Exceedingly fast preparation of trifluoromethyl tertiary alcohols has been accomplished from methyl ketones and trifluoromethyl ketones under solvent free conditions by cross Aldol reaction. The reaction was achieved ...Exceedingly fast preparation of trifluoromethyl tertiary alcohols has been accomplished from methyl ketones and trifluoromethyl ketones under solvent free conditions by cross Aldol reaction. The reaction was achieved in the presence of common inorganic base by grinding method at ambient temperature to give b-trifluoromethyl-b-hydroxyl ketones in high yields（up to 95%）.展开更多
Tertiary alcohols are generally considered difficult to oxidize.However,in this work,it was found that catalyzed by (NH_(4))_(2)Ce(NO_(3))_(6)(CAN)and in the presence of catalytic trifluoroacetic acid(TFA),the selecti...Tertiary alcohols are generally considered difficult to oxidize.However,in this work,it was found that catalyzed by (NH_(4))_(2)Ce(NO_(3))_(6)(CAN)and in the presence of catalytic trifluoroacetic acid(TFA),the selective oxidative C-C bond cleavage of tertiary alcohols could be achieved using O_(2) flow to produce carbonyl compounds.The benefits of this method include the use of simple and inexpensive catalysts,as well as the environmentally friendly nature of the process.This research significantly broadens the scope of alcohol oxidation chemistry.Since alcohol oxidation reactions involving C-C bond cleavage have potential applications as the key unit reaction in certain industrial processes,this finding holds significant promise for organic chemical engineering.展开更多
We report the first highly diastereo-and enantioselective C-C bond-forming reaction of racemic α-branched ketones to construct tertiary alcohols with adjacent stereocenters.Accordingly,a highly stereoselective cyanos...We report the first highly diastereo-and enantioselective C-C bond-forming reaction of racemic α-branched ketones to construct tertiary alcohols with adjacent stereocenters.Accordingly,a highly stereoselective cyanosilylation of racemic ketones is developed using our bifunctional cyanating reagent,Me_(2)(CH_(2)Cl)SiCN,giving C^(α)-tetrasubstituted silyl cyanohydrins withtwovicinal stereocenters inupto>20:1 diastereomeric ratio(dr)and 90-98% enantiomeric excess(ee)values,which can undergo various diversification reactions bymanipulating the chloromethyl group.A highly selective kinetic resolution of acyclicα-branched ketones is also developed that allows facile access to acyclic α-alkyl,allyl,and propargyl ketones with good recovery and excellent ee values.The synthetic value of this protocol is further demonstrated by the formal synthesis of the anti-obesity agent,taranabant(MK-0364).The activation of Jacobsen’s privileged catalyst(salen)AlCl by a suitable phosphorane plays a crucial role in the reaction.X-ray crystallographic analysis of single crystals of phosphorane-(salen)AlCl complexes and theoretical calculations help provide a working model.The present transformation opens a new path for the catalytic stereoselective synthesis of stereochemically complex tertiary alcohols featuring two stereocenters(adjacent or not)from racemic ketones.展开更多
The present work contributed to a new developed production method for enhancing the quality of isoamylene （IA） by adding a small amount of tertiary amyl alcohol （TAA） to the catalyst of strong acid cation exchange...The present work contributed to a new developed production method for enhancing the quality of isoamylene （IA） by adding a small amount of tertiary amyl alcohol （TAA） to the catalyst of strong acid cation exchange resin. TAA improved the selectivity of 2-methyl-2-butene （2M2B） at a high conversion level for the isomerization of IA. Compared with the other results from the current IA units, the conversion of 2-methyl- 1-butene （2M1B）, the mass ratio of 2M2B to 2M1B and the selectivity of 2M2B were increased from 0.5474, 7.32 and 0.6864 to 0.72, 12 and 0.95, respectively, while the dimers content in the products decreased from 4.38% to below 1.0%. Optimized conditions for IA isomerization consisted of temperature between 28 and 33℃ and system pressure of 0.5 MPa, weight hourly space velocity of 8.0 h-1 with TAA mass fraction of 0.7%-0.9% in raw material. The results in lab supported bases for the developed process in industrial application which was later proved to be successful. In addition, a possible mechanism of the isomerization process was speculated to propose a key step of water formation in the TAA-added isomerization process and a verified experiment was conducted to support this speculation.展开更多
