Selective Double CH Activation at a Methylene Carbon in Methylenediphenol Derivatives to Generate Carbene-Bridged Dinuclear Iridium Complexes

One-pot Syntheses of Benzo- and Benzofuran-fused Iridaoxabenzenes via CH Bond Activations of Alkyl-bridged Diphenol Derivatives

One-pot syntheses of new π-extended metallaaromatic compounds have been developed by utilizing Ir-mediated CH bond activation of ethylene- or ethylidene-bridged diphenol derivatives. Depending on the bridging alkyl groups, two types of iridaoxabenzenes, both of which are doubly fused with benzo and benzofuran units, have been obtained. Studies on their structures and electronic characters indicate that both complexes have an aromatic character on the iridaoxacycles, and their π-conjugated systems are fully delocalized over the whole molecular skeletons. These novel metallaaromatic complexes exhibited some reactivities which are distinct from those reported for the non-fused metallaaromatic compounds.

Carbonylative Formal Cycloaddition between Alkylarenes and Aldimines Enabled by Palladium-Catalyzed Double C-H Bond Activation

Double C-H bond activation can enable an expeditious reaction pathway to cyclic compounds, offering an efficient tool to synthesize valuable molecules. However, cyclization reaction enabled by double C-H bond activation at one carbon atom is nearly unknown. Herein, we report a carbonylative formal cycloaddition of alkylarenes with imines via double benzylic C-H bond activation at one carbon atom, allowing a straightforward synthesis of β-lactams from readily accessible alkylarenes and imines, which paves the way for developing an annulation reaction through double C-H bond activation at one carbon atom.

α-Rhenabenzofuran with nonaromatic T0 and aromatic S1 states

The first α-rhenabenzofuran complexes 2-5 are obtained from one-pot reactions of ReCl₃(PMePh₂)₃ with o-ethynyl phenols. With a delocalized structure, these paramagnetic compounds are nonaromatic at the ground state, which is a triplet. But they exhibit an aromatic singlet excited state, revealed by DFT studies.

Weakly Bound Dimer of a Diaryloxygermylene Derived from a tBuPh2Si-Substituted 2,2′-Methylenediphenol

Novel diaryloxygermylenes have been prepared by the reaction of Lappert’s germylene, Ge[N(SiMe3)2]2, with 2,2′-methylenediphenols bearing different substituents. The bulkiness of the substituents on the ortho positions of the phenolic oxygen (6 and 6′ positions) affects the structure of the products both in the solid-state and in solution. When the ortho substituents are SitBuPh2, the diaryloxygemylene crystalizes as a weakly bound dimer with intermolecular Ge…O distances of ca. 3.0 Å and exists as a monomer in solution. In contrast, the germylene with SiMePh2 groups as the ortho substituents form a tightly bound dimer featuring a Ge2O2 rhombus with cis-oriented terminal aryloxy groups in the crystalline state, which is confirmed to be maintained in solution through the VT (variable-temperature)-1H NMR studies. To the best of our knowledge, the former dimeric structure is unprecedented in the family of dioxytetrylenes.

Looking deep into C-H functionalization: the synthesis and application of cyclopentadienyl and related metal catalysts

Metal catalyzed C-H functionalization offers a versatile platform for methodology development and a wide variety of reactions now exist for the chemo- and site-selective functionalization of organic molecules. Cyclopentadienyl-metal (CpM) complexes of transition metals and their correlative analogues have found widespread application in this area, and herein we highlight several key applications of commonly used transition-metal Cp-type catalysts. In addition, an understanding of transition metal Cp-type catalyst synthesis is important, particularly where modifications to the catalyst structure are required for different applications, and a summary of this aspect is given.