Search

This study details the characterization of a novel and an unexpected cyclization reduction product of Calophyllolide (I), by using sodium borohydride. The structure of the derivative (II) was established as 6,10,11-tetramethyl-4-phenyl-6, 10-dihydro-2H-dipyrano [2, 3-f: 2′, 3′-h] chromen-2-one by 2D NMR experiments such as 1H-1H gCOSY, gHSQC, gHMBC, and LC-MS/MS along with 1H and 13C NMR spectra. A reversed-phase HPLC method and a chiral HPLC method were developed to evaluate the purity and chirality. A reaction mechanism for II was proposed. The synthesized compound was showing significant antimicrobial activity than the parent compound (I) when tested against various pathogenic bacteria and fungus. [ABSTRACT FROM PUBLISHER]

This account details the structural modification of Calophyllolide 1, using Ritter reaction with various nitriles to study the antimicrobial properties. Ritter reaction of calophyllolide results in a 1:1 mixture of two structurally related compounds 2 and 3. A stereogenic center was generated in the reaction products resulting in a racemic mixture. NMR mixture analysis strategy was employed for the chemical structural analysis. 2D NMR experiments such as gDQCOSY, gHSQC, gHMBC at 500 MHz, and LC-MS analysis allowed the complete assignment of 1H and 13C NMR spectra of mixture components 2 and 3. These results suggested an unusual carbon-carbon bond cleavage in the reaction product 3. Our effort highlights the NMR mixture analysis approach for characterization of mixture of compounds. An efficient and operationally simple chiral method by HPLC was developed to evaluate the enantiomer compositions. Based on the aforementioned spectral data, the compounds 2 and 3 were characterized as (E)-N-(5-methoxy-2,2-dimethyl-6-(2-methylbut-2-enoyl)-8-oxo-10-phenyl-2,8-dihydropyrano[2,3-f]chromen-4-yl)acetamide and N-(5-methoxy-2,2-dimethyl-8-oxo-10-phenyl-2,8-dihydropyrano[2,3-f]chromen-4-yl)acetamide, respectively. The possible mechanisms for these compounds formation were also proposed. [ABSTRACT FROM AUTHOR]