Shayna Shamim

Tandem imino-pinacol coupling-aza-Michael reaction promoted by Zn/InCl3: a novel multicomponent strategy for diastereoselective synthesis of monocyclic 1,4-diazepine in water

Aldimine formed in situ on bimolecular reductive coupling in the presence of zinc and accelerated by indium(III) chloride in water afforded N,N′-diphenyl-1,2-diaryl-1,2-diamino ethane which on aza-Michael addition with α,β-unsaturated ketone and subsequent dehydrative cycloaddition yielded monocyclic 1,4-diazepine in excellent yield and with high diastereoselectivity in one-pot. The whole reaction sequence proceeded smoothly with quantitative conversion of reactants into product. The reaction pathway was supported by isolation of N,N′-diphenyl-1,2-diaryl-1,2-diamino ethane and its conversion into product by reaction with α,β-unsaturated ketone under similar reaction conditions.

Ionic liquid promoted spiroannulation via hetero-Michael addition and intramolecular heterocyclisation

A sequential efficient method for the synthesis of novel spiro-5-thiazolidin-2-one-indolo[1,5]benzothiazepine from readily available isatin, 4-thioxothiazolidin-2-one and 2-aminothiophenol is reported. The synthesis involves formation of N-methyl-3-(2-oxo-4-thioxothiazolidinon-5-ylidene)-1,3-dihydro indol-2-one by [bmIm]OH promoted Knoevenagel condensation of 4-thioxo-2-thiazolidinone with isatin. The Knoevenagel product on ionic liquid promoted thia-Michael addition with 2-aminothiophenol and intramolecular cyclocondensation yielded the title compounds with high atom economy. The ionic liquid, [bmIm]OH was recovered completely and recycled thrice for the synthesis with no appreciable decrease in the efficiency of the process. The whole sequence of reactions proceeded with quantitative transformation of reactants into spiro [1,5]benzothiazepine at ambient temperature. The sequential reaction pathway is supported by the isolation of the thia-Michael adduct of the knoevenagel product with 2-aminothiophenol and quantitative conversion of the adduct into the final products under the same reaction conditions.

Diastereoselective synthesis of furopyranopyridine in ionic liquid/water without additional catalyst

3,5-Diarylidene-1-methyl-piperidin-4-one derived in situ from N-methylpiperidinone and benzaldehyde undergoes intermolecular [4 + 2] hetero-Diels–Alder reactions with 2,3-dihydrofuran in [bmim]BF4–H2O (1 : 1) to afford furopyranopyridine derivatives in high to quantitative yields. Heterodienes, 3,5-diaryldiene-1-methylpiperidin-4-one an electron deficient oxadiene added to 2,3-dihydrofuran an electron rich dienophile because of an inverse electron demand, yielding furopyranopyridines with a high atom economy.

[bmim]OH promoted hydroalkynylation of nitrile and intramolecular hydroamination of the carbon–carbon multiple bond: an efficient and eco-compatible strategy for the synthesis of indolizinones

An efficient and novel hydroalkynylation of 2-cyanopyridine with arylacetylene and a subsequent intramolecular hydroamination promoted by a basic ionic-liquid, [bmim]OH, under microwave activation in the absence of an organic solvent and an inorganic base, yielding biodynamic indolizinones has been developed. The protocol involves [bmim]OH mediated in situ generation and addition of a nucleophilic alkynide from the aryl substituted terminal on a carbon alkyne of a polar nitrile group of 2-cyanopyridine. This results in the formation of a 2-pyridylphenylethynyl methimine intermediate which, on subsquent intramolecular nucleophilic addition of a pyridyl nitrogen on the carbon–carbon triple bond of the imine intermediate, heterocyclized into indolizinone with high atom economy. The reaction proceeded smoothly and quantitatively at an ambient temperature. The task specific [bmim]OH was recovered and reused three times without any appreciable decrease in its activity and product yield.

MoO2Cl2(DMF)2 catalyzed microwave assisted reductive cyclisation of nitroaromatics into dibenzodiazepines

The paper describes a gentle and highly efficient protocol for the synthesis of dibenzodiazepines by reductive cyclisation of nitroaniline to dibenzodiazepines under microwave irradiation catalyzed by MoO2Cl2(DMF)2 involving Ph3P as reducing agent. This synergic approach results in the transformation of nitroaromatics into dibenzodiazepines in high yield and is applicable to the construction of a wide variety of dibenzo(di/ox)azepines and other structurally related heterocycles.

Domino Reaction Involving (Diacetoxyiodo)Benzene- Promoted Oxidative Rearrangement: A Novel Multicomponent and Efficient Strategy for the Synthesis of Thiadiazole N-Nucleosides

An efficient one-pot three-component synthesis of thiadiazole N-nucleosides with high atom economy from β-D-ribosylhydrazine, aryl thiamide, and aromatic aldehyde promoted by (diacetoxyiodo)benzene under microwave irradiation is reported. The strategy involves formation of thiourea derivatives by microwave-assisted addition of an arylisothiocyanate formed in situ by (diacetoxyiodo)benzene-promoted oxidative rearrangement of an aryl thiamide with Schiff bases of β-D-ribosylhydrazine and a substituted/unsubstituted aromatic aldehyde. The thiourea intermediate on intramolecular heterocyclization yielded thiadiazole N-nucleosides, 2-(arylimino)-3-(β-D-ribosyl)-5-aryl-1,3,4-thiadiazoles. The whole reaction sequence proceeded with quantitative transformation of reactants into thiadiazole N-nucleosides at an ambient temperature. The reaction sequence is supported by isolation of Schiff bases and their quantitative conversion into final product by reaction with arylisothiocyanate under the same reaction conditions.