Photoreduction of anthracenes catalyzed by peri ‐xanthenoxanthene: a scalable and sustainable Birch‐type alternative

The typical Birch reduction transforms arenes into cyclohexa‐1,4‐dienes by using alkali metals, an alcohol as a proton source, and an amine as solvent. Capitalizing on the strong photoreductive properties of peri‐xanthenoxanthene (PXX), herein we report the photocatalyzed “Birch‐type” reduction of acenes by employing visible blue light irradiation at room temperature in the presence of air. Upon excitation at 405 or 460 nm in the presence of a mixture of N, N‐diisopropylethylamine (DIPEA) and trifluoromethanesulfonimide (HNTf2) in DMSO, PXX photocatalyzes the selective reduction of full‐carbon acene derivatives (24–75 %). Immobilization of PXX onto polydimethylsiloxane (PDMS) beads (PXX‐PDMS) allowed the use of the catalyst in heterogeneous batch reactions, giving 9‐phenyl‐9,10‐dihydroanthracene in high yield (68 %). The catalyst could easily be recovered and reused, with no notable drop in performance observed after five reaction cycles. Integration of the PXX‐PDMS beads into a microreactor enabled the reduction of acenes under continuous‐flow conditions, thereby validating the sustainability and scalability of this heterogeneous‐phase approach

Stoichiometric Post‐Modification of Hydrogel Microparticles Dictates Neural Stem Cell Fate in Microporous Annealed Particle Scaffolds

Microporous annealed particle (MAP) scaffolds are generated from assembled hydrogel microparticles (microgels). It has been previously demonstrated that MAP scaffold are porous, biocompatible, and recruit neural progenitor cells (NPCs) to the stroke cavity after injection into the stroke core. Here, the goal is to study NPC fate inside MAP scaffolds in vitro. To create plain microgels that can later be converted to contain different types of bioactivities, the inverse electron‐demand Diels–Alder reaction between tetrazine and norbornene is utilized, which allows the post‐modification of plain microgels stoichiometrically. As a result of adhesive peptide attachment, NPC spreading leads to contractile force generation which can be recorded by tracking microgel displacement. Alternatively, non‐adhesive peptide integration results in neurosphere formation that grows within the void space of MAP scaffolds. Although the formed neurospheres do not impose a contractile force on the scaffolds, they are seen to continuously transverse the scaffolds. It is concluded that MAP scaffolds  can be engineered to either promote neurogenesis or enhance stemness depending on the chosen post‐modifications of the microgels, which can be key in modulating their phenotypes in various applications in vivo.The inverse electron‐demand Diels–Alder reaction between tetrazine and norbornene is used to create plain microgels for stoichiometric post‐modification with various peptides to control neural progenitor cell growth and differentiation in vitro. YIGSR peptide presentation leads to neurosphere formation while IKVAV leads to stem cell spreading and differentiation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/174794/1/adma202201921_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/174794/2/adma202201921.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/174794/3/adma202201921-sup-0001-SuppMat.pd