- A Br?nsted Acid Catalyzed Cascade Reaction for the Conversion of Indoles to α-(3-Indolyl) Ketones by Using 2-Benzyloxy Aldehydes
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A Br?nsted acid catalyzed, operationally simple, scalable route to several functionalized α-(3-indolyl) ketones has been developed and the long-standing regioisomeric issue has been eliminated by choosing appropriate carbonyls. A readily available and cheap bottle reagent was used as the catalyst. This protocol was also applicable to the synthesis of densely functionalized α-(3-pyrrolyl) ketones. A detailed mechanistic study confirmed the involvement of enolether as a reaction intermediate. Several postsynthetic modifications along with easy access to β-carboline, tryptamines, tryptophols, and spiro-indolenine proclaim the synthetic utility of this powerful building block. On the basis of this concept, functionalized carbazoles were constructed by a cascade annulation strategy.
- Banerjee, Ankush,Maji, Modhu Sudan
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supporting information
p. 11521 - 11527
(2019/08/16)
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- Versatile synthesis of functionalized β- And γ-carbolines: Via Pd-catalyzed C-H addition to nitriles/cyclization sequences
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The first example of versatile synthesis of functionalized β-carbolines and γ-carbolines via redox-free Pd-catalyzed C-H addition of indole to nitrile/cyclization sequences is reported. A wide range of functionalized β-carbolines and γ-carbolines can be prepared from readily accessible indoles and nitriles in good to excellent yields under the optimal conditions.
- Wang, Ting-Ting,Zhang, Di,Liao, Wei-Wei
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p. 2048 - 2051
(2018/03/01)
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- SUBSTITUTED PYRIDO[3,4-B]INDOLES FOR THE TREATMENT OF CARTILAGE DISORDERS
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Substituted pyrido[3,4-b]indoles and their use as pharmaceuticals The present invention relates to 8-aryl-substituted and 8-heteroaryl-substituted 9H-pyrido[3,4-b]indoles of the formula I, in which A, E, G, R1 to R6 and R10 are as defined in the claims, which stimulate chondrogenesis and cartilage matrix synthesis and can be used in the treatment of cartilage disorders and conditions in which a regeneration of damaged cartilage is desired, for example joint diseases such as osteoarthritis. The invention furthermore relates to processes for the synthesis of the compounds of the formula I, their use as pharmaceuticals, and pharmaceutical compositions comprising them.
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Paragraph 0155
(2018/05/24)
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- Fe-HCl: An efficient reagent for deprotection of oximes as well as selective oxidative hydrolysis of nitroalkenes and nitroalkanes to ketones
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Fe-HCl mixture was found to selectively perform oxidative hydrolysis of the nitroalkenes 1a-j and nitroalkanes 2a-j to the ketones 3a-j. Also, the reagent was observed to deprotect the oximes 7a-j to carbonyl compounds 8a-j in excellent yields.
- Pradhan, Prasun K.,Dey, Sumit,Jaisankar, Parasuraman,Giri, Venkatachalam S.
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p. 913 - 922
(2007/10/03)
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- A Direct Access to 3-(2-Oxoalkyl)indoles via Aluminum Chloride Induced C-C Bond Formation
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3-Methylindole is acylated regioselectively at the methyl group when treated with a variety of acyl chlorides in 1,2-dichloroethane in the presence of AlCl3, affording a mild and direct method for the synthesis of 3-(2-oxoalkyl)-indoles. The product formation in this one-pot reaction largely depends on the conditions of the reaction employed. The methodology does not require protection-deprotection steps and is amenable for the scale-up synthesis of these indole derivatives.
- Pal, Manojit,Dakarapu, Rambabu,Padakanti, Srinivas
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p. 2913 - 2916
(2007/10/03)
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- Synthesis of substituted carbazoles and β-carbolines by cyclization of diketoindole derivatives
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A new route to substituted β-carbolines and carbazoles is described. Diketoindole intermediates, prepared by Friedel-Crafts acylations of 3-substituted indoles, have been converted to 3-hydroxycarbazoles and β-carbolines in good yields, 51-96% and 82-97%, respectively. This method also allows for the formation of 4-substituted β-carbolines. The application of this methodology to the synthesis of the natural products hyellazole and 6-chlorohyellazole is also described.
- Duval, Eric,Cuny, Gregory D.
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p. 5411 - 5413
(2007/10/03)
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- Synthesis and serotonin receptor affinities of a series of enantiomers of α-methyltryptamines: Evidence for the binding conformation of tryptamines at serotonin 5-HT(1B) receptors
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A procedure for the preparation of optically pure α-methyltryptamines (AMTs) from substituted indoles was developed. The key step in the sequence was the reductive amination of substituted indole-2-propanones with the commercially available pure enantiomers of α-methylbenzylamine, followed by the chromatographic separation of the resulting pair of diastereomeric amines by preparative centrifugal (Chromatotron) chromatography. Catalytic N-debenzylation then afforded the pure AMT enantiomers. Optical purity was established by chiral HPLC analysis of the 2-naphthoylamide derivatives. An improved procedure for the preparation of indole-2-propranone was also developed. To probe structure-activity relationships of serotonin receptors, affinities of the α-methyltryptamine enantiomers were then measured at the 5-HT2 antagonist receptor subtype, with displacement of [3H]ketanserin, and were estimated at the 5-HT(1B) receptor, with displacement of [3H]serotonin, respectively, in rat frontal cortex homogenates. Enantioselectivity at the receptor subtypes varied, depending on aromatic substituents. For a 5-hydroxy or 5-methoxy, the S enantiomer had higher affinity or was equipotent to the R enantiomer. This selectivity at [3H]serotonin binding sites was reversed for 4-oxygenated α-methyltryptamines, where a 4-hydroxy or 4-methoxy did not enhance affinity over the unsubstituted compounds. These results can be explained, for the [3H]serotonin displacement data, if the binding conformation is one where the ethylamine side chain is trans and lying in a plane perpendicular to the indole ring plane.
- Nichols,Lloyd,Johnson,Hoffman
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p. 1406 - 1412
(2007/10/02)
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