Disodium Phenanthrenide

[84810-06-0]  · C14H10Na2  · Disodium Phenanthrenide  · (MW 224.22)

(organohalide reducing agent)

Preparative Method: prepared in situ by reaction of parent hydrocarbon with Sodium in dimethyl ether.1

The first reference to the use of the disodio derivative of phenanthrene is a fleeting comment on the similarity of the parent hydrocarbon to naphthalene in the presence of sodium metal in dimethyl ether.1 This tantalizing reference was exploited by Vogel et al. in the first efficient synthesis of bicyclo[4.2.0]octa-2,4,7-triene (1) (eq 1).2 Disodium phenanthrenide was found to be superior to the previously examined methods for preparation of this elusive cyclooctatetraene tautomer.3

The main employment of sodium phenanthrenide has been in the preparation of exotic hydrocarbons such as that shown above. For instance, this reductive dehalogenating reagent was used in preparation of hemi-Dewar naphthalene, benzobicyclo[2.2.0]hexa-2,5-diene (2) (eq 2). Sodium phenanthrenide was the only reagent able to carry out the reduction used to prepare this sensitive substrate.3,4

Finally, 5 mol equiv of disodium phenanthrenide reductively dechlorinates tetrachloride (3) to give functionalized Dewar benzene (4) (eq 3).5

1. Scott, N. D.; Walker, J. F.; Hansley, V. L. JACS 1936, 58, 2442.
2. Vogel, E.; Kiefer, H.; Roth, W. R. AG(E) 1964, 3, 442.
3. Benson, R. E.; Cairns, T. L. JACS 1950, 72, 5355.
4. McDonald, R. N.; Frickey, D. G. JACS 1968, 90, 5315.
5. McDonald, R. N.; Frickey, D. G.; Muschik, G. M. JOC 1972, 37, 1304.

Joseph Sweeney

University of Bristol, UK

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