A complete study of the asymmetric addition of phenylacetylene to ketones catalyzed by Schiff-base amino alcohol-Zn complex is reported in this article. The Schiff-base amino alcohols were easily prepared from amino a...A complete study of the asymmetric addition of phenylacetylene to ketones catalyzed by Schiff-base amino alcohol-Zn complex is reported in this article. The Schiff-base amino alcohols were easily prepared from amino acids in three steps. When the amount of ligand was 1%（molar fraction）, an e.e. value up to 94% was obtained. A series of practical chiral ligands were applied in the enantioselective addition of phenylacetylene to ketones without adding another stronger Lewis acid except zinc.展开更多
The easily prepared and recoverable chiral N-sulfonylated fl-amino alcohol 2 in combination with Ti（OPr-i）4 was found to be an effective chiral catalyst for the enantioselective addition of alkynylzinc to ketones, w...The easily prepared and recoverable chiral N-sulfonylated fl-amino alcohol 2 in combination with Ti（OPr-i）4 was found to be an effective chiral catalyst for the enantioselective addition of alkynylzinc to ketones, which gave the useful products, i.e. chiral tertiary propargyl alcohols, with the ee up to 92%.展开更多
A photocatalytic process was developed for intermolecular reductive coupling of aliphatic ketones with alkynes/alkenes to furnish tertiary alcohols.Mechanistic studies support that boron carbonitrides(BCN)promote the ...A photocatalytic process was developed for intermolecular reductive coupling of aliphatic ketones with alkynes/alkenes to furnish tertiary alcohols.Mechanistic studies support that boron carbonitrides(BCN)promote the single electron reduction of unactivated aliphatic ketones to generate ketyl radicals with visible light irradiation,which then react with alkynes and alkenes to afford the allylic and aliphatic alcohols,respectively.The heterogeneous photocatalytic system is compatible with diverse substrates including pharmaceutical-related molecules(43 examples)with reusability and scale-up experiments,verifying the complementary synthetic utility of this method to the homogeneous catalysts.展开更多
C(CO)–alkyl bonds are ubiquitous in a variety of organic molecules,and their selective activation and functionalization are important for the reconstruction of simple ketones into valuable building blocks.However,due...C(CO)–alkyl bonds are ubiquitous in a variety of organic molecules,and their selective activation and functionalization are important for the reconstruction of simple ketones into valuable building blocks.However,due to the thermodynamic and kinetic stability,the cleavage and transformation of the unstrained C(CO)–alkyl bonds remain a significant challenge.Herein,we report a novel silver-catalyzed scission of the unstrained C(CO)–alkyl bond of ketones by reacting with N-isocyanoiminotriphenylphosphorane(NIITP)under mild conditions.This method could transform a variety of unstrained ketones into iminophosphoranes and nitriles in high yields.Experimental and computational studies disclosed the reaction proceeded through an unprecedented[3+2]/retro-[3+2]cycloaddition mechanism.展开更多
基金financial support from the National Natural Science Foundation of China(No.21262031)Bioactive Product Engineering Research Center for Gansu Distinctive PlantsState Key Laboratory of Applied Organic Chemistry,Lanzhou University
文摘Exceedingly fast preparation of trifluoromethyl tertiary alcohols has been accomplished from methyl ketones and trifluoromethyl ketones under solvent free conditions by cross Aldol reaction. The reaction was achieved in the presence of common inorganic base by grinding method at ambient temperature to give b-trifluoromethyl-b-hydroxyl ketones in high yields（up to 95%）.
基金We thank the Cooperation Project of Yangzhou City with Yangzhou University(No.YZ2023209)Jiaxing Key Laboratory for Creation of Animal Models&Synthesis of Lead Compounds of New Drug(No.jxsz21006)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)for financial support.
文摘Tertiary alcohols are generally considered difficult to oxidize.However,in this work,it was found that catalyzed by (NH_(4))_(2)Ce(NO_(3))_(6)(CAN)and in the presence of catalytic trifluoroacetic acid(TFA),the selective oxidative C-C bond cleavage of tertiary alcohols could be achieved using O_(2) flow to produce carbonyl compounds.The benefits of this method include the use of simple and inexpensive catalysts,as well as the environmentally friendly nature of the process.This research significantly broadens the scope of alcohol oxidation chemistry.Since alcohol oxidation reactions involving C-C bond cleavage have potential applications as the key unit reaction in certain industrial processes,this finding holds significant promise for organic chemical engineering.
基金supported by the National Natural Science Foundation of China(grant no.21725203)the Ministry of Education(PCSIRT)The Fundamental Research Funds for the Central Universities is highly appreciated.
