Preparation of Quinazolinoquinazolinones via a Cascade Approach

A one-pot synthesis of quinazolino­[3,4-a]­quinazolin-13-ones was realized from the direct reaction of o-(methoxycarbonyl)­benzenediazonium salts, nitriles, and 2-cyanoanilines in moderate to good yields. This method utilizes the in situ generation of reactive N-arylnitrilium ion, which undergoes further amination/tandem cyclization/amidation to deliver the desired polycyclic scaffolds with consecutive formation of four N–C bonds. Flexibility in substitution patterns, mild reaction conditions, and operational simplicity are the salient features of this methodology

Preparation of Substituted Phenanthridines from the Coupling of Aryldiazonium Salts with Nitriles: A Metal Free Approach

A transition metal free approach for the synthesis of substituted phenanthridines from the coupling reaction of aryldiazonium tetrafluoroborates with nitriles has been developed. This operationally simple protocol proceeds through a substitution of aryldiazonium with nitriles followed by an intramolecular arylation to provide the corresponding phenanthridines in moderate to excellent yields

Diamination of Phenylene Dihalides Catalyzed by a Dicopper Complex

Diamination of phenylene dihalides with aqueous ammonia to give the corresponding phenylenediamines can be achieved by using a dicopper complex [Cu₂(bpnp)­(OH)­(CF₃COO)₃] (<b>1</b>) (bpnp = 2,7-bis­(pyridine-2-yl)-l,8-naphthyridine) as the catalyst in the presence of Bu₄NBr and Cs₂CO₃ in high yields. In addition, 1,3,5-tribromobenzene was converted into benzenetriamine quantitatively under the same conditions. This method offers a new opportunity, particularly simplifying steps and increasing yields, for the preparation of aryl diamines

One-Pot Reactions for Synthesis of 2,5-Substituted Tetrazoles from Aryldiazonium Salts and Amidines

One-pot sequential reactions of aryldiazonium salts with amidines followed by the treatment of I₂/KI under basic conditions provide 2,5-disubstituted tetrazoles in moderate to excellent yields. This one-pot synthesis has several advantages such as mild reaction conditions, short reaction time, convenient workup, and high yields, making this methodology practical

One-Pot Reactions for Synthesis of 2,5-Substituted Tetrazoles from Aryldiazonium Salts and Amidines

One-pot sequential reactions of aryldiazonium salts with amidines followed by the treatment of I₂/KI under basic conditions provide 2,5-disubstituted tetrazoles in moderate to excellent yields. This one-pot synthesis has several advantages such as mild reaction conditions, short reaction time, convenient workup, and high yields, making this methodology practical

One-Pot Reactions for Synthesis of 2,5-Substituted Tetrazoles from Aryldiazonium Salts and Amidines

One-pot sequential reactions of aryldiazonium salts with amidines followed by the treatment of I₂/KI under basic conditions provide 2,5-disubstituted tetrazoles in moderate to excellent yields. This one-pot synthesis has several advantages such as mild reaction conditions, short reaction time, convenient workup, and high yields, making this methodology practical

Air- and Moisture-Stable Cyclopalladated Complexes as Efficient Catalysts for Suzuki-Miyaura Coupling Reaction

A series of cylcopalladated complexes containing a six-membered chelating ring with the general formula [Pd(Cl)(k2N,C-CH2C6H2(Me)2CHNAr)]2 [where Ar = 2,6-(Me)2C6H3− (3a); 2,6-(iPr)2C6H3− (3b)] and the related phosphine-substituted species [PdCl(k2N,C-CH2C6H2(Me)2CHNAr)(PR3)] [Ar = 2,6-(Me)2C6H3−, R = Cy (5a); Ar = 2,6-(iPr)2C6H3, R = Cy (5b); Ar = 2,6-(Me)2C6H3−, R = Ph (5c); Ar = 2,6-(iPr)2C6H3−, R = Ph (5d)] have been synthesized. In addition, an ortho-metalated complex [PdCl(k2N,C-C6H4CHN(2,6-iPr2C6H3))(PCy3)] (7) was prepared by a similar manner. Crystal structures of 3a, 5b,c, and 7 have been determined. The use of these palladium complexes as catalysts for Suzuki−Miyaura coupling reaction of aryl halides with arylboronic acids in ethanol solution was examined. It is found that this series of palladacycles are considerably active under aerobic conditions. Typically, the best activity (TON ≈ 106) is seen with 3a,b in the coupling reaction of aryl bromide with phenylboronic acid. However, a TEM study showed that the palladium nanoparticles were formed under the reaction conditions, which might be the active species for the catalysis

