Rotameric properties of novel N-acyl and N-acyloxy dimeric 4-phenyl-1,4-dihydropridines derived from developed solid-state synthesis

Novel N-acyl and N-acyloxy dimeric 4-phenyl-1,4-dihydropyridines are given by solid-state photodimerization of their monomeric educts in excellent yie lds. The existence of rotamers was demonstrated by H-1 NMR spectroscopical measurement at certain temperatures and additionally supported by X-Ray cry stal structure analysis of centrosymmetrical cage-dimeric N-acetyl-3,5-dime thoxycarbonyl-4-phenyl-1,4-dihydropyridine (3b). Topochemical investigation s by X-Ray crystal structure analysis prove the formation of anti-dimeric N -Boc-3,5-dimethoxycarbonyl-4-phenyl-1,4-dihydropyridine (4e) to be controll ed by the nearest distance of potentially reacting double bonds with 3.667( 3) Angstrom.