Diaziridines 3- alkyl

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). 

Diaziridines also show slow nitrogen inversion, and carbon-substituted compounds can be resolved into enantiomers, which typically racemize slowly at room temperature (when Af-substituted with alkyl and/or hydrogen). For example, l-methyl-3-benzyl-3-methyl-diaziridine in tetrachloroethylene showed a half-life at 70 °C of 431 min (69AG(E)212). Preparative resolution has been done both by classical methods, using chiral partners in salts (77DOK(232)108l), and by chromatography on triacetyl cellulose (Section 5.08.2.3.1). 

In the diaziridine field many compounds are known bearing N-YL, A/-alkyl and A-acyl groups, but here no dramatic changes in reactivity are caused by A-substituents. N-Aryldiaziridines are underrepresented. The ring carbon is in the oxidation state of a carbonyl compound or, in the diaziridinones (5) and the diaziridinimines (6) that of carbonic acid. In single cases, diaziridine carbon bears chlorine or fluorine. 

Mass spectra of the same diaziridines were reported later (74JOU1140). Whereas in longer alkyl side chains of diaziridines the typical amine degradation by n -1 carbon atoms predominates, successive elimination of NH and methyl was observed in (37a). The 1-methyl compound (37b) undergoes competitive elimination of NH and MeN. 

Alkylation of diaziridines with simple alkylating agents has never been attempted, because N-alkyldiaziridines are as easily obtained by ring synthesis as the unsubstituted ones. There... 

Two substituents on two N atoms increase the number of diaziridine structures as compared with oxaziridines, while some limitations as to the nature of substituents on N and C decrease it. Favored starting materials are formaldehyde, aliphatic aldehydes and ketones, together with ammonia and simple aliphatic amines. Aromatic amines do not react. Suitable aminating agents are chloramine, N-chloroalkylamines, hydroxylamine-O-sulfonic acid and their simple alkyl derivatives, but also oxaziridines unsubstituted at nitrogen. Combination of a carbonyl compound, an amine and an aminating agent leads to the standard procedures of diaziridine synthesis. 

Here a typical property of three-membered rings wdth two hetero atoms is shown and this property is also found in the diaziridines. Only with the oxaziranes which are substituted by aryl groups in the 3-position does the hydrolysis by acids occur according to Eq. (14) with formation of an aromatic aldehyde and alkyl hydroxylamine. 

Habisch " investigated the action of chloramine on simple Schiff s bases. In the aliphatic series, diaziridine formation was observed in all the cases investigated. Ethereal solutions of chloramine react with Schiff s bases at room temperature within a few hours [Eq. (32)]. Table VI gives details of a few of the 1-alkyl-diaziridines prepared. 

A further synthesis of 1-alkyl-diaziridines is the addition of Grignard compounds to the NN double bond of diazirines [Eq. (35) ]. The... 

Diaziridines are weak bases, They can be extracted from organic solvents with aqueous mineral acids. With increasing number and chain length of alkyl substituents the solubility in aqueous mineral acids decreases. l-MethyI-2-n-butyl-3-hexyldiaziridine is soluble only in concentrated hydrochloric acid. Stable oxalates can in some cases be prepared from 1-aIkyI-diaziridines (43). The salts are stable indefinitely and by the action of alkali the diaziridines can be recovered. Diaziridines dialkylated on nitrogen (44) are hardly capable of salt... 

With aldehydes some diaziridines condense under the conditions of preparation. The formation of a fused triazolidine ring occurs regularly if aldehydes are treated with ammonia and chloramine to give diaziri-dines [Eq. (39)]. If, however, chloral is added previously to the reaction mixture, the 3-aIkyl-diaziridines (45) arc caught as their chloral adducts. By the alkali fission of these chloral adducts, 3-alkyl-diaziridines, e.g. (45), can be prepared. 

The hydrolysis of l-alkyl-2-acyldiaziridines to A -alkyl-A -acyl-hydrazines possesses preparative interest. For example, A -cyclohexyl-A" -toluenesulfonylhydrazine [Eq. (51), yield 67% ] and 1-cyclohexyl-4-phenylsemicarbazide [Eq, (52) yield 73%] can be prepared by hydrolysis of the substituted diaziridines 46 and 62. ... 

A class of compounds which react smoothly with diazirincs are the Grignard reagents. All investigated diazirines add Grignard reagents instantly at 0 0 to the NN double bond yielding 1-alkyl-diaziridines [Eq. (62)... 

Thus the diazirines could be related by a smooth reaction to a well investigated class of compounds. The three-membered ring structure of the diazirines was thus largely confirmed. They can be obtained from compounds which certainly have a three-membered ring structure [Eq. (54)] and are easily convertible into compounds which have equally well confirmed three-membered ring structures. The structure of the 1-alkyl-diaziridines (43) obtained by the Grignard reaction were confirmed by identification with known compounds, usually prepared by the reaction of Schiff s bases with chloramine [Eq. (32)]. The results of some of these reactions are collected in Table XII. 

The 1-alkyl-diaziridines can easily be hydrolyzed to alkyl hydrazines. Hence alkyl hydrazines are easily available from Grignard reagents and thus from alkyl halides. The three last examples of Table XII show the yield of alkyl hydrazine calculated on the diazirine used. The reaction has preparative interest because the alkylation of hydrazine with alkyl halides only gives monoalkyl hydrazines in exceptional cases. ... 

Alkyl-diaziridines from Diazirines and Grignard Compounds ... 

Yield of 1-alkjd-diaziridine, calculated on the diazirine which was not isolated. A ield of the alkyl hydrazine prepared by hydrolysis of the l-alkyl-diaziridine (calculated on diazirine). 

Diazirines are the cyclic isomers of the alphatic diazo compounds. Both the diaziridines and the diazirines are starting materials for the synthesis of alkyl hydrazines. 3,3-Pentamethyl-enediaziridine can be hydrolyzed quantitatively to hydrazine. Methylamine may be substituted for ammonia in the procedure resulting in l-methyl-3,3-pentamethylenediaziridine (m.p. 35-36°, yield 62% of theoretical) and then methyl hydrazine. Use of ethylenediamine leads to ethylene bis-hydrazine via a bifunctional diaziridine (m.p. 143-144°, yield 48% of theoretical). Ammonia can also be replaced by w-propylamine or cydo-hexylamine cyclohexanone by acetone. 

Pentamethylenediazirine and other diazirines easily add Grignard reagents to the N—N double bond. The reaction leads to N-alkyl diaziridines which can be hydrolyzed to alkyl hydrazines. Cyclohexylhydrazine (85% yield), -propylhydrazine (88%), isopropylhydrazine (95%), and benzylhydrazine were... 

Typical 1,3-dipolar cycloreversion is found for the decomposition of alkyl-substituted 2-tetrazolines (43) (88CB1213), l,4-dihydro-l,2,3,4-tetrazol-5-ones (44), and -thiones (45) (97JHC113). For these reactions two paths are possible that can be distinguished when the substituents on N-l and N-4 are different. For 2-tetrazolines ring contraction leading to diaziridines is also possible (discussed earlier). Cycloreversion of 43 yields imines and azides (88CB1213). 

Photoelectron spectroscopy (PES) has shown that in the case of tri- and tetra-alkylated diaziridines, all compounds exist in the /ra j-configuration, with a lone pair-lone pair dihedral angle of 100-110° <1994J(P2)2059>. 

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