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.