The sulfonation of various 1-phenylsulfonyl-1H-pyrroles and 1-phenylsulfonyl-1H-indoles using chlorosulfonic acid in acetonitrile has been studied, leading to the development of a clean and operationally simple protocol allowing direct synthesis of the corresponding 1-phenylsulfonyl-1H-pyrrole-3-sulfonyl chlorides and 1-phenylsulfonyl-1H-indole-3-sulfonyl chlorides, respectively, both of which may be easily converted to various sulfonamide derivatives by treatment with nitrogen nucleophiles. Efficient and selective removal of the phenylsulfonyl- or tosyl groups in the sulfonamide series may be achieved under mild conditions.

A new approach to 3-(arylthio)indoles and related compounds has been developed, based on the reactions of aryl Grignard reagents or lithiated heteroaroinatics with a phenylsulfonyl-protected 3,3'-bis(indolyl) disulfide. In addition, a rational approach to the 3,3'-bis(indolyl) sulfone core of the alkaloid echinosulfone A has been accomplished, involving treatment of a 3-lithioindole with bis(phenylsulfonyl) sulfide as the key step.

A short and efficient stereoselective synthesis of the indole alkaloid murrayacarine is described, including studies on its acid-induced isomerization.

The exocyclic analogue of the indole alkaloid isolated from the marine sponge Halichondria melanodocia has been prepared via olefination of a phosphonoester derived from 3-(2-bromoacyl)indole. The formation of an unexpected indolylazepine is also discussed.

Anthranilic acid (2-aminobenzoic acid, AA) is a versatile and low cost starting material for synthesis of benzofused heterocycles. It also plays a vital part in the biosynthesis of tryptophan and its derivatives, as well as in several types of alkaloids. Therefore the chemistry of anthranilic acid is of importance in medicinal and biological chemistry. The main emphasis of this review article is on the use of anthranilic acid as a starting material for synthesis of heterocycles, but it also covers the history, synthesis and reactivity, as well as a short account of the medicinal chemistry and biochemistry of anthranilic acids.

This chapter discusses the progress in synthesis and chemistry of pyrroles, indoles, and related fused ring systems. Several specialized reviews on the chemistry of indoles and pyrroles have appeared during the reporting period, providing more in-depth coverage. A comprehensive review on pyrrole natural products has appeared as well as a more limited one on the synthetic chemistry involving the pyrrole natural products roseophilin and prodigiosin is illustrated in this chapter. Likewise, the synthetic efforts in the field of the pyrrole-imidazole class of alkaloids have been covered. The isolation and synthesis of indole alkaloids containing a non-rearranged monoterpenoid unit is discussed in this chapter.

Reduction of indolo[2,3-b]quinoxalines with zinc in the presence of an anhydride gave N,N-diacyl trapped 6,11-dihydroindolo[2,3-b]quinoxalines in 43-92% yields. When the reduction with zinc was performed in TFA/TFAA, an unexpected ring opened product was isolated in 49% yield. The structure of this product could be identified as 1,2-dihydro-1-trifluoroacetyl-3-[(2-trifluoroacetylamino)phenyl]quinoxal ine.