Publikation

P. Wessig, M. Czarnecki, D. Badetko, U. Schilde, A. Kelling
Photochemical Synthesis of Both Strained and Macrocyclic (1,7)Naphthalenophanes
J. Org. Chem. 2016, 81, 9147
DOI: 10.1021/acs.joc.6b01707
Naphthalenophanes are a special type of cyclophanes. While in the past (1,5), (1,6) and (1,8)Naphthaleno-phanes were successfully prepared by using the (Photo)-Dehydro-Diels-Alder (DDA) reaction, the access to (1,7)Naphthalenophanes by this method was hitherto unknown. After numerous unsuccessful attempts to prepare these compounds by thermal DDA, we found that the photoinitiated variant (PDDA) represents a very efficient method to [k](1,7)Naphthalenophanes 13. The scope ranged from highly strained (k = 11, 12) to macrocyclic products (k = 22, 24). The extraordinary reactivity could be explained by folded ground state geometries of diketones 12 used as reactants of the PDDA. Furthermore, we calculated the ring strain energies with the help of an isodesmic reaction and evaluated structural and spectroscopic (NMR) consequences of ring strain.
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