Transition metal-catalyzed unimolecular fragment coupling (UFC) is defined as processes that forge new chemical bonds through the extrusion of molecules, such as CO and CO2, and the subsequent ...recombination of the remaining fragments. Herein, we report on a new UFC reaction that involves the palladium-catalyzed elimination of an isocyanate fragment from an amide, with the formation of carbon–carbon and carbon–heteroatom bonds. An organometallic intermediate that is relevant to the catalytic reaction was characterized by X-ray crystallography. This UFC reaction enables the late-stage transformation of an amide functionality, allowing amides to be used as a convertible directing or protecting group.
We report herein the catalytic conversion of allylic esters into the corresponding ketones by the formal deletion of an oxygen atom. The key to the success of the reaction is the dual use of nickel ...and photoredox catalysts; the former mediates C–O bond activation and C–C bond formation, while the latter is responsible for deoxygenation of the acyloxy group using PPh3 as a stoichiometric reductant. Catalytic replacement of an oxygen atom of an allyl ester with a tethered alkene is also accomplished.
In recent years, geosynthetic clay liners (GCLs) have been used for repair of deteriorated small earth dams because of exhaustion of high quality cohesive soils. However, the design method has not ...been established yet, and the long term performance remains unclear. In this study, in-situ water level measurement has been carried out for about one year in a small earth dam repaired with GCLs to examine the water barrier performance and the phreatic line. In addition to the field measurement, FEM seepage analysis have been performed for this site to estimate the phreatic line. As a result, the water barrier performance of the GCLs sufficiently maintained. Furthermore, it was revealed that the phreatic line rose by more than 1 m due to the heavy rainfall which occurred during this measurement period. As for the numerical analysis, the phreatic line obtained from FEM analysis was good agreement with the observed value, and a comparison of the models with and without GCLs showed the effects of lowering the phreatic line and reducing the leakage.
