A hydrazine- and phosgene-free synthesis of tetrazinanones, precursors to 1,5-dialkyl-6-oxoverdazyl radicals.
A complementary approach to published synthetic methods for tetrazinanones, precursors to verdazyl radicals, is described herein. This approach uses carbohydrazide, a commercially available reagent, as a common starting material. Unlike previous methods described in the literature, this synthetic scheme does not rely on phosgene, phosgene substitutes, or the limited pool of commercially available monosubstituted hydrazines for its execution. A large variety of alkyl substitution patterns at the N-1 and N-5 positions of verdazyl radicals are possible, including both symmetrically and unsymmetrically substituted products. An initial condensation reaction of carbohydrazide with a specific aldehyde introduces the desired C-3 substituent in the final verdazyl radical product and protects the NH(2) groups during the subsequent N-1 and N-5 alkylation reactions. A succeeding methanolysis and concomitant ring-closing reaction gives the tetrazinanone. A number of known oxidation methods can then be employed to form the final verdazyl radical product.
Department of Chemical and Physical Sciences, University of Toronto at Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada, L5L 1C6.
Matthew
M
Bancerz
Beom
B
Youn
Matthew V
MV
DaCosta
Michael K
MK
Georges
D005609:Free Radicals / Q000138:chemical synthesis / Q000737:chemistry; D006834:Hydrazines / Q000737:chemistry*; D015394:Molecular Structure; D010705:Phosgene / Q000737:chemistry; D013777:Tetrazoles / Q000138:chemical synthesis* / Q000737:chemistry
D005609:Free Radicals; D006834:Hydrazines; D013777:Tetrazoles; D010705:Phosgene; C029424:hydrazine; C019289:carbohydrazide