Current Organic Chemistry - Volume 23, Issue 11, 2019

Asymmetric catalysis holds a prestigious role in organic syntheses since a long time and chiral inductors such as ligands have been used to achieve the utmost desired results at this pitch. The asymmetric version of Tsuji-Trost allylation has played a crucial role in enantioselective synthesis. Various chiral ligands have been known for Pdcatalyzed Asymmetric Allylic Alkylation (AAA) reactions and exhibited excellent catalytic potential. The use of chiral ligands as asymmetric inductors has widened the scope of Tsuji-Trost allylic alkylation reactions. Therefore, in this review article, a variety of chiral inductors or ligands have been focused for palladium catalyzed asymmetric allylic alkylation (Tsuji-Trost allylation) and in this regard, recently reported literature (2013-2017) has been described. The use of ligands causes the induction of enantiodiscrimination to the allylated products, therefore, the syntheses of various kinds of ligands have been targeted by many research groups to employ in Pd-catalyzed AAA reactions.

Due to special properties of ILs (Ionic Liquids) like their wide liquid range, good solvating ability, negligible vapour pressure, non-inflammability, environment friendly medium, high thermal stability, easy recycling and rate promoters etc. they are used in organic synthesis. The investigation for the replacement of organic solvents in organic synthesis is a growing area of interest due to increasing environmental issues. Therefore, ionic liquids have attracted the attention of chemists and act as a catalyst and reaction medium in organic reaction with high activity. There is no doubt that ionic liquids have become a major subject of study for modern chemistry. In comparison to traditional processes the use of ionic liquids resulted in improved, complimentary or alternative selectivities in organic synthesis. The present manuscript reported the synthesis of multiple nitrogen containing five-membered heterocyclic compounds using ionic liquids. This review covered interesting discoveries in the past few years.

The present review is principally focused on the triazolium ILs (TILs) and its potential applications. The major part of this review deals with the use of triazolium ILs as catalysts in asymmetric synthesis, solvents, recognition abilities, and electrolytes in electrochemical, storage devices. Influences of stereochemistry in ion conducting properties, hydrolysis of sugar baggage, Dye-Sensitized Solar Cell (DSSC) and biological activity are also discussed. Our intention in this review is to make concise compilation and investigations of the latest key achievements, broad spectrum of developments and problems within triazolium ionic-liquid. We anticipate that this communication will encourage scientific researchers and industries to exploit triazolium ILs in addressing scientific accost.

Cyclodextrins (CDs) are naturally occurring cyclic oligosaccharides containing six (α-CD), seven (β-CD), eight (γ-CD) and more glucopyranose units linked with α-(1,4) bonds, having a terminal hydrophilic part and central lipophilic cavity. α-, β- and γ-CDs are widely used in many industrial products, technologies and analytical methods owing to their unique, versatile and tunable characteristics. In the pharmaceutical industry, CDs are used as complexing agents to enhance aqueous solubility, physico-chemical stability and bio-availability of administered drugs. Herein, special attention is given to the use of α-, β- and γ-CDs and their derivatives in different areas of drug and gene delivery systems in the past few decades through various routes of administration with a major emphasis on the more recent developments.

A green and efficient regioselective protocol was developed for the preparation of novel isoxazolines and isoxazoles of N-saccharin derivatives via the water-promoted cycloaddition reaction of nitrile oxides with alkenes and alkynes. It is noteworthy that KI/Oxone/water-promoted one-pot three-component reactions of aldehyde, hydroxylamine hydrochloride, and alkene or alkyne were observed to be very satisfactory. The synthesis of all adducts (4a-j/5a-j) has been carried out by this method with high to excellent yields (70-95%) at 25°C within 30 min, using ultrasonic probe. All the new compounds were thoroughly characterized by spectroscopic techniques and also 5b, 5c and 5f were structurally identified by single-crystal X-ray diffraction methods. X-ray crystallography structure analysis clearly supported the regioselectivity of the cycloaddition reaction.