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Pyrrole is an extremely weak base for an amine, with a conjugate acid pK a of −3.8. The most thermodynamically stable pyrrolium cation (C 4 H 6 N +) is formed by protonation at the 2 position. Substitution of pyrrole with alkyl substituents provides a more basic molecule—for example, tetramethylpyrrole has a conjugate acid pK a of +3.7.
Skeletal formula of retronecine, a pyrrolizidine alkaloid found in the common groundsel (Senecio vulgaris) and comfrey (Symphytum spp.) . Pyrrolizidine alkaloids (PAs), sometimes referred to as necine bases, are a group of naturally occurring alkaloids based on the structure of pyrrolizidine.
Pyrrolidine, also known as tetrahydropyrrole, is an organic compound with the molecular formula (CH 2) 4 NH. It is a cyclic secondary amine , also classified as a saturated heterocycle . It is a colourless liquid that is miscible with water and most organic solvents.
Nicotine is a molecule containing a pyrrolidine ring attached to a ring of pyridine (other heterocyclic amine). Nicotine belongs to a group of compounds known as alkaloids, which are naturally occurring organic compounds with nitrogen in them. Pyrrole is another compound made up of molecules with a five-membered heterocyclic ring. These ...
Proline (symbol Pro or P) [4] is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group-NH 2 but is rather a secondary amine.
The starting material was an N-substituted pyrrole derivative, which was heated to convert it by a [1,5] sigmatropic shift to the isomer with a carbon bond between the pyrrole and pyridine rings, followed by methylation and selective reduction of the pyrrole ring using tin and hydrochloric acid.
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Alkaloids with partial pyrrolidine structure are usually sub-categorized based on their occurrence and biogenetic origin. Hygrin and cuscohygrin were isolated from the leaves of the coca shrub, [2] while (-)-codonopsinine was isolated from the woodland vine tiger bell.