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Na Liu - One of the best experts on this subject based on the ideXlab platform.
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polymerization amplified stereoselectivity pass of asymmetric michael Addition Reaction and aldol Reaction catalyzed by helical poly phenyl isocyanide bearing secondary amine pendants
Macromolecules, 2018Co-Authors: Ling Shen, Xiao-hua Hou, Na LiuAbstract:A novel enantiopure phenyl isocyanide (1) carrying tert-butyloxycarboryl (Boc) protected l-prolinol ester was designed and synthesized. Living polymerization of 1 using a alkyne–Pd(II) catalyst afforded helical poly-1ms in high yields with controlled molecular weights (Mns) and narrow molecular weight distributions (Mw/Mns). Removing the protecting Boc groups on the l-prolinol ester pendants lead to the formation of helical poly-2m, which showed high optical activity owing to the preferred left-handed helix of polyisocyanide main chain. The poly-2ms showed excellent catalytic ability on asymmetric Michael Addition Reaction. Both the enantiomeric excess (ee) and diastereomeric ratio (dr) values of the product were linearly correlated to the Mn and optical activity of poly-2m. Increasing the Mn of poly-2ms will amplify the stereoselectivity of the asymmetric Michael Addition Reaction until the Mn reached to 44.9 kDa, revealing the polymerization amplified stereoselectivity (PASS) behavior of the asymmetric ...
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Polymerization Amplified Stereoselectivity (PASS) of Asymmetric Michael Addition Reaction and Aldol Reaction Catalyzed by Helical Poly(phenyl isocyanide) Bearing Secondary Amine Pendants
2018Co-Authors: Ling Shen, Xiao-hua Hou, Na LiuAbstract:A novel enantiopure phenyl isocyanide (1) carrying tert-butyloxycarboryl (Boc) protected l-prolinol ester was designed and synthesized. Living polymerization of 1 using a alkyne–Pd(II) catalyst afforded helical poly-1ms in high yields with controlled molecular weights (Mns) and narrow molecular weight distributions (Mw/Mns). Removing the protecting Boc groups on the l-prolinol ester pendants lead to the formation of helical poly-2m, which showed high optical activity owing to the preferred left-handed helix of polyisocyanide main chain. The poly-2ms showed excellent catalytic ability on asymmetric Michael Addition Reaction. Both the enantiomeric excess (ee) and diastereomeric ratio (dr) values of the product were linearly correlated to the Mn and optical activity of poly-2m. Increasing the Mn of poly-2ms will amplify the stereoselectivity of the asymmetric Michael Addition Reaction until the Mn reached to 44.9 kDa, revealing the polymerization amplified stereoselectivity (PASS) behavior of the asymmetric Reaction. Under optimized the Reaction condition, the ee and dr values of the Michael Addition Reaction product can be up to 99% and >99/1, respectively. Poly-2200 can be easily recovered and reused in the Michael Addition Reaction for at least 5 cycles without loss of its activity and stereoselectivity significantly. The poly-2200 can also be used to catalyze the asymmetric aldol Reaction. The ee and dr values of the model aldol Reaction were respectively up to 99% and >99/1. Moreover, the poly-2200 can be facilely recovered and alternatively catalyzed Michael Addition Reaction and aldol Reactions for at least six cycles with maintained selectivity and activity
Takashi Sugimura - One of the best experts on this subject based on the ideXlab platform.
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1 4 Addition Reaction of 5h oxazol 4 ones to vinyl ketones catalyzed by chiral guanidines
Tetrahedron Letters, 2015Co-Authors: Akane Morita, Tomonori Misaki, Takashi SugimuraAbstract:Abstract In this Letter, a chiral guanidine-catalyzed 1,4-Addition Reaction of 5H-oxazol-4-ones to vinyl ketones is described. The 1,4-Addition Reaction proceeded with a high enantioselectivity using 5H-oxazol-4-ones, substituted with a 3-chloro-5-methylphenyl group, as pronucleophiles and a newly developed chiral guanidine as a catalyst. The optimized Reaction conditions were also effective in achieving excellent enantioselectivity in the 1,6-Addition to dienones. Subsequent solvolysis of the 1,4-Addition adduct yielded the corresponding α-hydroxy-5-oxocarboxylates.
