Polymeric oxazolines

Polymeric oxazolines have also been used as vehicles for controlled drug release ° ° and DNA transfection, as polymeric micelles, which serve as carriers for drug transport (e.g., paclitaxel), and as formulation additives for controlled-release of insecticides. ... 

Macromonomers were prepared by polymerizing oxazolines with monofunctional initiators (e.g., methyl p-toluenosulfonate) and terminating the polymerization with salts of acrylic or methacrylic acid. Macromonomers with M varying from M — 500 to —2500 and MJM - 1.2-1.4 were obtained functionalities, however, depended strongly on reaction conditions and the values between 0.99 down to —0.5 and lower were reported [280]. 

Colwell et al. studied the a-benzyladon of polymeric oxazoline 61 and obtained optically active ester 63 after ethanolysis (Scheme 1.6.34). The chemical yield of 63 was poor due to incomplete cleavage. The recovered polymer consisted of amino alkohol 64, amino ester 6S and oxazoline... 

The eatalytic activity of these polymeric oxazolines was examined in the enantioselective diethylzine addition to benzaldehyde. Chiral supported-oxazoline 236b exhibited slightly better enantioselectivity (89%) and yield (90%) than its analog 236a when the reaction was carried out in a 20% CH2Cl2/toluene mixture at 0°C. This ehiral supported-ligand has been recycled three times without a significant loss of performance. 

Figure 32 Structures of the polymerized oxazoline derivatives 2-(9-decen-1-yl)-1,3-oxazoline 82, 2-(9-decen-1-yl)-4,4-dimethyl-1,3-oxazoline 83, and 2-[4-(10-undecene-1-oxy)phenyl]-1,3-oxazoline 84.

Moberg focused her attention on the immobilzation of oxazoline-derived ligands for the enantioselective allylic alkylation [159]. Pyridine-containing oxazolines 251 were first prepared and were supported on TentaGel resin to afford the corresponding polymeric oxazolines 252 (Scheme 102). These polymer-supported ligands were then tested in the... 

One product is poly(2-ethyl-2-oxa2oline) (PEOX). It is prepared by the ring-opening polymerization of 2-ethyl-2-oxazoline (19) with a cationic initiator (48) (eq. 6). 

Linear polyethyleneimine results only in low yields from low temperature polymerization of ethyleneimine for very long reaction times. It can, however, be synthesized in a targeted manner by polymerization of 2-oxazolines with subsequent hydrolytic cleavage of the resulting polyamides (355,358). 

Formaldehyde reacts with the hydrogen on the a-carbon of the fatty acid from which the oxazoline was formed to yield a vinyl monomer which can be polymerized or utilized for synthesis (4). Thus, esters of the oxazoline formed from TRIS AMINO undergo the reaction... 

Oxazoline, 2-alkenyl-polymerization, 1, 282 2-Oxazoline, 2,5-dimethyl-5-phenyl-synthesis, 5, 141 Oxazolines... 

Ring-opening polymerization of 2-methyl-2-oxazoline produces poly( V-acetyl-ethylenimine) (Scheme 2) [24-27], The resulting polymer can be regarded as a... 

The polymerization of 2-methyl-2-oxazoline is a clean reaction, which is not disturbed by chain transfer and termination. In this polymerization, the propagating species having the structure of an oxazolinium salt is not fragile, which is conveniently utilized for syntheses of block copolymers and end-reactive polymers [28],... 

Thus, the ring-opening polymerization of 2-methyl-2-oxazoline followed by the treatment of the resulting oxazolinium propagating end group with 3-aminopropyltriethoxysilane produced successfully triethoxysilyl-terminated poly-oxazoline as shown in Scheme 3 [29]. 

The relative rate of cationic homopolymerization is governed by three factors, ie. the concentration of the propagating species, the ring-opening reactivity of the growing species and the nucleophilic reactivity of the monomer. From kinetic studies196 197 of the polymerization of oxazolines and oxazines it was found that the second factor was the most important. On the other hand, the relative reactivity in the cationic copolymerization is mainly determined by the nucleophilicity of the monomer and for 2-substituted 2-oxazolines this is in the order of benzyl > methyl > > isopropyl > H > phenyl195. ... 

Polyamines can also be synthesized by cationic ring-opening polymerization of ethyleneimines (aziridines), trimethyleneimines (azetidines), and 2-oxazolines. 

Initial polymerization studies were conducted with 2,2 -tetramethylenebls(4,4-dimethyl-2-oxazolin-5-one) 4 and... 

Applying these methodologies monomers such as isobutylene, vinyl ethers, styrene and styrenic derivatives, oxazolines, N-vinyl carbazole, etc. can be efficiently polymerized leading to well-defined structures. Compared to anionic polymerization cationic polymerization requires less demanding experimental conditions and can be applied at room temperature or higher in many cases, and a wide variety of monomers with pendant functional groups can be used. Despite the recent developments in cationic polymerization the method cannot be used with the same success for the synthesis of well-defined complex copolymeric architectures. 

Symmetric triblock copolymers of the ABA type, where B was PTHF and A poly(2-methyl-2-oxazoline), PMeOx, were prepared by cationic polymerization with trifluoromethanesulfonic anhydride as a difunctional initiator [58]. Subsequent hydrolysis of the PMeOx blocks with HC1 in a methanol/ water mixture resulted in the formation of the corresponding polyethylen-imine blocks (Scheme 20). Samples with relatively low molecular weight distributions were obtained. 

The grafting from methodology was also utilized for the synthesis of poly(4-methylphenoxyphosphazene-g-2-methyl-2-oxazoline) graft copolymers [187]. The synthetic approach involved the thermal polymerization of hexachlorophosphazene, in the presence of aluminum chloride, to give low molecular weight poly(dichlorophosphazene). The chloro groups were subsequently replaced by 4-methylphenoxy groups, followed by partial bromi-... 

In a similar fashion, the cationic polymerization of 2-oxazolines has been extensively studied and was found to provide the first verified entry to linear-poly(alkyleneimine) architectures. These acylated polymers were first recognized as precursors to linear poly(ethyleneimines) in the early 1960s [25]. Hydrolysis experiments demonstrated that deacylation of these products to linear PEI was possible. The original polymerization mechanism proposed by Tomalia et al. 

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