Conjugate addition of organocopper reagents to γ-alkoxybutenolides and application to the synthesis of non-racemic alkyl cyclopentenones

Natural and synthetic α,β-unsaturated carbonyls for NF-κB inhibition

BACKGROUND

The nuclear transcription factor NF-κB has gained considerable importance due to its major involvement in inflammation and constitutive activity in malignant cells. It is induced by a variety of stimuli and controls the expression of several proteins involved in biological processes. Numerous natural products and synthesized organic molecules have been reported to inhibit NF-κB and have played an integral role in identifying implicated pathways. Prominent among them are the sesquiterpene lactones, polyphenolic enones and other α,β-unsaturated carbonyl-containing molecules, particularly α-methylene-γ-butyrolactones.

DISCUSSION

This mini-review provides an introductory overview of some of the associated pathways involving NF-κB in cancer and discusses the structures and mode of action of natural α,β-unsaturated carbonyl-containing inhibitors and their synthetic counterparts. A review of the recent methods for the synthesis of α-alkylidene-γ-butyrolactones is also provided, with the aim of arousing the interest of synthetic chemists for the design and development of novel NF-κB inhibitors.

CONCLUSIONS

Modulating damaging effects without harming the inflammatory and immune responses are crucial parameters for developing NF-κB inhibitors. Examination of novel α,β-unsaturated carbonyls and the further discovery of simple methods to prepare such molecules should lead to the identification of site-specific inhibitors.

The First Examples of Nazarov Cyclizations Leading to Annulated Pyrroles

[reaction: see text] Reactions between alpha-substituted unsaturated carboxylic acids 20 and N-tosylpyrroles [14, 23] in the presence of trifluoroacetic anhydride result in smooth alpha-acylation of the pyrrole, followed by Nazarov cyclization to give 50-80% yields of cyclopenta[b]pyrroles. The presence of an alpha-substituent in the unsaturated acid appears to be mandatory.