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1 6 Addition Reaction of 5h oxazol 4 ones to conjugated dienones catalyzed by chiral guanidines
Chemistry Letters, 2014Co-Authors: Akane Morita, Tomonori Misaki, Takashi SugimuraAbstract:A chiral guanidine-catalyzed 1,6-Addition Reaction of 5H-oxazol-4-ones to α,β,γ,δ-diunsaturated ketones is described in this study. The Addition Reaction proceeded regiospecifically to yield a 1,6-...
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1 4 Addition Reaction of 5h oxazol 4 ones to allenic esters and ketones catalyzed by chiral guanidines
Chemistry Letters, 2013Co-Authors: Nari Jin, Tomonori Misaki, Takashi SugimuraAbstract:In this paper, a chiral guanidine-catalyzed 1,4-Addition Reaction of 5H-oxazol-4-ones to allenic esters and ketones is described. 5H-Oxazol-4-ones substituted with a 2-chlorophenyl group were suita...
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highly z selective asymmetric 1 4 Addition Reaction of 5h oxazol 4 ones with alkynyl carbonyl compounds catalyzed by chiral guanidines
Journal of the American Chemical Society, 2011Co-Authors: Tomonori Misaki, Kei Kawano, Takashi SugimuraAbstract:An asymmetric 1,4-Addition Reaction of 5H-oxazol-4-ones with alkynyl carbonyl compounds was developed, and, for the first time, high enantiomeric and geometric control was achieved to afford the thermodynamically unstable Z-isomer predominantly using chiral guanidine catalysts bearing a hydroxy group at the appropriate position. The method provides synthetically useful γ-butenolide ester bearing a chiral quaternary stereogenic center.
Hu Yang - One of the best experts on this subject based on the ideXlab platform.
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Superelastic and pH-Responsive Degradable Dendrimer Cryogels Prepared by Cryo-aza-Michael Addition Reaction
VCU Scholars Compass, 2018Co-Authors: Wang Juan, Hu YangAbstract:Dendrimers exhibit super atomistic features by virtue of their well-defined discrete quantized nanoscale structures. Here, we show that hyperbranched amine-terminated polyamidoamine (PAMAM) dendrimer G4.0 reacts with linear polyethylene glycol (PEG) diacrylate (575 g/mol) via the aza-Michael Addition Reaction at a subzero temperature (−20 °C), namely cryo-aza-Michael Addition, to form a macroporous superelastic network, i.e., dendrimer cryogel. Dendrimer cryogels exhibit biologically relevant Young’s modulus, high compression elasticity and super resilience at ambient temperature. Furthermore, the dendrimer cryogels exhibit excellent rebound performance and do not show significant stress relaxation under cyclic deformation over a wide temperature range (−80 to 100 °C). The obtained dendrimer cryogels are stable at acidic pH but degrade quickly at physiological pH through self-triggered degradation. Taken together, dendrimer cryogels represent a new class of scaffolds with properties suitable for biomedical applications
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in situ forming polyamidoamine dendrimer hydrogels with tunable properties prepared via aza michael Addition Reaction
ACS Applied Materials & Interfaces, 2017Co-Authors: Juan Wang, Remy C. Cooper, Hu YangAbstract:In this work, we describe synthesis and characterization of novel in situ-forming polyamidoamine (PAMAM) dendrimer hydrogels (DHs) with tunable properties prepared via highly efficient aza-Michael Addition Reaction. PAMAM dendrimer G5 was chosen as the underlying core and functionalized with various degrees of acetylation using acetic anhydride. The nucleophilic amines on the dendrimer surface reacted with α, β-unsaturated ester in acrylate groups of polyethylene glycol diacrylate (PEG-DA, Mn = 575 g/mol) via aza-Michael Addition Reaction to form dendrimer hydrogels without the use of any catalyst. The solidification time, rheological behavior, network structure, swelling, and degradation properties of the hydrogel were tuned by adjusting the dendrimer surface acetylation degree and dendrimer concentration. The DHs were shown to be highly cytocompatible and support cell adhesion and proliferation. We also prepared an injectable dendrimer hydrogel formulation to deliver the anticancer drug 5-fluorouracil (...
