Pyridinium bromochromate has been found to be a highly efficient and selective reagent for the α-monobromination of 1,3- diketones and β-keto-esters in the absence of base, Lewis acid, or other catalyst. The product...Pyridinium bromochromate has been found to be a highly efficient and selective reagent for the α-monobromination of 1,3- diketones and β-keto-esters in the absence of base, Lewis acid, or other catalyst. The products were formed in high to excellent yields under mild reaction conditions and in short reaction times.展开更多
The chemoselective C-and O-prenylation of cyclic 1,3-diketones was achieved by tuning the prenyl source and catalyst.In the presence of the solid acid Nafion,the coupling of 1,3-cyclohexanediones with isoprene gave C-...The chemoselective C-and O-prenylation of cyclic 1,3-diketones was achieved by tuning the prenyl source and catalyst.In the presence of the solid acid Nafion,the coupling of 1,3-cyclohexanediones with isoprene gave C-prenylated 5-chromenones.Alternatively,using prenol as the substrate with the Lewis acid Al Cl3 as the catalyst resulted in the exclusive O-prenylation of 1,3-cyclohexanediones.Notably,the resulting products could easily undergo aromatization to deliver prenylated resorcinols that are otherwise difficult to prepare.Our methodology is highly selective,atom-economical,operationally simple,easily scalable,and has potential applications throughout organic synthesis.展开更多
An efficient magnesium bistrifluoromethanesulfonimide[Mg（NTf_2）_2]catalyzed hydroalkylation of aromatic olefins with 1,3- diketones under solvent-free conditions has been developed.The reactions proceed smoothly to ...An efficient magnesium bistrifluoromethanesulfonimide[Mg（NTf_2）_2]catalyzed hydroalkylation of aromatic olefins with 1,3- diketones under solvent-free conditions has been developed.The reactions proceed smoothly to give the desired products in good yields in short reaction times.展开更多
For the metal-catalyzed asymmetric hydrogenation of α-substituted ketones,cis reductive products are generally obtained due to steric hindrance of substituents.Herein,an unprecedented trans reductive products were ob...For the metal-catalyzed asymmetric hydrogenation of α-substituted ketones,cis reductive products are generally obtained due to steric hindrance of substituents.Herein,an unprecedented trans reductive products were observed in palladium-catalyzed hydrogenative desymmetrization of cyclic and acyclic 1,3-diketones,providing the chiral trans β-hydroxy ketones with two adjacent stereocenters including one α-tertiary or quaternary stereocenter with high enantioselectivity and diastereoselectivity.Mechanistic studies and DFT calculations suggested that the rarely observed diastereoselectivity reversal is ascribed to the charge-charge interaction between the palladium and aromatic ring of the substrate,which could not only result in the reversal of the diastereoselectivity,but also improve the reactivity.展开更多
An efficient protocol for the synthesis of asymmetric 1,3-diketones was reported through diacylation of1,1-diborylalkanes using two different acyl sources.In this transfo rmation,an enolate boron species was initially...An efficient protocol for the synthesis of asymmetric 1,3-diketones was reported through diacylation of1,1-diborylalkanes using two different acyl sources.In this transfo rmation,an enolate boron species was initially formed by introducing an acyl group,then it was trapped by another acyl group to form 1,3-diketone.This method not only provided the gateway to obtain a series of 1,3-diketones,but also afforded an operationally simple and efficient access to pyrazoles and isoxazoles.展开更多
An expedient and economic approach for constructing O,O,N-spiro compounds consisting of both a 1,3-oxazine and a furan ring through a catalyst-free formal[4+1]/[4+2]cycloaddition cascade sequence of isocyanides with t...An expedient and economic approach for constructing O,O,N-spiro compounds consisting of both a 1,3-oxazine and a furan ring through a catalyst-free formal[4+1]/[4+2]cycloaddition cascade sequence of isocyanides with two molecules of acylketene formed in situ through thermal-induced Wolff rearrangement of 2-diazo-1,3-diketones was developed.The reaction displayed good functional group tolerance and was compatible with different isocyanides and 2-diazo-1,3-diketones.Furthermore,preliminary asymmetric attempts of this reaction are made by utilizing optically pure isocyanides as inputs,and moderate diastereomeric induction was observed.展开更多
基金support from the Research Council of Mazandaran University
文摘Pyridinium bromochromate has been found to be a highly efficient and selective reagent for the α-monobromination of 1,3- diketones and β-keto-esters in the absence of base, Lewis acid, or other catalyst. The products were formed in high to excellent yields under mild reaction conditions and in short reaction times.
