The conjugate addition of in-situ generated(aza-)quinone methides(QMs)and indole imine methides(IIMs)emerged as a powerful protocol to access densely functionalized benzenes and indoles.Hydroxybenzyl alcohols,aminoben...The conjugate addition of in-situ generated(aza-)quinone methides(QMs)and indole imine methides(IIMs)emerged as a powerful protocol to access densely functionalized benzenes and indoles.Hydroxybenzyl alcohols,aminobenzhydryl alcohols,and varied indolylmethanols served as most effective precursors for the in-situ generation of such reactive species under acid conditions.The relevant propargylic alcohol has proven to be an elegant precursor to generate the propargylic-QMs and-IIMs via the acid promoted dehydration process,thus enabling diverse challenging remote activation to proceed conjugate1,6-and 1,8-additions.Moreover,the heteroarene has proven to be workable to transfer the LUMO of the p-QMs and 2-IIMs,thus inducing the remote nucleophilic dearomative additions.The conjugate additions of(aza-)p-QMs and varied IIMs has made significant contribution in the field of remote activation chemistry in past decade.This review summarizes the latest advances of the remote conjugate additions of the in-situ generated QMs and IIMs.展开更多
The effect of deep cryogenic treatment(DCT)on the electrochemical behavior of Ti-6Al-4V alloy in Hank's solution was experimentally investigated in the present work.Deep cryogenic treatments at-196℃soaking for 24...The effect of deep cryogenic treatment(DCT)on the electrochemical behavior of Ti-6Al-4V alloy in Hank's solution was experimentally investigated in the present work.Deep cryogenic treatments at-196℃soaking for 24(DCT-24) and 48(DCT-48) hours were conducted on the commercial annealed Ti-6Al-4V alloy.The methods of polarization and electrochemical impedance spectroscopy(EIS) were employed to evaluate the electrochemical behavior and corrosion mechanism.Furthermore,atomic force microscopy(AFM) was used to detect the corrosion surface.The results showed that deep cryogenic treatment shifted the corrosion potentials(E_(corr))to the positive direction.The corrosion current densities(i_(corr))of samples treated by DCT-24 and DCT-48decreased from 153.1 nA·cm^(-2) in the untreated(UT)sample to 86.3 nA·cm^(-2) and 43.3 nA·cm^(-2),respectively.Furthermore,the roughness of corrosion surfaces of samples subjected to DCT was smaller than that of the UT sample,which indeed demonstrated the improvement in corrosion resistance of Ti-6Al-4V alloy in Hank's solution.The results of EIS test indicated that deep cryogenic treatment had no influence on the corrosion mechanism of Ti-6Al-4V alloy in Hank's,while enhanced resistance value of outer porous layer R_p,which makes the surface more efficient to prevent the corrosion.The reduction of β-phase particles,improvement in dislocation density and release of residual stress caused by deep cryogenic treatment had great contribution to the improvement in corrosion resistance of Ti-6Al-4V alloy in Hank's solution.展开更多
Quenching partitioning tempering （QP-T） process were applied to a quenched carbide-free bainite/mar- tensite （CFB/M） multiphase steel 40Mn2Si2Cr and its effect on the mechanical properties was studied. The results...Quenching partitioning tempering （QP-T） process were applied to a quenched carbide-free bainite/mar- tensite （CFB/M） multiphase steel 40Mn2Si2Cr and its effect on the mechanical properties was studied. The results showed that the partitioning time of Q P T treatment can he increased greatly to 90 min or even longer. The tensile strength, elongation and product of strength and elongation （PSE） of the experimental steel can achieve 1650 MPa, about 20% and over 33 GPa ·%, respectively. The significant increase of partitioning time and excellent mechanical properties could be related to the CFB microstrueture introduced in the quenching process during the Q-P-T treat- ment.展开更多
A mild and efficient dearomatic [3＋2] annulation reaction of 3-nitro-7-azaindoles and Morita Baylis Hillman carbonates from isatins was developed catalyzed by DMAP, affording the corresponding polycyclic spirooxindol...A mild and efficient dearomatic [3＋2] annulation reaction of 3-nitro-7-azaindoles and Morita Baylis Hillman carbonates from isatins was developed catalyzed by DMAP, affording the corresponding polycyclic spirooxindoles containing fused azaindoline architectures and vicinal quaternary centers in excellent yields（up to 96%） with high regio- and diastereoselectivity（dr 〉 19：1）. Moderate enantioselectivity（79% ee） was obtained by employing a chiral DMAP-type Lewis base catalyst.展开更多
基金the financial support from the National Natural Science Foundation of China(No.22001216)the Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province(No.CSPC202315)+2 种基金the Science and Technology Department of Sichuan Province,China(No.2022NSFSC1203)the Higher Education Institution Key Research Project Plan of Henan Province(No.24B150031)the Program for Youth Backbone Teacher Training in University of Henan Province(No.2021GGJS163)。
文摘The conjugate addition of in-situ generated(aza-)quinone methides(QMs)and indole imine methides(IIMs)emerged as a powerful protocol to access densely functionalized benzenes and indoles.Hydroxybenzyl alcohols,aminobenzhydryl alcohols,and varied indolylmethanols served as most effective precursors for the in-situ generation of such reactive species under acid conditions.The relevant propargylic alcohol has proven to be an elegant precursor to generate the propargylic-QMs and-IIMs via the acid promoted dehydration process,thus enabling diverse challenging remote activation to proceed conjugate1,6-and 1,8-additions.Moreover,the heteroarene has proven to be workable to transfer the LUMO of the p-QMs and 2-IIMs,thus inducing the remote nucleophilic dearomative additions.The conjugate additions of(aza-)p-QMs and varied IIMs has made significant contribution in the field of remote activation chemistry in past decade.This review summarizes the latest advances of the remote conjugate additions of the in-situ generated QMs and IIMs.
