Recent Advances in Catalytic Enantioselective Synthesis of Pyrazolones with a Tetrasubstituted Stereogenic Center at the 4-Position

Abstract

Pyrazolone [2,4-dihydro-3H-pyrazol-4-one] represents one of the most important five-membered nitrogen heterocycles which is present in numerous pharmaceutical drugs and molecules with biological activity. Recently, many catalytic methodologies for the asymmetric synthesis of chiral pyrazolones have been established with great success, specially, for the synthesis of pyrazolones bearing a tetrasubstituted stereocenter at C-4. This review summarizes these excellent research studies since 2018, including representative examples and some mechanistic pathways explaining the observed stereochemistry.1 Introduction2 Catalytic Enantioselective Synthesis of Chiral Pyrazolones with a Full Carbon Tetrasubstituted Stereocenter at C-43 Catalytic Enantioselective Synthesis of Chiral Pyrazolones with a Quaternary Carbon Stereocenter at C-4 bearing a Heteroatom4 Catalytic Enantioselective Synthesis of Chiral Spiropyrazolones5 Conclusion

Recent Advances in Selected Asymmetric Reactions Promoted by Chiral Catalysts: Cyclopropanations, Friedel–Crafts, Mannich, Michael and Other Zinc-Mediated Processes—An Update

“…Moreover, Michael additions performed in the presence of zinc ions also enjoy quite a lot of interest [70]. Currently, target materials in the asymmetric Michael addition reaction are very often isoxazole-5-ones and isoxazolidin-5-ones [71], and pyrazolones [72].…”

Organocatalytic Enantioselective Synthesis of Chiral Spiro‐indoline‐pyrazolones through a formal [4+1] Annulation Reaction of 4‐Bromopyrazolones and aza‐ortho‐Quinone Methides

“…However, only one example has been described in the literature using chiral sulfur ylides ( Scheme 1 A ) [19] . On the other hand, spiropyrazolones have recently gained widespread attention because of its biological and medicinal features as well as its synthetic versatility [20–22] . This kind of scaffold is present in several compounds with biological activities ( Figure 1 B ) [23–26] .…”

Squaramide-catalyzed asymmetric regioselective allylic alkylation of 4-aminopyrazolones with Morita–Baylis–Hillman carbonates

“…Pyrazolone, one of the core five-membered heterocycles, is often found in bioactive molecules and pharmaceuticals. 3 For example, compound A shows an analgesic effect, 4 Telin ( B ) is an antineoplastic agent, 5 and WS9326H ( C ), 6 a new cyclic peptide isolated from a mudflat derived streptomyces strain, exhibits anti-angiogenesis property (Fig. 1).…”