Hyellazole indoles

Moody et al. reported the sjmthesis of the 3-oxygenated carbazoie alkaloids, hyellazole (245) (591,592) and carazostatin (247) (593,594) based on their pyrano[3,4- 7]indol-3-one methodology (Scheme 5.57). This synthetic strategy involves the use of a 1-substituted pyrano[3,4- 7]indol-3-one 542 as a stable... 

Sakamoto et al. reported the synthesis of hyellazole (245) and carazostatin (247) based on the benzannulation of indoles. This method involves an electrocyclization of the 3-(l,3-butadienyl)indoles 685, which derive from the indolin-3-one 686 and the phosphorus ylides 687 (Scheme 5.59). 

Finally, fused indole natural products that have been synthesized include thienodolin (thieno[2,3-f) indole) <04EJO258 and rutaecarpine (indoloquinazoline) <04TL997>. And lastly, in addition to previously mentioned examples, carbazole natural products that have been prepared include hyellazole <04TL5411>, carbazomycin B <04T1513>, and carbazoquinocin C <04OL329>. 

Indoles substituted at C-3 with butadienyl or styryl groups undergo electrocyclic reactions to give carbazole derivatives. The silyl enol ether (275) can be converted thermally directly into the carbazole (276), as the result of ready elimination of methanol this sequence is crucial for a hyellazole synthesis (Equation (96)) <89CC43>. Several related 3-styrylindole sequences have been developed and differ with respect to the placement of ethyl carbonate groups on the alkene. Both the substrates (277) and (279) undergo photocyclization to the respective benzocarbazoles (278) and (280) as a result of... 

Hyellazole (3a) has been synthesized according to Scheme 7 2-63. regioselective lithiation of 1-benzenesulphonylindole in the 2-position, followed by addition of propiophenone and alkaline hydrolysis, yielded the 2-vinylindole 17. A Vilsmeier reaction, followed by a Wittig reaction with methoxymethylenetriphenyl-phosphorane, gave the 2,3-divinylic indole 18. Finally, heating in decaline in the presence of Pd-C cyclized 18 to produce hyellazole (3a). Chlorohyellazole (3b) was similarly obtained. 

Moody, C.J., and P. Shah Diels-Alder Reactivity of Pyrano [3,4-6] Indol-3-ones Part 4, Synthesis of Alkaloids Carbazomycin A, B, and Hyellazole. J.C.S. Parkin Trans 1, 2463 (1989). 

Moody, C.J. and Shah, P. (1989h) Diels-Alder reactivity of pyrano[3,4-b]indol-3-ones. Part 4. Synthesis of the carbazole alkaloids carbazomycin A and B and hyellazole. J. Chem. Soc. Perkin Trans. I, 2463-2471. 

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