- Electrochemical oxidation of amides of type Ph2CHCONHAr
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Anodic oxidation of N-aryl-2,2-diphenylacetamides in acetonitrile undergoes three types of bond-cleavage, one between the benzylic carbon and the carbonyl group, the second between a carbonyl and 'N', and the third between the 'N' atom and aryl group. The selectivity of the cleavage and nature of emerged products is highly dependent on the nature of substituent attached to the aryl group. For example, electron-withdrawing groups direct the benzyl-carbonyl bond-breaking whereas electron-donating substituents favor the N-aryl bond cleavage. The type of products obtained involve benzophenone, 2,2-diphenylacetamide, N-(diphenylmethylene)acetamide, N-(diphenylmethyl)acetamide, α-lactam (1-acetyl-3,3-diphenylaziridin-2-one, as a 1:1 complex with 2,4-dinitroaniline) and aniline derivatives.
- Golub, Tatiana,Becker, James Y.
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experimental part
p. 3906 - 3912
(2012/06/04)
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- Synthesis and characterization of new ca-disubstituted (diarylaminomethyl)phosphonates
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A convenient and efficient three-step procedure for the preparation of W-protected or unprotected C-disubstituted (di-arylaminomethyOphosphonates 1 is reported. This method allows diversification of the substituents on the carbon in the a-position to the phosphorus, as well as the protective group on the amine and the phosphonate ester group.
- Cristau, Henri-Jean,Lambert, Jean-Marc,Pirat, Jean-Luc
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p. 1167 - 1170
(2007/10/03)
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- On the Structure of N-Methylenecarboxamides: X-Ray Data, Spectroscopy, and Quantum Mechanical Calculations
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N-(Diphenylmethylene)acetamide (1) has been studied by X-ray crystallography as an example for the polyfunctional, highly reactive N-methyleneamides.The dihedral angle (C=N-C=O = 73 deg) and the bond lengths indicate that there is only little interaction
- Allmann, Rudolf,Kupfer, Rainer,Nagel, Michael,Wuerthwein, Ernst-Ulrich
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p. 1597 - 1605
(2007/10/02)
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- The Timing of the Proton-Transfer Process in Carbonyl Additions and Related Reactions. General-Acid-Catalyzed Hydrolysis of Imines and N-Acylimines of Benzophenone
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Observed general-acid-catalyzed hydrolysis of benzophenone imines, Ph2C=NR, or the kinetically equivalent general-base-catalyzed hydrolysis of the conjugate acids Ph2C=N+HR, corresponds mechanistically to general-base-catalyzed amine expulsion from the conjugate acid (T+) of the tetrhedral intermediate from water addition to Ph2C=NR.Broensted β values for this catalysis by carboxylate and cacodylate ions are 0.96 (for R = H), 0.93 (for R = C2H4CN), and 0.76 (for R = CH2CN).These results, combined with calculations that suggest that amine expulsion from the zwitterionic intermediate, T+/-, from ammonia is slower than diffusion processes involving T+/- and catalyst, are consistent with a mechanism in which a simple proton transfer process is not rate determining.Because of the stability of T+/- it is likely that catalysis in this system is "enforced" by the lifetime of this intermediate.We suggest that catalysis of these reactions is observed because hydrogen bonding of T+/- to the conjugate acid of the catalyst provides an energetic advantage by stabilizing both T+/- and the transition state for amine expulsion from this species.Hydrolysis of N-acyl benzophenone imines, Ph2C=NC(O)CH2X (X = H, OCH3, or Cl), involves a rapid, favorable equilibrium for addition of water across the C=N bond, followed by amide expulsion from the carbinolamide.The latter process, analogous to amine expulsion from carbinolamines, is subject to weak general acid catalysis with Broensted α values of 0.5-0.6.This catalysis probably corresponds mechanistically either to (1) bifunctional or "one-encounter" catalysis in which one or both of the proton-transfer processes is "concerted" with C-N cleavage, or (2) general base catalysis of the expulsion of the O-protonated amide from Ph2C(OH)N+HC(OH)CH2X.For uncatalyzed carbinolamide cleavage a cyclic transition state with intramolecular proton transfer to the acyl oxygen is suggested to explain the observed insensitivity to substituents, X, of amide expulsion from the neutral carbinolamides, Ph2C(OH)NHC(O)CH2X.
- Sayer, J. M.,Conlon, Patrick
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p. 3592 - 3600
(2007/10/02)
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