An intriguing Brønsted acid-catalyzed 1,6-hydrophosphination of in situ generated propargylic para-quinone methides(p-QMs)and aza-para-quinone methides(aza-p-QMs)with H-phosphorus oxides via dehydration/1,6-addit...An intriguing Brønsted acid-catalyzed 1,6-hydrophosphination of in situ generated propargylic para-quinone methides(p-QMs)and aza-para-quinone methides(aza-p-QMs)with H-phosphorus oxides via dehydration/1,6-addition under ultrasonic irradiation is described.This methodology provides a rapid and green approach for the construction of diarylmethyl phosphorus oxides bearing phosphorus-substituted quaternary carbon centers in high yields(up to 98%yield)within merely 5min.This environmentally benign protocol represents a unique example of 1,6-conjugate additions of propargylic p-QMs and aza-p-QMs for site-selective C-P bond formation in an operationally simple and atom-economical manner.The use of readily available Brønsted acid catalyst,operationally simplicity,high yields,and high atom economy make this protocol very facile,practical,easily scaled-up and environmentally friendly.展开更多
The transition-metal-catalyzed migratory functionalization has emerged as a robust protocol for the building of C–C bonds remote from the“initiation”position.However,a similar strategy for the construction of quate...The transition-metal-catalyzed migratory functionalization has emerged as a robust protocol for the building of C–C bonds remote from the“initiation”position.However,a similar strategy for the construction of quaternary carbon centers is still underdeveloped and only a limited number of reports exist.Herein,we report a nickel-catalyzed migratory hydrocyanation of unconjugated dienes to construct remote cyano-substituted quaternary carbon centers.This transformation features exceptional regioselectivity,mild reaction conditions,broad substrate scope and high yields.The synthetic utility of this method has been highlighted by a series of product derivatizations,and the potential of this transformation has been extended to synthesize TRPV1 antagonist and the key intermediate in the total synthesis of quebrachamine.Density functional theory(DFT)studies unveiled that the specific catalytic pocket assumed a significant role in the selective formation of cyano-substituted quaternary carbon centers.展开更多
Tartaric acid, oxalic acid, glucose, and fructose are highly important compounds. A comprehensive study of these substances is fascinating from a scientific perspective. They are key components found in wine, vegetabl...Tartaric acid, oxalic acid, glucose, and fructose are highly important compounds. A comprehensive study of these substances is fascinating from a scientific perspective. They are key components found in wine, vegetables, and fruits. Understanding the isotopic compositions in organic compounds is crucial for comprehending various biochemical processes and the nature of substances present in different natural products. Tartaric acid, oxalic acid, glucose, and fructose are widely distributed compounds, including in vegetables and fruits. Tartaric acid plays a significant role in determining the quality and taste properties of wine, while oxalic acid is also prevalent but holds great interest for further research, especially in terms of carbon isotopic composition. We can unveil the mechanisms of processes that were previously impossible to study. Glucose and fructose are the most common monosaccharides in the hexose group, and both are found in fruits, with sweeter fruits containing higher amounts of these substances. In addition to fruits, wheat, barley, rye, onions, garlic, lentils, peppers, dried fruits, beans, broccoli, cabbage, tomatoes, and other foods are also rich sources of fructose and glucose. To determine the mass fraction of the carbon-13 isotope in these compounds, it is important to study their changes during natural synthesis. These compounds can be modified with a carbon center. According to the existing isotopic analysis method, these compounds are converted into carbon oxide or dioxide [1]. At this point, the average carbon content in the given compound is determined, but information about isotope-modified centers is lost. Dilution may occur through the transfer of other carbon-containing organic compounds in the sample or by dilution with natural carbon or carbon dioxide during the transfer process. This article discusses the possibility of carbon-13 isotope propagation directly in these compounds, both completely modified and modified with individual carbon centers. The literature provides information on determining carbon-13 substance in organic compounds, both with a general approach and for individual compounds [2] [3].展开更多
A NHC-catalyzed hypervalent iodine reagents and transition-metal free redox-neutral dearomatization of phenols is reported.This protocol provides an efficient access for highly congested quaternatry carbon centers con...A NHC-catalyzed hypervalent iodine reagents and transition-metal free redox-neutral dearomatization of phenols is reported.This protocol provides an efficient access for highly congested quaternatry carbon centers construction.It also features operationally simplicity,mild reaction conditions and good functional group tolerance.Moreover,the reported procedure can be easily emplified to 1 g scale.Mechanism study reveals the dearomative transformation possibly undergoes a single electron transfer process with NHC radical cation as a reactive intermediate.展开更多
