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A study on the reactivity of 3-amino α,β-unsaturated γ-lactam derivatives obtained from a multicomponent reaction is presented. Key features of the substrates are the presence of an endocyclic α,β-unsaturated amide moiety and an enamine functionality. Following different synthetic protocols, the functionalization at three different positions of the lactam core is achieved. In the presence of a soft base, under thermodynamic conditions, the functionalization at C-4 takes place where the substrates behave as enamines, while the use of a strong base, under kinetic conditions, leads to the formation of C-5-functionalized γ-lactams, in the presence of ethyl glyoxalate, through a highly diastereoselective vinylogous aldol reaction. Moreover, the nucleophilic addition of organometallic species allows the functionalization at C-3, through the imine tautomer, affording γ-lactams bearing tetrasubstituted stereocenters, where the substrates act as imine electrophiles. Taking into account the advantage of the presence of a chiral stereocenter in C-5 substituted γ-lactams, further diastereoselective transformations are also explored, leading to novel bicyclic substrates holding a fused γ and δ-lactam skeleton. Remarkably, an example of a highly stereoselective formal [3+3] cycloaddition reaction of chiral γ-lactam substrates is reported for the synthesis of 1,4-dihidropyridines, where a non-covalent attractive interaction of a carbonyl group with an electron-deficient arene seems to drive the stereoselectivity of the reaction to the exclusive formation of the cis isomer. In order to unambiguously determine the substitution pattern resulting from the diverse reactions, an extensive characterization of the substrates is detailed through 2D NMR and/or X-ray experiments. Likewise, applications of the substrates as antiproliferative agents against lung and ovarian cancer cells are also described.

Cellulose ester derivatives having phosphoryl side-chains were synthesized by phosphorylation of two types of cellulose propionate (CP); the difference between the two CPs was whether the primary hydroxyl group at C6 had been fully propionylated or not. Dimethyl phosphate, dimethyl thiophosphate, diethyl phosphate, or diethyl thiophosphate was introduced into the residual hydroxyl positions of the CPs. Chemical composition of the respective derivatives was characterized by elemental analysis and a combined use of saponification and HPLC quantification of the released propionic acid. Their thermal properties were investigated by DSC and TGA, and an intermediate residue of the pyrolysis was also examined by FT-IR spectroscopy. From the thermal degradation measurements using TGA, the C6-O phosphorylation was found to noticeably prevent the CP derivatives from weight loss in the pyrolysis process under dynamic air, i.e., providing them with a flame-resistance functionality, whereas the C2-O and C3-O phosphorylation did not give rise to such an appreciable resistance effect. A discussion was focused on the difference in pyrolysis mechanism between the phosphorylated CPs. However, most samples of the CP derivatives showed a clear T g considerably lower than the onset temperature of the thermal degradation. Thus we suggest that it is possible to design thermoplastic flame resistant/retardant materials based on cellulose, by controlling the substitution distribution of the phosphoryl and propionyl groups introduced.

A straightforward methodology for the synthesis of isothiocyanate-functionalized mesoporous silica nanoparticles (MSNs) by exposure of aminated MSNs to 1,1′-thiocarbonyldi-2(1H)-pyridone is reported. These nanoparticles are chemically stable, water tolerant, and readily react with primary amines without the formation of any by-product. This feature allows the easy modification of the surface of the nanoparticles for tuning their physical properties and the introduction of gatekeepers on the pore outlets. As a proof-of-concept, amino-isothiocyanate-functionalized MSNs have been used for the design of a nanocontainer able to release the drug Ataluren. The release profile of the drug can be easily fine-tuned with the careful choice of the capping amine.

The synthesis of methyl celluloses with a regioselective functionalization in position 2 and 3 starting from trityl cellulose is described. The effects of methylation conditions upon the degree of substitution (DS) and the distribution of the methyl moieties were investigated in detail. The synthesis was focused on products with a DS < 2. The methyl celluloses were characterized by one and two dimensional NMR spectroscopy in order to determine the substitution pattern and quantify the fractions of the different repeating units, i.e., 2,3-di-O-, 2-mono-O-, 3-mono-O-methyl units, and non-methylated anhydroglucose units.

