An efficient Sn(ii)-catalyzed one-pot synthesis of a 3-substituted azetidine-2,4-dione framework.

A novel Sn(ii)-catalyzed tandem cyclization reaction of aromatic aldehydes with ethyl cyanoacetate has been achieved to afford a series of 3-substituted azetidine-2,4-diones in good to excellent yields. This protocol provides straightforward access to construct the azetidine core through sequential Knoevenagel condensation, hydration and the C-N cyclization reaction.

In silico sequence analysis, homology modeling and function annotation of leishmanolysin from Leishmania donovani.

Leishmaniases are a complex of diseases that range from the deadly visceral disease and some self-curing lesions to gross disfigurations. About 12 million peoples from 88 different countries get infected by this protozoan parasite through the sand flies. Visceral leishmaniasis is a potentially fatal disease endemic to large parts of Asia and Africa, primarily caused by the protozoan parasite Leishmania donovani. L. donovani is a species of Leishmania, a hemoflagellate parasite and causative agent of visceral leishmaniasis. Leishmanolysin is the major surface protein of the parasitic Leishmania. Leishmanolysin has been described as a parasite virulence factor and is involved in the direct interaction of promastigotes and host macrophage receptors and interaction with the complement cascade. In the current study we predicted the 3D structure of leishmanolysin using homology modeling as 3D structure prediction approach. Leishmanolysin is a stable extracellular stable protein of 561 amino acid residues. 3D structure of the leishmanolysin was determined using Protein Structure Prediction Server (PS2 Server) selecting MODELLER as 3D structure prediction method. Quality analysis of the model through its Ramchandran Plot and ERRAT value (94.25) indicated that it is a reliable model. Functional annotation showed that this protein is a member of the superfamily cl18220. The information thus discussed provides insight to the molecular understanding of structure and function of leishmanolysin from L. donovani. The predicted 3-D model may be further used in characterizing the protein in wet laboratory.

Fluoride-Assisted Synthesis of 1,4,5,6-Tetrahydropyridazines via [4 + 2] Cyclodimerization of in Situ-Generated Azoalkenes Followed by a C-N Bond Cleavage.

An unexpected CsF-assisted C-N bond cleavage was exploited to synthesize highly functionalized and biologically important 1,4,5,6-tetrahydropyridazine derivatives from α-halo N-acylhydrazones in excellent yields. The extrusion of nitrogen and the [4 + 2] cycloaddition between in situ-generated azoalkenes is a key reaction in the process. The identified methodology is suitable for synthesizing a wide variety of analogues of tetrahydropyridazines, which are prevalent in many medicinally important small molecules. The reaction conditions are mild, high-yielding, and amenable for the gram scale.

An efficient one pot regioselective synthesis of a 3,3'-spiro-phosphonylpyrazole-oxindole framework via base mediated [1,3]-dipolar cycloaddition reaction of the Bestmann-Ohira reagent with methyleneindolinones.

A one pot, highly regioselective synthesis of racemic 3,3'-spiro-phosphonylpyrazole-oxindole by 1,3-dipolar cycloaddition of an in situ generated anion of dialkyl 1-diazomethylphosphonate from the Bestmann-Ohira reagent (BOR) & methyleneindolinones has been developed. The synthesis affords the highly functionalized pyrazole scaffolds in good yields with excellent regioselectivity under mild reaction conditions within a short reaction time.