Transition metal free large-scale synthesis of aromatic vinyl chlorides from aromatic vinyl carboxylic acids using bleach

While continuing our research on Hunsdiecker reaction, we came across an interesting application of bleach, sodium hypochlorite (NaOCl) for decarboxylative chlorination reaction. The reaction is easily scaled up to 10?mmol. The reaction has good tolerance towards wide variety of functional groups. The reaction has mild conditions and gave relatively high chemical yield of the desired product.     

Solvent‐Driven Conformational Exchange for Amide‐Linked Bichromophoric BODIPY Derivatives

The fluorescence lifetime and quantum yield are seen to depend in an unexpected manner on the nature of the solvent for a pair of tripartite molecules composed of two identical boron dipyrromethene (BODIPY) residues attached to a 1,10‐phenanthroline core. A key feature of these molecular architectures concerns the presence of an amide linkage that connects the BODIPY dye to the heterocyclic platform. The secondary amide derivative is more sensitive to environmental change than is the corresponding tertiary amide. In general, increasing solvent polarity, as measured by the static dielectric constant, above a critical threshold tends to reduce fluorescence but certain hydrogen bond accepting solvents exhibit anomolous behaviour. Fluorescence quenching is believed to arise from light‐induced charge transfer between the two BODIPY dyes, but thermodynamic arguments alone do not explain the experimental findings. Molecular modelling is used to argue that the conformation changes in strongly polar media in such a way as to facilitate improved rates of light‐induced charge transfer. These solvent‐induced changes, however, differ remarkably for the two types of amide.     

Synthesis of Polyheterocyclic Dimers Containing Restricted and Constrained Peptidomimetics via IMCR-Based Domino/Double CuAAC Click Strategy

A novel strategy via the triple process (multicomponent reactions (MCR)-domino)/tandem was developed for the synthesis of restricted and constrained bis-1,2,3-triazole-linked pyrrolo[3,4-b]pyridine peptidomimetics dimers in overall yields of 20–55%. This strategy allows the construction of six heterocycles in two stages of the reaction.     

Metal-free synthesis of 2-aminothiadiazoles via TBHP-Mediated oxidative C-S bond formation

An efficient one-pot synthesis of 2-amino-1,3,4-thiadiazoles from easily available aldehydes and thiosemicarbazide using TBHP as an oxidant has been described. Notably, these reactions were carried out at room temperature using ethanol as solvent. This is the first example for one-pot synthesis of 2-amino-1,3,4-thiadiazole derivatives from aldehydes. This new synthetic methodology provides a simple procedure utilizing a safer oxidizing system that affords the target products in mild reaction condition with satisfactory yields and wide substrate scope.     

Ultrasound assisted green synthesis of bound type bis-heterocyclic carbazolyl imidazo[1,2-a]pyridines via Groebke-Blackburn-Bienayme reaction

A series of seventeen novel 3-imidazo[1,2-a]pyridine carbazoles bound type bis-heterocycles were synthesized by Ultrasound irradiation (USI) assisted Groebke-Blackburn-Bienaymé reaction (GBBR), by employing ammonium chloride (10?mol%) as a catalyst in excellent yields (90–96%). This new, efficient and mild protocol has silent features such as green inexpensive and easily available catalyst and solvent at room temperature.     

The Use of Pinner Type Reaction for the Synthesis of New Indeno[2,1‐c]pyridine‐4‐carbonitrile Derivatives

An efficient and convenient route was developed for the synthesis of new pyridinecarbonitrile derivatives by using the Pinner type of reaction. The 2‐((E)‐2‐((dimethylamino)methylene)‐1,2‐dihydro‐5,6‐dimethoxyinden‐3‐ylidene) malononitrile 2 was reacted in the presence of dry HCl gas to yield 3‐chloro‐6,7‐dimethoxy‐9H‐indeno[2,1‐c]pyridine‐4‐carbonitrile ( 3 ) in good yield. The S_NAr reaction on compound 3 with various nucleophiles yielded 3‐substituted pyridinecarbonitriles 4 , 5 , 6 , 7 , 8 , 9 in moderate to good yield.     

Rational approximant pentagonal crystals based on icosa-hedral structures

The generation of periodic quasicrystals by the projection method is considered. The effects of the simulteneous distortion of the projected icosahedron and 6D hyperlattice are presented.     

Diffraction From 1D quasicrystals

Levine and Steinhardt's expression is generalised for the structure factor of a binary quasicrystal with AτB composition. The atomic model used in this generalisation is based on the embedding of quasiperiodic chains of A and B atoms such that there is a B atom within every long interval of the A-chain. For the proposed embedding scheme, the range of interpenetration length as well as the ratio of long and short intervals in the two chains are shown to affect the diffracted intensities drastically. The effect of order-disorder on the motif, average quasilattice constant and diffracted intensities is also considered. Conditions for the composite chain to become self-similar, which for the most general embedding is not necessary, are obtained. The application of present decoration scheme to vacancy ordered phases is discussed.