Strained bridged rings bicyclo[3.2.1]octane and tricyclo[3.2.1.0^(2,7)]octane are prevalent in natural products known for their significant biological activities.However,strategies for efficiently synthesizing these c...Strained bridged rings bicyclo[3.2.1]octane and tricyclo[3.2.1.0^(2,7)]octane are prevalent in natural products known for their significant biological activities.However,strategies for efficiently synthesizing these complex frameworks from simple starting materials via de novo synthesis remain underexplored.This article presents an efficient strategy that combines phosphine catalysis and photocatalysis to execute a stepwise tandem reaction involving allenoates and α-cyano cinnamaldehydes,including[3+2]cyclization,[5+2]cyclization,acyl transfer,and decarboxylation reactions,synthesizing a series of functional bicyclo[3.2.1]octa-2,6-diene and tricyclo[3.2.1.0^(2,7)]oct-3-ene skeleton derivatives with excellent chemoselectivity demonstrated throughout the process.Meanwhile,the reaction can also be performed via a onepot,scalable phosphine/photocatalytic cascade process,efficiently yielding the bridged products which can serve as versatile intermediates for further applications.展开更多
用HP4294A型阻抗分析仪测量了经不同温度预退火后再540℃退火的Fe73.5Cu1Nb3S i13.5B9纳米晶合金薄带的巨磁阻抗,并结合XRD衍射图谱和AFM图谱,研究了预退火对纳米晶介观结构的影响.结果发现,200℃、300℃和400℃预退火处理40 m in对随后...用HP4294A型阻抗分析仪测量了经不同温度预退火后再540℃退火的Fe73.5Cu1Nb3S i13.5B9纳米晶合金薄带的巨磁阻抗,并结合XRD衍射图谱和AFM图谱,研究了预退火对纳米晶介观结构的影响.结果发现,200℃、300℃和400℃预退火处理40 m in对随后540℃退火的Fe73.5Cu1Nb3S i13.5B9薄带-αFe(S i)纳米晶介观结构产生了影响,颗粒团聚优势明显减弱,横向各向异性场减小,巨磁阻抗比得到了显著的提高.展开更多
The single phase La2（CO3）3·3.4H2 O was synthesized by hydrothermal method. The thermal decomposition and intermediates and final solid products of La2（CO3）3·3.4H2O from 30 to 1000 °C were characteri...The single phase La2（CO3）3·3.4H2 O was synthesized by hydrothermal method. The thermal decomposition and intermediates and final solid products of La2（CO3）3·3.4H2O from 30 to 1000 °C were characterized by XRD, FTIR and DTA-TG. The kinetics of dehydration of La2（CO3）3·3.4H2O in the temperature range of 30-366 °C was investigated under non-isothermal conditions. Flynn-Wall-Ozawa and Friedman isoconversion methods were used to calculate the activation energy and analyze the reaction steps; multivariate non-linear regression program was applied to determine the most probable mechanism and the kinetic parameters. The results show that the thermal dehydration of La2（CO3）3·3.4H2O is a kind of three-step competitive reaction, and controlled by an n-order initial reaction followed by n-order competitive reaction（FnFnFn model）. The activation energy matching with the most probable model is close to value obtained by Friedman method. The fitting curves match the original TG-DTG curves very well.展开更多
基金financial support from National Natural Science Foundation of China(Nos.82374020 and 22401025)Science&Technology Department of Sichuan Province(No.2024NSFTD0023)Xinglin Scholar Research Promotion Project of Chengdu University of TCM。
文摘Strained bridged rings bicyclo[3.2.1]octane and tricyclo[3.2.1.0^(2,7)]octane are prevalent in natural products known for their significant biological activities.However,strategies for efficiently synthesizing these complex frameworks from simple starting materials via de novo synthesis remain underexplored.This article presents an efficient strategy that combines phosphine catalysis and photocatalysis to execute a stepwise tandem reaction involving allenoates and α-cyano cinnamaldehydes,including[3+2]cyclization,[5+2]cyclization,acyl transfer,and decarboxylation reactions,synthesizing a series of functional bicyclo[3.2.1]octa-2,6-diene and tricyclo[3.2.1.0^(2,7)]oct-3-ene skeleton derivatives with excellent chemoselectivity demonstrated throughout the process.Meanwhile,the reaction can also be performed via a onepot,scalable phosphine/photocatalytic cascade process,efficiently yielding the bridged products which can serve as versatile intermediates for further applications.
基金Project(201011005-5)supported by the National Land and Resources Public Welfare Scientific Research Project of ChinaProject(41030426)supported by the National Natural Science Foundation of China+1 种基金Project(20095122110015)supported by Specialized Research Fund for the Doctoral Program of Higher Education of ChinaProject(2010-32)supported by Scientific Research Foundation of the Education Ministry for Returned Chinese Scholars,China
文摘The single phase La2（CO3）3·3.4H2 O was synthesized by hydrothermal method. The thermal decomposition and intermediates and final solid products of La2（CO3）3·3.4H2O from 30 to 1000 °C were characterized by XRD, FTIR and DTA-TG. The kinetics of dehydration of La2（CO3）3·3.4H2O in the temperature range of 30-366 °C was investigated under non-isothermal conditions. Flynn-Wall-Ozawa and Friedman isoconversion methods were used to calculate the activation energy and analyze the reaction steps; multivariate non-linear regression program was applied to determine the most probable mechanism and the kinetic parameters. The results show that the thermal dehydration of La2（CO3）3·3.4H2O is a kind of three-step competitive reaction, and controlled by an n-order initial reaction followed by n-order competitive reaction（FnFnFn model）. The activation energy matching with the most probable model is close to value obtained by Friedman method. The fitting curves match the original TG-DTG curves very well.
