Determination of the Chemical Structure of novel colored 1H‐pyrrol‐3(2H)‐one derivatives formed by Maillard‐type reactions

Abstract

The determination of the chemical structure of a previously unknown Maillard reaction product with an amino acid incorporated in a four-ring structure is reported. The red compounds 1a and 1b, isolated from a thermally treated aqueous solution of furan-2-carbaldehyde and L-alanine, were identified as (S)-4{(E)-1-formyl -2-(2-furyl)ethenyl}-5-(2-furyl)-2-{(E)-(2-furyl)methylidene}-2, 3-dihydro-α-methyl-3-oxo-1H-pyrrole-1-acetic acid and its 2-{(Z)-(2-furyl)methylidene}isomer, respectively, by several 1D- and 2D-NMR techniques, MS, UV, and IR spectroscopy as well as by synthetic experiments. 2D-NOESY and 2D-ROESY experiments performed for conformation analysis indicated the existence of two atropisomers.