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The Knorr pyrrole synthesis involves the reaction of an α-amino ketone or an α-amino-β-ketoester with an activated methylene compound. [15] [16] [17] The method involves the reaction of an α-amino ketone (1) and a compound containing a methylene group α to (bonded to the next carbon to) a carbonyl group (2). [18] The Knorr pyrrole synthesis
[3] [4] This has inspired the work of his student Paul Rothemund to develop a simple one pot synthesis of porphyrins. In 1935, Paul Rothemund reported the formation of porphyrin, from a simple reaction of pyrrole with gaseous acetaldehyde or formaldehyde in methanol followed by treatment with various concentrations of hydrochloric acid. [5]
It can also be synthesized in the laboratory. To do so, sodium hydroxide and bromine are added to an ice-water solution of succinimide. The NBS product precipitates and can be collected by filtration. [1] Crude NBS gives better yield in the Wohl–Ziegler reaction. In other cases, impure NBS (slightly yellow in color) may give unreliable results.
The Knorr pyrrole synthesis is a widely used chemical reaction that synthesizes substituted pyrroles (3). [ 1 ] [ 2 ] [ 3 ] The method involves the reaction of an α- amino - ketone (1) and a compound containing an electron-withdrawing group (e.g. an ester as shown) α to a carbonyl group (2) .
[1] [2] Pyrroles are found in a variety of natural products with biological activity, so the synthesis of substituted pyrroles has important applications in medicinal chemistry. [3] [4] Alternative methods for synthesizing pyrroles exist, such as the Knorr Pyrrole Synthesis and Paal-Knorr Synthesis. The Hantzsch pyrrole synthesis
2-mesityl-3-methylpyrrole was synthesized in 2004 via the Trofimov reaction. The reaction of the ketoxime with acetylene yielded a mixture of products with the primary one being the N-H pyrrole. Small amounts of the N-vinyl product were also observed as well as O-vinylketoxime. The N-vinyl product was then used in the synthesis of a new BODIPY. [5]
In organic chemistry, the Paal–Knorr synthesis is a reaction used to synthesize substituted furans, pyrroles, or thiophenes from 1,4-diketones.It is a synthetically valuable method for obtaining substituted furans and pyrroles, which are common structural components of many natural products.
Succinimide is an organic compound with the formula (CH 2) 2 (CO) 2 NH. This white solid is used in a variety of organic syntheses, as well as in some industrial silver plating processes. The compound is classified as a cyclic imide. It may be prepared by thermal decomposition of ammonium succinate. [4]