Fluorinated organoboranes serve as versatile synthetic precursors for the preparation of value‐added fluorinated organic compounds. Recent progress has been mainly focused on the transition‐metal catalyzed defluoroborylation. Herein, we report a photocatalytic defluoroborylation platform through direct B−H activation of N‐heterocyclic carbene boranes, through the synergistic merger of a photoredox catalyst and a hydrogen atom transfer catalyst. This atom‐economic and operationally simple protocol has enabled defluoroborylation of an extremely broad scope of multifluorinated substrates including polyfluoroarenes, gem‐difluoroalkenes, and trifluoromethylalkenes in a highly selective fashion. Intriguingly, the defluoroborylation protocol can be transition‐metal free, and the regioselectivity obtained is complementary to the reported transition‐metal‐catalysis in many cases.

The synthesis and characterization of a series of Ni, Co, and Fe complexes bearing a tridentate bis(phosphino)silyl ligand (κ 3 -(2-Ph 2 PC 6 H 4 ) 2 SiMeH, [PSiP]-H, 1) are reported. 1 reacted with Ni(PMe 3 ) 4 to afford the mononuclear nickel(0) complex [η 2 (Si−H)-PSiP]Ni(PMe 3 ) (2). The halogeno nickel complexes [PSiP]Ni(X)(PMe 3 ) (X = Cl (3), Br (4), I (5)) were synthesized in the reactions of 2 with Me 3 SiCl or MeHSiCl 2 , EtBr, and MeI. Complex 2 underwent ligand substitution of PMe 3 by CO to give [η 2 (Si−H)-PSiP]Ni(CO) (6). Complex 3 reacted with NaOMe to deliver [PSiP]Ni-(OMe)(PMe 3 ) (7) through anionic ligand substitution, while the neutral ligand replacement of PMe 3 by CO in 3 afforded the rare hexacoordinate 20-electron nickel(II) complex [PSiP]Ni(Cl)(CO) 2 (8). Unexpectedly, reaction of 1 with NiMe 2 (PMe 3 ) 3 produced the tetracoordinate nickel(0) complex [Me 2 PSiP] 2 Ni (9). The complex [Me 2 PSiP]Ni(CO) 2 (10) was acquired from 9 after the substitution of one [PSiP] ligand by two carbonyl ligands. 1 reacted with Co(PMe 3 ) 4 or CoCl(PMe 3 ) 3 to afford the hydrido cobalt(II) complex [PSiP]CoH(PMe 3 ) (11) or hydrido cobalt(III) complex [PSiP]Co(H)(Cl)(PMe 3 ) (13). Complex 12, [PSiP]Co(H)(I)(PMe 3 ), could be obtained from the reaction of MeI with 11 or 13. Treatment of 13 with 1 equiv of MeLi or n-BuMgBr in THF resulted in the clean formation of cobalt(I) complex [PSiP]Co(PMe 3 ) 2 ( 14) via reductive elimination. The simple anhydrous inorganic salt NiCl 2 or CoCl 2 could also react with 1 in the presence of PMe 3 to form the corresponding silyl complexes 3 and [PSiP]Co(Cl)(PMe 3 ) (15) via Si−H bond cleavage. 1 reacted with Fe(PMe 3 ) 4 to form the hexacoordinate octahedral hydrido iron(II) complex [PSiP]Fe(H)(PMe 3 ) 2 ( 16). The molecular structures of complexes 2−5, 10, 12, 13, 15, and 16 were determined by X-ray single crystal diffraction. 16 has excellent catalytic reactivity for the reduction of aldehydes and ketones.

N-alkyl and N-aryl imines have been frequently used as directing groups in rhodium- and cobalt-catalyzed hydroarylation reactions of olefins and alkynes. However, the scope of such hydroarylation reactions has been limited by the difficulty of preparation of sterically hindered imines by condensation, and also by the steric bulkiness of the imine group itself. Reported herein is that an N-H imine serves as an alternative and highly effective directing group for cobalt-catalyzed hydroarylation of olefins, and unlocks many of the limitations associated with the previously employed N-aryl imine directing group. The power of this minimal nitrogen directing group is manifested in a fourfold ortho alkylation of benzophenone imine, and it occurs rapidly at ambient temperature.

Pivalophenone N–H imine undergoes facile directed C–H functionalization and subsequent iminyl radical fragmentation, thus efficiently affording ortho-functionalized benzonitriles.

Chlorosilanes are versatile reagents in organic synthesis and material science.Amild pathway is nowreported for the quantitative conversion of hydrosilanes to silyl chlorides under visible-light irradiation using neutral eosin Ya s ah ydrogen-atom-transfer photocatalyst and dichloromethane as ac hlorinating agent. Stepwise chlorination of di-and trihydrosilanes was achieved in ah ighly selective fashion assisted by continuous-flowm icro-tubing reactors.T he ability to access silyl radicals using photocatalytic SiÀHa ctivation promoted by eosin Yoffers new perspectives for the synthesis of valuable silicon reagents in aconvenient and green manner.

This study demonstrates a good radiologic-pathologic tumor thickness correlation. Intrarater and interrater reliability for radiologic tumor thickness was excellent. Radiologically thicker tumor was predictive of inferior survival.

The reactions of pentafluoropyridine C5NF5, hexafluorobenzene C6F6, and perfluoronaphthalene C10F8 with cobalt(0) complex, Co(PMe3)4, were investigated. The Co(I) complexes (4-C5NF4)Co(PMe3)3 (1), (C6F5)Co(PMe3)3 (2), (C10F7)Co(PMe3)3 (3), (4-C5NF4)Co(PMe3)4 (4) and (C10F7)Co(PMe3)4 (6) were obtained by selective activation of the C–F bonds. The reactions of 1 and 2 with CO afforded dicarbonyl cobalt(I) complexes (4-C5NF4)Co(CO)2(PMe3)2 (7), (C6F5)Co(CO)2(PMe3)2 (8). Under similar reaction conditions, 2 as a C–H bond activation product was obtained from the reaction of pentafluorobenzene, C6F5H, with Co(PMe3)4. The byproducts, hydrodefluorination product 1,2,4,5-C6F4H2 and F2PMe3 from the reaction of C6F5H and Co(PMe3)4 were also observed. The reaction mechanism of C6F5H with Co(PMe3)4 is proposed and partly-experimentally verified. The reaction of C6F5H with Co(PMe3)4 under 1 bar of CO at room temperature afforded hydrido dicarbonyl cobalt(II) complex (C6F5)Co(H)(CO)2(PMe3)2 (11). Treatment of the mixtures of C6F5H/Co(PMe3)4 with hexachlorobenzene, C6Cl6, resulted in (C6F5)CoCl(PMe3)3 (12) via C–H bond cleavage with the hydrodechlorination product pentachlorobenzene, C6Cl5H, and 1,2,4,5-tetrachlorobenzene, C6Cl4H2. The structures of complexes 1, 2, 6, 7, 8, 11 and 12 were determined by X-ray diffraction.

Highly linear selective, imine-directed hydroarylation of styrene has been achieved with cobalt-based catalytic systems featuring bis(2,4-dimethoxyphenyl)(phenyl)phosphine and either 2-methoxypyridine or DBU as a ligand and a Lewis base additive, respectively, thus affording a variety of 1,2-diarylethanes (bibenzyls) in good yields under mild reaction conditions. The triarylphosphine controls the regioselectivity, while the Lewis base significantly accelerates the reaction. Ligand screening and deuterium-labeling studies provide implications about the roles of the ligand and the Lewis base in the crucial C-C reductive elimination step.