3599-61-9Relevant academic research and scientific papers
One-step synthesis of 2-amino-5h-pyrimido[5,4-b]indoles, substituted 2-(1,3,5-triazin-2-yl)-1h-indoles, and 1,3,5-triazines from aldehydes
Biswas, Subhasish,Batra, Sanjay
scheme or table, p. 3492 - 3499 (2012/08/13)
An efficient one-step synthesis of 2-amino-5H-pyrimido[5,4-b]indoles through a copper-catalyzed cascade reaction between 3-haloindole-2-carbaldehydes and guanidine hydrochloride is described. In contrast, the base-mediated reactions of either 3-haloindole-2-carbaldehydes or substituted indole-2-carbaldehydes with substituted amidine hydrochlorides in DMSO result in the formation of 2-(1,3,5-triazin-2-yl)-1H-indole derivatives in one step in excellent yields. Studies toward exploring the utility of the method demonstrate that even substituted benzaldehydes undergo a similar reaction to efficiently yield 2,4,6-trisubstituted 1,3,5-triazines. A plausible mechanism for the formation of substituted 1,3,5-triazines identifies the role of DMSO as an oxidant during the reaction. The synthesis of 2-amino-5H-pyrimido[5,4-b]indoles from 3-haloindole-2-carbaldehyde and guanidine hydrochloride is described. In contrast, 3-haloindole-2-carbaldehydes or indole-2-carbaldehydes react with substituted amidine hydrochlorides to give 2-(1,3,5-triazin-2-yl)-1H-indole derivatives in excellent yields. The latter protocol was used to prepare 2,4,6-trisubstituted 1,3,5-triazines.
Photochemistry of phenyl-substituted 1,2,4-thiadiazoles. 15N-labeling studies
Pavlik, James W.,Changtong, Chuchawin,Vikki
, p. 4855 - 4861 (2007/10/03)
Irradiation of 5-phenyl-1,2,4-thiadiazole (6) resulted in the formation of benzonitrile (5), 3-phenyl-1,2,4-thiadiazole (4), phenyl- and diphenyl-1,3,5-triazines (7 and 8), and a trace quantity of diphenyl-1,2,4-thiadiazole (9). The formation of 4, 5, 7, and 8 can be explained in terms of photoinduced electrocyclic ring closure resulting in the formation of an intermediate 4-phenyl-1,3-diaza-5-thiabicyclo[2.1.0]pentene. 15N-labeling experiments revealed that sulfur can undergo sigmatropic shifts around all four sides of the diazetine ring. Thus, irradiation of 6-4-15N led to the formation of 6-2-15N and an equimolar mixture of 4-2-15N and 4-4-15N. The thiabicyclo[2.1.0]pentene intermediate is also suggested to undergo sulfur elimination resulting in the formation of phenyldiazacyclobutadiene, which can undergo complete fragmentation to benzonitrile or [4+2] cycloaddition leading to unstable tricyclic adducts, the suggested precursors of the 1,3,5-triazine products 7 and 8. The observed 15N distribution in 7 and 8 is consistent with this mechanism. Irradiation of 4 led only to the formation of 5. 15N-labeling experiments show that 4 does not undergo electrocyclic ring closure but reacts exclusively by photofragmentation of the thiadiazole ring.
Amidrazones. VII (1a). Formation of s-Triazines by Thermolysis of N1-Benzyl-Substituted Amidrazone Ylides
Smith, Richard F.,Soelch, Richard R.,Feltz, Timothy P.,Martinelli, Michael J.,Geer, Susan M.
, p. 319 - 325 (2007/10/02)
The preparation of ylides of the general structure RC(=NR')N-N+(CH3)2CH2Ar (14) is described.Thermolysis of 14a (R = CH3, R' = H, Ar = C6H5) gave dimethylamine and 2,4-dimethyl-6-phenyl-s-triazine.Thermolysis of ylides 14b (R = C6H5; R' = CH3, Ar = C6H5) and 14c (R = C6H5, R' = CH3, Ar = p-tolyl) gave dimethylamine, ArCH=NCH3 and 1-methyl-2-Ar-4,6-diphenyl-1,2-dihydro-s-triazines (19a,b).Triazines 19a and 19b were also prepared by condensation of N-methylbenzamidine with benzaldehyde and p-tolualdehyde, respectively.Thermolysis of 14d (R = C6H5, R' = CH2C6H5, Ar = C6H5) gave 1-benzyl-2,4,6-triphenyl-1,2-dihydro-s-triazine (19c) and N-benzylidenebenzylamine.Mechanistic aspects of these reactions are discussed.
