Organocatalyzed ROP of a Glucopyranoside Derived Five-Membered Cyclic Carbonate

Abstract

Saccharides, based on their wide bioavailability, high chemical functionality and stereochemical diversity, are attractive starting materials for the development of new synthetic polymers. Established carbonylation methodologies were used to synthesize a 5-membered cyclic carbonate monomer, 4,6-O-benzylidene-2,3-O-carbonyl-α-d-glucopyranoside (MBGC), in high yield (>95%) from a commercially available d-glucopyranoside derivative. The ability of this monomer to undergo ring-opening polymerization (ROP) with a range of organocatalysts, rather than the previously reported anionic initiators, was investigated. These new conditions were developed to widen the functional group tolerance in the polymerization, and achieve better control over the final properties of the polymers. The most promising of the catalysts examined, 1,5,7-triazabicyclo[4.4.0]­dec-5-ene (TBD), was used in a kinetic study to confirm the well-controlled nature of the ROP. Optimized conditions were then successfully applied to the synthesis of polymers of different molecular weights. Two post-polymerization modifications were completed via the removal of the benzylidene acetal protecting group to release a water-soluble poly­(glucose carbonate), and then addition of acetyl groups to facilitate characterization studies. MALDI-TOF MS analysis was performed to further probe the chemistry of the polymerization and deprotection. A wide range of thermal decomposition temperatures (233–347 °C), glass transition temperatures (87–233 °C), and water contact angles (38–128°) was achieved by this series of polymers. The hydrolytic degradability of these polymers was also examined, demonstrating differing degradation mechanisms based on the acidic vs. basic conditions used. Consequently, this single monomer was successfully employed in the straightforward synthesis of a polymeric system with tunable properties based on the molecular weight and repeat unit composition.

Polymers Based on Cyclic Carbonates as Trait d'Union Between Polymer Chemistry and Sustainable CO2 Utilization

“…[110] In 2005, Haba et al reportedt he anionic homopolymerization of 3h initiatedb yD BU or by potassium tert-butoxide, thus claiming the first 5CCs anionic polymerization withoutd ecarboxylation. [112] As in the case of 1c and 3b,t he strained trans configuration of the carbonate moiety fused to a six-membered ring is likely to act as driving force for the homopolymerizationo f3h. [112] As in the case of 1c and 3b,t he strained trans configuration of the carbonate moiety fused to a six-membered ring is likely to act as driving force for the homopolymerizationo f3h.…”

“…[111] More recently,W ooley and coworkers expanded the scope of the organocatalyzedr ingopeningh omopolymerizationo f3h,c onfirming the controlled nature of the process. [50c] To note, 3h is generally prepared by the reactiono fm ethyl 4,6-O-benzylidene-a-d-glucopyranoside with phosgene-based triphosgene [112] or ECF. [50c] To note, 3h is generally prepared by the reactiono fm ethyl 4,6-O-benzylidene-a-d-glucopyranoside with phosgene-based triphosgene [112] or ECF.…”

“…[111] More recently,W ooley and coworkers expanded the scope of the organocatalyzedr ingopeningh omopolymerizationo f3h,c onfirming the controlled nature of the process. [112] As in the case of 1c and 3b,t he strained trans configuration of the carbonate moiety fused to a six-membered ring is likely to act as driving force for the homopolymerizationo f3h. [50c] To note, 3h is generally prepared by the reactiono fm ethyl 4,6-O-benzylidene-a-d-glucopyranoside with phosgene-based triphosgene [112] or ECF.…”

A Synthetic Bioinspired Carbohydrate Polymer with Mucoadhesive Properties

“…These novel materials, however, fail to recapitulate all of the key physicochemical and biointerfacial properties of polysaccharides. Indeed, previously reported carbohydrate‐inspired polymers largely suffer from poor aqueous solubility to complete insolubility, a lack of deprotected functional groups important for biological interaction (e.g., hydroxyls, amines, phosphates, carboxylates), and/or rapid degradation in acidic or basic pH . Moreover, the rigid pyranose ring backbone absent in some carbohydrate‐mimic and glyco‐polymers plays an essential role in polymer structure and resulting macroscale properties .…”

A Synthetic Bioinspired Carbohydrate Polymer with Mucoadhesive Properties

“…[18][19][20][21][22] Consequently,efforts are ongoing to develop carbohydrate-inspired polymers with non O-glycosidic linkages [23,24] such as amide, [25] carbonate, [26,27] and phosphodiester [28] linkages.T hese novel materials,h owever, fail to recapitulate all of the key physicochemical and biointerfacial properties of polysaccharides.I ndeed, previously reported carbohydrate-inspired polymers largely suffer from poor aqueous solubility to complete insolubility, al ack of deprotected functional groups important for biological interaction (e.g., hydroxyls,a mines,p hosphates, carboxylates), [23,24,[26][27][28] and/or rapid degradation in acidic or basic pH. [23,24,29] Moreover,t he rigid pyranose ring backbone absent in some carbohydrate-mimic [25] and glyco-polymers [30] plays an essential role in polymer structure and resulting macroscale properties. [31][32][33] Thus,there is as ignificant unmet need for well-defined materials that closely resemble polysaccharides and possess their highly desirable properties,such as water solubility and deprotected functional groups,t o harness in biomedical applications.…”