At face value the evidence from the above synthesis
appears almost conclusive. However, on further study
of Nenitzescu's publication (3), it seems probable that the
cyclodehydration of the tertiary alcohol (XVII) does not give
a homogeneous product. Further support for this view comes
from the work of Evans and Smith (11) who have reported the
disproportionation of a tetrahydro-10,11-benzfluoranthene (XIX)
in the presence of polyphosphoric acid. They treated
a -tetralone at 1700 with polyphosphoric acid and isolated
10,11- benzfluoranthene and the hydrocarbon of Dansi and
Ferri (A) as products.
The ketone ( XVIII) originally produced reacts in
its enol form to give a tetrahydro -10,11 -benzfluoranthene
(XIX), which then disproportionates into the octahydro10,11- benzfluoranthene (A), and 10,11- benzfluoranthene
(II). From the results of this work, the possibility
of disproportionation during Nenitzescu's cyclodehydration
reaction cannot be ruled out entirely.
One further factor which Nenitzescu did not consider
concerns the stereochemistry of the hydrogen atoms at
positions 9 and 14 in the molecule. Each of the substances
A and B should be capable of existing in two forms depending
on the configuration of these two hydrogen atoms. Since
Nenitzescu's synthesis involves the interaction of two
reduced naphthalene moieties, it would neither preclude
the formation of nor engender a particular configuration of
these hydrogen atoms.
Further study of the structure of A therefore appeared
worthwhile, and an unambiguous synthesis of A by classical
organic techniques is described in the sequel. This
synthesis also provides information about the configuration
of the hydrogen atoms 011 carbon atoms 9 and 14.