FeCl3-mediated selenylative benzannulation of aryl alkynones to 3-selenyl ß-naphthols.

An efficient selenylative cyclization of aryl-alkynones with diselenides in the presence of iron(III)chloride at room temperature to prepare 3-seleno-2-naphthols in good yields has been described. Furthermore, the resulting products were transformed into selenyl-naphthofuran and selenyl-1,2-naphthoquinone derivatives.

Domino Reaction of 2,4-Diyn-1-ols with 1,3-Dicarbonyl Compounds: Direct Access to Aryl/Heteroaryl-Fused Benzofurans and Indoles.

A domino propargylation/furanylation (intramolecular exo-dig-cyclization)/benzannulation reaction of 2,4-diyn-1-ols with 1,3-dicarbonyl compounds has been developed for the first time. This provides a novel and effective method for the preparation of aryl/heteroaryl-fused benzofurans from easily accessible starting materials in a single step. The methodology was extended to pyrrolyl-benzannulation to obtain aryl/heteroaryl-fused indoles. Further, application of this approach in the synthesis of eustifoline D and dictyodendrin structural frameworks has been demonstrated.

Ag-Catalyzed Oxidative ipso-Cyclization via Decarboxylative Acylation/Alkylation: Access to 3-Acyl/Alkyl-spiro[4.5]trienones.

A strategy to functionalized spiro[4.5]trienones, by domino silver-catalyzed decarboxylative acylation or alkylation/ ipso-cyclization of N-arylpropiolamides with α-keto acids/alkyl carboxylic acids, is presented. This transformation offers a wide range of substituted 3-acyl/alkyl-spiro[4.5]trienones in high yields with a broad substrate scope. The approach was further extended to access fused tricyclic frameworks, 6,7-dihydro-3H-pyrrolo[2,1-j]quinoline-3,9(5H)-diones.

Metal-free propargylation/aza-annulation approach to substituted ß-carbolines and evaluation of their photophysical properties.

An efficient acid-catalyzed propargylation/aza-annulation sequence was developed under metal-free reaction conditions, thus leading to a one-pot synthesis of a variety of substituted ß-carbolines starting from propargylic alcohols and indole 2-carbonyls. This versatile strategy was further extended to the synthesis of 5-azaindoles and 5-azabenzothiazoles. Optical properties suggested that manipulation of electron donor and acceptor moieties on ß-carbolines has an impact on their ground and excited state electronic behavior. This leads to blue or green emission and should facilitate the development of organic light emitting diodes (OLEDs). Electrochemical and stability studies revealed that 4a-6 shows ease of redox activity and photostability during illumination.

Clean synthesis of biolubricant range esters using novel liquid lipase enzyme in solvent free medium.

In view of the rising global problems of environment pollution and degradation, the present process provides a 'green solution' to the synthesis of higher esters of lubricant range, more specifically in the range C12-C36, using different combinations of acids and alcohols, in a single step reaction. The esters produced are biodegradable in nature and have a plethora of uses, such as in additives, as lubricating oils and other hydraulic fluids. The enzymatic esterification was performed using liquid (non-immobilized or free) lipase enzyme, without any additional organic solvent. Soluble lipase proves to be superior to immobilized enzymes as it is more cost effective and provides a faster process for the production of higher esters of lubricant range. An interesting finding was, that the lipase enzyme showed higher conversion rates with increasing carbon number of straight chain alcohols and acids. Reactions were carried out for the optimization of initial water concentration, temperature, pH of the substrate mixture and the chain length of the substrates. Under optimized conditions, the method was suitable to achieve ~ 99% conversion. Thus, the process provides an environment friendly, enzymatic alternative to the chemical route which is currently used in the industrial synthesis of lubricant components.