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In Situ-Forming Polyamidoamine Dendrimer Hydrogels with Tunable Properties Prepared via Aza-Michael Addition Reaction
2017Co-Authors: Juan Wang, Remy C. Cooper, Hu YangAbstract:In this work, we describe synthesis and characterization of novel in situ-forming polyamidoamine (PAMAM) dendrimer hydrogels (DHs) with tunable properties prepared via highly efficient aza-Michael Addition Reaction. PAMAM dendrimer G5 was chosen as the underlying core and functionalized with various degrees of acetylation using acetic anhydride. The nucleophilic amines on the dendrimer surface reacted with α, β-unsaturated ester in acrylate groups of polyethylene glycol diacrylate (PEG-DA, Mn = 575 g/mol) via aza-Michael Addition Reaction to form dendrimer hydrogels without the use of any catalyst. The solidification time, rheological behavior, network structure, swelling, and degradation properties of the hydrogel were tuned by adjusting the dendrimer surface acetylation degree and dendrimer concentration. The DHs were shown to be highly cytocompatible and support cell adhesion and proliferation. We also prepared an injectable dendrimer hydrogel formulation to deliver the anticancer drug 5-fluorouracil (5-FU) and demonstrated that the injectable formulation efficiently inhibited tumor growth following intratumoral injection. Taken together, this new class of dendrimer hydrogel prepared by aza-Michael Addition Reaction can serve as a safe tunable platform for drug delivery and tissue engineering
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In Situ-Forming Polyamidoamine Dendrimer Hydrogels with Tunable Properties Prepared Via Aza-Michael Addition Reaction
'American Chemical Society (ACS)', 2017Co-Authors: Wang Juan, He Hongliang, Cooper, Remy C., Hu YangAbstract:In this work, we describe synthesis and characterization of novel in situ-forming polyamidoamine (PAMAM) dendrimer hydrogels (DHs) with tunable properties prepared via highly efficient aza-Michael Addition Reaction. PAMAM dendrimer G5 was chosen as the underlying core and functionalized with various degrees of acetylation using acetic anhydride. The nucleophilic amines on the dendrimer surface reacted with α, ß-unsaturated ester in acrylate groups of polyethylene glycol diacrylate (PEG-DA, Mn = 575 g/mol) via aza-Michael Addition Reaction to form dendrimer hydrogels without the use of any catalyst. The solidification time, rheological behavior, network structure, swelling, and degradation properties of the hydrogel were tuned by adjusting the dendrimer surface acetylation degree and dendrimer concentration. The DHs were shown to be highly cytocompatible and support cell adhesion and proliferation. We also prepared an injectable dendrimer hydrogel formulation to deliver the anticancer drug 5-fluorouracil (5-FU) and demonstrated that the injectable formulation efficiently inhibited tumor growth following intratumoral injection. Taken together, this new class of dendrimer hydrogel prepared by aza-Michael Addition Reaction can serve as a safe tunable platform for drug delivery and tissue engineering
Ling Shen - One of the best experts on this subject based on the ideXlab platform.
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polymerization amplified stereoselectivity pass of asymmetric michael Addition Reaction and aldol Reaction catalyzed by helical poly phenyl isocyanide bearing secondary amine pendants
Macromolecules, 2018Co-Authors: Ling Shen, Xiao-hua Hou, Na LiuAbstract:A novel enantiopure phenyl isocyanide (1) carrying tert-butyloxycarboryl (Boc) protected l-prolinol ester was designed and synthesized. Living polymerization of 1 using a alkyne–Pd(II) catalyst afforded helical poly-1ms in high yields with controlled molecular weights (Mns) and narrow molecular weight distributions (Mw/Mns). Removing the protecting Boc groups on the l-prolinol ester pendants lead to the formation of helical poly-2m, which showed high optical activity owing to the preferred left-handed helix of polyisocyanide main chain. The poly-2ms showed excellent catalytic ability on asymmetric Michael Addition Reaction. Both the enantiomeric excess (ee) and diastereomeric ratio (dr) values of the product were linearly correlated to the Mn and optical activity of poly-2m. Increasing the Mn of poly-2ms will amplify the stereoselectivity of the asymmetric Michael Addition Reaction until the Mn reached to 44.9 kDa, revealing the polymerization amplified stereoselectivity (PASS) behavior of the asymmetric ...
