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Substituted cyclohexylamines are becoming increasingly important in drug discovery. Asymmetric Heck insertion/amination of nonconjugated cyclodienes proceeds to give 5-aryl cyclohexenylamines with good enantioselectivity and exclusive trans configurations. Primary and secondary anilines, indoline, and benzylamines are suitable amines. The weakly donating diphosphite Kelliphite forms a deep unsymmetrical pocket, which is essential for stereoselective anti attack of amines. Agency for Science, Technology and Research (A*STAR) Economic Development Board (EDB) Accepted version We acknowledge financial support from Peking UniversityShenzhen Graduate School, Shenzhen Bay Laboratory(21230011-Scripps), Nanyang Technological University,GSK-EDB Trust Fund (2017 GSK-EDB Green and Sustain-able Manufacturing Award) and A*STAR Science andEngineering Research Council (AME IRG A1783c0010).

Gob-side entry retaining (GSER) is a popular no-pillar mining technology that can increase coal recovery rate. We propose the application of high-strength lightweight (HSLW) concrete to construct the gob-side support body (GSSB) in NO. 411 inclined working face of Jingang Coal Mine. Firstly, the mechanical model of retained roadway was established, and the calculation for limit angle of GSSB stability and support resistance was mathematically derived. Using the performance test, the optimal proportion of LC50 concrete was determined as follows: the water-binder ratio was 0.3; the silica fume dosage was not more than 10%; the fly ash dosage was 10–20%; and the sand ratio was 0.45–0.50. Based on theoretical deduction and laboratory analysis, the width of GSSB was obtained to be 0.75 m, and the optimal arrangement of concrete blocks with “two longitudinal and one horizontal, crisscross, and staggered joints” was determined. FLAC3D software was used to study the influence of different widths and material strengths on the surrounding rock deformation and verify the reasonable width and strength of the designed GSSB. Finally, field monitoring of retained roadway shows that the deformation is controlled in a small range, and the retained roadway effect is better, thus proving the feasibility of HSLW for constructing the support body for GSER. Our findings can serve as a theoretical guide for safety and effective implementation of HSLW as GSSB.

A nickel-catalyzed arylation of both aliphatic and aromatic aldehydes proceeds with air-stable (hetero)arylboronic acids, with an exceptionally wide substrate scope. The neutral condition tolerates acidic hydrogen and sensitive polar groups and also preserves α-stereocenters of some chiral aldehydes. Interestingly, this nickel(0) catalysis does not follow common 1,2-insertion of arylmetal species to aldehydes and β-hydrogen elimination.

To solve the difficulty in controlling floor heave of a retained goaf-side roadway, a new control technique was investigated from the perspective of the pressure relief by roof cutting by combining mechanical analysis, numerical simulation, and engineering tests. The mechanical principle of controlling the floor heave based on pressure relief by roof cutting was attained by analyzing the movement of overlying strata and mechanical characteristics of key blocks before and after the roof cutting. A new technique for controlling the floor heave based on pressure relief by roof cutting was proposed. Research results have shown that after performing pressure relief by roof cutting, the caved gangues in the goaf can support the overlying strata and, thereby, change the movement law thereof and weaken the abutment pressure on the coal wall. Furthermore, the pressure exerted on the roadway floor by the coal wall is lowered to prevent plastic deformation of the floor, thus controlling floor heave in the roadway; a new integrated technique for controlling the floor heave based on pressure relief by roof cutting, flexible yielding, controlling with double-direction-control anchor bolts, and controlling with reinforcing anchor cables is developed, and the technological processes of support, cutting, and protection are summarised. The results of field testing showed that, after applying the new technique, the average floor heave amount of the roadway declines by 64% and the average speed of the floor heave up to 231 m behind the working face decreases by 61%.

In this study, the roof-cutting-type gob-side entry retaining is introduced, and its application in medium-thickness coal seams is studied. Based on the analysis of the construction procedure and principle, the mechanical model of the retained roadway structure and cantilever beam formed by roof cutting was established, and the support resistance and roof deformation were obtained. In addition, through technological design analysis and numerical simulation, the parameters of roof cutting were determined. The roof-cutting height and angle were designed to be 9 m and 15°, respectively. Flac3 D was used to analyze the stress evolution law under different mining conditions. The stress on the integrated coal side and roof subsidence was lower when the roof-cutting height was 8∼10 m and the cutting angle was 15°. Through field monitoring, the roof pressure, gob-side lateral gangue retaining pressure, anchor cable stress, and deformation of the surrounding rock eventually reached a stable state. This indicates that the roof cutting can effectively cut down the overlying strata over the gob and form a stable entry structure to meet the requirements of the next working face.

