Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
1994-04-14
2001-04-24
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
Reexamination Certificate
active
06222068
ABSTRACT:
FIELD OF USE
This invention describes the direct functionalization of nitrocubanes via irradiation in the presence of an oxalyl halide.
BACKGROUND OF THE INVENTION
Considerable effort in recent years has been directed toward the synthesis of polynitrocubanes because of the potential use of this class of energetic materials as explosives, propellants, fuels and binders (Chemistry of Energetic Materials; Ed., G. A. Olah; D. R. Squire; Academic Press, Inc., San Diego, Calif., 1991. Also see Carbocyclic Cage Compounds; Ed., E. J. Osawa; O. Yonemitsu; VCH Publishers, Inc., New York, N.Y., 1992). The compact structures of cage molecules result in high densities, and the introduction of NO
2
groups further enhances the density. The strain energy present in the cubane skeleton (>166 kcal/mol) is an added bonus to its performance. Furthermore, preliminary results with polynitrocubanes indicate that such compounds are thermally very stable and are also very insensitive energetic materials. Consequently, it is of interest to introduce functional groups on the cubane skeleton which can be converted to nitro group or other active functionalities.
Direct functionaliztion of nitrocubanes, while an attractive approach, has not heretofore been realized. Cationic or anionic reactions, due to the activity of the nitro groups give either decomposed products or recovered starting materials. We report here an efficient direct functionalization of a nitrocubane molecule by its irradiation in a solution of oxalyl halide (for a related case see Wiberg, K. B.; 10
th
Annual Working Group Meeting, Jun. 3-6, 1992, Kiamesha Lake, N.Y. For much simpler cases see Wiberg, K. B.; Williams, Jr., V. Z.; J. Org. Chem., 1970, 35, 369; Applequist, D. E.; Saski, T.; J. Org. Chem.; 1978, 43, 2399). This new and potentially powerful synthetic development will greatly shorten the number of steps necessary to obtain nitrocubane derivatives which are otherwise difficult to synthesize.
SUMMARY OF THE INVENTION
A solution of 1,4-dinitrocubane (Eaton, P. E.; et al; J. Org. Chem.; 1984, 49, 185; Eaton, P. E.; Wicks, G. E.; J. Org. Chem.; 1988, 53, 5353) in oxalyl chloride was irradiated under a sunlamp for 12 h at room temperature. After removing oxalyl chloride under reduced pressure, the reaction mixture was hydrolyzed and partioned between ethyl acetate and 5% aqueous NaOH. From the organic phase was isolated 2-chloro-1,4-dinitrocubane, 3, and 2,5-dichloro-1,4-dinitrocubane, 4. After acidification of the alkaline layer with HCl and extraction with ethyl acetate, 2-carboxy-1,4-dinitrocubane, 5, was obtained in 68% yield.
The structures of 3, 4, and 5 were confirmed by NMR spectrometry. Furthermore, Compound 5 was converted to the corresponding 2-carbomethoxy-1,4-dinitrocubane 6 by esterification using MeOH, and the molecular structure of 6 was confirmed by X-ray crystallographic analysis.
REFERENCES:
patent: 3418368 (1968-12-01), Dunn
patent: 3517055 (1970-06-01), Loeffler
patent: 3558704 (1971-01-01), Gregory
Moran John F.
Shippen Michael L.
The United States of America as represented by the Secretary of
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