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The First 1,10-Diaza[2.2]metacyclophanes – Strained Medium Membered Heterocycles⋆

1998; Wiley; Volume: 1998; Issue: 7 Linguagem: Inglês

10.1002/(sici)1099-0690(199807)1998

1434-193X

Mathias Habel, Christoph Niederalt, Stefan Grimme, Martin Nieger, Fritz Vögtle,

Chemical Reaction Mechanisms

The N-protected 1,10-diaza[2.2]metacyclo- and 1,10-diaza-[2]metacyclo[2](2,6)-pyridinophanes 4 and 5 have been synthesized for the first time using high dilution conditions. The free secondary diamine 7 was obtained from 4 by alkaline hydrolysis. – Quantum chemical calculations support the hypothesis that 7 is one of the most strained anti-hetera[2.2]metacyclophanes known. This is also evident from the 1H-NMR spectrum of 7, which shows one of the strongest high field shifts for the intraannular protons in comparison to other anti-[2.2]metacyclophanes.