An efficient synthesis of tetrahydrofuro[3,2-b]quinolin-2（3H）-ones from α-angelica lactone and 2-aminobenzaldehydes via a tandem Aldol-Michael addition is described. The reactions were carried out using DBU as the ...An efficient synthesis of tetrahydrofuro[3,2-b]quinolin-2（3H）-ones from α-angelica lactone and 2-aminobenzaldehydes via a tandem Aldol-Michael addition is described. The reactions were carried out using DBU as the base in i-Pr OH at 0 ℃, affording tetrahydrofuro[3,2-b]quinolin-2（3H）-ones in moderate to good yields.展开更多
An unprecedented enzyme-catalyzed asymmetric domino aza-Michael/aldol reaction of 2-aminobenzaldehyde and a,b-unsaturated aldehydes is achieved. Pepsin from porcine gastric mucosa provided mild and efficient access to...An unprecedented enzyme-catalyzed asymmetric domino aza-Michael/aldol reaction of 2-aminobenzaldehyde and a,b-unsaturated aldehydes is achieved. Pepsin from porcine gastric mucosa provided mild and efficient access to diverse substituted 1,2-dihydroquinolines in yields of 38%–97% with 6%–24%enantiomeric excess（ee）. This work not only provides a novel method for the synthesis of dihydroquinoline derivatives, but also promotes the development of enzyme catalytic promiscuity.展开更多
Six compounds including five proline derivatives have been prepared and tested as chiral organocatalysts for enantioselective aldol reactions and Michael additions. The enantiomeric excesses, which are highly dependen...Six compounds including five proline derivatives have been prepared and tested as chiral organocatalysts for enantioselective aldol reactions and Michael additions. The enantiomeric excesses, which are highly dependent on the molecular structure of catalysts as well as experimental conditions, have reached over 98%.展开更多
A direct Michael addition reaction between imidazo[1,2-a]pyridines andα,β-unsaturated ketones using acidic alumina as a C(sp3)—H acid catalyst has been developed.The abundant C(sp3)—H acid sites(Al^(3+))on the aci...A direct Michael addition reaction between imidazo[1,2-a]pyridines andα,β-unsaturated ketones using acidic alumina as a C(sp3)—H acid catalyst has been developed.The abundant C(sp3)—H acid sites(Al^(3+))on the acidic alumina surface effectively activate the carbonyl group ofα,β-unsaturated ketones,significantly enhancing the electrophilicity of theβ-carbon and thereby facilitating selective alkylation at the C3 position of imidazo[1,2-a]pyridines.This method demonstrates excellent functional group compatibility,mild reaction conditions,low reagent costs,and operational simplicity,providing a novel strategy for the efficient synthesis of alkylated imidazo[1,2-a]pyridine derivatives.展开更多
Continuous-flow upgrading of pentaerythritol synthesis technology via base-catalyzed aldol and Cannizzaro reactions of formaldehyde and acetaldehyde faces the challenge of effectively controlling the critical side rea...Continuous-flow upgrading of pentaerythritol synthesis technology via base-catalyzed aldol and Cannizzaro reactions of formaldehyde and acetaldehyde faces the challenge of effectively controlling the critical side reaction of hydroxymethyl acetaldehyde(HA)to the acrolein intermediate.Here,we first identified the forms of industrial formaldehyde as methane diol that easily converts to the alkaline formaldehyde under alkaline(NaOH)environment.The carbonyl group of alkaline formaldehyde induces deprotonation of acetaldehyde instead of the recognized base-hydroxyl group-induced deprotonation,and it needs to overcome only 18.31 kcal·mol^(-1)(1 kcal=4.186 kJ)energy barrier to form key intermediates of HA.The sodium solvation cage formed by NaOH hexa-coordinated formaldehyde effectively inhibits the alkalinity,thus contributing to a high energy barrier(46.21 kcal·mol^(-1))to unwanted acrolein formation.In addition,the solvation cage gradually opens to increase the alkalinity with the consumption of formaldehyde,thus facilitating the subsequent Cannizzaro reaction(to overcome 11.77 kcal·mol^(-1)).In comparison,strong alkalinity promotes the formation of acrolein(36.65 kcal·mol^(-1))to initiate the acetal side reaction,while weak alkalinity reduces the possibility of the Cannizzaro reaction(to overcome 20.44 kcal·mol^(-1)).This theoretically reveals the importance of the segmented feeding of weak and strong bases to successively control the aldol reaction and Cannizzaro reaction,and the combination of Na_(2)CO_(3) or HCOONa with NaOH improves the pentaerythritol yield by 7%to 13%compared to that of NaOH alone(70%yield)within 1 min at a throughput of 155.7 ml·min^(-1).展开更多
Studies on the use of renewable materials for various applications,including polymers,have gained momentum due to global climate change and the push towards a circular economy.In this study,polymer resins were develop...Studies on the use of renewable materials for various applications,including polymers,have gained momentum due to global climate change and the push towards a circular economy.In this study,polymer resins were developed through Michael 1,4-addition.The precursors were synthesized from tall oil-based acetoacetates derived from epoxidized tall oil fatty acids or their methyl esters.Two different epoxidation methods were employed:enzymatic epoxidation of tall oil fatty acids and ion-exchange resin epoxidation of tall oil fatty acid methyl esters.Following oxirane opening and transesterification with trimethylolpropane,further esterification or transesterification was carried out to obtain the acetoacetates.These synthesized acetoacetates were then reacted with acrylates of various functionalities to obtain polymer resins with differing degrees of crosslinking.The developed polymer resins were characterized using differential scanning calorimetry,dynamic mechanical analysis,and thermogravimetric analysis.The results indicated that the glass transition temperature and storage modulus of the polymer resins were significantly influenced by both the functionality of the acrylates used and the epoxidation technique employed.Higher acrylate functionality resulted in increased stiffness,while enzymatic epoxidation enhanced the polymer’s mechanical properties,nearly doubling the storage modulus,achieving approximately 470 MPa,compared to the ion-exchange resin technique.Therefore,selecting the appropriate acrylate functionality and epoxidation method could tailor the mechanical properties of the polymer resins.展开更多
基金National Natural Science Foundation of China(Grant No.21372019)
文摘An efficient synthesis of tetrahydrofuro[3,2-b]quinolin-2（3H）-ones from α-angelica lactone and 2-aminobenzaldehydes via a tandem Aldol-Michael addition is described. The reactions were carried out using DBU as the base in i-Pr OH at 0 ℃, affording tetrahydrofuro[3,2-b]quinolin-2（3H）-ones in moderate to good yields.
