Injectable and Self-Healing Thiazolidine-Crosslinked Hydrogels: Synthesis and Characterization

Self-healing, injectable, and responsive hydrogels are of increasing interest, particularly for biomedical applications. In this work, an original thiazolidine-based polyacrylamide hydrogel was synthesized via the condensation of two polyacrylamides carrying aldehyde and 1,2-aminothiol side groups, respectively. The hydrolytic stability and the viscoelastic properties of the hydrogel were investigated under acidic and physiological pHs. Rheological studies showed that the thiazolidine-based hydrogels exhibit dynamic properties resulting from the reversible formation of the thiazolidine linkages. Attractive self-healing ability and shear-thinning behavior were observed, rendering these hydrogels injectable through a needle. In addition, the hydrogels display a highly pH-dependent stability, making them potential candidates for drug encapsulation and controlled delivery

Lewis Basicity Modulation of <i>N</i>‑Heterocycles: A Key for Successful Cross-Metathesis

Cross-metathesis involving <i>N</i>-heteroaromatic olefinic derivatives is disclosed. The introduction of an appropriate substituent on the heteroaromatic ring decreases the Lewis basicity of the nitrogen atom, thus preventing the deactivation of the ruthenium-centered catalyst. The reaction is quite general in terms of both <i>N</i>-heterocycles and olefinic partners

Heck Coupling Using a Vinyliodo-MIDA Boronate: An Efficient and Modular Access to Polyene Frameworks

A simple Heck coupling between an alkenyl iodo-boronate and a variety of terminal olefins is disclosed. This method gives access to a wide range of dienic moieties including valuable bis-functionalized dienes. The synthetic potential of the coupling reaction is demonstrated by a short and modular preparation of several tetraenic compounds

Iron-Catalyzed Synthesis of C2 Aryl- and <i>N</i>‑Heteroaryl-Substituted Tetrahydropyrans

An iron-catalyzed cyclization of hydroxy allylic derivatives into tetrahydropyrans possessing an <i>N</i>-heteroaryl at C2 is disclosed. The reaction proceeds with good yield and in high diastereoselectivity in favor of the more stable isomer. The diastereoselectivity results from an iron-induced reopening of the tetrahydropyrans, allowing a thermodynamic equilibration. The method allows access to a variety of 2,6-disubstituted as well as 2,4,6-trisubstituted tetrahydropyrans that could be considered as attractive scaffolds for the pharmaceutical industry

Synthetic Studies toward the C14–C29 Fragment of Mirabalin

A convergent synthesis of one isomer of the C14–C29 fragment of mirabalin is disclosed. The key steps include a Marshall allenylation, a Mukaiyama aldol reaction and a Crimmins aldolization, which allow the control of 10 out of 25 stereogenic centers present in the molecule

Iron-Catalyzed Synthesis of Sulfur-Containing Heterocycles

An iron-catalyzed synthesis of sulfur- and sulfone-containing heterocycles is reported. The method is based on the cyclization of readily available substrates and proceeded with high efficiency and diastereoselectivity. A variety of sulfur-containing heterocycles bearing moieties suitable for subsequent functionalization are prepared. Illustrative examples of such postcyclization modifications are also presented

Oxidative 1,2- and 1,3-Alkyl Shift Processes: Developments and Applications in Synthesis

Oxidative 1,2- and 1,3- alkyl shifts mediated by a hypervalent iodine reagent were performed on simple and inexpensive phenol derivatives. These transpositions enable rapid redesign of the main aromatic skeleton to generate good yields of highly functionalized scaffolds containing a prochiral dienone system, a quaternary carbon center connected to as many as four sp² centers, and a carbonyl functionality or precursor. An efficient enantioselective version of this process resulting in the formation of a challenging quaternary carbon center is also described. The products represent the central cores of several natural products having important bioactivities. As an illustration of the potential of this method, we describe the rapid synthesis of several functionalized polycyclic systems as well as a formal synthesis of acetylaspidoalbidine, a hexacyclic alkaloid belonging to the <i>Aspidosperma</i> family

Iron- and Cobalt-Catalyzed Arylation of Azetidines, Pyrrolidines, and Piperidines with Grignard Reagents

Iron- and cobalt-catalyzed cross-couplings between iodo-azetidines, -pyrrolidines, -piperidines, and Grignard reagents are disclosed. The reaction is efficient, cheap, chemoselective and tolerates a large variety of (hetero)­aryl Grignard reagents

Synthetic Strategy toward the C44–C65 Fragment of Mirabalin

A convergent and flexible stereoselective synthesis of one isomer of the C44–C65 fragment of mirabalin is described. The key steps include organocatalytic aldolization, ruthenium-catalyzed asymmetric hydrogenation, amide formation, Marshall stereoselective allenylation, and the Nozaki–Hiyama–Kishi reaction