41844-71-7Relevant articles and documents
Urethanes synthesis from oxamic acids under electrochemical conditions
Ogbu, Ikechukwu Martin,Lusseau, Jonathan,Kurtay, Gülbin,Robert, Frédéric,Landais, Yannick
supporting information, p. 12226 - 12229 (2020/10/26)
Urethane synthesis via oxidative decarboxylation of oxamic acids under mild electrochemical conditions is reported. This simple phosgene-free route to urethanes involves an in situ generation of isocyanates by anodic oxidation of oxamic acids in an alcoholic medium. The reaction is applicable to a wide range of oxamic acids, including chiral ones, and alcohols furnishing the desired urethanes in a one-pot process without the use of a chemical oxidant.
Catalysts and temperature driven melt polycondensation reaction for helical poly(ester-urethane)s based on natural L-amino acids
Anantharaj, Santhanaraj,Jayakannan, Manickam
, p. 1065 - 1077 (2016/03/12)
Catalyst and temperature driven melt polycondensation reaction was developed for natural L-amino acid monomers to produce new classes of poly(ester-urethane)s. Wide ranges of catalysts from alkali, alkali earth metal, transition metal and lanthanides were developed for the condensation of amino acid monomers with diols to yield poly(ester-urethane)s. A-B Diblock and A-B-A triblock species were obtained by carefully choosing mono- or diols in model reactions. More than two dozens of transition metal and lanthanide catalysts were identified for the polycondensation to yield high molecular weight poly(ester-urethane)s. Theoretical studies revealed that the carbonyl carbon in ester possessed low electron density compared to the carbonyl carbon in urethane which driven the thermo-selective polymerization process. Optical purity of the L-amino acid residues in the melt polycondensation process was investigated using D- and L-isomers and the resultant products were analyzed by chiral-HPLC and CD spectroscopy. CD analysis revealed that the amino acid based polymers were self-assembled as β-sheet and polyproline type II secondary structures. Electron and atomic force microscopic analysis confirmed the formation of helical nano-fibrous morphology in poly(ester-urethane)s. The newly developed melt polycondensation process is very efficient and optimized for wide range of catalysts to produce diverse polymer structures from natural L-amino acids.
Possible origin of electronic effects in Rh(I)-catalyzed enantioselective hydrogenation
Wu, Hai-Chen,Hamid, Shafida Abd,Yu, Jin-Quan,Spencer, Jonathan B.
supporting information; experimental part, p. 9604 - 9605 (2011/03/19)
(Chemical Equation Presented) Reducing the electron density of ligands switches the regioselectivity of Rh(I)-catalyzed hydrometalation. A reversal of the sense of chiral induction was also observed when chiral ligands are electronically tuned in the same