Medicinal interest pyrrole

In 2011, Li, Antilla, and co-workers reported an intramolecular AFC reaction of Af-aminoethyl pyrroles 61 with various aldehydes catalyzed by CPA (i )-13d, affording medicinally interesting chiral l,2,3,4-tetrahydropyrrolo[l,2-a] pyrazines 62 in excellent yields (up to 95%) and enantioselectivity (up to 94% ee) (Scheme 6.22). ... 

The indole and pyrrole nucleus are common structural motifs in a range of natural products and medicinal agents (Fig. 1). Therefore, methods for their selective and efficient functionalization are important targets for chemical synthesis. The inherent reactivity of these heteroarenes has attracted widespread interest as ideal substrates for direct metal-catalyzed C-H bond functionalization reactions. However, related to their intrinsic reactivity is their sensitivity to harsh aerobic reaction conditions, and so methods to enable direct transformations on these heteroarenes must take this into account. 

Pyrrolo[3,2-df pyridazines are a class of interesting and useful A -heterocycles [40—42]. However, synthetic methods for such heterocyclic compounds have been very much limited such as condensation of pyrrole-2,3-diones with hydrazine. There are no reports on one-pot multi-component synthesis of pyrrolo[3,2-(f py-ridazines [43]. Moreover, synthetic methods for pyrrole-2,3-diones are also very limited [43]. On the other hand, transition-metal-mediated reactions of azides are of great importance and versatility in organic synthesis, because azides could be readily transformed into a wide variety of valuable A -containing natural products and medicinal agents [44-50]. 

The metabolism of tryptophan has been of interest to investigators in many different fields of biochemistry and medicine. The biological transformations of this indole derivative are very complex and involve a series of enzymes, which cause i) changes of the side chain (transaminases, decarboxylases, etc.) ii) splitting of the indole nucleus from the side chain (tryptophanase) iii) changes in the pyrrole nucleus (tryptophan pyrrolase, kynureninase, etc.) iiii) changes in the benzene ring (hydroxylases, etc.). 

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