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Molecules 2007, 12(2), 173-182; doi:10.3390/12020173
Article

Synthesis, NMR and Crystallographic Studies of 2-Substituted Dihydroquinazolinones Derived from (S)-Phenylethylamine

1,* , 1, 1, 1 and 2,*
Received: 5 December 2006 / Revised: 2 February 2007 / Accepted: 5 February 2007 / Published: 12 February 2007
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Abstract

2,3-Dihydro-3-[(S)-1-phenethyl]quinazolinone and some new 2-substitutedderivatives bearing isopropyl, o-nitrophenyl and p-nitrophenyl groups were prepared in40-90% yield by amidation of isatoic anhydride with (S)-phenylethylamine, followed bycondensation with triethyl orthoformate, isopropylaldehyde, o-nitro- and p-nitro-benzaldehyde, respectively. The two 2-subtituted dihydroquinazolinones obtained eitherby using isopropylaldehyde, o-nitro- or p-nitrobenzaldehyde, were separated and purifiedbefore their NMR spectra in CDCl3 solutions were recorded. The detection of the lowenergy conformation of O=C-N-phenethyl segment in solution allowed the correlation ofthe NMR data with the configuration of newly stereogenic carbon C-2; thus, onediastereomer was labeled SS while the other was RS. Configurations determined by theNMR method were corroborated by X-ray diffraction analysis. X-ray structures of eachdiastereomeric series showed characteristic conformational types: a propeller-like for theSS and a hairpin for the RS series. Interatomic distances of the hairpin conformationsuggest the existence of intramolecular face-to-face interactions between two aromaticrings.
Keywords: Chiral dihydroquinazolinones; π-stacking interactions; NMR method; configurational analysis. Chiral dihydroquinazolinones; π-stacking interactions; NMR method; configurational analysis.
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Escalante, J.; Ortíz-Nava, C.; Flores, P.; Priego, J.M.; García-Martínez, C. Synthesis, NMR and Crystallographic Studies of 2-Substituted Dihydroquinazolinones Derived from (S)-Phenylethylamine. Molecules 2007, 12, 173-182.

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