- Catalytic asymmetric benzidine rearrangement
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A chiral Br?nsted acid catalyzes the asymmetric benzidine rearrangement of N,N′-dinaphthylhydrazines. Different electronically and structurally diverse axially chiral 2,2′-binaphthyl diamine (BINAM) derivatives are obtained with high enantioselectivity. Copyright
- De, Chandra Kanta,Pesciaioli, Fabio,List, Benjamin
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p. 9293 - 9295
(2013/09/12)
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- Heavy-Atom Kinetic Isotope Effects in the Acid-Catalysed and Thermal Rearrangements of 2,2'-Hydrazonaphthalene. Transition-State Differences in their Concerted Rearrangements
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Acid-catalyzed (70percent aqueous dioxane at 0 deg C) and thermal rearrangement (95percent ethanol at 80 deg C) of 2,2'-hydrazonaphthalene (1) into 2,2'-diamino-1,1'-binaphthyl (2) have been shown to be concerted, -sigmatropic shifts.This was accomplished by measuring the nitrogen and carbon kinetic isotope effects (KIE), for which purpose mixtures of 1 with 1 and 1 were used.KIE were calculated from whole-molecule mass ratios, measured by multiscan mass spectrometry, in the bis(trifluoroacetyl) derivative of product 2, isolated after low and high conversions.The results (averaged) were, for two isotopic atoms, k(14N)/k(15N') = 1.0904, k(12C)/k(13C) = 1.0086 in the one-proton, acid-catalyzed rearrangement and 1.0611 and 1.0182, respectively, in the neutral, thermal rearrangement.These results indicate that although the rearrangements are concerted processes, the breaking of the N-N bond and the forming of the C-C bond proceed to different extents in the transition states.Furthermore, the differences in the timing of these events is greater in the acid-catalyzed than in the thermal rearrangement, a difference which may be attributable to earlier C-C bonding in the polar transition state of the former.
- Shine, Henry J.,Gruszecka, Ewa,Subotkowski, Witold,Brownawell, Marilyn,Filippo, Joseph San, Jr.
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p. 3218 - 3223
(2007/10/02)
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- PHOTOCHEMISTRY OF NAPHTHYL AND PYRENYL AZIDES: CHEMICAL PROPERTIES OF THE TRANSIENT INTERMEDIATES PROBED BY LASER SPECTROSCOPY
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The photochemistry of 1-naphthyl azide, 2-naphthyl azide, 1-pyrenyl azide, and 2-pyrenyl azide was examined in inert (benzene) and reactive (diethylamine) solvents.These studies employ a combination of product analysis, low-temperature spectroscopy, and laser-flash photolysis to reveal the chemical and physical properties of the highly reactive, short-lived intermediates formed in these reactions.In all cases two intermediates account for the observations.One of these is the triplet nitrene and the other is a ground-state singlet transient identified as an azirine.The relationship between these intermediates controls the chemical outcome of the reaction.
- Schrock, Alan A.,Schuster, Gary B.
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p. 5234 - 5240
(2007/10/02)
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- PHOTOCHEMICAL DECOMPOSITION OF 2-AZIDOPHENAZINE IN ALCOHOLS AND IN THE PRESENCE OF CYANIDE ION
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The photochemical decomposition of 2-azidophenazine in alcoholic solvents has been investigated. 1-Amino-2-alkoxyphenazines are formed in neutral and (in higher yield and together with 2-amino-1-chlorophenazine) in acidic conditions, while the azepinoquinoxaline 7 is formed in basic conditions.With cyanide ion nucleophilic attack takes place giving 1-amino-2-phenazine carbonitrile.To allow comparison, 2-azidonaphthalene, 2-azidoanthracene and 2-azidoanthraquinone have also been photodecomposed in the conditions in which the most interesting results are obtained from 2-azidophenazine.The mechanism of these reactions is briefly discussed.
- Albini, Angelo,Bettinetti, Gian Franco,Fasani, Elisa,Pietra, Silvio
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- Thermal Decomposition of Aromatic Azides. Formation of Phenazines and Related Compounds
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The decomposition of some aromatic azides yielding significant amounts of phenazines, and thereby constituting a potential synthetic procedure, is reported.
- Nay, Barry,Scriven, Eric F. V.,Suschitzky, Hans,Thomas, Desmond R.
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p. 611 - 613
(2007/10/02)
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