基金supported by the National Natural Science Foundation of China (Nos. 21276211 and 21472152)
文摘An unprecedented enzyme-catalyzed asymmetric domino aza-Michael/aldol reaction of 2-aminobenzaldehyde and a,b-unsaturated aldehydes is achieved. Pepsin from porcine gastric mucosa provided mild and efficient access to diverse substituted 1,2-dihydroquinolines in yields of 38%–97% with 6%–24%enantiomeric excess（ee）. This work not only provides a novel method for the synthesis of dihydroquinoline derivatives, but also promotes the development of enzyme catalytic promiscuity.
文摘Six compounds including five proline derivatives have been prepared and tested as chiral organocatalysts for enantioselective aldol reactions and Michael additions. The enantiomeric excesses, which are highly dependent on the molecular structure of catalysts as well as experimental conditions, have reached over 98%.
文摘A direct Michael addition reaction between imidazo[1,2-a]pyridines andα,β-unsaturated ketones using acidic alumina as a C(sp3)—H acid catalyst has been developed.The abundant C(sp3)—H acid sites(Al^(3+))on the acidic alumina surface effectively activate the carbonyl group ofα,β-unsaturated ketones,significantly enhancing the electrophilicity of theβ-carbon and thereby facilitating selective alkylation at the C3 position of imidazo[1,2-a]pyridines.This method demonstrates excellent functional group compatibility,mild reaction conditions,low reagent costs,and operational simplicity,providing a novel strategy for the efficient synthesis of alkylated imidazo[1,2-a]pyridine derivatives.
基金funded by the National Natural Science Foundation of China(22478632)Key Scientific and Technological Project of Henan Province(242102321032).
文摘Continuous-flow upgrading of pentaerythritol synthesis technology via base-catalyzed aldol and Cannizzaro reactions of formaldehyde and acetaldehyde faces the challenge of effectively controlling the critical side reaction of hydroxymethyl acetaldehyde(HA)to the acrolein intermediate.Here,we first identified the forms of industrial formaldehyde as methane diol that easily converts to the alkaline formaldehyde under alkaline(NaOH)environment.The carbonyl group of alkaline formaldehyde induces deprotonation of acetaldehyde instead of the recognized base-hydroxyl group-induced deprotonation,and it needs to overcome only 18.31 kcal·mol^(-1)(1 kcal=4.186 kJ)energy barrier to form key intermediates of HA.The sodium solvation cage formed by NaOH hexa-coordinated formaldehyde effectively inhibits the alkalinity,thus contributing to a high energy barrier(46.21 kcal·mol^(-1))to unwanted acrolein formation.In addition,the solvation cage gradually opens to increase the alkalinity with the consumption of formaldehyde,thus facilitating the subsequent Cannizzaro reaction(to overcome 11.77 kcal·mol^(-1)).In comparison,strong alkalinity promotes the formation of acrolein(36.65 kcal·mol^(-1))to initiate the acetal side reaction,while weak alkalinity reduces the possibility of the Cannizzaro reaction(to overcome 20.44 kcal·mol^(-1)).This theoretically reveals the importance of the segmented feeding of weak and strong bases to successively control the aldol reaction and Cannizzaro reaction,and the combination of Na_(2)CO_(3) or HCOONa with NaOH improves the pentaerythritol yield by 7%to 13%compared to that of NaOH alone(70%yield)within 1 min at a throughput of 155.7 ml·min^(-1).
基金funded by the Latvian State Institute of Wood Chemistry Bioeconomic grant no.04-24“Development of Composites from Polymer Resin Synthesized from Tall Oil Fatty Acids and Reinforced with Various Fillers”(FiTeCo).
文摘Studies on the use of renewable materials for various applications,including polymers,have gained momentum due to global climate change and the push towards a circular economy.In this study,polymer resins were developed through Michael 1,4-addition.The precursors were synthesized from tall oil-based acetoacetates derived from epoxidized tall oil fatty acids or their methyl esters.Two different epoxidation methods were employed:enzymatic epoxidation of tall oil fatty acids and ion-exchange resin epoxidation of tall oil fatty acid methyl esters.Following oxirane opening and transesterification with trimethylolpropane,further esterification or transesterification was carried out to obtain the acetoacetates.These synthesized acetoacetates were then reacted with acrylates of various functionalities to obtain polymer resins with differing degrees of crosslinking.The developed polymer resins were characterized using differential scanning calorimetry,dynamic mechanical analysis,and thermogravimetric analysis.The results indicated that the glass transition temperature and storage modulus of the polymer resins were significantly influenced by both the functionality of the acrylates used and the epoxidation technique employed.Higher acrylate functionality resulted in increased stiffness,while enzymatic epoxidation enhanced the polymer’s mechanical properties,nearly doubling the storage modulus,achieving approximately 470 MPa,compared to the ion-exchange resin technique.Therefore,selecting the appropriate acrylate functionality and epoxidation method could tailor the mechanical properties of the polymer resins.
