Tert.-Butylurea

Iron(II) complex of tris(N -tert-butylurea-ylato)-N-ethylene]aminato activates dioxygen at room temperature to afford an iron(III) complex containing a single terminal oxo ligand. X-ray structures show that the three urea molecules act as a tridentate N,N,N-hgand [52]. The tripodal ligand was also used to synthesise complexes of cobalt, iron or zinc with terminal hydroxo ligands (Scheme 8) [53]. 

The electrochemistry of diazirines and diaziridines was discussed in Part I.1 Di-tert-butyldiaziridone (178) can be reduced in aprotic media in an irreversible two-electron reduction.275 Whereas diaziridines require acidic conditions for the splitting of the N—N bond and are electrochemically inert toward reduction in alkaline solutions, 178 is reduced in aprotic media to di-tert-butylurea [Eq. (108)]. 

This step may be omitted if a practical grade of tert.-butylurea is purchased from the Eastman Kodak Company. Since the commercial product may contain sodium sulfate and di-teri.-butylurea it should be recrystallized from hot water, about 1 1. of solvent being used for 100 g. of the urea. 

A-tert-Butylphthalimide is obtained in 75% yield by heating tert-butylurea for 15 min at about 220° with somehat more than twice the molar amount of phthalic anhydride.740... 

B. tert.-Butylphthalimide. Thirty-five grams (0.3 mole) of terL-butylurea and 100 g. (0.675 mole) of phthalic anhydride are ground together in a mortar. The mixture is placed in a Tl. Erlenmeyer flask which is then immersed in a metal bath previously heated to 200°. The mixture melts and effervesces vigorously after 10 minutes the temperature of the bath is... 

Di-tert-butyldiaziridinone in pentane added all at once under Ng to a soln. of rerr-butyllithium as hydrogen atom transfer agent in the same solvent N,N -di-ter -butylurea. Y 95%. - Electron transfer by electrodiemical means or by Na-naphthalenide also effects reduction of the N-N-bond, whereas hydride transfer agents such as NaBH4 effect reduction of the C-N-bond. F. e. by Na-naphthalenide reduction s. A. J. Fry, F. D. Greene et al., J. Org. Chem. 38, 2620 (1973). 

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