Chiral HPLC Separation and Absolute Configuration of Novel S-DABO Derivatives

Chiral 2-(sec-butylthio)-6-[1-(2,6-dichlorophenyl)propyl]-5-methylpyrimidin-4(3H)-one (compound 1) was synthesized to serve as a model compound for structural elucidation of novel S-DABO (dihydroalkoxybenzyloxopyrimidine) derivatives endowed with potential HIV-1 reverse transcriptase inhibitory activity. Stereochemical characterization of four stereoisomers of 1 was achieved by an experimental approach based on the following steps: (a) direct HPLC enantio- and diastereoseparation at semi-preparative scale; (b) determination of elution order of stereomeric mixture by using chiroptical detection (polarimeter or circular dichroism (CD)); (c) X-ray crystallography of two diastereoisomers isolated at semipreparative scale. The CD analysis of 1 and its two analogues (compounds 2 and 3), both having a single stereogenic center located in two different alkyl side chains of the dihydropyrimidinone structure, was carried out. The results of this study indicated a correlation between the absolute configuration at C-1 of alkyl side chain of the dihydropyrimidinone structure and the sign of the CD band at around 245 nm. Chirality 21:604-612, 2009. (C) 2008 Wiley-Liss, Inc.