Steric Shielding vs Structural Constraint in a Boron-Containing Polycyclic Aromatic Hydrocarbon

The highly reactive boron-doped polycyclic aromatic hydrocarbon 8H-8-bromo-8-borabenzo­[gh]­tetraphene has been synthesized via a multistep sequence encompassing a Peterson olefination, a stilbene-type photocyclization, and an Si/B exchange reaction. The compound was subsequently treated with mesityllithium to give the derivative 3 or with [2,6-bis­(propen-2-yl)­phenyl]lithium to furnish the intermediate 4. A scandium­(III) triflate mediated Friedel–Crafts reaction transformed 4 into the rigid, planarized triarylborane 5. Compounds 3 and 5 are both inert toward air and moisture but are still able to bind fluoride ions, where the affinity of 3 in CHCl3 is higher than that of 5. Both arylboranes are yellow solids, and their solutions exhibit an intense blue fluorescence (ΦPL = 85% (3), 89% (5)). According to cyclic voltammetry, reversible reduction occurs at half-wave potentials of E1/2 = −2.05 V (3) and −2.14 V (5; in THF, vs FcH/FcH+). The crystal lattices consist of π-stacked dimers, arranged in herringbone patterns. Importantly, 3 and 5 share nearly identical properties, despite possessing fundamentally different structures

Multistep Photoisomerization of Dimesitylboron-Functionalized Stilbene Analogues

Dimesitylboron-functionalized stilbene derivatives have been found to undergo an unusual regioselective photoisomerization upon irradiation at 365 nm. Using NMR to follow the photoreaction, the structures of key reaction intermediates and the final products were established. This photoisomerization occurs in four steps: trans–cis isomerization, Diels–Alder reaction, di-π-methane rearrangement, and ring opening with [1,3]-H migration. This results in the formation of a rare structure with three fused five-membered rings and a six-membered one

Steric Shielding vs Structural Constraint in a Boron-Containing Polycyclic Aromatic Hydrocarbon

The highly reactive boron-doped polycyclic aromatic hydrocarbon 8<i>H</i>-8-bromo-8-borabenzo­[<i>gh</i>]­tetraphene has been synthesized via a multistep sequence encompassing a Peterson olefination, a stilbene-type photocyclization, and an Si/B exchange reaction. The compound was subsequently treated with mesityllithium to give the derivative <b>3</b> or with [2,6-bis­(propen-2-yl)­phenyl]lithium to furnish the intermediate <b>4</b>. A scandium­(III) triflate mediated Friedel–Crafts reaction transformed <b>4</b> into the rigid, planarized triarylborane <b>5</b>. Compounds <b>3</b> and <b>5</b> are both inert toward air and moisture but are still able to bind fluoride ions, where the affinity of <b>3</b> in CHCl₃ is higher than that of <b>5</b>. Both arylboranes are yellow solids, and their solutions exhibit an intense blue fluorescence (Φ_PL = 85% (<b>3</b>), 89% (<b>5</b>)). According to cyclic voltammetry, reversible reduction occurs at half-wave potentials of <i>E</i>_1/2 = −2.05 V (<b>3</b>) and −2.14 V (<b>5</b>; in THF, vs FcH/FcH⁺). The crystal lattices consist of π-stacked dimers, arranged in herringbone patterns. Importantly, <b>3</b> and <b>5</b> share nearly identical properties, despite possessing fundamentally different structures

LpxC Inhibitors: Design, Synthesis, and Biological Evaluation of Oxazolidinones as Gram-negative Antibacterial Agents

Herein we report a scaffold-hopping approach to identify a new scaffold with a zinc binding headgroup. Structural information was used to give novel oxazolidinone-based LpxC inhibitors. In particular, the most potent compound, <b>23j</b>, showed a low efflux ratio, nanomolar potencies against <i>E. coli</i> LpxC enzyme, and excellent antibacterial activity against <i>E. coli</i> and <i>K. pneumoniae</i>. Computational docking was used to predict the interaction between <b>23j</b> and <i>E. coli</i> LpxC, suggesting that the interactions with C207 and C63 contribute to the strong activity. These results provide new insights into the design of next-generation LpxC inhibitors

DataSheet1_Multiple resonance type thermally activated delayed fluorescence by dibenzo [1,4] azaborine derivatives.docx

We studied the photophysical and electroluminescent (EL) characteristics of a series of azaborine derivatives having a pair of boron and nitrogen aimed at the multi-resonance (MR) effect. The computational study with the STEOM-DLPNO-CCSD method clarified that the combination of a BN ring-fusion and a terminal carbazole enhanced the MR effect and spin-orbit coupling matrix element (SOCME), simultaneously. Also, we clarified that the second triplet excited state (T2) plays an important role in efficient MR-based thermally activated delayed fluorescence (TADF). Furthermore, we obtained a blue–violet OLED with an external EL quantum efficiency (EQE) of 9.1%, implying the presence of a pronounced nonradiative decay path from the lowest triplet excited state (T1).</p

Discovery of Novel Bicyclic Pyrazoles as Potent PIP5K1C Inhibitors

Phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) is generated by phosphatidylinositol 4-phosphate 5-kinases (PIP5Ks) from phosphatidylinositol 4-phosphate (PI4P). Structurally diverse and selective inhibitors against PIP5Ks are required to further elucidate the therapeutic potential for PIP5K inhibition, although the effects of PIP5K inhibition on various diseases and their symptoms, such as cancer and chronic pain, have been reported. Our medicinal chemistry efforts led to novel and potent PIP5K1C inhibitors. Compounds 30 and 33 not only showed potent activity but also demonstrated low total clearance in mice and high levels of kinase selectivity. These compounds might serve as tools to further elucidate the complex biology and therapeutic potential of PIP5K inhibition