Copper-catalyzed aerobic annulation of hydrazones with dienones: an efficient route to pyrazole-linked hybrid molecules

A copper-catalyzed aerobic [3 + 2] annulation reaction to access various pyrazole-bound chalcones starting from readily available and cost-effective hydrazones and dienones is reported. These pyrazole-bound chalcones were further utilized effectively to prepare a series of pyrazole-linked hybrid molecules, such as pyrazole-pyrazoline, pyrazole-aziridine, and pyrazole-pyridine hybrids by efficient simple transformations. Synthetically challenging hybrid molecules were obtained in a simple, two-step process with high atom economy under aerobic copper catalysis.

Cobalt carbonyl-catalyzed carbonylation of functionalized aziridines to versatile β-lactam building blocks

Aziridine to azetidin-2-one carbonylation as a convenient entry to pyrrolidines,C-fused bi- and tricyclic β-lactams and monocyclic carbapenem analogs.

Synthesis of 2-aryl-3-(2-cyanoethyl)aziridines and their chemical and enzymatic hydrolysis towards γ-lactams and γ-lactones

Trans- andcis-2-aryl-3-(2-cyanoethyl)aziridines were transformed into 4-[aryl(alkylamino)methyl]butyrolactones and/or 5-[aryl(hydroxy)methyl]pyrrolidin-2-onesviachemical and enzymatic hydrolysis of the cyano group, followed by ring expansion.

Design, synthesis, and antiviral evaluation of purine-β-lactam and purine-aminopropanol hybrids

Purine-β-lactam chimera were prepared as a novel class of hybrid systems through N-alkylation of 6-benzylamino- or 6-benzyloxypurine with (ω-haloalkyl)-β-lactams, followed by reductive ring opening of the β-lactam ring by LiEt(3)BH to provide an entry into the class of purine-aminopropanol hybrids. Both new types of hybrid systems were assessed for their antiviral activity and cytotoxicity, resulting in the identification of eight purine-β-lactam hybrids and two purine-aminopropanol hybrids as promising lead structures.

Synthesis of 2-amino-3-arylpropan-1-ols and 1-(2,3-diaminopropyl)-1,2,3-triazoles and evaluation of their antimalarial activity

A variety of 2-amino-3-arylpropan-1-ols, anti-2-amino-3-aryl-3-methoxypropan-1-ols and anti-2-amino-1-arylpropan-1,3-diols were prepared selectively through elaboration of trans-4-aryl-3-chloro-β-lactams. In addition, a number of 2-(azidomethyl)aziridines was converted into novel 2-[(1,2,3-triazol-1-yl)methyl]aziridines by Cu(I)-catalyzed azide-alkyne cycloaddition, followed by microwave-assisted, regioselective ring opening by dialkylamine towards 1-(2,3-diaminopropyl)-1,2,3-triazoles. Although most of these compounds exhibited weak antiplasmodial activity, six representatives showed moderate antiplasmodial activity against both a chloroquine-sensitive and a chloroquine-resistant strain of Plasmodium falciparum with IC₅₀-values of ≤25 μM.

Regioselectivity in the ring opening of non-activated aziridines

In this critical review, the ring opening of non-activated 2-substituted aziridines via intermediate aziridinium salts will be dealt with. Emphasis will be put on the relationship between the observed regioselectivity and inherent structural features such as the nature of the C2 aziridine substituent and the nature of the electrophile and the nucleophile. This overview should allow chemists to gain insight into the factors governing the regioselectivity in aziridinium ring openings (81 references).

One-pot highly stereoselective synthesis of cyano aziridines via the CuCl-catalyzed aminochlorination of α,β-unsaturated nitriles and intramolecular S(N) 2 substitution

An efficient one-pot system has been developed for the synthesis of cyano aziridine by using α,β-unsaturated nitriles as the alkene substrates and N,N-dichloro-p-toluenesulfonamide (4-TsNCl(2) ) as the nitrogen source. A good scope of alkene substrates was achieved for this reaction. The one-pot reaction, via aminohalogenation and intramolecular S(N) 2 substitution, was very convenient to carry out at room temperature without the protection of inert gases. Modest to good yields and excellent have been obtained. This method provides an easy route to the cyano aziridine. The structure of the resulting products has been unambiguously confirmed by X-ray structural analysis.