Homalium alkaloids

Scheme 65 Internal rearrangement on P-lactams leading to homalium alkaloids containing spermine backbones...

A (-)-homaline synthesis, which is adaptable for the synthesis of the natural unsymmetrical Homalium alkaloids, is given in Scheme VI/11 [40] [41]. The eight-membered diaza part, VI/52, was synthesized by a transamidation reaction. It was possible to prepare homaline (VI/50) and the three other minor bases, hopromine, hopromalinol, and hoprominol, by combination of different eight-membered ring building blocks. As shown in Scheme VI/11, homaline (VI/50) was synthesized in 36% yield. 

Finally, in an accompanying communication, Crombie et al. described an innovative diazocine ring expansion, in which intramolecular transami-dation was used to convert the Homalium alkaloid precursor 180 (R = R1 = H) into the alkaloid dihydroperiphylline (for details, see Section IV,D) (86TL5151). 

The Homalium Alkaloids Isolation, Synthesis, and Absolute Configuration Assignment... 

Stephen Davies andjames Thomson from the Department of Chemistry at the University of Oxford describe in Chapter 2 the isolation, structural elucidation, and synthesis of homalium alkaloids. This relatively small class of alkaloids currently comprises only four members. Although homalium alkaloids have been known for more than 45 years, so far they were not covered in our series. 

Homalium alkaloids isolation, synthesis and absolute configuration assignment, 74, 121 (2015)... 

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