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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 30, Number 2
BKCSDE 30(2)
February 20, 2009 

Chirality Conversion of Dipeptides in the Schiff Bases of Binol Aldehydes with Multiple Hydrogen Bond Donors
Hyunjung Park, Jooyeon Hong, Sihyun Ham*, Raju Nandhakumar, Kwan Mook Kim*
Deracemization, Schiff base, Dipeptide, Stereoselective recognition, DFT calculation
Novel binol aldehydes derivatized at 2' hydroxy position with both uryl and acetamide groups (2), and diuryl groups (3) have been synthesized. Both were designed for streospecific binding and chirality conversion of general dipeptides with support of multiple hydrogen bonding donor sites in the receptors. The receptors, 2 and 3, converted the chirality of N-terminal amino acids of peptides such as Ala-Gly, Met-Gly, Leu-Gly and His-Gly with stereoselectivity on D-form over L-form. The stereoselectivity ratios were in the range of 5-11, somewhat higher than those of the binol receptor with mono uryl group (1). The DFT calculation at the B3LYP/6-31G*//MPWB1K/6-31G* level revealed that 3-D-Ala-Gly was 2.2 kcal/mol more stable than 3-L-Ala-Gly. The considerable steric hindrance between the methyl group of the alanine and the imine CH moiety of the receptor seems to be the main contributing factor for the thermodynamic preference.
409 - 414
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