Structural insight into the aggregation of L-prolyl dipeptides and its effect on organocatalytic performance.
NMR and organocatalytic studies of four dipeptides derived from L-proline are described. Results indicate that important conformational changes around the catalytic L-proline moiety are observed for free dipeptides upon changing the adjacent amino acid. Also, an aggregation process is detected as the concentration increases. The self-association of the dipeptides has been fitted to a cooperative binding model. All the compounds have been assayed as catalysts for the conjugated addition of cyclohexanone to trans-β-nitrostyrene in toluene. In agreement with the structural studies, noticeable changes in the catalytic performance are detected upon changing the catalyst concentration, as the catalyst is activated by self-aggregation.
Departament de Química Inorgànica i Orgànica, Universitat Jaume I, Avda. SosBaynat s/n, Castelló, 12071, Spain. miravet@uji.es escuder@uji.es.
Cristina
C
Berdugo
Beatriu
B
Escuder
Juan F
JF
Miravet
D002384:Catalysis; D004151:Dipeptides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009930:Organic Chemicals / Q000737:chemistry*; D011392:Proline / Q000737:chemistry*; D011487:Protein Conformation; D021241:Spectrometry, Mass, Electrospray Ionization
D004151:Dipeptides; D009930:Organic Chemicals; D011392:Proline