文摘The chemoselective C-and O-prenylation of cyclic 1,3-diketones was achieved by tuning the prenyl source and catalyst.In the presence of the solid acid Nafion,the coupling of 1,3-cyclohexanediones with isoprene gave C-prenylated 5-chromenones.Alternatively,using prenol as the substrate with the Lewis acid Al Cl3 as the catalyst resulted in the exclusive O-prenylation of 1,3-cyclohexanediones.Notably,the resulting products could easily undergo aromatization to deliver prenylated resorcinols that are otherwise difficult to prepare.Our methodology is highly selective,atom-economical,operationally simple,easily scalable,and has potential applications throughout organic synthesis.
基金financially supported by the Special Scientific Research Project of Shaanxi Education Commission (Nos.09JK332,2010JS069)the Science Research Foundation of Baoji University of Arts and Sciences(No. ZK1053)
文摘An efficient magnesium bistrifluoromethanesulfonimide[Mg（NTf_2）_2]catalyzed hydroalkylation of aromatic olefins with 1,3- diketones under solvent-free conditions has been developed.The reactions proceed smoothly to give the desired products in good yields in short reaction times.
基金supported by the National Natural Science Foundation of China(21871255,21532006,21873096)Chinese Academy of Sciences(XDB17020300,XDB17010200)
文摘For the metal-catalyzed asymmetric hydrogenation of α-substituted ketones,cis reductive products are generally obtained due to steric hindrance of substituents.Herein,an unprecedented trans reductive products were observed in palladium-catalyzed hydrogenative desymmetrization of cyclic and acyclic 1,3-diketones,providing the chiral trans β-hydroxy ketones with two adjacent stereocenters including one α-tertiary or quaternary stereocenter with high enantioselectivity and diastereoselectivity.Mechanistic studies and DFT calculations suggested that the rarely observed diastereoselectivity reversal is ascribed to the charge-charge interaction between the palladium and aromatic ring of the substrate,which could not only result in the reversal of the diastereoselectivity,but also improve the reactivity.
基金the National Natural Science Foundation of China(Nos.91745110,21673261,21603245,21703265,21872156,21802150,21773210 and 21603190)Natural Science Foundation of Jiangsu Province(Nos.BK20190002,BK20181194 and BK20180247)+1 种基金Support from the Young Elite Scientist Sponsorship Program by CAST(No.YESS20170217)the Youth Innovation Promotion Association CAS(No.2018458)。
文摘An efficient protocol for the synthesis of asymmetric 1,3-diketones was reported through diacylation of1,1-diborylalkanes using two different acyl sources.In this transfo rmation,an enolate boron species was initially formed by introducing an acyl group,then it was trapped by another acyl group to form 1,3-diketone.This method not only provided the gateway to obtain a series of 1,3-diketones,but also afforded an operationally simple and efficient access to pyrazoles and isoxazoles.
基金supported by the National Natural Science Foundation of China(21801050)the Scientific Research Project of Guangzhou Municipal Colleges and Universities(201831816)。
文摘An expedient and economic approach for constructing O,O,N-spiro compounds consisting of both a 1,3-oxazine and a furan ring through a catalyst-free formal[4+1]/[4+2]cycloaddition cascade sequence of isocyanides with two molecules of acylketene formed in situ through thermal-induced Wolff rearrangement of 2-diazo-1,3-diketones was developed.The reaction displayed good functional group tolerance and was compatible with different isocyanides and 2-diazo-1,3-diketones.Furthermore,preliminary asymmetric attempts of this reaction are made by utilizing optically pure isocyanides as inputs,and moderate diastereomeric induction was observed.
