Pyrido/2,3-b/indoles

Yoshida et al (25) Isolated 2-amino-91/-pyrIdo[2,3- ]Indole (AcxC) and 2-amino-3-me thy l-9 -pyrido[ 2,3-b ] indole (MeActC) from pyrolysate of soybean globulin. 

III) and 2-am no-3-methyl-9H-pyrido[2,3-b]indole (IV) in a pyro-lyzate of soy protein. These fluorescent compounds could be protein-bound in roasted foods. Detailed experiments on the interaction between food proteins and such compounds of toxicological importance are being carried out in Japan. 

Dodd and Abouabdellah performed the cyclization below with a BINAP/Pd-catalyst to furnish, after air oxidation, the pyrido[2,3-b]indole in 51% yield, Eq.(174) [140]. 

Other intramolecular cyclization reactions involving arylcarbodiimides with an ortho vinyl group to form 2-aminoquinolines and pyrido[2,3-b]indoles are listed in Table 3.1. The latter reactions involve a [2-1-4] cycloaddition in which the carbodiimide intermediate acts as an azadiene and the bond of the ortho vinyl group acts as the dienophile. Calculated transition states for electrocyclization and cycloaddition reactions show that the mode of reaction depends on substituents, stereoelectronic, eutropic and steric factors." ... 

SYNS 2-AMINO-a-CARBOLINE 2-AMINO-9H-PYRIDO(2,3-B)INDOLE... 

C12H10O 2,6-diallyl phenol 3382-99-8 562.81 49.951 2 23659 C12H11N3 2-amino-3-methyl-9H-pyrido(2,3-b)indole 68006-83-7 621.50 55.672 2... 

Bei der Photolyse von 1 -Pyridyl-(2)-III-(benzotriazol) erhalt man in analoger Weise Pyrido- [1,2-a]-benzimidazole I und 9H-Pyrido -[2,3-b]-indole II1 ... 

FIGURE 9.3 Total gas chromatogram obtained from standard heterocyclic amines (containing 5 ng of each amine). GC conditions-peaks 1. 2-amino-9H-pyrido[2,3-b]indole (AaC) + 2-aminodipyrido [l,2-a 3 2Cd]imidazole (Glu-p-2) 2. 2-amino-6-methyldipyrido[l,2-a 3 2Cd]imidazole (Glu-P-1) 3. 3-amino-l,4-dimethyl-5H-pyrido[3,4-b]indole (Trp-P-1) 4. 3-amino-l-methyl-5H-pyrido[3,4-b]indole (Trp-P-2) ... 

Heckman and Best (1587) reported the identification of nearly 270 previously unidentified and over 150 previously identified V-containing components in CSC. These included several components structurally similar to the V-heterocyclic amines 97/-pyiido[2,3-/>]indole, 2-methyl-9//-pyrido[2,3-b]indole, 2-(2-methylpropyl)-9//-pyiido[2,3-/>]indole, 2-pentyl-9//-pyrido[2,3-b] indole, l-butyl-97/-pyrido[3,4-/ ]indole, 9//-l-propenyl-pyrido[3,4-/>]indole, and a partially characterized norharman isomer. 

Yoshida and Matsumoto (4388) and Matsumoto et al. (2492) reported the identification of 2-amino-9//-pyrido[2,3-b]indole (AaC) and 2-amino-3-methyl-9//-pyrido[2,3-/ ]indole (MeAaC) in CSC. 

Frederiksen, H. and Frandsen, H. 2004. Excretion of metabolites in urine and faeces from rats dosed with the heterocyclic amine, 2-amino-9H-pyrido[2,3-b]indole. Food Chem Toxicol. 42 879-85. 

One representative example in enantioselective alkylation of benzylic C-H bond was disclosed by Gong and co-workers in 2010. Highly enantioselective alkylation of 3-arylmethylindoles with dibenzyl malonate was achieved in the presence of catalytic amounts of chiral copper complex L4 (Scheme 2.31) [169]. This protocol provides an excellent enantioselective route to natural product skeleton of 2,3,4,4a,9,9a-hexahydro-lH-pyrido[2,3-b]indoles. 

The carboline core is of high interest due to its presence in an array of compoimds, some of which are widely distributed in nature, including various plants, foodstuffs, marine creatures, insects, mammalians as well as human tissues and body fluids. Ghahremanzadeh et al. investigated the synthesis of a-carbolines, i.e., pyrido[2,3-b]indoles 169 (Scheme 94) in good yield via a four-component condensation reaction of indolin-2-one, 3-oxo-3-phenylpro-panenitrile, and various hydrazines and aldehydes in the presence of p-toluenesulfonic acid (p-TSA) at 140 °C in IL [BMlM][Br]. The reaction performed well with aromatic aldehydes, however, reaction with aliphatic aldehydes, for example, butanal or pentanal, complications such as incompletion of reaction, by-product formation, and difficulty in purifications arose, and the yield of the expected products were extremely poor. The authors claimed the methodology efficacious in terms of yield and product purity without p-TSA, only a trace of product was obtained even after 12 h. A similar reaction conducted in organic solvents afforded traces of tiie desired products [261]. 

SCHEME 94 Synthesis of pyrido[2,3-b]indoles using [BMIM][Br]. 

Achab, S., Guyot, M., and Potier, P. (1993) A short entry into the pyrido [2,3-b]indole ring system. Synthesis of the tetracyclic segment of the marine antitumor agents grossularines-1 and —2. Tetrahedron Lett., 34, 2127-2130. 

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