A Review on Onychine and its Analogs: Synthesis and Biological Activity
Claudia R B Gomes1, Marcus V N de Souza1, Victor Facchinetti1
1Fundacao Oswaldo Cruz, Instituto de Tecnologia em Farmacos - Farmanguinhos. Rua Sizenando Nabuco 100, Manguinhos, 21041- 250, RJ, Brazil.
Background:
Onychine is a 4-azafluorenone alkaloid isolated from the Annonaceae family, in low concentrations. Onychine and its analogs exhibit a wide range of pharmacological activities such as antifungal, antibacterial, anticancer, and antimalarial. Because of the high bioactivity of some 4-azafluorenone derivatives, several synthetic methods have been developed for their procurement.
Objective:
Considering the importance of these alkaloids, we aim to present the main synthetic approaches to onychines and its derivatives and the biological activity of some 4-azafluorenones.
Methods:
The most prominent methodologies for the synthesis of onychines were reviewed.
Results:
In this work, we cover many synthetic approaches for the synthesis of onychine and 4-azafluorenone derivatives including intramolecular cyclizations, multicomponent reactions, microwave-assisted multicomponent reactions, Diels-alder reactions, among others. Moreover, we also review the biological activity of 4-azafluorenones.
Conclusion:
4-azafluorenones have risen as prominent structures in medicinal chemistry; however, most of the time, access to new derivatives involves toxic catalysts, harsh reaction conditions, and long-step procedures. Therefore, the development of new synthetic routes with more operational simplicity, simple purification procedure, good yields, and low environmental impact, is desirable.
