59616-80-7Relevant academic research and scientific papers
Heavy-Atom Kinetic Isotope Effects in the Acid-Catalysed and Thermal Rearrangements of 2,2'-Hydrazonaphthalene. Transition-State Differences in their Concerted Rearrangements
Shine, Henry J.,Gruszecka, Ewa,Subotkowski, Witold,Brownawell, Marilyn,Filippo, Joseph San, Jr.
, p. 3218 - 3223 (1985)
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.
On the Role of Leucine in Terpenoid Metabolism
Anastasis, Panayiotis,Freer, Isabel,Overton, Karl H.,Picken, Douglas,Rycroft, David S.,Singh, Sheo Bux
, p. 2427 - 2436 (2007/10/02)
Incorporation of -, -, (4R)-- and (4S)--leucines into paniculide by tissue cultures of Andrographis paniculata shows that (a) (3S)-3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) from leucine breakdown is not incorporated direct into
