Data_Sheet_1_A Simple Metal-Free Cyclization for the Synthesis of 4-Methylene-3-Substituted Quinazolinone and Quinazolinthione Derivatives: Experiment and Theory.ZIP

A new series of 3-substituted 4-methylene-quinazolinthiones and 4-methylene-quinazolinones were synthesized in moderate to excellent yield through a simple reaction of 2-aminoacetophenones with isocyanates or isothiocyanates. The reaction shows good tolerance of many important functional groups in the presence of air and water under metal-free conditions. Only water is produced as a coproduct, rendering this “green” methodology a highly versatile and eco-friendly alternative to the existing methods for the construction of the quinazolinone/quinazolinthione framework. We have interpreted the reaction mechanism by use of quantum chemical calculations on the basis of state-of-the-art computational methods SMD-B3LYP-D3(BJ)/BS1//B3LYP/BS1.</p

Self-Assembly of Palladium-Based Macrocycles with N-Heterocyclic Carbene as the “Corner” Ligand

Metallacyclic complexes [(MesC−Cmeth)Pd(L)]2(OTf)4 (MesC−Cmeth = 1,1′-dimesityl-3,3′-methylenediimidazolin-2,2′-diylidene; L = 4,4′-dithiodipyridine (L1) (5), 1,2-bis(4-pyridylthio)ethane (L2) (6), 1,3-bis(4-pyridylthio)propane (L3) (7)) were obtained by the self-assembly of [(MesC−Cmeth)Pd(CH3CN)2](OTf)2 with flexible pyridine-based ligands L1−L3 in high yields. The reaction of [(MesC−Cmeth)Pd(CH3CN)2](OTf)2 with a rigid pyrazine ligand led to the formation of mononuclear [(MesC−Cmeth)Pd(pyrazine)2](OTf)2 (4), which can be ascribed to the effect of the steric bulk of the substituent. Complexes 4−6 have been well characterized by elemental analyses, 1H NMR and IR spectra, and single-crystal molecular structure analysis

Nickelacarborane-Supported Bis‑<i>N</i>‑heterocyclic Carbenes

Metallacarboranes have attracted significant attention due to their unique properties. Considerable efforts have been made on the reactions around the metal centers or the metal ion itself, while transformations of functional groups of the metallacarboranes have been much less explored. We presented here the formation of imidazolium-functionalized nickelacarboranes (2), their subsequent conversion to nickelacarborane-supported N-heterocyclic carbenoids (NHCs, 3), and the reactivities of 3 toward Au­(PPh3)Cl and Se powder, which resulted in the formation of bis-gold carbene complexes (4) and NHC selenium adducts (5). Cyclic voltammetry of 4 shows two reversible peaks, corresponding to the interconversion transformations NiII ↔ NiIII and NiIII ↔ NiIV. Theoretical calculations demonstrated relatively high-lying lone-pair orbitals, weak B–H···H–C interactions between the BH units and the methyl group, and weak B–H···π interactions between the BH groups and the vacant p-orbital of the carbene

Reactions of an Isolable Dialkylstannylene with Carbon Disulfide and Related Heterocumulenes

The reaction of isolable dialkylstannylene <b>1</b> with an excess amount of CS₂ produces an isomeric mixture of 3,3′-distanna-2,2′,4,4′-tetra­thia­bicyclo­butylidene <b>8</b> and 3,7-distanna-2,4,6,8-tetra­thia­bicyclo­[3.3.0]­oct-1(5)-ene <b>9</b> with a ratio depending on the reaction conditions. Compounds <b>8</b> and <b>9</b> are separated by column chromatography and characterized by NMR spectroscopy and X-ray crystallography. Detailed investigation of the reaction has revealed that the initial product is <b>8</b>, which isomerizes to <b>9</b> irreversibly under the catalytic influence of <b>1</b> as a Lewis acid. The above view is supported by the theoretical DFT calculations. Treatment of <b>1</b> with ArNCO [Ar = 2,6-<i>i</i>Pr₂C₆H₃] affords the corresponding carbamoyl­(hydroxyl)­stannane <b>11</b> via the hydrolysis of the corresponding sila­aziridinone formed by the [1 + 2] cycloaddition reaction of <b>1</b> with the NC double bond of the isocyanate. Stannylene <b>1</b> reacts with ArNCS, giving a mixture of complex products, while <b>1</b> does not react with CO₂

