115313-20-7Relevant articles and documents
Room temperature palladium-catalysed coupling of amino acid-derived organozinc reagents with aryl triflates
Dexter, Charles S.,Jackson, Richard F.W.,Elliott, Jason
, p. 4539 - 4540 (2000)
Aryl triflates may be cross-coupled with the amino acid derived zinc reagents 1, 2 and 3 using palladium catalysis at room temperature, in the presence of anhydrous lithium chloride, conveniently yielding phenylalanine 4, β-homophenylalanine 5 and γ-bisho
Detection and elimination of product inhibition from the asymmetric catalytic hydrogenation of enamines
Hansen, Karl B.,Rosner, Thorsten,Kubryk, Michele,Dormer, Peter G.,Armstrong III, Joseph D.
, p. 4935 - 4938 (2005)
(Chemical Equation Presented) The catalytic asymmetric hydrogenation of enamine amides and esters with catalyst Rh-1a, prepared from ferrocenyl based ligand 1a or 1b and [(COD)RhCl]2, has been shown through kinetic studies to suffer from product inhibition. Enamine ester substrates have also been shown to be incompatible with the amine products of the reaction in methanol. In situ protection of the amine products with di-tert-butyl dicarbonate eliminates functional group incompatibility of ester substrates and eliminates product inhibition in the reaction.
NMR kinetic studies on the decomposition of β-amidozinc reagents: Optimization of palladium-catalyzed cross-coupling with acid chlorides
Dexter,Hunter,Jackson,Elliott
, p. 7417 - 7421 (2000)
The decomposition of β-amidozinc reagent 4 by β-elimination has been shown to be a unimolecular process in both THF and DMF as solvent, with relative rates of 4:1 at room temperature, and activation parameters have been determined. These results indicate
Kinetic studies on the stability and reactivity of β-amino alkylzinc iodides derived from amino acids
Rilatt, Ian,Jackson, Richard F. W.
scheme or table, p. 8694 - 8704 (2009/04/11)
(Chemical Equation Presented) β-Amino alkylzinc iodides are intrinsically unstable toward β-elimination and protonation. The aim of this study was to determine the rates of these processes and also to understand how the reactivity of a range of β-amino alkylzinc iodides in Negishi cross-coupling reactions is influenced by the presence of functional groups within the zinc reagent. Decomposition of β-benzamido alkylzinc iodides occurs by protonation, and the first-order rate constant for the self-protonation of the carbon-zinc bond in reagent 4b was determined to be 5.2 × 10-6 s-1 (at 291 K). In contrast, the carbamate derivative 2 decomposes by a first-order elimination process. The homologous reagent 3, derived from glutamic acid, decomposes more quickly by β-elimination, with a first-order rate constant of 24 × 10 -6 s-1 (at 291 K). Reagents 23 and 25, in which the Boc group has been replaced with a trifluoroacetyl group, are more stable toward β-elimination than the corresponding reagents 2 and 3, a striking outcome given that the trifluoroacetamido group is a better leaving group. Moreover, this replacement also changes the mechanism of the elimination to a second order process. Pseudo-second-order rate constants for the Negishi cross-coupling of reagents 2, 3, 23, and 25 with iodobenzene have been determined, revealing the higher reactivity of the glutamic acid-derived reagents 3 and 25. The main factor influencing reactivity, therefore, is determined to be the proximity of the ester group, rather than the nature of the nitrogen protecting group. Finally, β-amino alkylzinc iodides 46-48 containing Weinreb amides have been prepared, rate constants for their decomposition through elimination determined, and their synthetic potential for the preparation of β-amino ketones established.
Optimization of the β-aminoester class of factor Xa inhibitors. Part 1: P4 and side-chain modifications for improved in vitro potency
Czekaj, Mark,Klein, Scott I.,Guertin, Kevin R.,Gardner, Charles J.,Zulli, Allison L.,Pauls, Henry W.,Spada, Alfred P.,Cheney, Daniel L.,Brown, Karen D.,Colussi, Dennis J.,Chu, Valeria,Leadley, Robert J.,Dunwiddie, Christopher T.
, p. 1667 - 1670 (2007/10/03)
A systematic modification of the C3 side-chain of the β-aminoester class of factor Xa inhibitors and a survey of P4 variations is described. These changes have resulted in the identification of sub-nanomolar inhibitors with improved selectivity versus related proteases. Coagulation parameters (i.e., APTT doubling concentrations) are also improved.
