4110-35-4Relevant articles and documents
Anomalous Equilibrium and Kinetic α-Deuterium Secondary Isotope Effects Accompanying Hydride Transfer from Reduced Nicotinamide Adenine Dinucleotide
Kurz, Linda C.,Frieden, Carl
, p. 4198 - 4203 (1980)
The kinetic α-deuterium secondary isotope effect on the second-order rate constant has been measured for the nonenzymatic direct hydride transfer reduction of 4-cyano-2,6-dinitrobenzenesulfonate by NADH (deuterium substitution of the hydrogen bonded to the 4 carbon of NADH which is not transferred to the acceptor).Values of 1.156 +/- 0.018 and 1.1454 +/- 0.0093 were obtained using direct and intramolecular competition methods, respectively.The corresponding (enzyme catalyzed) equilibrium isotope effects were found to be 1.013 +/- 0.020 and 1.0347 +/- 0.0087 as determined by direct and intermolecular competition methods, respectively.Thus, the value of the kinetic effect is significantly greater than that on the equilibrium.It is suggested that this may arise either from participation of the α hydrogen in a hyperconjugative stabilization of an early transition state or from its participation in the reaction coordinate motion of a nonlinear activated complex.The values of the equilibrium effect allow calculation of a fractional factor (relative to acetylene) for hydrogen bonded to the 4 carbon of NAD+ of 1.448 +/- 0.028 or 1.418 +/- 0.020.This is larger than expected based on comparison with hydrogen bound of sp2 carbon in propene (1.136) or benzene (1.368) but is consistent with the decreased aromatic character of pyridinium vibrational spectra.The lack of a significant inverse value for the equilibrium α-deuterium effect suggests complications in the interpretation of reported kinetic secondary effects of 0.85 and 1.2 for the forward (sp3 -> sp%&2) and reverse (sp2 -> sp3) rate constants for the nonenzymatic transhydrogenation of N-benzyl-1,4-dihydronicotinamide and its nicotinamide salt.
Double Dehydrogenation of Primary Amines to Nitriles by a Ruthenium Complex Featuring Pyrazole Functionality
Dutta, Indranil,Yadav, Sudhir,Sarbajna, Abir,De, Subhabrata,H?lscher, Markus,Leitner, Walter,Bera, Jitendra K.
supporting information, p. 8662 - 8666 (2018/07/09)
A ruthenium(II) complex bearing a naphthyridine-functionalized pyrazole ligand catalyzes oxidant-free and acceptorless selective double dehydrogenation of primary amines to nitriles at moderate temperature. The role of the proton-responsive entity on the ligand scaffold is demonstrated by control experiments, including the use of a N-methylated pyrazole analogue. DFT calculations reveal intricate hydride and proton transfers to achieve the overall elimination of 2 equiv of H2.
Activated dimethyl sulfoxide dehydration of amide and its application to one-pot preparation of benzyl-type perfluoroimidates
Nakajima, Noriyuki,Saito, Miho,Ubukata, Makoto
, p. 3561 - 3577 (2007/10/03)
Various types of primary amides were treated under an activated dimethyl sulfoxide (DMSO) species, (COCl)2-DMSO and Et3N, as a dehydrating agent to obtain nitriles in excellent yield. This dehydration system was extended to a one-pot preparation of perfluoroimidates via volatile perfluoronitriles from perfluoroamides. Fifteen benzyl-type perfluoroimidates can be prepared in 70-90% yield as more stable imidates than the trichloro analogue. MPM- and DMPM-perfluoroimidates can be used to protect alcohols in place of the trichloroacetimidate with excellent chemical properties and in comparable yields.
