26342-08-5Relevant articles and documents
NEW 1,2,4-OXADIAZOL DERIVATIVES, PROCESS FOR THEIR PREPARATION AND USE THEREOF AS INTERMEDIATES IN THE PREPARATION OF INDOLIC ALKALOIDS
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Paragraph 0061, (2015/02/25)
The present invention relates in general terms to a variously substituted 1,2,4-oxadiazol derivative, a process for their preparation, and use thereof as an intermediate in the preparation of indolic alkaloids, including phidianidine B and A.
Influence of calcium-induced aggregation on the sensitivity of aminobis(methylenephosphonate)-containing potential MRI contrast agents
Henig, Joerg,Mamedov, Ilgar,Fouskova, Petra,Toth, Eva,Logothetis, Nikos K.,Angelovski, Goran,Mayer, Hermann A.
body text, p. 6472 - 6481 (2011/08/07)
A novel class of 1,4,7,10-tetraazacyclododecane-1,4,7- tris(methylenecarboxylic) acid (DO3A)-based lanthanide complexes with relaxometric response to Ca2+ was synthesized, and their physicochemical properties were investigated. Four macrocyclic ligands containing an alkyl-aminobis(methylenephosphonate) side chain for Ca 2+-chelation have been studied (alkyl is propyl, butyl, pentyl, and hexyl for L1, L2, L3, and L4, respectively). Upon addition of Ca2+, the r1 relaxivity of their Gd3+ complexes decreased up to 61% of the initial value for the best compounds GdL3 and GdL4. The relaxivity of the complexes was concentration dependent (it decreases with increasing concentration). Diffusion NMR studies on the Y3+ analogues evidenced the formation of agglomerates at higher concentrations; the aggregation becomes even more important in the presence of Ca2+. 31P NMR experiments on EuL1 and EuL4 indicated the coordination of a phosphonate to the Ln3+ for the ligand with a propyl chain, while phosphonate coordination was not observed for the analogue bearing a hexyl linker. Potentiometric titrations yielded protonation constants of the Gd 3+ complexes. log KH1 values for all complexes lie between 6.12 and 7.11 whereas log KH2 values are between 4.61 and 5.87. Luminescence emission spectra recorded on the Eu3+ complexes confirmed the coordination of a phosphonate group to the Ln3+ center in EuL1. Luminescence lifetime measurements showed that Ca-induced agglomeration reduces the hydration number which is the main cause for the change in r1. Variable temperature 17O NMR experiments evidenced high water exchange rates on GdL1, GdL2, and GdL3 comparable to that of the aqua ion.
Al-NiCl(2°)6H2O-THF: A new, mild and neutral system for selective reduction of organic functional groups
Sarmah,Barua
, p. 8587 - 8600 (2007/10/02)
A mild and neutral reducing system consisting of Al-NiCl(2°)6H2O-THF has been developed and reacted with a series of organic compounds containing different functional groups in order to evaluate its synthetic utility. It was observed that this system very efficiently reduces the α-enones to the saturated ketones, aromatic aldehydes and ketones to the corresponding alcohols, nitriles and nitroarenes to amines, acid anhydrides and acid chlorides to aldehydes, disulphides to thiols and epoxides to the corresponding alcohols. On the other hand isolated double bonds, carboxylic acids, esters, lactones, primary, benzyl and allyl halides, aliphatic aldehydes and ketones and aliphatic nitro compounds were found to remain inert to this system. Furthermore, the reducing properties of Al-NiCl(2°)6H2O in several other organic solvents were also studied.
