SYNTHESIS OF THE 4-PYRIDINE ANALOG OF KOSTANECKI TRIKETONE - DETERMINATION OF CONSTITUTION AND STEREOCHEMISTRY BY 2D-NMR SPECTROSCOPY AND X-RAY STRUCTURAL-ANALYSIS

4-Acetylpyridine reacts stereoselectively with benzaldehyde under basic conditions to afford rac-1. The constitution of 1 was determined by the long-range connectivities revealed by the H,C-COLOC spectrum. The relative stereochemistry of the chiral centers C-2 to C-6 was obtained from 3J(HH) couplings. The stereochemistry at the non-proton bearing C-1 was established by through-space connectivities from ROESY and semiquantitative analysis of 3j(CH) from an inverse 2D-NMR spectrum (HMBC). The NMR findings were confirmed by single crystal X-ray diffraction.