Here, we report a simple, efficient, and green protocol for the one-pot synthesis of pyrano[2,3-c]pyrazole derivatives via a sequential three-component strategy using aromatic aldehydes, malononitrile and pyrazolinone in a water–SDS–IL system.
Chiral self‐sorting during the formation of cage‐like molecules continues to fascinate and advance our understanding of the phenomenon in general. Herein, we report the chiral self‐sorting in the Pd6L12‐type metal‐organic cages. When a racemic mixture of axially chiral bis‐pyridyl ligands undergo coordination‐driven self‐assembly with Pd(II) ions to form Pd6L12‐type cages, the system has the option of chiral self‐sorting to afford any of at least 70 pairs of (one homochiral and 69 heterochiral) enantiomers and 5 meso isomers or a statistical mixture of everything. However, the system resulted in diastereoselective self‐assembly through a high‐fidelity chiral social self‐sorting to form a racemic mixture of D3 symmetric heterochiral [Pd6(L6R/6S)12]12+/[Pd6(L6S/6R)12]12+ cages.
The origin of chiral self‐sorting in the building blocks of life remains a fundamental question. Chiral self‐sorting in the formation of supramolecular cages expands our understanding of the phenomenon in general. It controls the choice of the selective chiral isomer against numerous possible mixtures. This work reports chiral social self‐sorting in the diastereoselective self‐assembly of Pd6L12 metal‐organic cages with a racemic mixture of axially chiral bis‐pyridyl ligand with Pd(II) ions. More information can be found in the Research Article by Ramalingam Natarajan et al.
This paper introduces a base and catalyst‐free “on water” protocol for the “Green” access to a series of privileged, potential biologically active important synthetic targets coumarin‐3‐carboxylic acids of diverse structures bearing electron withdrawing/donating groups, hydrophobic long chain alkyl groups in aromatic ring. The target compounds were synthesized by reacting substituted o‐hydroxy‐aryldehydes with Meldrum's acid in the water ‐ SDS micellar system. Water‐SDS is a proven, yet powerful surfactant system to provide hydrophobic cavities in water as a reactor for the organic reactants. It is believed that the condensation occurs inside the hydrophobic cavity which helps the completion of the reaction. Multi‐gram scale reaction was also performed to demonstrate the scalability and practical applicability of the developed methodology. Moreover, the reusability of the post‐reaction waste shows that the waste can be reused in consecutive cycles without compromising the yield. The structure of one of the synthesized compounds was further confirmed by single‐crystal XRD studies. This developed protocol promises advantages like energy efficiency, operational simplicity, easy workup, chromatography‐free purification, recyclability of post‐reaction waste, scalable method and provides excellent yields of the targeted coumarin ‐3‐carboxylic acids.
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