One-Pot Double Modification of Polymers Based on Thiolactone Chemistry

Abstract

One-pot multistep reactions based on thiolactone chemistry have emerged as a powerful tool for modifying thiolactone-containing polymers in one-pot and in an elegant manner. In general, thiolactones can be opened by a wide variety of functional amines and the released thiol can react with thiol 'scavengers' of choice. This overview highlights the most important features of this approach, illustrated by the versatile and site-specific double postpolymerization modification of various reactive systems.

Homocysteine Thiolactone: Biology and Chemistry

“…Thiolactones are an interesting class of compounds that gained much attention within the last decade in several research fields [47,[49][50][51][52][53][54][55][56]. Especially, homocysteine thiolactone (HTL, Figure 3), a five-membered cyclic thioester of Hcy, plays an important role in polymer material syntheses, such as hydrogels, polyurethanes, and functional hybrid materials [49][50][51][52]. The derivative N-acetyl HTL, also known as a citiolone, is a commercial compound that was introduced as a thiolating agent for proteins, antioxidants, and mucolytic drugs.…”

Human Serum Albumin Labelled with Sterically-Hindered Nitroxides as Potential MRI Contrast Agents

“…Attempts to obtain the free base for reaction results in the self-condensation of two HTL molecules [47,48]. The intrinsic instability of the HTL free base requires an electrophile with enhanced reactivity for efficient reaction with the amino group; examples include acid halides, activated carboxylic acids and anhydrides [39,49,50]. Therefore, commercially-available nitroxide carboxylic acids 1 and 2, as well as the sterically-shielded, reduction-resistant nitroxide 3 [51], were first converted in situ into chloroanhydrides with thionyl chloride and then used to construct ORCAs.…”

Sequential Reactions for Post-polymerization Modifications

“…Another possibility for the introduction of thiols at the polymer side chains, as well as their further modification, is described in the chapter on thiolcatones by Espeel and Du Prez in this book [5]. In their approach, polymers with γ-thiolactone side groups were used as starting materials.…”