The synthesis of 3-mono-O-hydroxyethyl cellulose using orthogonal protecting groups was realized. The reaction of 2,6-di-O-thexyldimethylsilyl cellulose with 2-(2-bromoethoxy)tetrahydropyran leads to a completely functionalized cellulose derivative. The complete removal of the protecting groups was possible by split off of the TDMS functions with tetrabutylammonium fluoride trihydrate and subsequently the tetrahydropyran moieties with hydrochloric acid. The structure of 3-mono-O-hydroxyethyl cellulose was confirmed by applying one and two-dimensional NMR spectroscopy. The novel polymer is soluble in water and does not show thermoreversible gelation.

6-O-Alkyl-celluloses with well-defined ratio of ethyl and methyl groups at position 6 were prepared by ring-opening copolymerization of 6-O-ethyl and 6-O-methyl glucose 1,2,4-orthopivalate derivatives. An aqueous solution of 6-O-ethyl-cellulose having no methyl group was found to be thermo-responsive to be turbid at ~70 °C. An aqueous solution of 6-O-ethyl-cellulose with higher molecular weight showed endothermic and exothermic peaks in the heating and cooling curves of DSC measurements, respectively. However, 6-O-alkyl-cellulose having 10% methyl group lost its thermo-responsive character. 6-O-Alkyl-celluloses having more than ten percent of ethyl group at position 6 became water-soluble, though 6-O-methyl-cellulose is insoluble in water. Thus, 6-O-ethyl group was found to be of importance for the water solubility of regioselective 6-O-alkyl-celluloses. Furthermore, a small amount of methyl group introduced at C6 position was found to affect some of physical properties of 6-O-alkyl-celluloses such as thermo responsive property.

The importance of functionalized imidazo heterocycles has often been featured in several impactful research both from academia and industry. Herein, we report a direct C-3 acetoxymalonylation of imidazo heterocycles using relay C–H functionalization enabled by organophotocatalysis starring zinc acetate in the triple role of an activator, ion scavenger as well as an acetylating reagent. The mechanistic investigation revealed a sequential sp 2 and sp 3 C–H activation, followed by functionalization driven by zinc acetate coupled with the photocatalyst PTH. A variety of imidazo[1,2- a ]pyridines and related heterocycles were explored as substrates along with several active methylene reagents, all generating the products with excellent yields and regioselectivity, thus confirming excellent functional group tolerability.

C-H activation is a powerful strategy for forming C-C bonds without the need for prefunctionalization. In this paper, we present a general, direct, and regioselective palladium-catalyzed functionalization of a phosphorus heterocycle, 2-phenyl-1H-isophosphinoline 2-oxide. The mild reaction conditions enabled the introduction of various functionalized alkenes. Moreover, the flame-retardant properties of selected products clearly highlighted the synergy between the phosphine oxide and another heteroatom-based group, even in the condensed phase.

Cytochrome P450 monooxygenases are a large class of enzymes, which have evolved to carry out a myriad of oxidation reactions across all kingdoms of life. Reflecting the functional diversity of naturally evolved P450s, these enzymes have proven to be remarkably pliable to protein engineering for improving or altering their substrate profile, catalytic properties, selectivity, and stability. In this chapter, major contributions made in this area are discussed with an emphasis on the different protein engineering strategies, including directed evolution, rational design, or semi‐rational approaches, applied for the development of engineered P450 catalysts for biotechnological applications. This survey illustrates the diverse and growing range of applications of engineered P450s, which encompasses the synthesis of chiral building blocks, the preparation of drug metabolites, and the late‐stage functionalization of natural products, highlighting their potential toward enabling the synthesis and discovery of bioactive molecules and toward developing sustainable processes for manufacturing of pharmaceuticals and other high‐value compounds.

This chapter contains sections titled: Introduction Chemical Derivatization of Mono‐Metallofullerenes Chemical Derivatization of Di‐Metallofullerenes Chemical Derivatization of Trimetallic Nitride Template Fullerene Chemical Derivatization of Metallic Carbaide Fullerene Missing Metallofullerene Supramolecular Chemistry Conclusion References