Syntheses of fused pyrroloheterocycles, isatins, approach towards the indole fragment of nosiheptide and a base-mediated formation of 3-hydroxycarbazoles .

摘要

The nitro group has been and still is one of the few functional groups widely studied in synthetic organic chemistry. The reactivity of the nitro group has had important applications in the syntheses of many complex organic molecules, either through its assistance in the formation of new carbon-carbon bonds or in the formation of carbon-heteroatom bonds. Of late, the nitro group has become an important source of nitrogen in organic molecules, thus spawning the syntheses of a range of nitrogen heterocycles.;This dissertation is one such work, wherein the reactivity of the nitro group has been exploited with respect to the syntheses of nitrogen heterocycles. The palladium-catalyzed reductive N-heteroannulation reaction discovered in our laboratories a decade ago, has been utilized to synthesize a group of fused pyrroloheterocycles from the corresponding nitro-alkenylarenes. Also, these annulation conditions, when applied to 1-(2-haloethynyl)-2-nitrobenzenes, led to the formation of isatins. The isolation of a few stable 2-haloisatogens en route to the isatins is an important aspect in this conversion.;In addition, the possibility of executing an intramolecular nucleophillic attack on 3-(2-nitrophenyl)-2-cyclohexenone derivatives to afford hydroxy-carbazoles was investigated. A short synthetic approach to a model indole fragment of the natural product nosiheptide was also designed and attempted.