Quinolizidine metacyclophane alkaloid

Although a number of alkaloids belonging to the simple arylquinolizidine class and the lactonic type had been synthesized, no successful synthesis of cyclophane alkaloids was accomplished until that of lythranidine (94), a unique alkaloid with a 2,6-trans disubstituted piperidine structure, was reported (28, 29). Quinolizidine metacyclophane alkaloids lythrancepines II (95) and III (96) have also been synthesized recently (30, 31). A review on the synthesis of lythranidine (94) is available in Japanese (32). 

Some quinolizidine metacyclophane alkaloids have vicinal dioxygen substitution in the quinolizidine ring. Lythrancine V (115) is an example of this type. In model studies, the vicinal diacetate 116 was prepared from 117 through four steps (36). 

In 1967, Fujita et al. (5,6) isolated three piperidine metacyclophane alkaloids (type B) from Lythrum anceps Makino. The third structural variant of the Lythraceae alkaloids, quinolizidine metacyclophane (type C), was... 

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