BIRCH REDUCTION OF (2.2)METACYCLOPHANE

Metal‐ammonia‐reduction of [2.2] metacyclophan led to 5, 8, 13, 16‐tetrahydro‐[2.2] metacyclophan (II). The structure of this new ring system was confirmed by UV.‐, NMR.‐and mass spectra analyses. The NMR.‐spectrum of II in solution shows an AA′ BB′‐system for the ‐CH2CH2‐groups. This part of the spectrum is temperature dependant. It collapses and coalesces to a broad singlet at approximately 145°C. A chair‐like conformation and conformational changes of II are discussed. Copyright © 1969 Verlag GmbH & Co. KGaA, Weinheim