基金financially supported by the Beijing Natural Science Foundation (No.2164072)the Youth Innovation Promotion Association of CAS (No.2016021)the Key Laboratory of Cryogenics,TIPC,CAS (No.CRYOQN201504)。
文摘The effect of deep cryogenic treatment(DCT)on the electrochemical behavior of Ti-6Al-4V alloy in Hank's solution was experimentally investigated in the present work.Deep cryogenic treatments at-196℃soaking for 24(DCT-24) and 48(DCT-48) hours were conducted on the commercial annealed Ti-6Al-4V alloy.The methods of polarization and electrochemical impedance spectroscopy(EIS) were employed to evaluate the electrochemical behavior and corrosion mechanism.Furthermore,atomic force microscopy(AFM) was used to detect the corrosion surface.The results showed that deep cryogenic treatment shifted the corrosion potentials(E_(corr))to the positive direction.The corrosion current densities(i_(corr))of samples treated by DCT-24 and DCT-48decreased from 153.1 nA·cm^(-2) in the untreated(UT)sample to 86.3 nA·cm^(-2) and 43.3 nA·cm^(-2),respectively.Furthermore,the roughness of corrosion surfaces of samples subjected to DCT was smaller than that of the UT sample,which indeed demonstrated the improvement in corrosion resistance of Ti-6Al-4V alloy in Hank's solution.The results of EIS test indicated that deep cryogenic treatment had no influence on the corrosion mechanism of Ti-6Al-4V alloy in Hank's,while enhanced resistance value of outer porous layer R_p,which makes the surface more efficient to prevent the corrosion.The reduction of β-phase particles,improvement in dislocation density and release of residual stress caused by deep cryogenic treatment had great contribution to the improvement in corrosion resistance of Ti-6Al-4V alloy in Hank's solution.
基金Item Sponsored by National Natural Science Foundation of China(51271013)Key Project of Chinese Ministry of Railways(2012G011-C)Central College Basic Scientific Research Business Expenses Special Funds of China(2011JBZ021)
文摘Quenching partitioning tempering （QP-T） process were applied to a quenched carbide-free bainite/mar- tensite （CFB/M） multiphase steel 40Mn2Si2Cr and its effect on the mechanical properties was studied. The results showed that the partitioning time of Q P T treatment can he increased greatly to 90 min or even longer. The tensile strength, elongation and product of strength and elongation （PSE） of the experimental steel can achieve 1650 MPa, about 20% and over 33 GPa ·%, respectively. The significant increase of partitioning time and excellent mechanical properties could be related to the CFB microstrueture introduced in the quenching process during the Q-P-T treat- ment.
基金financial support from the NSFC(21572135 and 21321061)
文摘A mild and efficient dearomatic [3＋2] annulation reaction of 3-nitro-7-azaindoles and Morita Baylis Hillman carbonates from isatins was developed catalyzed by DMAP, affording the corresponding polycyclic spirooxindoles containing fused azaindoline architectures and vicinal quaternary centers in excellent yields（up to 96%） with high regio- and diastereoselectivity（dr 〉 19：1）. Moderate enantioselectivity（79% ee） was obtained by employing a chiral DMAP-type Lewis base catalyst.
