Diaziridines basicity

On the basis of IR data the basicity of some diaziridines was discussed. The basicity of the spirodiaziridines (36) increased on alkylation of one nitrogen from pAT = 4.6 (R = H) to pK = 6.4 (R = Bu"). pK values of diaziridines alkylated on both nitrogens were always below 5.0 (69IZV1847). 

The action of strong reducing agents on diazirines leads to basic products. Diaziridines can be detected as intermediates in the reaction. The reduction of 3,3-diethyldiazirine to 3,3-diethyldiaziridine [Eq. (61)1 serves as a proof of structure of the diazirines. 

The protonated diaziridine (138) is more easily reducible than the diazirine which is too weakly basic to be protonated in aqueous solution. In alkali, where both are unprotonated, the diazirine is the... 

The simple 1,2,3,4-tetrahydro-5//-2,3-benzodiazepine (47) and 3,4-dihydro-5//-2,3-benzodiazepine (48) have been prepared.30 Thermal decomposition of 49 yielded the dihydro compound (48) which was catalytically reduced to 47. Compound 47 was also obtained by basic cleavage of the diazepine (50), which was prepared by reaction of phthaloyl hydrazide and o-chloromethyl-2-phenylethyl chloride.39 Compound 49 was prepared from the diaziridine (51, R = H) which together with 51 (R = CH3)40,41 can be considered as bridged 1,2-... 

The protonated diaziridine is more easily reducible than the diazirine, which has too weakly basic properties to be protonated in aqueous solution. In alkaline medium in which both are unprotonated, the diazirine is the more easily reducible. This explains why it has been difficult to obtain good yields of diaziridine by chemical and catalytic reduction of a diazirine if such a reduction is to result in a high yield of diaziridine, it must be performed in an alkaline medium. 

It was observed that the last reaction works only when basic impurities are trapped by some added acetic acid or carbon dioxide. Later this stabilization of oxaziridine solutions by carbon dioxide was claimed in a patent. The amination occurs intramolecularly when the oxaziridine 40, formed from 34 and dimethylol urea, is treated with strong alkali. This amination gives rise to the parent compound of the diaziridines. ... 

Smooth diaziridine formation even in the presence of additional functional groups in the starting ketone, allowed many individual diaziridines to be made for pharmacological testing. More than fifty compounds of types 92 and 93 with the basic piperidone and tropine structures, were synthesized. ... 

Diaziridines are crystalline, weakly basic compounds. As already explained in connection with oxaziridines (see p 33), the N-atoms are configurationally stable so that stereoisomerism is possible. 

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