A series of poly(ethylene glycol) (PEG) hydrogels were successfully prepared via Michael-type addition between 4-arm PEG-maleimide (PEG-4MAL) and MMP degradable peptide. The gelation time was significantly short (∼10 min) in a low concentration of TEA (4 mM). Thermogravimetric analysis indicated the thermal stabilities of hydrogels. SEM images confirmed a porous structure and the pore size increased with the increase of the PEG chain length. Rheological measurements indicated that all the hydrogels exhibited the characteristics of elastomer and the cross-linking density had a correlation to the polymer weight percentage. After immersing in 0.9% sodium chloride injection, PEG hydrogels exhibited a good water absorption capacity, and their swelling ratio were directly related to the amount of cross-linking. Biological activities of the hydrogels were evaluated by in vitro enzymatic degradation and in vitro cell compatibility on mesenchymal stem cells (MSCs) and the results showed that the hydrogels were biocompatible and could be degraded by exogenously delivered MMPs or cell-secreted MMPs. Thus, PEG hydrogels exhibited the potential for tissue engineering scaffolds.

The synthesis of high loading and recyclable pentaerythritol supported imidazolidin-4-one catalyst I and its application in enantioselective Diels–Alder reactions of cyclopentadiene and α,β-unsaturated aldehydes with high performance were described. Especially noteworthy, the pentaerythritol supported imidazolidin-4-one with high loading capacity can be recovered by simple precipitation and filtration, and recycled for up to four runs without observing significant decrease in catalytic activity.

Four distinct microgel supported hydantoin chiral auxiliaries were prepared with four different cross-linkers and evaluated in asymmetric Mannich reactions, which proceeded in good chemical yields and with excellent stereoselectivities. Moreover, the microgel supported hydantoin chiral auxiliaries could be reused for at least four cycles without an appreciable reduction in the yield or stereoselectivity.(2R,3S)-Methyl 2-methyl-3-(p-methoxyphenylamino)-3-phenylpropanoateC18H21NO3[α]D20 = −48.7 (c 0.96, CH2Cl2)Absolute configuration: (2R,3S)Source of chirality: chiral auxiliary induced Mannich reactions(2R,3S)-Methyl 2-methyl-3-(p-methoxyphenylamino)-3-(p-chloro-phenyl) propanoateC18H20ClNO3[α]D20 = −44.6 (c 0.85, CH2Cl2)Absolute configuration: (2R,3S)Source of chirality: chiral auxiliary induced Mannich reactions(2R,3S)-Methyl 2-methyl-3-(p-methoxyphenylamino)-3-(m-nitro-phenyl) propanoateC18H20N2O5[α]D20 = −47.9 (c 1.12, CH2Cl2)Absolute configuration: (2R,3S)Source of chirality: chiral auxiliary induced Mannich reactions(2R,3S)-Methyl 2-methyl-3-(p-methoxyphenylamino)-3-(2′,3′-dimethoxyphenyl) propanoateC20H25NO5[α]D20 = −50.7 (c 1.08, CH2Cl2)Absolute configuration: (2R,3S)Source of chirality: chiral auxiliary induced Mannich reactions(2R,3S)-Methyl 2-methyl-3-(p-methoxyphenylamino)-3-(2′-furyl)-propanoateC16H19NO4[α]D20 = −47.8 (c 1.10, CH2Cl2)Absolute configuration: (2R,3S)Source of chirality: chiral auxiliary induced Mannich reactions(2R,3S)-Methyl 2-methyl-3-(p-methoxyphenylamino)-3-(2′-thienyl)-propanoateC16H19NO3S[α]D20 = −45.1 (c 1.24, CH2Cl2)Absolute configuration: (2R,3S)Source of chirality: chiral auxiliary induced Mannich reactions

A new non-cross-linked polystyrene supported chiral hydantoin was prepared and it was shown to be a particularly effective chiral auxiliary for asymmetric aldol reactions, affording high yields and excellent diastereoselectivity. Furthermore, the recovery and recycling of the polymer-supported chiral auxiliary have been successfully achieved without an appreciable reduction in the yield or diastereoselectivity.(S)-5-(4-Hydroxybenzyl)-3-phenylhydantoinC16H14N2O3[α]D20=-86.7 (c 0.3, CH3COCH3)Absolute configuration: (S)Source of chirality: l-tyrosine methyl ester hydrochloride(S)-5-(4-(4-Vinylbenzyloxy)benzyl)-3-phenylhydantoinC25H22N2O3[α]D20=-9.3 (c 1.0, CH2Cl2)Absolute configuration: (S)Source of chirality: l-tyrosine methyl ester hydrochloride(S)-5-(4-(4-Vinylbenzyloxy)benzyl)-3-phenyl-1-propionylhydantoinC28H26N2O4[α]D20=-8.75 (c 0.4, CH2Cl2)Absolute configuration: (S)Source of chirality: l-tyrosine methyl ester hydrochloride(2S,3S)-3-Hydroxy-2-methyl-3-phenylpropanoic acidC10H12O3[α]D20=-28.8 (c 0.4, CH2Cl2)Absolute configuration: (2S,3S)Source of chirality: chiral auxiliary induced aldol reactions(2S,3S)-3-Hydroxy-2-methyl-3-(3-nitrophenyl)propanoic acidC10H11NO5[α]D20=-38.0 (c 0.4, CH2Cl2)Absolute configuration: (2S,3S)Source of chirality: chiral auxiliary induced aldol reactions(2S,3S)-3-(4-Chlorophenyl)-3-hydroxy-2-methylpropanoic acidC10H11ClO3[α]D20=-15.9 (c 0.8, CH2Cl2)Absolute configuration: (2S,3S)Source of chirality: chiral auxiliary induced aldol reactions(2S,3S)-3-Hydroxy-3-(4-methoxyphenyl)-2-methylpropanoic acidC11H14O4[α]D20=-19.0 (c 0.4, CH2Cl2)Absolute configuration: (2S,3S)Source of chirality: chiral auxiliary induced aldol reactions(2S,3S)-3-Hydroxy-2-methyl-3-(thiophen-2-yl)propanoic acidC8H10O3S[α]D20=+15.5 (c 0.4, CH2Cl2)Absolute configuration: (2S,3S)Source of chirality: chiral auxiliary induced aldol reactions(2S,3R)-3-Hydroxy-2-methylhexanoic acidC7H14O3[α]D20=+11.2 (c 0.4, CH2Cl2)Absolute configuration: (2S,3R)Source of chirality: chiral auxiliary induced aldol reactions

In this work it was presented an application of task specific onium salt as soluble support for the synthesis of 3-amino-5-aryl-2,5-dihydropyridazines. This soluble support is of wide applicability and combines advantages of solid phase synthesis without its limitations with those of solution phase chemistry. After a simple washing step, products were cleaved from the supports and obtained in good yields.