium salt (150) the methoperchlorate, under similar conditions, is oxidized to a 2 2 dimer. A bisphenethylisoquinoline, jolantinine (151), has been isolated from Merendera jolantae its structure has been assigned on the basis of spectroscopic evidence. 

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