Palladium catalyzes a domino Heck arylation and alkylation of nonconjugated cyclodienes to produce trans isomers of disubstituted cyclohexenes in exceptionally high enantiomeric ratios, reaching 100:1 to 200:1 in many cases. Importantly, the interactions of the two CF bonds of Josiphos and the sodium ion of malonates facilitates stereoselective allylic attack through DFT calculations and experiments. This is a new type of attractive noncovalent interactions found in organometallic catalysis. Economic Development Board (EDB) Nanyang Technological University We acknowledge financial support from Peking University Shenzhen Graduate School and Shenzhen Bay Laboratory for J.S.Z.; the National Natural Science Foundation of China (NSFC 21933004) for Y.-D.W.; Nanyang Technological University and GlaxoSmithKline and the Singapore Economic Development Board Trust Fund (2017 GSK-EDB Green & Sustainable Manufacturing Award) for Y.R.C.

The effects of roof cutting techniques on the movement law of the overlying strata and deformation features of the surrounding rock in gob-side entry retaining mines were studied using 200 working faces of the Dianping coal mine in Shanxi Province. Using a mechanical analysis, a cantilever beam model formed by roof cutting was used to derive a deformation equation. The physical model test based on the field prototype revealed an asymmetrically distributed displacement curve and reduced collapse displacement when the rock stratum was far from the cutting seam. Outside of the roof cutting height, the collapse of the overlying strata gradually reached a symmetric distribution with increasing height. The deformation of the retained roadway was mainly concentrated on the roof, and the maximum deformation was 14 mm near the roof cutting side. A numerical simulation of the original size of the model test proved that the laws of strata movement and surrounding rock deformation were consistent with the physical test results. Finally, field measurements were performed, which verified the rationality of this study.

In order to explore the monitoring and control method of rock slope, indoor physical model testing of collapse control and monitoring were carried out with the example of a rock slope collapse area project in Jietai Temple in Beijing, China, as the prototype. Based on the similarity theory, in this study, a new structural support with Negative Poisson’s Ratio bolt and flexible anchored net was utilized to reinforce the rock slope. Following a graded loading sequence, the collapse failure characteristics and the overall control effect of energy absorption reinforcement measures were explored. The experimental results demonstrated that the entire process of slope collapse presented four distinct stages of failure: fracture generation, fracture propagation, partial collapse, and overall collapse. The full-field displacement nephogram and the displacement monitoring point of the collapse area indicated that the large deformation and failure of the collapsed surrounding rock were effectively controlled, while the Negative Poisson’s Ratio bolt and the flexible anchored net had good reinforcement effects. The experimental stress record presented that the change of pressure curve was an apparent regularity in the entire process of slope collapse, which reflects the change state of internal force of surrounding rock; it includes the function of monitoring of slope collapse. It was indicated that the Negative Poisson’s Ratio bolt along with the large-deformation flexible anchored net had good reinforcement monitoring effect on the rock slope collapse disaster.

Coal is among the most important energy sources, and gob-side entry retention by roof cutting (GERRC) is an innovative non-pillar mining technique that can effectively increase coal recovery rates and avoid coal wastage. To investigate the characteristics of mine strata pressure using the GERRC technique, a field case study under conditions involving a medium-thick coal seam and a compound roof was performed, and the mine strata behavior mechanisms were studied by theoretical analysis. Field monitoring shows that the distributions of the weighting step and strength along the longwall working face are asymmetrical. The periodic weighting length on the entry retaining side is longer than that on the other sides of the longwall working face, and the average increase is appropriately 4 m. Compared to the other sides of the longwall, on the entry retaining side, the periodic weighting strength is weaker, the average pressure is reduced by 2.1 MPa, and the peak pressure is reduced by 10.2 MPa. The lateral distance affected by roof cutting along the longwall is approximately 29.75 m, and the closer to the cutting slit, the more significant the roof cutting effect is. The retained entry becomes stable when it is more than 230 m behind the mining face, and the final cross section of the retained entry can meet the reuse demand of the next mining face. Theoretical analysis shows that the roof pressure mechanism in GERRC can be explained using cantilever beam theory. Within the area affected by roof cutting, the thickness of the immediate roof increases, and the suspension plate length of the roof immediately behind the longwall decreases. Then, the gangue pile in the goaf behind the longwall formed by the immediate roof&rsquo, s collapse and expansion can support the main roof and other overlying strata much better. Therefore, the rotational breaking angle of the main roof is smaller, the periodic weighting step strength increases, and the periodic weighting decreases. According to the structural state of the surrounding rocks during the entire entry retaining process, the retained entry can be divided into coal support, dynamic pressure and stable entry areas.