It has become a common pursuit of designers to construct comfortable,energy-conserving,high-efficiency and natural living environment since the early 21st century.In the coming low-carbon age,the evolution of low-carb...It has become a common pursuit of designers to construct comfortable,energy-conserving,high-efficiency and natural living environment since the early 21st century.In the coming low-carbon age,the evolution of low-carbon concepts will surely bring positive influence on the present planning concepts of residential community,and meanwhile,propose higher requirements on the natural and ecological properties of residential community,such as its infrastructure construction,traffic organization,environment greening and so on.Through analyzing relevant concepts of low carbon,the authors studied the development of low-carbon concepts in "human-centered" designs,and its applications in architecture,traffic and green spaces.This study proposed that the improvement of low-carbon society could be started from the design of low-carbon residential communities,so as to satisfy the increasing ecological needs of people on living environment,and play a promotional role in facilitating the sustainable development of society.展开更多
We present the first findings of the new electrically- and optically-detected magnetic resonance technique [ED electron spin resonance (EDESR) and (ODMR)] which reveal single point defects in the ultra-narrow silicon ...We present the first findings of the new electrically- and optically-detected magnetic resonance technique [ED electron spin resonance (EDESR) and (ODMR)] which reveal single point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor δ-barriers. This technique allows the ESR identification without the application of the external cavity as well as a high frequency source and recorder, with measuring the only magnetoresistance (EDESR) and transmission (ODMR) spectra within frameworks of the excitonic normal-mode coupling (NMC) caused by the microcavities embedded in the Si-QW plane. The new resonant positive magnetoresistance data are interpreted here in terms of the interference transition in the diffusive transport of free holes respectively between the weak antilocalization regime in the region far from the ESR of a paramagnetic point defect located inside or near the conductive channel and the weak localization regime in the nearest region of the ESR of that defect.展开更多
基金We are grateful for financial support from the National Natural Science Foundation of China(No.21762005)Natural Science Foundation of Guangxi Province(No.2021GXNSFDA075005).
文摘An intriguing Brønsted acid-catalyzed 1,6-hydrophosphination of in situ generated propargylic para-quinone methides(p-QMs)and aza-para-quinone methides(aza-p-QMs)with H-phosphorus oxides via dehydration/1,6-addition under ultrasonic irradiation is described.This methodology provides a rapid and green approach for the construction of diarylmethyl phosphorus oxides bearing phosphorus-substituted quaternary carbon centers in high yields(up to 98%yield)within merely 5min.This environmentally benign protocol represents a unique example of 1,6-conjugate additions of propargylic p-QMs and aza-p-QMs for site-selective C-P bond formation in an operationally simple and atom-economical manner.The use of readily available Brønsted acid catalyst,operationally simplicity,high yields,and high atom economy make this protocol very facile,practical,easily scaled-up and environmentally friendly.
基金the National Natural Science Foundation of China(22278265,U22B20137 and 22203069)the Zhejiang Provincial Natural Science Foundation of China(LR24B020002)+1 种基金the start-up funding from Hangzhou Normal University(4095C50222204165 and 4095C50223204074)the Interdisciplinary Research Project of Hangzhou Normal University(2024JCXK04)for financial support of this research。
文摘The transition-metal-catalyzed migratory functionalization has emerged as a robust protocol for the building of C–C bonds remote from the“initiation”position.However,a similar strategy for the construction of quaternary carbon centers is still underdeveloped and only a limited number of reports exist.Herein,we report a nickel-catalyzed migratory hydrocyanation of unconjugated dienes to construct remote cyano-substituted quaternary carbon centers.This transformation features exceptional regioselectivity,mild reaction conditions,broad substrate scope and high yields.The synthetic utility of this method has been highlighted by a series of product derivatizations,and the potential of this transformation has been extended to synthesize TRPV1 antagonist and the key intermediate in the total synthesis of quebrachamine.Density functional theory(DFT)studies unveiled that the specific catalytic pocket assumed a significant role in the selective formation of cyano-substituted quaternary carbon centers.
