Selective Oxidation of Heterocyclic Amines

ABSTRACT: The ability to oxidize organic functional groups in a selective manner is of major importance in preparing compounds of interest to the Air Force and DoD. This is particularly critical in the preparation of high energy density compounds and fuels. Heterocyclic ring systems that contain both nitro and amino groups have been found to be an important class of compounds that are useful in these applications. Their synthesis by oxidation of the corresponding polyamino systems would be particularly advantageous in terms of cost, ease of preparation and handling, and safety. The USAF is primarily interested in conversion of 4,4"-azobis(3-aminofurazan) to 4-[(4-nitro-furazan-3-yl)azo]-furazan-3-amine. Unfortunately, the only practical large scale synthesis of this compound makes it necessary to produce 3,3"-azobis(4-nitrofurazan) first, which is friction sensitive. The safety of this process could be greatly improved by avoiding this intermediate. Infoscitex Corporation and University of Massachusetts at Lowell developed a concept and laid out biocatalytic route to selectively oxidize only one amino-group of the insensitive diamine, 4,4"-azobis(3-aminofurazan). Thus, 4,4"-azobis(3-aminofurazan) will be converted directly into to 4-[(4-nitro-furazan-3-yl)azo]-furazan-3-amine. This oxidation will open new molecular design space for the synthesis of asymmetric amino-nitro-heterocycles and will create low-cost access to new energetic and/or pharmaceutical ingredients. BENEFIT: The proposed biocatalytic oxidation reaction is anticipated to be a viable production process to manufacture 4,4"-azobis(3-aminofurazan) safely and affordably. In addition to production of energetic materials the oxidation process may be useful in the field of pharmaceuticals.