Polyisobutylene supports—a non-polar hydrocarbon analog of PEG supports

Li, Jun; Sung, Shayna D.; Tian, Jinying; Bergbreiter, David E.

doi:10.1016/j.tet.2005.07.119

Cited by 55 publications

(108 citation statements)

References 17 publications

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“…20 The solubility that PIB groups confer on their reactive terminal functionality allows these PIB bound species to both be nonpolar phase anchored species in separations after reactions and highly soluble catalysts for reactions with substrates that can be readily conducted under homogeneous conditions. Inspired by these prior examples, we have explored the potential for these same soluble hydrocarbon oligomer supports as solubilizing and recycling handles for two common oxidizing agents-catalytic tetraalkylammonium perruthenate oxidants and stoichiometric hypervalent iodine oxidants.…”

Section: Resultsmentioning

confidence: 99%

Recyclable soluble polyisobutylene-bound oxidizing agents

Samunual

Bergbreiter

2016

Tetrahedron Letters

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a b s t r a c tThis Letter describes the use of alkene-terminated polyisobutylene (PIB) as a support for oxidizing agents. Two oxidizing agents, an ionically immobilized PIB-bound perruthenate oxidation catalyst and a PIBbound 2-iodoxybenzoic acid (IBX) oxidizing reagent, were studied. A perruthenate catalyst ionically bound to PIB was prepared by binding the perruthenate anion to PIB that contained either a terminal tetraalkylammonium or an imidazolium salt. The PIB supported ammonium and imidazolium perruthenate were both selectively soluble in heptane and effective in the oxidation of alcohols. While these PIBbound perruthenate catalysts could be readily separated from products, recycling was less successful. A PIB bound 2-iodoxybenzoic (IBX) oxidizing agent was coupled to a PIB support with an ester bond. It was highly soluble in nonpolar and moderately polar organic solvents. By taking advantage of PIB's heptane solubility, the spent IBX reagent could be easily separated from products by a liquid/liquid heptane/acetonitrile biphasic separation. The recovered IBX reagent could then be regenerated and used in multiple cycles for oxidation of both primary and secondary alcohols.

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Section: Resultsmentioning

confidence: 99%

Recyclable soluble polyisobutylene-bound oxidizing agents

Samunual

Bergbreiter

2016

Tetrahedron Letters

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“…PIB or at least the PIB derivatives we used [9] also has a vinyl terminus that can be modified by simple chemistry to prepare viable precursors to many sorts of soluble polymeric reagents and ligands. [10] Because PIB is noncrystalline, it is readily soluble in nonpolar and weakly polar solvents like alkanes, chlorinated alkanes, arenes, and ethers even at low temperatures. It is not soluble or only weakly soluble in polar solvents, like acetonitrile, DMF, ethanol, and water though it does dissolve in many solvent mixtures at elevated temperature.…”

Section: Introductionmentioning

confidence: 99%

“…Previous work from our groups showed that PIB is a viable alternative to PEG and can be readily used to prepare phase selectively soluble ligands or sequestrants for commonly used transition metal catalysts. [10][11][12][13][14][15] Here we describe a variety of ways that PIB can be used as a phase anchor to ligate or sequester ruthenium complexes related to those widely used now in ring-closing metathesis (RCM), cross metathesis (CM), and ring-opening metathesis polymerization (ROMP) reactions.…”

Section: Introductionmentioning

confidence: 99%

Polyisobutylene Phase‐Anchored Ruthenium Complexes

Hongfa

Bazzi

et al. 2010

Macromolecular Symposia

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Summary: The use of polymers in general as ligands or sequestrants for metals has often focused on the use of cross-linked polymers or readily available soluble polar polymers like poly(ethylene glycol). Our work shows that functional nonpolar polymers like polyisobutylene are viable alternatives and can be readily used as phase selectively soluble ligands or sequestrants for commonly used transition metal catalysts. This is illustrated in this work by the synthesis of ligands and sequestrants for ruthenium catalysts widely used in ring-closing-metathesis, cross-metathesis, and ring-opening metathesis polymerization. We show that a polyisobutylene terminally functionalized with a vinyl group can be converted by electrophilic aromatic substitution into species that phase immobilize a benzylidene Ru catalyst precursor, an N-heterocyclic carbene ligand, or that can sequester a Ru complex by conversion of a reactive Ru alkylidene into a phase-immobilized Fischer carbene complex. In all these cases, the Ru complexes that are formed are selectively soluble in a nonpolar or weakly polar phase of a liquid/liquid biphasic system -a system that can be efficiently formed either thermomorphically, by perturbation of an initially miscible solvent mixture, or by extraction.

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“…[1][2][3][4][5][6][7][8] The synthesis of these materials was summarized and reviewed in a 1991 book, 1 and since that time the field has steadily grown. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Regretfully, however, all the published procedures involve relatively expensive transformations and/or afford incomplete end-functionalization. For example, the preparation of PIB alcohols is typically carried out by hydroboration/oxidation, which requires expensive hydroborating reagents.…”

Section: Introductionmentioning

confidence: 99%