Dialkylamino-chloro-addition

Addition of Halogen and an Amino Group (Addition of Halogen. Nitrogen) Dialkylamino-chloro-addition... 

Benzannulated NHPs are straightforwardly accessible from AUV-disubsti luted o-phenylenediamines either via base-induced condensation with substituted dichlorophosphines [25] or PC13 [26], or via transamination with tris(dialkylamino) phosphines [13, 14, 27], respectively. An analogous NH-substituted derivative was obtained in low yield via transamination of o-phcnylcncdiaminc with ethoxy-bis(diethylamino)phosphine [28], and condensation of o-phenylenediamine with excess tris(diethylamino)phosphine furnished a l,3-bis(phosphino)-substituted heterocycle [29], Intermediates with one or two NH functions were detectable by spectroscopy but could not be isolated in pure form under these conditions. However, 2-chloro-benzo-l,3,2-diazaphospholene and the corresponding 1-phenyl derivative were prepared in acceptable yield via condensation of PC13 with o-phenylenediamine under microwave irradiation [30], or with A-phenyl-o-phenylenediamine under reflux [27], respectively, in the absence of additional base. The formation of tetrameric benzo-NHPs during transamination of A-alkyl-o-phenylenediamines with P(NMe2)3 has already been mentioned (cf. the section entitled 1,3,2-Diazaphospholes and 1,3,2-Diazaphospholides ). 

The IR spectra of all diazonium salts 2.296 exhibit an intensive absorption for the diazonio group between 2130 and 2155 cm Reactions with most nucleophiles result in either no reaction or total destruction, leading to dark oils or tars, besides loss of N2. The diazonium salts react smoothly, however, with water to give 2-(di-alkylcarbamoyl)-2-(dialkylamino)ethenediazonium salts 2.301 (2-115). Thermolysis of the solid hexachloroantimonate salt at 130 °C resulted in the l,2-bis(dialkyl-amino)-3-chloro-cyclopropenium antimonate 2.302 (25%), i.e., in a Balz-Schie-mann chloro-de-diazoniation, in addition to unidentified products. 

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