Straightforward Xanthate-Mediated Synthesis of Functional γ-Thiolactones and Their Application to Polymer Synthesis and Modification

Abstract

Thiolactones allow catalyst-free polymer synthesis and modification under stoichiometric conditions at mild temperatures, without the need for tedious and costly purification steps. However, there is a need for simple and general methods for the preparation of functional thiolactones. We have developed a modular platform for γ-thiolactone synthesis based on free-radical xanthate addition to alkenes. Because of the ready availability of a great variety of functional vinyl, allyl, and maleimido derivatives, numerous substituents (exemplified here through alkyl, perfluoroalkyl, diethyl phosphonate, and N-substituted succinimidyl groups) could be efficiently attached to the γ-position of the thiolactone ring. A second substituent may be added in the α-position by proper selection of the xanthate leaving group. In all cases the target thiolactone was obtained in good yield from the xanthate:alkene monoadduct by consecutive Chugaev elimination and cyclization. The potential of these new substituted thiolactone building blocks for polymer chemistry was demonstrated via an amine–thiol–ene conjugation strategy which resulted in successful end-functionalization of amino-terminated polymers and a thiol–acrylate step-growth polymerization to prepare functional poly­(ester amide)­s. This versatile method for making functional thiolactones should find broad applications as a means to prepare new materials with original properties.

Study on Post‐Polymerization Modification of Ring‐Opening Metathesis Polymers Involving Pendant Thiolactone Units

“…For instance, the group reacted thiolactone compound bearing allyl or acrylate groups, with a variety of amine compounds through the radical thiol‐ene or nucleophilic thiol‐Michael addition reactions to prepare various linear polymers simultaneously . After that, various polymer topologies such as graft, hyperbranched, cyclic, and so forth as well as polymers with various applications through the thiolactone chemistry have been accomplished …”

“…12,13 After that, various polymer topologies such as graft, hyperbranched, cyclic, and so forth as well as polymers with various applications through the thiolactone chemistry have been accomplished. [14][15][16][17][18][19][20][21][22][23][24] In 2015, Rudolph et al synthesized a versatile monomer namely, maleimide thiolactone that can undergo homo and copolymerization through the radical polymerization. The resulting polymers possessing pendant thiolactone group were in situ reacted with butylamine and methyl acrylate (MA) at room temperature to demonstrate the versatility of maleimide thiolactone group toward the aminolysis and subsequent thiol-Michael reactions.…”

Study of the zinc action on the 2-chloroethyl 2-bromo-2-perfluoroalkylethanoates

“…The prolonged heat of the same reagents 2 with a zinc excess, yield the bis(vinyl perfluoroalkyl) oxyethylene 6 as exclusive products. The highly fluorinated obtained compounds 2-perfluoroalkyl acids 3 and bis(vinyl perfluoroalkyl ester) ethoxides 6, among many others applications, may have interesting surface properties [64][65][66] and can also undergo some interesting reactions, particularly in the synthesis of organofluorinated heterocyclic compounds [67,68] …”

Organocatalytic Michael Addition as a Method for Polyisobutylene Chain‐End Functionalization

“…[7] Such macromolecular thiols can be also prepared in situ via sunlight induced polymer chain-end degradation [8] or nucleophilic ring opening of thiolactone with amines. [9] Owing to its low glass transition temperature (T g ≈ 200 K), remarkable adhesiveness, chemical inertness and unique gas barrier properties, polyisobutylene (PIB) has been utilized in a broad range of applications such as performance tires, adhesives and membrane manufacturing [10] to being used as a base for the chewing gum. [11] In addition, multiblock copolymers of PIB and polystyrene are considered as perspective biomaterials for stents, prosthetics and drug release systems, due to their excellent inertness and biocompatibility.…”

“…An alternative approach to the functionalization of (meth) acrylates with amines is the so called amino-thiol-ene reaction (Scheme 2). [9] The first step of this reaction is the nucleophilic ring opening of the functional thiolactone using the amine functional reagents 9, 10 or 15. Herein, the commercially available N-acetylhomocysteine thiolactone TL was used.…”