Blue Chemistry. Marine Polysaccharide Biopolymers in Asymmetric Catalysis: Challenges and Opportunities

Abstract

Alginate, chitin (precursor of chitosan) and carrageenan are natural polysaccharides derived from marine sources and available in nearly unlimited amounts. In contrast with other natural polysaccharides (i.e. cellulose), their monomers bear functional groups (amine, carboxylate, sulfate). These functional groups can be used to anchor catalytic species, or even as catalytically active units. In this mini-review, the utilization of marine polysaccharides in asymmetric catalysis is discussed. Examples include: i) combinations with chiral catalysts, resulting in heterogeneous catalytic systems, and ii) utilization of the biopolymers as chirality inducing elements -serving as chiral ligands or organocatalysts. The reviewed works propose innovative and unconventional utilizations of these renewable materials, providing not only a useful alternative to oil-based polymers, but also unforeseen and fascinating opportunities in the field of asymmetric catalysis.

Organocatalytic esterification of polysaccharides for food applications: A review

“…In the following sections, commonly used structural and reserve polysaccharides in the food industry, will be individually discussed for their potential enhancement as functional materials for food and food packaging applications through organocatalytic esterification. The reaction mechanisms involved in the synthesis of OEPs have already been well-reviewed and discussed by other authors elsewhere (Aguilera et al, 2020;Bjelić et al, 2020;Faísca Phillips, 2014;Kamber et al, 2007;Mahé et al, 2015;Meninno, 2020;Pan & Ganguly, 2019;Song & Zheng, 2017). Nevertheless, the type of organocatalyst, degree of substitution (DS), and functional properties, among others, are some hot spots that will be discussed in this review, since they can determine their potential in food applications (Table 1).…”

“…In this regard, the synthesis of carbohydrate polymer derivatives by means of organocatalysis-assisted esterification reactions using green catalysts is promising (Crabtree, 2013a,b,c), since toxic catalysts, reagents and solvents are not required to obtain high yields of OEPs under diverse reaction conditions (Mahrwald 2015a,b;Williams & Galan, 2017). Although there are many review papers covering green reactions for carbohydrate esterification (Aguilera, Tanchoux, Fochi, & Bernardi, 2020;Bjelić, Hočevar, Grilc, Novak, & Likozar, 2020;Faísca Phillips, 2014;Kamber et al, 2007;Mahé, Brière, & Dez, 2015;Meninno, 2020;Pan & Ganguly, 2019;Song & Zheng, 2017), esterification using naturally-occurring donors and organocatalysts, which are of particular importance for the food industry, has received less attention. The objective of this review article was to provide a perspective of the reaction mechanisms and additional functionalities of food-grade OEPs.…”

Chitosan as a chiral ligand and organocatalyst: preparation conditions–property–catalytic performance relationships

“…65,66 Chitosan, owing to its free amino groups and the chirality of the carbohydrate backbone is a promising material for these purposes. Although, this biopolymer was already used to prepare chiral organocatalysts, 21,26,27,67 only few publications reported the use solely its catalytic activity and chirality. 29,32 Conjugate additions are among the most versatile C-C coupling reactions, which may be catalysed by primary amines.…”

“…However, in most catalytic applications, either as support, ligand or organocatalyst, to achieve appropriate performances it was necessary to modify its structure by various functionalization. [19][20][21][22][23][24][25][26][27] Thus, the catalytic efficiency in asymmetric catalytic processes of many chitosan derivatives has been studied, whereas that of unfunctionalized materials so far received less attention. [28][29][30][31][32][33][34][35][36][37][38][39][40] In our recent studies, we have examined the asymmetric transfer hydrogenations (ATH) of prochiral ketones catalysed by chiral Ru complexes formed in situ using commercially available chitosan as ligand, 41,42 knowing from Noyori's pioneering work, that chiral 1,2-aminoalcohols may be efficient in these reductions.…”

Heparanized chitosans: towards the third generation of chitinous biomaterials

“…of these polysaccharides and their derivatives, making chitosan an exciting and promising biopolymer for biomedical applications. [6][7][8][9][10] However, it should be taken into account that the term "chitosan" represents a large group of structurally different chemicals that may not only demonstrate various biological activities, but also different functionalities (i.e. non-toxicity, biodegradability, up-take…).…”