文摘We report the first highly diastereo-and enantioselective C-C bond-forming reaction of racemic α-branched ketones to construct tertiary alcohols with adjacent stereocenters.Accordingly,a highly stereoselective cyanosilylation of racemic ketones is developed using our bifunctional cyanating reagent,Me_(2)(CH_(2)Cl)SiCN,giving C^(α)-tetrasubstituted silyl cyanohydrins withtwovicinal stereocenters inupto>20:1 diastereomeric ratio(dr)and 90-98% enantiomeric excess(ee)values,which can undergo various diversification reactions bymanipulating the chloromethyl group.A highly selective kinetic resolution of acyclicα-branched ketones is also developed that allows facile access to acyclic α-alkyl,allyl,and propargyl ketones with good recovery and excellent ee values.The synthetic value of this protocol is further demonstrated by the formal synthesis of the anti-obesity agent,taranabant(MK-0364).The activation of Jacobsen’s privileged catalyst(salen)AlCl by a suitable phosphorane plays a crucial role in the reaction.X-ray crystallographic analysis of single crystals of phosphorane-(salen)AlCl complexes and theoretical calculations help provide a working model.The present transformation opens a new path for the catalytic stereoselective synthesis of stereochemically complex tertiary alcohols featuring two stereocenters(adjacent or not)from racemic ketones.
文摘The present work contributed to a new developed production method for enhancing the quality of isoamylene （IA） by adding a small amount of tertiary amyl alcohol （TAA） to the catalyst of strong acid cation exchange resin. TAA improved the selectivity of 2-methyl-2-butene （2M2B） at a high conversion level for the isomerization of IA. Compared with the other results from the current IA units, the conversion of 2-methyl- 1-butene （2M1B）, the mass ratio of 2M2B to 2M1B and the selectivity of 2M2B were increased from 0.5474, 7.32 and 0.6864 to 0.72, 12 and 0.95, respectively, while the dimers content in the products decreased from 4.38% to below 1.0%. Optimized conditions for IA isomerization consisted of temperature between 28 and 33℃ and system pressure of 0.5 MPa, weight hourly space velocity of 8.0 h-1 with TAA mass fraction of 0.7%-0.9% in raw material. The results in lab supported bases for the developed process in industrial application which was later proved to be successful. In addition, a possible mechanism of the isomerization process was speculated to propose a key step of water formation in the TAA-added isomerization process and a verified experiment was conducted to support this speculation.
基金the National Natural Science Foundation of China(Nos.20472026 and 20525206)Chang Jiang Scholar Program of the Ministry of Education, China.
文摘A complete study of the asymmetric addition of phenylacetylene to ketones catalyzed by Schiff-base amino alcohol-Zn complex is reported in this article. The Schiff-base amino alcohols were easily prepared from amino acids in three steps. When the amount of ligand was 1%（molar fraction）, an e.e. value up to 94% was obtained. A series of practical chiral ligands were applied in the enantioselective addition of phenylacetylene to ketones without adding another stronger Lewis acid except zinc.
基金Project supported by the National Natural Science Foundation of China （Nos. 29925205, 30271488, 20021001 and 203900501）.
文摘The easily prepared and recoverable chiral N-sulfonylated fl-amino alcohol 2 in combination with Ti（OPr-i）4 was found to be an effective chiral catalyst for the enantioselective addition of alkynylzinc to ketones, which gave the useful products, i.e. chiral tertiary propargyl alcohols, with the ee up to 92%.
基金supported by the National Key Technologies R&D Program of China(2021YFA1502100)the National Natural Science Foundation of China(22071026,22372035,22072020,22302039,2247020090)+1 种基金the Science Foundation of the Fujian Province(2022HZ027004,2022L3082)the 111 Project(D16008)。
文摘A photocatalytic process was developed for intermolecular reductive coupling of aliphatic ketones with alkynes/alkenes to furnish tertiary alcohols.Mechanistic studies support that boron carbonitrides(BCN)promote the single electron reduction of unactivated aliphatic ketones to generate ketyl radicals with visible light irradiation,which then react with alkynes and alkenes to afford the allylic and aliphatic alcohols,respectively.The heterogeneous photocatalytic system is compatible with diverse substrates including pharmaceutical-related molecules(43 examples)with reusability and scale-up experiments,verifying the complementary synthetic utility of this method to the homogeneous catalysts.
基金provided by the National Natural Science Foundation of China(21871043,21961130376)Department of Science and Technology of Jilin Province(20180101185JC,20190701012GH,20200801065GH)the Fundamental Research Funds for the Central Universities(2412019ZD001,2412019FZ006)。
文摘C(CO)–alkyl bonds are ubiquitous in a variety of organic molecules,and their selective activation and functionalization are important for the reconstruction of simple ketones into valuable building blocks.However,due to the thermodynamic and kinetic stability,the cleavage and transformation of the unstrained C(CO)–alkyl bonds remain a significant challenge.Herein,we report a novel silver-catalyzed scission of the unstrained C(CO)–alkyl bond of ketones by reacting with N-isocyanoiminotriphenylphosphorane(NIITP)under mild conditions.This method could transform a variety of unstrained ketones into iminophosphoranes and nitriles in high yields.Experimental and computational studies disclosed the reaction proceeded through an unprecedented[3+2]/retro-[3+2]cycloaddition mechanism.