文摘Tartaric acid, oxalic acid, glucose, and fructose are highly important compounds. A comprehensive study of these substances is fascinating from a scientific perspective. They are key components found in wine, vegetables, and fruits. Understanding the isotopic compositions in organic compounds is crucial for comprehending various biochemical processes and the nature of substances present in different natural products. Tartaric acid, oxalic acid, glucose, and fructose are widely distributed compounds, including in vegetables and fruits. Tartaric acid plays a significant role in determining the quality and taste properties of wine, while oxalic acid is also prevalent but holds great interest for further research, especially in terms of carbon isotopic composition. We can unveil the mechanisms of processes that were previously impossible to study. Glucose and fructose are the most common monosaccharides in the hexose group, and both are found in fruits, with sweeter fruits containing higher amounts of these substances. In addition to fruits, wheat, barley, rye, onions, garlic, lentils, peppers, dried fruits, beans, broccoli, cabbage, tomatoes, and other foods are also rich sources of fructose and glucose. To determine the mass fraction of the carbon-13 isotope in these compounds, it is important to study their changes during natural synthesis. These compounds can be modified with a carbon center. According to the existing isotopic analysis method, these compounds are converted into carbon oxide or dioxide [1]. At this point, the average carbon content in the given compound is determined, but information about isotope-modified centers is lost. Dilution may occur through the transfer of other carbon-containing organic compounds in the sample or by dilution with natural carbon or carbon dioxide during the transfer process. This article discusses the possibility of carbon-13 isotope propagation directly in these compounds, both completely modified and modified with individual carbon centers. The literature provides information on determining carbon-13 substance in organic compounds, both with a general approach and for individual compounds [2] [3].
基金supported by the“Fundamental Research Funds for the Central Universities”(Nos.21620318 and 2019QNGG22)the“Guangdong Basic and Applied Basic Research Fund”(No.2021A1515012023)“the Open Fund of Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications”(No.2020B121201005).
文摘A NHC-catalyzed hypervalent iodine reagents and transition-metal free redox-neutral dearomatization of phenols is reported.This protocol provides an efficient access for highly congested quaternatry carbon centers construction.It also features operationally simplicity,mild reaction conditions and good functional group tolerance.Moreover,the reported procedure can be easily emplified to 1 g scale.Mechanism study reveals the dearomative transformation possibly undergoes a single electron transfer process with NHC radical cation as a reactive intermediate.
文摘It has become a common pursuit of designers to construct comfortable,energy-conserving,high-efficiency and natural living environment since the early 21st century.In the coming low-carbon age,the evolution of low-carbon concepts will surely bring positive influence on the present planning concepts of residential community,and meanwhile,propose higher requirements on the natural and ecological properties of residential community,such as its infrastructure construction,traffic organization,environment greening and so on.Through analyzing relevant concepts of low carbon,the authors studied the development of low-carbon concepts in "human-centered" designs,and its applications in architecture,traffic and green spaces.This study proposed that the improvement of low-carbon society could be started from the design of low-carbon residential communities,so as to satisfy the increasing ecological needs of people on living environment,and play a promotional role in facilitating the sustainable development of society.
文摘We present the first findings of the new electrically- and optically-detected magnetic resonance technique [ED electron spin resonance (EDESR) and (ODMR)] which reveal single point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor δ-barriers. This technique allows the ESR identification without the application of the external cavity as well as a high frequency source and recorder, with measuring the only magnetoresistance (EDESR) and transmission (ODMR) spectra within frameworks of the excitonic normal-mode coupling (NMC) caused by the microcavities embedded in the Si-QW plane. The new resonant positive magnetoresistance data are interpreted here in terms of the interference transition in the diffusive transport of free holes respectively between the weak antilocalization regime in the region far from the ESR of a paramagnetic point defect located inside or near the conductive channel and the weak localization regime in the nearest region of the ESR of that defect.
