L-proline catalyzed asymmetric transfer aldol reaction between diacetone alcohol and aldehydes

We demonstrate for the first time, L-proline as a chiral catalyst for transfer aldol reaction between aldehydes and diacetone alcohol.     

Practical, efficient, stereoselective, formal synthesis of (2R,3R,4R)-3-hydroxy-4-methylproline

A highly efficient and stereoselective synthesis of (2R,3R,4R)-HMP is disclosed employing the sulfinyl group as an internal nucleophile to functionalize an olefin in the key step of the reaction sequence. The proline ring is elaborated by a (4C+N) cyclization.     

A simpler and greener protocol for the preparation of β-acetylamino ketones by a one-pot reaction of aryl aldehydes, enolisable ketones, acetyl chloride and acetonitrile in the presence of zeolite Hβ as a reusable catalyst

β-Acetylamino ketones have been obtained in a one-pot coupling of an aldehyde with an enolisable ketone, acetyl chloride and acetonitrile in the presence of zeolite Hβ as catalyst at room temperature (26-28 °C). The procedure has the advantages of mild workup, circumvention of high temperature and inert atmosphere. The catalyst was found to be recyclable.     

Spectrophotometric determination of mercury(II) as the ternary complex with rhodamine 6g and iodide

The formation of a pink-coloured product when rhodamine 6G is treated with tetraiodomercurate(II) is used to determine mercury (5–25 μg) in a final volume of 25 ml. The reaction occurs immediately over the pH range 1–7 and, when the system is stabilized with gelatin, the absorbance remains unchanged at 575 nm for at least 24 h. The few interfering ions can be masked by the addition of appropriate reagent solutions. The method is simple and reliable and provides a molar absorptivity of 7.0·10⁴ l mole^-1 cm^-1.     

Recovery of americium from nitric acid solutions containing calcium by different co-precipitation methods

Recovery of americium from nitric acid solutions was studied by co-precipitation as hydroxide with various ions like calcium, ferric, nickel using sodium hydroxide and ammonium hydroxide. Studies were also carried out to recover americium using lanthanum fluoride and bismuth phosphate co-precipitation. All the methods are able to co-precipitate Am quantitatively. However, co-precipitation of Am with optimum concentration iron using ammonia is found to be better from nitric acid solutions containing large concentrations of calcium ions. Approximately 2 g of Am was recovered from 150 litres of solution batch wise using iron.     

Di-μ-hydroxy-bis(N,N,N′,N′-tetramethylenediamine)-copper(II) chloride [Cu(OH)·TMEDA]2Cl2: an efficient, practical catalyst for benzylation and allylation of amides

An efficient protocol for the benzylation or allylation of amides using the corresponding benzyl or allyl chlorides as electrophiles under basic conditions with commercially available 5 mol % of [Cu(OH)TMEDA]₂Cl₂ as catalyst was developed. Under these conditions, unprotected amino acids were benzylated without any racemization.     

Regio- and stereoselective transfer of p-toluenesulfonamido group from sulfur to carbon: preparation of aminoalcohol derivatives from allylalcohols

A novel methodology for the regio- and stereoselective synthesis of amino alcohol derivatives from allylalcohols/ethers via intramolecular nucleophilic participation by the sulfilimine moiety is disclosed. The sulfilimine moiety is stereospecifically transformed to a sulfinyl moiety with an inverted configuration. The reaction is general and affords highly functionalised products.     

Exchange interactions in some low-dimensional metal dithiolene complexes

Low-dimensional systems are formed by planar metal dithiolene complexes which stack as columnar structures in the solid state. Stronger interactions among units within a chain leads to highly anisotropic magnetic properties. The magnetic effects are a manifestation of exchange interaction,J and can be studied through detailedepr techniques in conjunction with magnetic susceptibility and x-ray crystal structure. A brief review of such studies carried out mostly in our laboratory is presented along with the relevant background materials.     

Highly selective deblocking of propargyl carbonates in the presence of propargyl carbamates with tetrathiomolybdate

Propargyloxycarbonyl chloride, 1, has been used to protect the hydroxyl and amino functionalities of amino alcohols and aminophenols in one pot using triethylamine or pyridine as a base. The increased reactivity of benzyltriethylammonium tetrathiomolybdate, 2, toward propargyl carbonates over propargyl carbamates is studied in detail and has been exploited further to develop an orthogonal protection strategy for the hydroxyl and amino functionalities. For example, 2-amino-1-butanol, 6a, was treated with 1 to get the N,O-diPoc compound 7a in 90% yield, which when treated with 1.1 equiv of 2 at room temperature removes the Poc group attached to oxygen while leaving the one attached to nitrogen intact to yield compound 8a in 85% yield. This particular observation offers a new protecting strategy where an amine and an alcohol group can be protected simultaneously in one pot, and in a later synthetic step, if the alcohol group has to be deprotected selectively, it can be achieved with 1 equiv of 2.