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Paper | Regular issue | Vol 51, No. 10, 1999, pp.2367-2376
Published online, 1st January, 1970
DOI: 10.3987/COM-99-8627
Rotameric Properties of Novel N-Acyl and N-Acyloxy Dimeric 4-Phenyl-1,4-dihydropyridines Derived from Developed Solid-State Synthesis

Andreas Hilgeroth,* Ute Baumeister, and Frank Heinemann

*Institute of Pharmaceutical Chemistry, Department of Pharmacy, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany

Abstract

Novel N-acyl and N-acyloxy dimeric 4-phenyl-1,4-dihydropyridines are given by solid-state photodimerization of their monomeric educts in excellent yields. The existence of rotamers was demonstrated by 1H NMR spectroscopical measurement at certain temperatures and additionally supported by X-Ray crystal structure analysis of centrosymmetrical cage-dimeric N-acetyl-3,5-dimethoxycarbonyl-4-phenyl-1,4-dihydropyridine (3b). Topochemical investigations 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 controlled by the nearest distance of potentially reacting double bonds with 3.667(3) Å.