Homalium alkaloids syntheses

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. 

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)... 

Finally in this section, a novel ring expansion reaction of 3-lactams has been described by Crombie et al. for the synthesis of members of the Homalium family of alkaloids such as hopromalinol (152) (Scheme 2).43... 

The history of the isolation and structure elucidation of the spermine alkaloids dates from 1968, when homaline was isolated from the leaf of Homalium pronyense (Flacourtiaceae). The total synthesis of this alkaloid was reported in 1982, and the chemical structure, including absolute stereochemistry, was confirmed [2]. 

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