Synthesis of 2-arylpropionic acids by electrocarboxylation of benzylchlorides catalysed by PdCl2(PPh3)2

Electrochemical carboxylation of benzylchlorides catalysed by Pd(II) complex afforded 2-arylpropionic acids in good yields under atmospheric pressure of carbon dioxide at constant current of 10 mA cm⁻². Mechanistic and electrochemical studies revealed the cooperative role of reduced palladium species in the activation of carbon dioxide.     

A Copper‐Based Metal–Organic Framework Acts as a Bifunctional Catalyst for the Homocoupling of Arylboronic Acids and Epoxidation of Olefins

A copper(I)‐based metal–organic framework ({[Cu₂Br₂(pypz)]_n?nH₂O} (Cu—Br–MOF) [pypz=bis[3,5‐dimethyl‐4‐(4’‐pyridyl)pyrazol‐1‐yl] methane] has been synthesized by using an elongated and flexible bridging ligand. The structure analysis reveals that each pypz ligand acts as a tritopic ligand connected to two Cu₂Br₂ dimeric units, forming a one‐dimensional zig–zag chain, and these chains further connected by a Cu₂Br₂ unit, give a two‐dimensional framework on the bc‐plane. In the Cu₂Br₂ dimeric unit, the copper ions are four coordinated, thereby possessing a tetrahedral geometry; this proves to be an excellent heterogeneous catalyst for the aerobic homocoupling of arylboronic acids under mild reaction conditions. This method requires only 3 mol % of catalyst and it does not require any base or oxidant—compared to other conventional (Cu, Pd, Fe, and Au) catalysts—for the transformation of arylboronic acids in very good yields (98 %). The shape and size selectivity of the catalyst in the homocoupling was investigated. The use of the catalyst was further extended to the epoxidation of olefins. Moreover, the catalyst can be easily separated by simple filtration and reused efficiently up to 5 cycles without major loss of reactivity.     

Synthesis and Characterization of New (Z)‐5‐((1H‐1,2,4‐Triazol‐1‐yl)methyl)‐3‐arylideneindolin‐2‐ones

Ten compounds of new (Z)‐5‐((1H‐1,24‐triazol‐1‐yl)methyl)‐3‐arylideneindolin‐2‐ones ( 5a – j ) have been synthesized by the Knoevenagel condensation of 5‐((1H‐1,2,4‐triazol‐1‐ylmethyl)indolin‐2‐one ( 3 ) with 4‐substituted aromatic aldehydes ( 4a – j ).     

A modular CuI-L-proline catalyzed one-pot route for the rapid access of constrained and privileged hetero-atom-linked medium-sized ring systems

An efficient CuI-L-proline catalyzed one-pot synthesis was developed to generate a collection of skeletally diverse heterocyclic ring systems with sizes ranging from 6 to 9. A salient feature of this design strategy is its modular synthetic utility using an S_N2 reaction followed by a microwave assisted CuI-L-proline hetero-arylation, which has granted access to a series of heterocyclic frameworks including: benzo[e]pyrrolo[1,2-a][1,4]diazepin, benzo[e]pyrrolo[1,2-a][1,4]diazocin, benzo[e]pyrido[1,2-a][1,4]diazocinones, dibenzo[b,f][1,5]diazoninones, dihydrodibenzo[b,e][1,4]thiazepine, dibenzo[b,e][1,4]thiazocine and benzo[6,7][1,4]diazepino[1,2-a]indole. Moreover, the synthetic procedures described herein, allows rapid entries to synthetically challenging medium-sized heterocyclic systems with good overall yields.     

Tween-20: An Efficient Catalyst for One-Pot Synthesis of α-Aminophosphonates in Aqueous Media

Abstract

A green one-pot three-component synthesis has been developed for α-aminophosphonates by condensation of aldehydes, amines, and diethylphosphite by using nonionic surfactant Tween-20 as catalyst in aqueous media. The results showed that this synthetic route for α-aminophosphonates takes just 25–60 min for completion at 60 °C and affords 64%–91% yields depending on the nature of the amine substrates. The major advantages of this novel method are green reaction conditions with water as solvent, simple workup, less reaction times, and high to moderate yields.     

