Pyrrole natural products and materials

PYRROLE NATURAL PRODUCTS AND MATERIALS 5.2.4.1 Natural Products and Biologically Active Small Molecules... 

Pyrroles are an important class of heterocyclic compounds and are structural units found in a vast array of natural products, synthetic materials, and bioactive molecules. 

Pyrrole is one of the most prominent heterocycles, having been known for more than 150 years, and it is the structural skeleton of several natural products, synthetic pharmaceuticals, and electrically conducting materials. A simple access to the pyrrole ring system involves the conversion of cyclic anhydrides into five-membered imides. Mortoni and coworkers have described the conversion of 2-methylquinoline-3,4-dicarboxylic acid anhydride to a quinoline-3,4-dicarboximide library by treatment of the anhydride with a diverse set of primary amines under microwave conditions (Scheme 6.180) [341]. The authors studied a range of different conditions, including dry media protocols (see Section 4.1) whereby the starting materials were adsorbed onto an inorganic support and then irradiated with microwaves. For the transforma-... 

Anderson and co-workers86 used the cycloaddition of acetylenic esters to 19a and 19 (R = COPh) in the synthesis of the antimitotic agent Verrucarin E (28). The pyrrole 19a and DMAD gave 35% of 21a, whereas 19 (R = COPh) gave 67% of 21 (R = COPh) and 23% of recovered starting material 1-benzoylpyrrole gave 54% of 29 with DEAD. Further transformations produced the natural product. 

The synthesis and chemistry of pyrroles, indoles, and fused pyrrole and indole compounds reported during the past year (2007) are the subjects of this monograph. Pyrroles and indoles continue to draw a lot of attention from the scientific community due to their prevalence in natural products, diverse biological activity, and materials science applications. Pyrroles and indoles are treated separately. A review article describing the synthesis of highly functionalized pyrroles has appeared <07S3095>. Specialized review articles will be mentioned in the relevant sections. 

Pyrroles, indoles, and, to a lesser extent, carbazoles comprise an immense group of natural products, medicinal agents, polymers, and other materials. According to Chemical Abstracts, during... 

Prolonged action of acid upon pyrrole causes the formation, by oxidative condensation, of pyrrole red, xhe nature of this material and of pyrrole black, the product of other oxidations, is obscure. ... 

This review presents a systematic survey of the literature (through the end of 2014) for de novo syntheses of 3-pyrrolin-2-ones from acyclic precursors or via transformation of other cyclic systems such as pyrroles, pyrrolldinone, and malelmides. One-component Intramolecular cycllzatlon approaches, two-component Intermolecular cycllzatlon approaches, and multicomponent intermolecular cycllzatlon approaches are treated separately and organized based on the location(s) of the new bonds that are formed in the construction of the 3-pyrrolin-2-one ring system. 3-Pyrrolin-2-ones make important synthetic targets due to their occurrence in natural products, their diverse biological activity, and their utility as building blocks for the preparation of other materials. 

Pyridine is a polar, stable, relatively unreactive liquid (bp 115°C) with a characteristic strong penetrating odor that is unpleasant to most people. It is miscible with both water and organic solvents. Pyridine was first isolated, like pyrrole, from bone pyrolysates. Its name is derived from the Greek for fire (pyr) and the suffix idine used to designate aromatic bases. Pyridine is used as a solvent, in addition to many other uses including products such as pharmaceuticals, vitamins, food flavorings, paints, dyes, rubber products, adhesives, insecticides, and herbicides. Pyridine can also be formed from the breakdown of many natural materials in the environment. 

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