Samuel H. Liggero

Homoadamantane. II Analysis of the NMR Spectrum of Homoadamantane

Abstract Due to a fortuitous coincidence of chemical shifts, the nmr spectra of diamondoid hydrocarbons are often exceedingly simple. At 60 MHz the spectrum of adamantane consists of superimposed bands due to the two types of protons present2 A field strength corresponding to 220 MHz3 is needed (Fig. 1A) to cleanly separate bridgehead (δ = 1.87 ppm) and methylene (1.74 ppm) signals. The three kinds of protons in diamantane have even smaller chemical shift differences, and only a single, relatively sharp peak (1.68 ppra) at 100 MHz is seen in the nmr spectrum of this molecule. 4 Noradamantane (II)5 possesses five different types of hydrogens, but even the 220 MHz spectrum (Fig. 1B) shows only three distinct bands: the two broad bridgehead singlets (2.40 and 2.10 ppm) and the multiplet near 1.6 ppm due to the three types of methylene protons. In striking contrast to this behavior, the nmr spectrum of homoadamantane (III) (Fig. 1C, 2A) is unexpectedly complex. In this communication we report the analysis of ...

The degenerate isomerization of adamantane

Treatment of specifically labelled [2-14C]adamantane with aluminium bromide in CS2 solution at 110° for 8 h leads to 78.4% of the total scrambling of carbon atoms possible on a statistical basis.

The synthesis of 2,4-dehydrohomoadamantane

2,4-Dehydrohomoadamantane (IVa)†; was prepared by the pyrolysis of the sodium salt of 4-homoadamantyl tosylhydrazone (I); hydrogenolysis of (IVa) gave homoadamantane exclusively.