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Polymerization Amplified Stereoselectivity (PASS) of Asymmetric Michael Addition Reaction and Aldol Reaction Catalyzed by Helical Poly(phenyl isocyanide) Bearing Secondary Amine Pendants
2018Co-Authors: Ling Shen, Xiao-hua Hou, Na LiuAbstract:A novel enantiopure phenyl isocyanide (1) carrying tert-butyloxycarboryl (Boc) protected l-prolinol ester was designed and synthesized. Living polymerization of 1 using a alkyne–Pd(II) catalyst afforded helical poly-1ms in high yields with controlled molecular weights (Mns) and narrow molecular weight distributions (Mw/Mns). Removing the protecting Boc groups on the l-prolinol ester pendants lead to the formation of helical poly-2m, which showed high optical activity owing to the preferred left-handed helix of polyisocyanide main chain. The poly-2ms showed excellent catalytic ability on asymmetric Michael Addition Reaction. Both the enantiomeric excess (ee) and diastereomeric ratio (dr) values of the product were linearly correlated to the Mn and optical activity of poly-2m. Increasing the Mn of poly-2ms will amplify the stereoselectivity of the asymmetric Michael Addition Reaction until the Mn reached to 44.9 kDa, revealing the polymerization amplified stereoselectivity (PASS) behavior of the asymmetric Reaction. Under optimized the Reaction condition, the ee and dr values of the Michael Addition Reaction product can be up to 99% and >99/1, respectively. Poly-2200 can be easily recovered and reused in the Michael Addition Reaction for at least 5 cycles without loss of its activity and stereoselectivity significantly. The poly-2200 can also be used to catalyze the asymmetric aldol Reaction. The ee and dr values of the model aldol Reaction were respectively up to 99% and >99/1. Moreover, the poly-2200 can be facilely recovered and alternatively catalyzed Michael Addition Reaction and aldol Reactions for at least six cycles with maintained selectivity and activity
Tomonori Misaki - One of the best experts on this subject based on the ideXlab platform.
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1 4 Addition Reaction of 5h oxazol 4 ones to vinyl ketones catalyzed by chiral guanidines
Tetrahedron Letters, 2015Co-Authors: Akane Morita, Tomonori Misaki, Takashi SugimuraAbstract:Abstract In this Letter, a chiral guanidine-catalyzed 1,4-Addition Reaction of 5H-oxazol-4-ones to vinyl ketones is described. The 1,4-Addition Reaction proceeded with a high enantioselectivity using 5H-oxazol-4-ones, substituted with a 3-chloro-5-methylphenyl group, as pronucleophiles and a newly developed chiral guanidine as a catalyst. The optimized Reaction conditions were also effective in achieving excellent enantioselectivity in the 1,6-Addition to dienones. Subsequent solvolysis of the 1,4-Addition adduct yielded the corresponding α-hydroxy-5-oxocarboxylates.
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1 6 Addition Reaction of 5h oxazol 4 ones to conjugated dienones catalyzed by chiral guanidines
Chemistry Letters, 2014Co-Authors: Akane Morita, Tomonori Misaki, Takashi SugimuraAbstract:A chiral guanidine-catalyzed 1,6-Addition Reaction of 5H-oxazol-4-ones to α,β,γ,δ-diunsaturated ketones is described in this study. The Addition Reaction proceeded regiospecifically to yield a 1,6-...
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1 4 Addition Reaction of 5h oxazol 4 ones to allenic esters and ketones catalyzed by chiral guanidines
Chemistry Letters, 2013Co-Authors: Nari Jin, Tomonori Misaki, Takashi SugimuraAbstract:In this paper, a chiral guanidine-catalyzed 1,4-Addition Reaction of 5H-oxazol-4-ones to allenic esters and ketones is described. 5H-Oxazol-4-ones substituted with a 2-chlorophenyl group were suita...
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highly z selective asymmetric 1 4 Addition Reaction of 5h oxazol 4 ones with alkynyl carbonyl compounds catalyzed by chiral guanidines
Journal of the American Chemical Society, 2011Co-Authors: Tomonori Misaki, Kei Kawano, Takashi SugimuraAbstract:An asymmetric 1,4-Addition Reaction of 5H-oxazol-4-ones with alkynyl carbonyl compounds was developed, and, for the first time, high enantiomeric and geometric control was achieved to afford the thermodynamically unstable Z-isomer predominantly using chiral guanidine catalysts bearing a hydroxy group at the appropriate position. The method provides synthetically useful γ-butenolide ester bearing a chiral quaternary stereogenic center.