Polyethylene glycol support

Scheme 10.13. Polyethylene glycol)-supported domino synthesis of 1,2,3,4-tetrahydroquinolines.

Pillai, V.N.R., and Mutter, M. (1980) New, easily removable polyethylene glycol supports for liquid phase method of peptide synthesis./. Org. Chem. 45, 5364-5367. 

Microwave irradiation coupled with polyethylene glycol)-supported Burgess reagent reduced the reaction time to 2-4 min and led to improved yields. Use of harsh reagents, e. g. SOCl2, POCl3, and polyphosphoric acid, for the cydodehydration were avoided. 

An efficient one-pot synthesis of isoxazolines, using soluble polymer-supported acrylate has been described (174). Thus, the addition of 1,4-benzenedicarbonitrile N,N -dioxide (generated from N, N -dihydroxy-1,4-benzenedicarboximidoy 1 dichloride) to polyethylene glycol-supported 2-propenoic acid 2-hydroxyethyl ester 32 (P = polyethylene glycol support) followed by cleavage of the bond with the support gave 3,3/-(l,4-phenylene)bis[4,5-dihydro-5-isoxazolecarboxylic acid] di-Me ester (33) in 97% yield. 

Scheme 4.69 Disaccharide synthesis on a soluble polyethylene glycol support.

In a continuation of their initial study, Janda and Wentworth disclosed an optimized version of the polyethylene glycol-supported triarylphosphine reagent (20)... 

In a similar manner to the [4+2] cycloaddition, Benagha has shown that a polyethylene glycol supported imidazolidinone leads to similar levels of enantioselec-tivity in the [3+2] cycloaddition of nitrones with a,P-unsaturated aldehydes when compared to a non-supported catalyst, however, significantly lower chemical yields were obtained, which deteriorated upon catalyst recycling [65]. 

Du Y, Wang J-Q, Chen J-Y et al (2006) A polyethylene glycol)-supported quaternary ammonium salt for highly efficient and environmentally friendly chemical fixation of C02 with epoxides under supercritical conditions. Tetrahedron Lett 47(8) 1271—1275... 

Kong D-L, He L-N, Wang J-Q (2010) Synthesis of urea derivatives from C02 and amines catalyzed by polyethylene glycol supported potassium hydroxide without dehydrating agents. Synlett 8 1276-1280... 

Similar conditions are also effective for the direct enantioselective epoxidation of a,p-unsaturated carbonyls, as exemplified by the conversion of chalcone (30) to the corresponding ft,/ -epoxide in 97% yield and 84% ee using the 4-iodophenyl cinchonine derivative 32 <02T1623>. Alternatively, the novel polyethylene glycol-supported oligo(L-leucine) catalyst... 

Benaglia M, Annunziata R, Cinquini M, Cozzi F, Tocco G (2000) A polyethylene glycol)-supported quaternary ammonium salt an efficient, recoverable, and recyclable phase-transfer catalyst. Qrg Lett 2 1737-1739... 

The one-pot three-component reaction of polyethylene glycol-supported acrylate 623 with aldehydes 621 and hydrazines 622 in the presence of chloramine-T followed by methanolysis afforded pyrazolines 624 in good yields and high purities (Scheme 77) <2003SL1467>. 1,3-Dipolar cycloaddition of resin-supported acrylic acid 625 with the nitrilimines generated in situ by oxidation of the aldehyde phenylhydrazones with (diacetoxy)iodobenzene under microwave irradiation gave 626, which was converted into l-phenyl-3-substituted-2-pyrazolinyl-5-carboxylates 627 (Scheme 78) <2004SC3521>. 

Scheme 2.71 Principle of "orthogonal glycosidic activation on a polymer (e.g. polyethylene glycol) support, lb facilitate purification, a hydrophobic tag (e.g. 2-(trimethylsilyl)ethyl) is introduced [158]. Conditions A are for thioglycoside activation, conditions B for activation of glycosyl fluorides.

Dipolar cycloaddition of polyethylene glycol-supported azide with various dipolarophiles followed by acidic cleavage afforded 4- and 5-substituted-1,2,3-triazoles 05T4983>. Trimethylsilyl-directed 1,3-dipolar cycloaddition reactions in the solid-phase synthesis of 1,2,3-triazoles have been developed <05OL1469>. 

Scremin CL, Bonora GM. Liquid phase synthesis of phosphorothioate oligonucleotides on polyethylene glycol support. Tetrahedron Lett 34 4663-4666, 1993. 

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