Solution and Solid-State Photochemistry of 2-Anilino-5-phenyl-2,4-pentadienenitriles
摘要:
2-(N-Methylanilino)-5-phenyl-2,4-pentadienenitrile (3) undergoes either isomerization or oxidative cleavage at the 2,3-double bond upon irradiation in solution, whereas it dimerizes in a regiospecific manner to give the [2 + 2] cycloaddition product 12 upon irradiation in the solid state. From the fluorescence spectra and semiempirical calculation, the excited state of 3 is proposed to be a twist intramolecular charge transfer species. The X-ray analysis indicates that molecules 3b orient appropriately with a reasonable distance for the [2 + 2] cycloaddition in the solid state. The distance between C2 and C3' is 525 pm, the longest distance known in solid-state [2 + 2] cycloadditions. 2-(N-Methyl-p-bromoanilino)-5-phenyl-2,4-pentadienenitrile (4) shows behavior similar to that of 3 in the solution and solid-state photochemistry, whereas analogs 7-10 having nitro substituents on the 5-phenyl rings do not dimerize upon irradiation in the solid state. Semiempirical calculation of the electronic structures is used to interprete the discrepancy of reactivity.
2-(N-methylanilino)-2-phenylsulfanylacetonitrile, a reagent tested for electrophilic, nucleophilic and radical reactions
摘要:
2-(N-Methylanilino) -2-phenylsulfanylacetonitrile 1 has been readily prepared from 2-(N-methylanilino)acetonitrile and diphenyl disulfide. Alkylation of the anion of 1 with halogenoalkanes resulted in concurrent elimination of benzenethiol to give conjugated alpha-aminoalkenenitriles of 2E-configuration. Autoxidation of 1 in the presence of alkoxide ions afforded alkyl N-methyl-N-phenylcarbamates. Nucleophilic substitution of 1 with Grignard reagent or appropriate silyl compounds were promoted by Cul or Lewis acids to give varied alpha-amino nitriles. The 4-oxo-2-amino nitriles 9 obtained by condensation of 1 and titanium enolates can be considered as derivatives of 1,3-dicarbonyl compounds with the aldehyde group being activated to give an amino nitrile umpolung. When 1 was treated with tributylstannane, the corresponding amino nitrile alpha-radical was formed and the self-coupling product was isolated.