Silica sulfuric acid: A simple,efficient, and reusable heterogeneous catalyst for the one-pot synthesis of aryl-14H-dibenzo[<Emphasis Type="Italic">a,j</Emphasis>]xanthenes under conventional heating and solvent-free conditions

A novel approach towards the one-pot synthesis of aryl-14H-dibenzo[a,j]xanthenes is described from a known reaction between substituted aldehydes and β-naphthol in the presence of heterogeneous catalyst silica sulfuric acid under conventional heating as well as solvent-free conditions to afford good to excellent yields. The catalyst is reusable; it can be used several times without any decrease in the product yield. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 196–201, February, 2008.     

Domino Transformations of Ene/Yne Tethered Salicylaldehyde Derivatives: Pluripotent Platforms for the Construction of High sp3 Content and Privileged Architectures

Diversity-oriented synthesis (DOS) has become a powerful synthetic tool that facilitates the construction of nature-inspired and privileged chemical space, particularly for sp³-rich non-flat scaffolds, which are needed for phenotypic screening campaigns. These diverse compound collections led to the discovery of novel chemotypes that can modulate the protein function in underrepresented biological space. In this context, starting material-driven DOS is one of the most important tools used to build diverse compound libraries with rich stereochemical and scaffold diversity. To this end, ene/yne tethered salicylaldehyde derivatives have emerged as a pluripotent chemical platform, the products of which led to the construction of a privileged chemical space with significant biological activities. In this review, various domino transformations employing o-alkene/alkyne tethered aryl aldehyde/ketone platforms are described and discussed, with emphasis on the period from 2011 to date.     

Electrical transport mechanism in Al/V2O5/Al microdevices

The current-voltage characteristics of metal-insulator-metal microdevices fabricated with electron-beam evaporated vanadium pentoxide films have been studied in order to understand the electrical transport mechanism in these films. The dependence of transport properties on various factors such as film thickness, substrate temperature, and applied field, has been established. The results revealed that the electrical transport follows a Schottky-type mechanism at lower electrical fields and a Poole-Frenkel-type at higher electrical fields than 2×10⁶ V/m.     

Ferroelectric phases in non-symmetric achiral bent liquid crystals towards ambient temperatures: a novel series with oxadiazol as central moiety

Extensive survey carried out in bent liquid crystals (BLCs) exhibiting ferroelectric (FE) phases suggested for the design of non-symmetric (NS) frame. Novel series of BLCs (C₈C_m) with distinct lateral moieties and heterocyclic central (oxadiazole) moiety, viz., octyl 4-(5-(4´-(alkyloxy) biphenyl-4-yl)-1,2,4-oxadiazol-3-yl)benzoates, are reported. NS BLC frame is realised by incorporating differing number of aromatic cores and varied length of end chains in the lateral moieties. Lateral moiety with biphenyl core is prepared by Suzuki coupling. Purity of the BLC product is confirmed by ¹H NMR and elemental analysis. LC phases exhibited by C₈C_m series of BLCs for m = 8, 10, 12, 15 and 16 are characterised by polarisation optical microscopy (POM), differential scanning calorimetry (DSC) and spontaneous polarisation (P_S) techniques. C₈C_m series are found to exhibit SmA, CrystalB, B₂, B₅, SmG and SmE phase variance. SmG occurs as monotropic phase. Temperature variation of P_S(T) studied in FE B₂ and B₅ phases by field reversal method infers a moderate P_S value of ~80–100 nC · cm^?2. Order parameter growth in FE B₂ and B₅ phases is analysed through P_S(T). Normalised order parameter θ_N exhibits asymptotic behaviour with universal temperature T^U. Influence of aromatic cores and length of end chains (in lateral moieties) on the thermal stability of FE phases is discussed in the wake of the data on other BLCs.