Ring-opening polymerization of lactones using binaphthyl-diyl hydrogen phosphate as organocatalyst and resulting monosaccharide functionalization of polylactones

Organocatalytic Ring-Opening Polymerization of ϵ-Caprolactone with Phosphoramidimidates (PADIs) as a Bifunctional Brønsted Acid Catalyst

In this study, an organocatalytic ring-opening polymerization (ROP) of ϵ-caprolactone (ϵ-CL) has been developed by employing PADIs as a novel and efficient acid/base bifunctional organocatalyst, which could afford metal-free poly(ϵ-caprolactone) with predictable molecular weight and narrow dispersity at a low catalyst loading under mild conditions. NMR and kinetic studies indicate that the ring-opening polymerizations of lactones catalyzed by PADIs proceed in a living and well controlled manner. Moreover, this organic Brønsted acid catalytic system could allow the synthesis of PCL with molecular weight above 60 kg/mol, as well as well-defined star polymers.

A one pot one step combined radical and ring-opening route for the dual functionalization of starch in aqueous medium

Starch based materials are attractive bio-based alternative to fully synthetic polymers. Native starch has however limited thermoprocessability and properties and must be modified. In order to improve the properties of starch-graft-poly(butyl-acrylate-co-styrene) copolymers via a process as green as possible, we report herein a new method for the dual functionalization of the polysaccharide via a one pot one step reaction in aqueous medium combining free radical polymerizations and ring-opening chemistry. Poly(butyl acrylate) or poly(butyl acrylate-co-styrene) (ca. 60 000 g/mol) and oligo(ε-caprolactone) were grafted on starch with a grafting percentage up to 75 %. The copolymers show two glass transition temperatures: one around 55-60 °C related to starch and a second attributed to the grafted vinyl polymers, from -46 °C to 20 °C depending on butyl acrylate/styrene ratio. The resulting dual functionalized materials exhibit excellent mechanical properties, with elongation at break in the range 20-210 %, while single functionalized starch shows less than 5 %.

Tailoring chain structures of l-lactide and ε-caprolactone copolyester macromonomers using rac-binaphthyl-diyl hydrogen phosphate-catalyzed ring-opening copolymerization with monomer addition strategy

rac-BNPH catalyzed ring-opening copolymerization of l-lactide and ε-caprolactone with monomer addition strategy effectively tailoring chain structures of macromonomers.

Examination of Pyridazine as a Possible Scaffold for Nucleophilic Catalysis

Pyridazines with amino groups positioned para to each aromatic ring nitrogen and fixed in six-membered rings were prepared. The representative symmetric amino N-Et derivative was found to slightly exceed DMAP in catalytic activity in the acetylation reaction of a tertiary alcohol in C₆D₆. Nucleophilicity eclipsing that of DMAP was established in competitive reactions using phenacyl bromide as the electrophile, and the unsymmetric N-Et derivative was revealed to have even higher nucleophilicity.

Adenine as an organocatalyst for the ring-opening polymerization of lactide: scope, mechanism and access to adenine-functionalized polylactide

Straightforward access to a bioconjugate is reported via adenine initiated ring-opening polymerization without a co-catalyst. The mechanism is elucidated by DFT.

Organophosphate-catalyzed bulk ring-opening polymerization as an environmentally benign route leading to block copolyesters, end-functionalized polyesters, and polyester-based polyurethane

To expand the potential of an organophosphate catalyst, ring-opening polymerization of cyclic esters, cyclic ester-ether, and cyclic carbonate was demonstrated under bulk conditions.

Polymerization of 5-alkyl δ-lactones catalyzed by diphenyl phosphate and their sequential organocatalytic polymerization with monosubstituted epoxides

One-pot sequential organocatalytic polymerization reactions of 5-alkyl δ-lactones and monosubstituted epoxides were carried out using the base→acid “catalyst switch” strategy, leading to well-defined polyether–polyester block copolymers with various alkyl substituents.