- Mild N-deacylation of secondary amides by alkylation with organocerium reagents
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Secondary amides are a class of highly stable compounds serving as versatile starting materials, intermediates and directing groups (amido groups) in organic synthesis. The direct deacylation of secondary amides to release amines is an important transformation in organic synthesis. Here, we report a protocol for the deacylation of secondary amides and isolation of amines. The method is based on the activation of amides with Tf2O, followed by addition of organocerium reagents, and acidic work-up. The reaction proceeded under mild conditions and afforded the corresponding amines, isolated as their hydrochloride salts, in good yields. In combination with the C-H activation functionalization methodology, the method is applicable to the functionalization of aniline as well as conversion of carboxylic derivatives to functionalized ketones.
- Wang, Ai-E.,Chang, Zong,Liu, Yong-Peng,Huang, Pei-Qiang
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supporting information
p. 1055 - 1058
(2015/09/01)
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- Synthesis, mesomorphic and dielectric properties of 4-(cyanomethoxy)phenyl 4-alkoxybenzoates, 4-(cyanomethoxy)-4′-alkoxyazo- and -azoxybenzenes
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Preparation methods were developed for homologs of 4-(cyanomethoxy)phenyl 4-alkoxybenzoates (C7, C8, C9), 4-(cyanomethoxy)-4′-alkoxyazo (C2, C3, C 6), -azoxybenzenes (C3, C6) whose composition and structure were proved by elemental analysis and 1H NMR spectra. 4-(Cyanomethoxy) group destabilizes the mesophase, consequently, only four among the compounds obtained exhibit the thermotropic nematic mesomorphism.
- Kuvshinova,Burmistrov,Novikov,Litov,Aleksandriiskii,Koifman
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p. 615 - 620
(2014/07/08)
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- A facile and efficient method for the selective deacylation of N-arylacetamides and 2-chloro-Narylacetamides catalyzed by SOCl2
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Thionyl chloride efficiently and selectively promoted the deacylation of N-arylacetamides and 2-chloro-N-arylacetamides, under anhydrous conditions, without effecting the ester group, aminosulfonyl group, or benzyloxyamide group. This method, which has been successfully applied to a variety of substrates including different N-arylacetamides and 2-chloro-N-arylacetamides, has the attractive advantages of inexpensive reagents, satisfactory selectivity, excellent yields, short reaction time, and convenient workup. This new method can probably be used to selectively deacylate between aromatic amides and alkyl amides. Springer Science+Business Media B.V. 2011.
- Wang, Gong-Bao,Wang, Lin-Fa,Li, Chao-Zhang,Sun, Jing,Zhou, Guang-Ming,Yang, Da-Cheng
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experimental part
p. 77 - 89
(2012/05/20)
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- A systematic entropy relationship for the general-base catalysis of the deprotonation of a carbon acid. A quantitative probe of transition-state solvation
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The general-base-catalyzed deprotonation of a carbon acid, the l-methyl-4-(phenylacetyl)pyridinium cation (pKa = 9.02 at 25 °C), has been investigated for 32 general-base catalysts (25 amines and seven phenoxide ions) in aqueous solution. Amines give a generally scattered Bronsted plot; ring-substituted benzylamines have ?= 0.52, and ring-substituted phenoxides have ?= 0.60, with the phenoxides being more reactive than amines of similar basicity. The temperature dependences of the general-base-catalyzed deprotonation of this carbon acid have been measured over the range 15-45 °C for 12 base catalysts (eight primary, secondary, and tertiary amines; 4-(dimethylamino)pyridine; two phenoxide ions; hydroxide ion). The entropies of activation for these deprotonations show a clean curvilinear dependence upon the entropies of protonation of these base species, with the hydroxide ion being the only significant deviant from this relationship. This observation quantitatively establishes the importance of solvation effects as the major source of deviations that are commonly observed in Bronsted relationships for general-base-catalyzed processes.
- Bunting, John W.,Stefanidis, Dimitrios
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p. 779 - 786
(2007/10/02)
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- Comparative Structure-Activity Relationships of Antifolate Triazines Inhibiting Murine Tumor Cells Sensitive and Resistant to Methotrexate
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The inhibitory effect of 108 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazines on murine L5178Y tumor cells, resistant and sensitive to methotrexate (MTX), has been studied.From the pI50 values, quantitative structure-activity relationships have been formulated which show that the lipophilic triazines are much more inhibitory against resistant cells than methotrexate or hydrophilic triazines.The results are compared with the behavior of other antifolate drugs that have been used in chemotherapy, as well as with eight antitumor drugs that are notantifolates.The acquired resistance of these cells toward hydrophilic antifolates may be attributed to the combined effect of an impaired active-transport system, a change in the conformation of dihydrofolate reductase in the resistant cells, and an amplified production of dihydrofolate reductase in the resistant cells.
- Selassie, Cynthia Dias,Hansch, Corwin,Khwaja, Tasneem A.,Dias, Cecilia B.,Pentecost, Stephanie
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p. 347 - 357
(2007/10/02)
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