Monosubstituted 1,2-phenylenediamines

In the case of the interaction of [Pg.19]

Benzannulated 1,3,2-diazaphospholes 5 form readily upon condensation of monosubstituted o-phenylenediamines (R=H, alkyl, Ph) with P(NMe2)3 [13, 14] (Scheme 2). A -Alkylated products can be detected by NMR but evade isolation by... 

When 2-anisidine, p-acetylaniline, 1,2-phenylenediamine, and 2-trifluro-methylaniline were used, the above procedure gave oifly monosubstituted or A-phenylglycine derivatives. 

Dialkyl or diaryl group substituents hold the molecule more rigidly out of the plane of the benzene ring than corresponding monosubstituted amine groups. The free radicals produced from unsymmetrical p-phenylenediamine derivatives should react more slowly with ozone than those formed from analogous symmetrical compounds. 

Dimethyl-3-(diphenylmethylene)benzodiazepine was prepared by condensation of o-phenylenediamine with 3-(diphenylmethylene) pentane-2,4-dione in ethanol-acetic acid.9 3-Methylenepentane-2,4-diones monosubstituted in the methylene group do not condense under these... 

Phenylendiamine reacts with formic acid at 100°C to give benzimidazole in a yield of over 80%. A-Monosubstituted o-phenylenediamines react with other carboxylic acids more slowly, necessitating the addition of hydrochloric or phosphoric acid. A mixture of trifluoromethanesulfonic acid anhydride and triphenylphosphane oxide in dichloromethane is a very efficient dehydrating agent [122]. 

A new route to nucleophilically substituted o-phenylenediamines (145), which are potentially powerful in heterocyclic synthesis, has been introduced. This involves the reaction of isobenzimidazole-2-spirocyclohexane (146) (obtained in high yield from o-phenylenediamine and cyclohexanone) with secondary amines in ethanol to give the monosubstituted isobenzimidazole (147), or in DMSO or sulpholan to give the disubstituted compound (148), as shown in Scheme 22. The reaction is essentially nucleophilic addition followed by oxidation of the resultant dihydro-isobenzimidazole (149) by an unchanged molecule of (146). 

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