Reactions of an Isolable Dialkylstannylene with Propynoates and Benzyne

The reactions of stable monomeric dialkylstannylene <b>1</b> with methyl and ethyl propynoates give the corresponding 1:2 adducts, alkenyl­(alkynyl)­stannane <b>2</b> and <b>3</b> in high yields, while <b>1</b> does not react with parent acetylene or common mono- and disubstituted acetylenes such as phenylacetylene, trimethylsilylacetylene, diethyl 2-butynedioate, etc. Notably, <b>2</b> and <b>3</b> have the <i>Z</i>-configuration of the alkenyl moieties, in contrast to similar adducts obtained by the known reactions of silylenes with terminal acetylenes. It is suggested that the formation of a carbonyl oxygen-coordinate cyclic zwitterion as a key intermediate is essential for the reactions. Stannylene <b>1</b> adds to in situ generated benzyne, forming a 1:1 adduct having a unique 3-stanna-1-silaindane ring system

Cyclic Carbonate Synthesis from Epoxides and CO₂ Catalyzed by Aluminum–Salen Complexes Bearing a <i>nido</i>-C₂B₉ Carborane Ligand

The active and well-designed Schiff base ligands are considered “privileged ligands”. The so-called salen ligands, i.e., the tetradentate [O, N, N, O] bis-Schiff base ligands, have also found broad applications in many homogeneous catalytic reactions. Modification of the salen ligands has concentrated on altering the substituents in the phenolate rings and variations in the diamine backbones. Herein, o-carborane-supported salen ligands (2) were designed and prepared. A series of aluminum–salen complexes (3·(sol)2), which were supported by the nido-C2B9 carborane anions, were synthesized. These Al­(III) complexes showed high activities (TOF up to 1500 h–1) in catalyzing the cycloaddition of epoxides and CO2 at atmospheric pressure and near room temperature. Complexes 3·(sol)2 are one of the rare examples of Al-based catalysts capable of promoting cycloaddition at 1 bar pressure of CO2. Density functional theory (DFT) studies combined with the catalytic results reveal that the catalytic cycles occur on two axial sites of the Al­(III) center

Reactions of an Isolable Dialkylstannylene with Propynoates and Benzyne

The reactions of stable monomeric dialkylstannylene <b>1</b> with methyl and ethyl propynoates give the corresponding 1:2 adducts, alkenyl­(alkynyl)­stannane <b>2</b> and <b>3</b> in high yields, while <b>1</b> does not react with parent acetylene or common mono- and disubstituted acetylenes such as phenylacetylene, trimethylsilylacetylene, diethyl 2-butynedioate, etc. Notably, <b>2</b> and <b>3</b> have the <i>Z</i>-configuration of the alkenyl moieties, in contrast to similar adducts obtained by the known reactions of silylenes with terminal acetylenes. It is suggested that the formation of a carbonyl oxygen-coordinate cyclic zwitterion as a key intermediate is essential for the reactions. Stannylene <b>1</b> adds to in situ generated benzyne, forming a 1:1 adduct having a unique 3-stanna-1-silaindane ring system

Reactions of an Isolable Dialkylgermylene with Acyl Chlorides Forming Acyl(chloro)germanes and Diacylgermanes

The reactions of isolable dialkylgermylene 1 with benzoyl and substituted benzoyl chlorides afford the corresponding aroyl­(chloro)­germanes in high yields. While 2,2-dimethylpropanoyl chloride reacts similarly, the reactions of more reactive alkanoyl chlorides such as acetyl, propanoyl, and butanoyl chlorides give rather unexpectedly the corresponding dialkanoylgermanes 3 together with alkanoyl­(chloro)­germanes 2 (2:3 = 4:1). Aroyl- and alkanoyl­(chloro)­germanes 2a–2g and dialkanoylgermanes 3e–3g obtained were fully characterized by multinuclear NMR spectroscopy, high-resolution mass spectrometry (HRMS), and by single-crystal X-ray diffraction studies for 2a and 3f. UV–vis spectra of 3e–3g and a TDDFT study of the model diacylgermanes showed two separated n → π* absorption bands, suggesting significant electronic interaction between the two carbonyl groups in a molecule through the central germanium atom

A 12-Vertex Metallacarborane of Silver(I)

The discovery of ferrocene in 1951 was a significant landmark in the field of organometallic chemistry, and since then, numerous sandwich- or half-sandwich metallic complexes have been reported. However, silver stands as an intriguing exception in this regard, and knowledge of its bonding situation has remained undisclosed. Herein, unprecedented 12-vertex metallacarboranes of Ag­(I) (2a and 2b) were synthesized through the reaction of sodium hexamethyldisilazide (NaHMDS) with the mixture of nido-C2B9 carborane anion-supported N-heterocyclic carbene precursors (1a and 1b) and [Ag­(PPh3)­Cl]4. The X-ray structural analysis of the resulting metallacarboranes revealed a unique “slipped” half-sandwich structure, which is a rarity among cyclopentadienyl analogues. DFT calculations provided insights into the asymmetric π-interactions between the pentagonal C2B3 face and the silver ion