An Anthyridine-Based Pentanitrogen Donor Switches from Mono- to Tetradentate with Pd(II) Ions

Treatment of 5-phenyl-2,8-bis­(2-pyridinyl)­anthyridine (L) with (PPh3)2PdCl2 or (dppe)­PdCl2 in the presence of a silver salt resulted in the formation of [trans-(PPh3)2PdLCl]­(BF4) (1a), [trans-(PPh3)2PdL(MeCN)]­(BF4)2 (1b), [trans-(PPh3)2PdLCl]­(PF6) (1c) ,or [cis-(dppe)­PdLCl]­(BF4) (4), respectively. The ligand L in these complexes acts as a monodentate ligand with N(10) of anthyridine binding to the metal center. In the presence of PPh3, dinuclear complexes [Pd2L(CH3CN)2Cl2]­(BF4)2 (2) and [Pd2L(CH3CN)4]­(BF4)4 (3) readily underwent dechelation to yield 1a,b, respectively, whereas the reaction of 2 with dppe gave 4. On the other hand, treatment of 1a and 4 with S8 in the presence of a sufficient amount of palladium ions provided the corresponding dinuclear complex 2. Furthermore, this kind of substitution is also applicable with the Pd-Me complex [Pd2L(CH3CN)2Me2]­(BF4)2 (5), which could be prepared from complexation of L with 2 equiv of [(COD)­Pd­(CH3CN)­Me]­(BF4). Thus, [trans-(PPh3)2PdLMe]­(BF4) (7) was obtained by the reaction of 5 with PPh3. However, the reaction of PPh3 with [Pd2L(CH3CN)2(MeCO)2]­(BF4)2 (6), a CO insertion product of 5, gave a messy result. The catalytic activity of these complexes in the Suzuki–Miyaura coupling of aryl halide with arylboronic acid under a CO atmosphere was investigated. Crystal structures of 1c, 4, 5, and 7 are reported to confirm their structural details. This work demonstrates the novelty of L as a hypodentate ligand toward palladium ions

Dicopper Complexes with Anthyridine-Based Ligands: Coordination and Catalytic Activity

Two new anthyridine-based ligands, 5-phenyl-2,8-bis­(2-pyridinyl)-1,9,10-anthyridine (<b>L</b>_<b>3</b>) and 5-phenyl-2,8-bis­(6′-bipyridinyl)-1,9,10-anthyridine (<b>L</b>_<b>4</b>), were designed for accommodation of dimetallic systems with the metal ions separated by ∼5 Å. Complexation of Cu­(ClO₄)₂ with <b>L</b>_<b>3</b> and <b>L</b>_<b>4</b> provided the corresponding dicopper complexes [{Cu₂(<b>L</b>_<b>3</b>)­(H₂O)₄­(CH₃CN)₂}­(ClO₄)₄] (<b>3</b>) and [{Cu₂(<b>L</b>_<b>4</b>)­(μ-ClO₄)₂}­(PF₆)₂] (<b>4</b>), respectively. Both complexes were characterized by spectroscopic methods, and the detail structural features were further confirmed by X-ray crystallography. Structural analyses of <b>3</b> and <b>4</b> reveal the Cu···Cu distances in the complexes being 4.9612(7) and 5.013 (2) Å, respectively. Both complexes are active in the catalytic oxidation of benzyl alcohols into the corresponding aldehydes. Furthermore, complex <b>4</b> appears to be a good catalyst for the oxidative coupling of primary alcohols into the corresponding esters with the use of hydrogen peroxide as the oxidant in an aqueous medium. The possible cooperative interactions between the metal ions during the catalysis are discussed