An iron-catalyzed reaction of pyridine and α-substituted allenoate has been disclosed. The present strategy incorporates the aerobic oxidation into annulation involving substituted allenoate, thus providing a new access to functionalized indolizine.

A TBAI (tetrabutylammonium iodide)-catalyzed direct α-oxyacylation of carbonyl compounds from readily available toluene derivatives has been developed. The distinguished features of this metal-free protocol include the employment of simple starting material, a wide carbonyl compound scope, and mild reaction conditions.

Polycyclic aromatic hydrocarbons (PAHs) are prominent lead structures for organic optoelectronic materials. This work describes the synthesis of three B,S-doped PAHs with heptacene-type scaffolds via nucleophilic aromatic substitution reactions between fluorinated arylborane precursors and 1,2-(Me3SiS)2C6H4/1,8-diazabicyclo­[5.4.0]­undec-7-ene (72–92% yield). All compounds contain tricoordinate B atoms at their 7,16-positions, kinetically protected by mesityl (Mes) substituents. PAHs 1/2 feature two/four S atoms at their 5,18-/5,9,14,18-positions; PAH 3 is a 6,8,15,17-tetrafluoro derivative of 2. For comparison, we also prepared the skewed naphtho­[2,3-c]­pentaphene-type isomer 4. The simultaneous presence of electron-accepting B atoms and electron-donating S atoms results in a redox-ambiphilic behavior; the radical cations [1 • ] + and [2 • ]+ were characterized by electron paramagnetic resonance spectroscopy. Several low-lying charge-transfer states exist, some of which (especially S-to-B and Mes-to-B transitions) compete on the excited-state potential-energy surface. Consistent with the calculated state characters and oscillator strengths, this competition results in a spread of fluorescence quantum yields (2–27%). The optoelectronic properties of 1 change drastically upon addition of Ag+ ions: while the color of 1 in CH2Cl2 changes bathochromically from yellow to red (λmax from 463 to 486 nm; −0.13 eV), the emission band shifts hypsochromically from 606 to 545 nm (+0.23 eV), and the fluorescence quantum yield increases from 12 to 43%. According to titration experiments, higher order adducts [Ag n 1 m ] n+ are formed. As a suitable system for modeling Ag+ complexation, our calculations predict a dimer structure (n = m = 2) with Ag2S4 core, approximately linear S–Ag–S fragments, and Ag–Ag interaction. The computed optoelectronic properties of [Ag2 1 2]2+ agree well with the experimentally observed ones.

2,3-Difluoro-5,14-dihydro-5,14-diborapentacene (DBP) was endowed with two vicinal Ph 2 P groups by an S N Ar reaction at both CF sites using Ph 2 PSiMe 3 . Computations reveal the ambipolar product P to undergo P-to-B charge transfer under ambient light irradiation. Consequently, P is prone to photooxidation by air, yielding the Ph 2 P(O) species PO. With S 8 or [Me 3 O][BF 4 ], P furnishes the Ph 2 P(S) or Ph 2 P(Me) + derivatives PS or [PMe][BF 4 ] 2 . Along the series P, PO, PS, and [PMe][BF 4 ] 2 , the redox potentials shift anodically from E 1/2 = À 1.89 V to À 1.02 V (CH 2 Cl 2 ). Thus, derivatization of the Ph 2 P group allows late-stage modulation of the LUMOenergy level of the DBP. Derivatization also influences the emission properties of the compounds, as PO shows green (521 nm) and [PMe][BF 4 ] 2 red (622 nm) fluorescence in C 6 H 6 , while P and PS are dark. With CuBr and AgBr, P forms dimeric [M(μ-Br)] 2 complexes [PCu] 2 and [PAg] 2 , which show pronounced metal-to-ligand charge transfer (MLCT), making P a promising ligand for photocatalysts.

Vicinally diiodinated polycyclic aromatic hydrocarbons (I2‐PAHs) are accessible from the corresponding diborylated B2‐PAHs through boron/iodine exchange. The B2‐PAHs have been prepared via twofold electrophilic borylation reactions templated by a vicinally disilylated benzene. Our protocol is applicable to fluorenes, acenes, annulated acenes, oligoaryls, and even [5]helicene. Using B2‐naphthalene as the example, we have shown that the reaction scope can, in principle, be expanded to include the synthesis of vicinally dibrominated and dihydroxylated PAHs. The usefulness of the building blocks provided by our method in the field of optoelectronic materials was demonstrated by the successful conversion of I2‐fluoranthene to the analogous doubly alkynylated fluoranthene emitter.