114166-32-4Relevant articles and documents
Design and synthesis of urea-linked aromatic oligomers-a route towards convoluted foldamers
Mousseau, James J.,Xing, Liyan,Tang, Nathalie,Cuccia, Louis A.
supporting information; experimental part, p. 10030 - 10038 (2010/06/15)
Herein we report the design and synthesis of crescent-shaped and helical urea-based foldamers, the curvature of which is controlled by varying the constituent building blocks and their connectivity. These oligomers are comprised of two, three or five alternating aromatic heterocycles (pyridazine, pyrimidine or pyrazine) and methyl-substituted aromatic carbocycles (tolyl, o-xylyl or m-xylyl) connected together through urea linkages. A crescent-shaped conformational preference is encoded within these π-conjugated urea-linked oligomers based on intramolecular hydrogen bonding and steric interactions; the degree of curvature is tuned by the urea connectivity to the heterocycles and the aryl groups. NMR characterization of these foldamers confirms the intramolecular hydrogen-bonded conformation expected (Z,E configuration of the urea bond) in both the pyridazyl and pyrimidyl foldamers in solution. An X-ray crystal structure of the N3,N6-diisobutylpyridazine-4,6- diamine-o-tolyl urea-linked foldamer (4) confirms the presence of N-H...N hydrogen bonds between the heterocyclic nitrogen atom and the free hydrogen of the urea linkage. Additionally, the tolyl methyl group interacts unfavourably with the urea carbonyl oxygen, thus destabilising the alternate planar conformation.
Ozone-mediated Reaction of Anilides and Phenyl Esters with Nitrogen Dioxide: Enhanced Ortho-reactivity and Mechanistic Implications
Suzuki, Hitomi,Tatsumi, Atsuo,Ishibashi, Taro,Mori, Tadashi
, p. 339 - 344 (2007/10/02)
In the presence of ozone, anilides 1 can be nitrated rapidly with nitrogen dioxide in chloroform at 0 deg C to give a high proportion of ortho-nitro derivatives (ortho:para = 1.2-4.4) in good yields.The phenyl esters 15 can be similarly nitrated on the aromatic ring without significant cleavage of the ester bond, giving a mixture of isomeric nitro derivatives in which the ortho-isomer predominantes (ortho:para = 1.1-1.5).The oridin of the enhanced ortho reactivity is discussed in terms of an electron-transfer process involving the nitrogen trioxide as initial electrophile.
Studies of Reactions of Amines with Sulfur Trioxide. VI. Thermal Reactions of Anilinium, Dimethylanilinium, and Trimethylanilinium Salts of Butylamidosulfuric Acid
Kanetani, Fujio,Yamaguchi, Hachiro
, p. 3048 - 3058 (2007/10/02)
When the title compounds were heated in an evacuated reaction vessel, both transsulfonation and rearrangement occurred.At lower temperatures (80-120 deg C) the corresponding phenylamidosulfates and sulfophenylamidosulfates (transsulfonation products) were the main products.Increasing temperature led to the formation of ring mono- and disulfonates (rearrangement products) at the expense of the transsulfonation products.The sulfonate group always migrated to the ortho and/or para position(s) to the amino group.In no case was any meta-product detected.There was no significant difference in the ease of transsulfonation among the anilinium salts studied exept 2,6-dimethyl- and 2,4,6-trimethylanilinium salts.On the other hand, the ease of rearrangement and the orientation of ring sulfonation depended strongly on the structure of the substrate anilines.The thermal reactions of 2,4,6-trimethylanilinium butylamidosulfate produced (2,4,6-trimethylphenylimido)bis(sulfate) in addition to (2,4,6-trimethylphenylamido)sulfate.This is the first isolation of an arylimidobis(sulfate) from such reactions.Mechanisms of the transsulfonation and rearrangement have been discussed.
