AbstractThe classical Lossen rearrangement converts activated hydroxamic acids to isocyanates that form numerous products upon their reaction with nucleophiles. We report a simple and highly efficient method of using Heck reaction conditions to initiate Lossen rearrangements of hydroxamic acids. In addition, Lossen rearrangements occur in the presence of palladium(II) acetate or triethylamine, components of the Heck reaction, alone. A potential mechanism is provided to explain this reactivity and these results show that Heck reactions and Lossen rearrangements occur under the same conditions and may provide new methods for facile initiation of Lossen rearrangements.magnified image
Ureaderivatives are obtained in mild to good yield from the reactions of primary aliphatic amines with CO2 in the absence of any catalysts, organic solvents or other additives. To optimize reaction conditions, experimental variables including temperature, pressure, the concentration of amine, reaction time etc. were studied. Satisfactory yields were obtained at the optimized conditions that are comparable
Lanthanum(III) Trifluoromethanesulfonate Catalyzed Direct Synthesis of Ureas from N-Benzyloxycarbonyl-, N-Allyloxycarbonyl-, and N-2,2,2-Trichloroethoxycarbonyl-Protected Amines
作者:Hee-Kwon Kim、Tien Tan Bui
DOI:10.1055/s-0040-1707991
日期:2020.6
A novel lanthanum triflate mediated conversion of N-benzyloxycarbonyl-, N-allyloxycarbonyl-, and N-trichloroethoxycarbonyl-protected amines into nonsymmetric ureas was discovered. In this study, lanthanum triflate was found to be an effective catalyst for preparing various nonsymmetric ureas from protected amines. A variety of protected aromatic and aliphatic carbamates reacted readily with various
This invention relates to uracil-derived compounds of forumlas(I) and (II) which are agonists of the parathyroid hormone type I receptor (PTH1R) and as such are useful for the treament of osteoporosis.
A high-yielding, expeditious, and multicomponent synthesis of urea and carbamate derivatives by using triphenylphosphine/trichloroisocyanuric acid system
作者:Sara S. E. Ghodsinia、Batool Akhlaghinia
DOI:10.1080/10426507.2015.1085038
日期:2016.1.2
GRAPHICAL ABSTRACT Abstract An efficient method for the synthesis of urea and carbamate derivatives from amines and alcohols is described by using triphenylphosphine (PPh3)/trichloroisocyanuric acid system. The protocol allows for the preparation of symmetrical, unsymmetrical di, tri-, and tetra-substituted ureas and carbamates and is tolerant of a wide range of functional groups. To optimize the reaction
Friedel-Crafts alkylation reactions of benzene with amide bond containing compounds
作者:Kun Hoe Chung、Jae Nyoung Kim、Eung K. Ryu
DOI:10.1016/s0040-4039(00)76658-5
日期:1994.5
The reactions of benzene and various amide derivatives in the presence of anhydrous aluminium chloride or concentrated sulfuric acid have been examined, and found that these amide derivatives could be used as the electrophile sources in the Friedel-Crafts alkylation reactions.