DABCO-based chiral ionic liquids as recoverable and reusable organocatalyst for asymmetric Diels-Alder reaction.

New DABCO-based chiral ionic liquids were synthesized and evaluated in asymmetric Diels-Alder reaction of cyclopentadiene with α,ß-unsaturated aldehydes or 4-phenyl-3-buten-2-one. Chiral ionic liquid of modified MacMillan catalyst having a DABCO cation and hexafluorophosphate anion acts as organocatalyst (5 mol%) for the Diels-Alder reaction of crotonaldehyde and cyclopentadiene producing 98% of the product and 87% ee (endo) in CH3 CN/H2 O (95/5) at 25°C in 2 h. The scope and limitations of the catalysis were also studied by using cyclopentadiene and α,ß-unsaturated aldehydes, and the Diels-Alder products were obtained in 18%-92% yields with 68%-93% ee. The catalyst was recycled and reused up to 6 cycles with a slight drop in ee and conversion of the product.

Chiral Imidazolidin-4-one with catalytic amount of Dicationic ionic liquid act as a recoverable and reusable Organocatalyst for asymmetric Diels-Alder reaction.

Imidazolidin-4-one is used as a recoverable organocatalyst for the asymmetric Diels-Alder reaction in the presence of catalytic amount of dicationic ionic liquid and trifluoroacetic acid as a co-catalyst. The Diels-Alder reaction between model substrate cyclopentadiene and crotonaldehyde gave the product in 95% conversion and 87% ee of the endo-product. The catalyst was shown better reusability when the 20 mol% of dicationic ionic liquid was used and catalyst was reused upto 5 cycles, conversion remains upto 3 recycles but ee of endo-9 was slightly droped.

A simple protocol for determination of enantiopurity of amines using BINOL derivatives as chiral solvating agents via 1H- and 19F-NMR spectroscopic analysis.

A rapid and simple protocol for the determination of enantiopurity of primary and secondary amines was developed by using (S)-BINOL/(S)-BINOL derivatives/(R)-1,1'-binaphthyl-2,2'-diyl hydrogenphosphate as chiral solvating agents via 1H- and 19F-NMR spectroscopic analysis. In this protocol, the analyte and chiral solvating agent were directly mixed in an NMR tube in chloroform-d and after shaking for 30 seconds the 1H- and 19F-NMR spectra were recorded, which affords well-resolved resonance peaks for both the enantiomers present in an analyte. The enantiomeric excess of 1,2-diphenylethylenediamine was determined and linear relationship with coefficient of R 2 = 0.9995 was observed. The binding constant and associated ΔG values were also calculated for diastereomeric complexes formed between both the enantiomers of analyte 5 with CSA (S)-3a by using UV-visible spectroscopy.