Hyellazole, chloro

Since the late 1960s, several carbazole alkaloids oxygenated in the 3-position were isolated from diverse natural sources, the majority of which were isolated from different plant sources. However, in 1979, Moore et al. reported the isolation of two unusual, non-basic, 3-oxygenated carbazole alkaloids, hyellazole (245) and chloro-hyellazole (246), from the blue-green marine algae Hyella caespitosa (225). These alkaloids have structures entirely different from those of the carbazole alkaloids isolated from terrestrial plants. 

These two steps can be combined to a one-pot procedure affording 6-bromohyella-zole (45) in 69% yield. Compound 45 can be readily transformed into 6-chloro-hyellazole (46) in 96% yield using copper(I) chloride in dimethylformamide. Direct chlorination of 44 with Al-chlorosuccinimide (NCS) occurs at C-4 and, thus, provides no access to the naturally occurring 6-chlorohyellazole (46) [111]. 

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