Asymmetric synthesis of (+)-stagonolide C and (−)-aspinolide A via organocatalysis

A new enantioselective synthesis of two important fungal metabolites, (+)-stagonolide C and (?)-aspinolide A, has been described from readily available raw materials. Proline catalyzed asymmetric α-aminooxylation and Jorgensen’s epoxidation of aldehydes are the key reactions employed in the introduction of chirality. The formation of the 10-membered lactone core structure was finally accomplished via Steglich esterification and ring closing metathesis reactions.     

Chitosan hydrochloride mediated efficient,green catalysis for the synthesis of perimidine derivatives

Chitosan hydrochloride as biopolymer‐based, renewable, and recyclable heterogeneous catalyst was used for efficient one‐pot synthesis of perimidine derivatives. This newly developed greener methodology provides a very simple and greener route for the synthesis of perimidines in short time with excellent yield.     

Eco‐friendly,ultrasound‐assisted,and facile synthesis of one‐pot multicomponent reaction of acridine‐1,8(2H,5H)‐diones in an aqueous solvent

A one‐pot, multistep synthesis of acridine‐1,8(2H,5H)‐diones ( 4a–m ) was achieved by three‐component reaction of dimedone ( 1 ) with an aromatic aldehyde ( 2a–m ) and an ammonium acetate ( 3 ) using water as a green solvent without any catalyst and a simple, easily handled, and ultrasonic technique as well as conventional method.     

2,4,6-Tris(4-iodophenoxy)-1,3,5-triazine as a new recyclable “iodoarene” for in situ generation of hypervalent iodine(III) reagent for α-tosyloxylation of enolizable ketones

The synthesis of 2,4,6-tris[(4-iodo)phenoxy)]-1,3,5-triazine 6, as a new recyclable nonpolymeric analogue of iodobenzene is achieved using the reaction of 2,4,6-trichloro-1,3,5-triazine with 4-iodophenol in the presence of KOH. The application of 6 as a recyclable ‘iodoarene’ is demonstrated for α-tosyloxylation of enolizable ketones via in situ generation of hypervalent iodine(III) species using PTSA and MCPBA as the terminal oxidant. The recyclability of the reagent 6 was possible owing to the facile recovery and reuse from the reaction mixture due to its near insolubility in methanol.     

Plasmon‐Enhanced Photocurrent Generation from Click‐Chemically Modified Graphene

The visible‐light response of Au nanoparticles (AuNPs) assembled on rGO through different molecular bridges was investigated by transient photocurrent generation. We prepared rGO with two self‐assembled monolayers (SAMs), one linear and the other with aromatic triazoles through a click cycloaddition reaction. A fivefold photocurrent enhancement was observed for triazole linkers over the aminopropyltrimethoxysilane (APTMS) linker. Cyclic voltammetry (CV) and impedance measurements also suggest fast electron transfer on account of the low resistance offered by the click‐modified rGO surface whereby introduction of triazoles offers the efficient bridge between the donor AuNPs and acceptor rGO.     

Cellulose sulphuric acid as a biodegradable and reusable catalyst for the Knoevenagel condensation

A green, mild and efficient method for Knoevenagel condensation of 3-formylchromone/2-chlroquinoline-3-carbaldehyde with active methylene compounds such as Meldrum’s acid/ethyl cyanoacetate using biosupported cellulose sulphuric acid (CSA) in the solid-state by grinding under solvent-free condition has been developed. This method provides several advantages including environmental friendliness, shor t reaction times, high yields and a simple work-up procedure. Moreover, the CSA was successfully reused for four cycles without significant loss of activity.     

Reliable and reproducible colorimetric detection of mercury ions (Hg2+) using green synthesized optically active silver nanoparticles containing thin film on flexible plastic substrate

Journal of Solid State Electrochemistry - Green synthesis of optically active silver nanoparticles (Ag) containing thin film on flexible plastic strip substrate has been carried using guava leaf...