REGIOSELECTIVE 1,4-ADDITION OF AMMONIA TO 1-ARYLALKA-1,3-DIENES AND 1-ARYL-4-PHENYLBUTA-1,3-DIENES BY PHOTOINDUCED ELECTRON-TRANSFER

The photoamination of 1-arylalka-1,3-dienes 1a-f and 1-aryl-4-phenylbu ta-1,3-dienes 1g-k with NH3 in the presence of p-dicyanobenzene (DCB) gives 4-amino-1-arylalk-2-enes 2a-f and 1-amino-1,4-diarylbut-2-enes 2 g-k, respectively, The photoamination proceeds by nucleophilic additio n of NH3 to the cation radicals of 1(+.) generated by photoinduced ele ctron transfer to DCB, The regiochemistry of 2 is related to the distr ibution of the positive charge in 1(+.) calculated by the PM3-UHF/RHF method, the stability of the aminated radicals formed by the addition of NH3 to 1(+.) and the stability of the aminated anion formed by the reduction of the aminated radicals by DCB-.. The stabilities of these intermediates are estimated by the calculation of the heat of formatio n by the PM3-UHF/RHF method, Distributions of the positive charge in 1 (+.) and the stabilities of the aminated anion show a good agreement w ith the product analysis.