Triphyophylline synthesis

The first asymmetric synthesis of a 7,1 linked alkaloid was that of (-)-dioncophylline A (8) (triphyophylline) which resulted in the revision of the initially proposed stereostructure (ref. 77). The synthesis utilised the intramolecular approach that was successful for the synthesis of racemic 8 (see Scheme 7) and began with the production of optically pure tetrahydroisoquinoline 79... 

A first total synthesis of the trans configurated tetrahydroisoquinoline alkaloid triphyophylline (23), via the lactone intermediate 108, was accomplished (see Scheme 26) (69). The use of an ester type auxiliary bridge, as in 107, still offered several crucial advantages over the above mentioned ether type prefixation of the molecular moieties. 

This first synthesis of triphyophylline (23) confirms its relative trans configuration of the two secondary methyl groups. A synthesis of this main Triphyophyl-lum alkaloid in optically active form, which is supposed to establish the chirality at the biphenyl linkage as well as the entire absolute stereochemistry, is under investigation in the author s laboratory. 

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