6943-00-6Relevant articles and documents
Studies of hydrogen isotope scrambling during the dehalogenation of aromatic chloro-compounds with deuterium gas over palladium catalysts
Lockley, William J.S.,Venanzi, Niccolò A. E.,Crane, Georgie J.
, p. 531 - 552 (2020/09/22)
Catalytic dehalogenation of aromatic halides using isotopic hydrogen gas is an important strategy for labelling pharmaceuticals, biochemicals, environmental agents and so forth. To extend, improve and further understand this process, studies have been carried out on the scrambling of deuterium isotope with protium during the catalytic deuterodehalogenation of model aryl chlorides using deuterium gas and a palladium on carbon catalyst in tetrahydrofuran solution. The degree of scrambling was greatest with electron-rich chloroarene rings. The tetrahydrofuran solvent and the triethylamine base were not the source of the undesired protium; instead, it arose, substantially, from the water content of the catalyst, though other sources of protium may also be present on the catalyst. Replacement of the Pd/C catalyst with one prepared in situ by reduction of palladium trifluoroacetate with deuterium gas and dispersed upon micronised polytetrafluoroethylene led to much reduced scrambling (typically 0–6% compared with up to 40% for palladium on carbon) and to high atom% abundance, regiospecific labelling. The improved catalytic system now enables efficient polydeuteration via the dehalogenation of polyhalogenated precursors, making the procedure viable for the preparation of MS internal standards and, potentially, for high specific activity tritium labelling.
A one pot protocol to convert nitro-arenes into: N-aryl amides
Massolo, Elisabetta,Pirola, Margherita,Puglisi, Alessandra,Rossi, Sergio,Benaglia, Maurizio
, p. 4040 - 4044 (2020/02/04)
A two-step one pot, experimentally simple protocol, based on readily available and inexpensive reagents allowed the conversion of nitro-arenes directly to N-aryl amides. A metal-free reduction of the nitro group, mediated by trichlorosilane, followed by the addition of an anhydride afforded the corresponding N-aryl carboxyamide, that was isolated after a simple aqueous work up in good-excellent yields. When the methodology was applied to the reaction with γ-butyrolactone, the desired N-aryl butanamide derivative was obtained, featuring a chlorine atom at the γ-position, a functionalized handle that can be used for further synthetic manipulation of the reaction product. Such an intermediate has already been employed as a key advanced precursor of pharmaceutically active compounds.
Synthesis of 3-(5-amino-1: H -1,2,4-triazol-3-yl)propanamides and their tautomerism
Lim, Felicia Phei Lin,Tan, Lin Yuing,Tiekink, Edward R. T.,Dolzhenko, Anton V.
, p. 22351 - 22360 (2018/07/03)
Two complementary pathways for the preparation of N-substituted 3-(5-amino-1H-1,2,4-triazol-3-yl)propanamides (5) were proposed and successfully realized in the synthesis of 20 representative examples. These methods use the same types of starting material
