Conference paper

Cyclobutene-Fused Aromatic Molecules

R. P. Thummel ; Department of Chemistry, University of Houston, Houston, Texas 77004 U .S.A.

Abstract

The Diels-Alder cycloaddition of dimethyl-1,2-cyclobutenedicarboxylate
to a 1,3-diene results in the formation of an adduct
which can subsequently be decarboxylated and dehydrogenated
to provide a cyclobutene-fused benzenoid system. The use of ·
appropriate dienes has led to the preparation of a series of paraand
meta- bis-annelated benzenes. Variations i n the 1H and 1 3 C
NMR and in the UV spectra are found to be a func tion of the size
of the annelated rings as well as their relative orientation.
A similar approach has been employed in a preparation of the
very elusive tricyclobutabenzene which may r e present the missing
link between 1,5,9-cyclododecatriyne and 6-radialene. Tricyclobutabenzene
is a stable crystalline material (mp 141-142 °C) whose
physical properties are quite consistent with higher homologs. An
X-ray structure of its perfluoro analog shows no e vidence for any
bond alternation.
A double-barreled application of the Diels-Alder approach has
led to the synthesis of naphtho[b,e]dicyclobutene. The physical
properties of this molecule are also compared t o higher homologs.

Keywords

Hrčak ID:

194489

URI

https://hrcak.srce.hr/194489

Publication date:

25.1.1981.

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