Phormidolides B and C,Cytotoxic Agents from the Sea: Enantioselective Synthesis of the Macrocyclic Core

New cytotoxic polyketide macrolides named phormidolides B and C were isolated from a marine sponge of the Petrosiidae family collected off the coast of Pemba (Tanzania). The isolation, structure elucidation, and enantioselective synthesis of three diastereomers of the macrocyclic core is described herein. The described synthetic methodology started from 2‐deoxy‐D ‐ribose or 2‐deoxy‐L ‐ribose and afforded the desired macrocycles with high enantiomeric purity. The key step of the synthesis is the formation of the Z‐trisubstituted double bond using a Julia–Kocienski olefination. The versatility of the synthetic methodology may provide access to other enantiopure macrocycles by making changes in the starting materials or chiral inductors.     

Lignosulfonate/silica hybrid nanoparticles as a novel biobased filler in polybenzoxazine matrix

Lignin is an abundant and sustainable resource that exhibits numerous attractive functional properties as a reinforcing agent for benzoxazine-based composites, due to its stiffness, thermal stability, and high carbon content. However, the low quality of lignin particles dispersions associated with the weak particles-matrix interactions reduces the reinforcement capability. In this work, hybrid lignin/silica (NaLS/SiO₂) nanoparticles were obtained from sodium lignosulfonate (NaLS) and tetraethylorthosilicate (TEOS) under basic conditions. The particles were characterized by transmission electron microscopy (TEM) confirming their spherical morphology and narrow nanometric-size distributions. The hybrid particles were incorporated into conventional benzoxazine (BA-a) and a difuran biobased benzoxazine (SA-dfda) to prepare nanocomposites with different mass compositions (3, 5, and 10 wt%). Morphological, mechanical, dynamo-mechanical, and thermal properties of the obtained composites were assessed. All the materials exhibited a homogenous filler dispersion that contributed to improve the reinforcement properties. Hybrid nanoparticles proved to be an interesting alternative as a filler in the benzoxazine matrix to prepare high-performance thermosetting composites.