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Paper | Regular issue | Vol 57, No. 6, 2002, pp.1003-1016
Published online, 1st January, 1970
DOI: 10.3987/COM-01-9423
First Rotameric Anti Dimers and 3,9-Diazatetraasteranes from Unsymmetrically Substituted N-Acyl and N-Acyloxy-4-aryl-1,4-dihydropyridines

Andreas Hilgeroth,* Frank W. Heinemann, and Ute Baumeister

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

Abstract

A series of unsymmetrically substituted N-acyl- and N-acyloxy-1,4-dihydropyridines (1) have been photochemically investigated. On irradiating the crystals of one derivative (1a) containing centrosymmetrical pairs of molecules with a distance of 3.894(3) Å between the potentially reacting double bonds favorable for a photodimerisation reaction, the formation of an anti-dimer (2a) was observed. Two other solid derivatives (1b, c) merely decomposed on irradiation to give substituted pyridine compound (3). Solution irradiation of 1,4-dihydropyridines (1) led to the centrosymmetric cage compounds 3,9-diazatetraasteranes (4) and to anti dimers (2) as main products, both existing as rotamers. Symmetric as well as rotameric properties of selected compounds (4) have been demonstrated by X-Ray crystal structure analysis and 1H NMR spectroscopy.