Sujit Roy

Bio: Sujit Roy is an academic researcher from Indian Institute of Technology Bhubaneswar. The author has contributed to research in topics: Catalysis & Alkylation. The author has an hindex of 37, co-authored 204 publications receiving 3682 citations. Previous affiliations of Sujit Roy include Bhabha Atomic Research Centre & Indian Institute of Technology Kanpur.

In vivo response of porous hydroxyapatite and beta-tricalcium phosphate prepared by aqueous solution combustion method and comparison with bioglass scaffolds.

Abstract: Pure hydroxyapatite (HAp) and a biphasic calcium phosphate [containing 90% of beta-tri-calcium phosphate (beta-TCP) and 10% HAp] were tailored through an aqueous solution combustion synthesis. Porous struts were prepared using all the powders along with bioglass, a known bioactive material, and subsequently characterized. Sterilized struts were implanted to the lateral side of radius bone of 24 black Bengal goats of either sex, in which a blank hole was left unfilled in a group of six specimens to act as control. The bone formation response of the three implanting materials in vivo has been studied using scanning electron microscope and histological analysis in contrast with positive controls. Push-out tests were used to assess the mechanical strength at the bone-biomaterial interface. It was observed that interfacial response was strongly dependent on combinations of different physical and chemical parameters. The surface of beta-TCP exhibited similar characteristics of bone and was distinct from those of intervening apatite layer of bioglass. Lower bone ingrowth and reduced strength was observed with HAp compared to beta-TCP/bioglass-based implants. Bone formation response of the Ca-P material varied according to the composition of the implanting material, which could be tailored through this novel synthesis.

Cooperative friedel-crafts catalysis in heterobimetallic regime : Alkylation of aromatics by π-activated alcohols

Abstract: The highly active Friedel−Crafts alkylation (FCA) catalyst, [Ir(COD)Cl(SnCl3)(SnCl4)(arene)]+Cl- (1-SnCl4), is easily generated in one-pot from [Ir(COD)Cl]2 or [Ir(COD)(μ-Cl)Cl(SnCl3)]2 (1) and SnC...

Catalytic Hunsdiecker Reaction of α,β-Unsaturated Carboxylic Acids: How Efficient Is the Catalyst?

Abstract: UV-vis spectrophotometry is utilized to measure the relative efficiency of lithium acetate, tetrabutylammonium trifluoroacetate, and triethylamine as catalysts for the conversion of 4-methoxycinnamic acid to 4-methoxy-β-bromostyrene. In acetonitrile-water as solvent, the efficiency order is lithium acetate > triethylamine > tetrabutylammonium trifluoroacetate. For triethylamine as catalyst, solvent-dependent order is acetonitrile-water > dichloromethane > acetonitrile. Using triethylamine as catalyst (5-20 mol %), cinnamic acids, and propiolic acids are converted to corresponding β-bromostyrenes and 1-halo-1-alkynes in 60-98% isolated yields within 1-5 min.

Dual-reagent catalysis within Ir-Sn domain: highly selective alkylation of arenes and heteroarenes with aromatic aldehydes.

Abstract: Reactions of arenes and heteroarenes with aromatic aldehydes proceeded smoothly in the presence of a catalytic combination of [Ir(COD)Cl] 2 -SnCl 4 to afford the corresponding triarylmethane derivatives (TRAMs) in high yields. This 100% TRAM selective transformation is clean and eliminates the use of acid systems.

Organic Reactions in Aqueous Media with a Focus on Carbon−Carbon Bond Formations: A Decade Update

Abstract: 4.2.8. Reductive Coupling 3109 5. Reaction of Aromatic Compounds 3110 5.1. Electrophilic Substitutions 3110 5.2. Radical Substitution 3111 5.3. Oxidative Coupling 3111 5.4. Photochemical Reactions 3111 6. Reaction of Carbonyl Compounds 3111 6.1. Nucleophilic Additions 3111 6.1.1. Allylation 3111 6.1.2. Propargylation 3120 6.1.3. Benzylation 3121 6.1.4. Arylation/Vinylation 3121 6.1.5. Alkynylation 3121 6.1.6. Alkylation 3121 6.1.7. Reformatsky-Type Reaction 3122 6.1.8. Direct Aldol Reaction 3122 6.1.9. Mukaiyama Aldol Reaction 3124 6.1.10. Hydrogen Cyanide Addition 3125 6.2. Pinacol Coupling 3126 6.3. Wittig Reactions 3126 7. Reaction of R,â-Unsaturated Carbonyl Compounds 3127

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Chemistry of Polyvalent Iodine

Abstract: Starting from the early 1990’s, the chemistry of polyvalent iodine organic compounds has experienced an explosive development. This surging interest in iodine compounds is mainly due to the very useful oxidizing properties of polyvalent organic iodine reagents, combined with their benign environmental character and commercial availability. Iodine(III) and iodine(V) derivatives are now routinely used in organic synthesis as reagents for various selective oxidative transformations of complex organic molecules. Several areas of hypervalent organoiodine chemistry have recently attracted especially active interest and research activity. These areas, in particular, include the synthetic applications of 2-iodoxybenzoic acid (IBX) and similar oxidizing reagents based on the iodine(V) derivatives, the development and synthetic use of polymer-supported and recyclable polyvalent iodine reagents, the catalytic applications of organoiodine compounds, and structural studies of complexes and supramolecular assemblies of polyvalent iodine compounds. The chemistry of polyvalent iodine has previously been covered in four books1–4 and several comprehensive review papers.5–17 Numerous reviews on specific classes of polyvalent iodine compounds and their synthetic applications have recently been published.18–61 Most notable are the specialized reviews on [hydroxy(tosyloxy)iodo]benzene,41 the chemistry and synthetic applications of iodonium salts,29,36,38,42,43,46,47,54,55 the chemistry of iodonium ylides,56–58 the chemistry of iminoiodanes,28 hypervalent iodine fluorides,27 electrophilic perfluoroalkylations,44 perfluoroorgano hypervalent iodine compounds,61 the chemistry of benziodoxoles,24,45 polymer-supported hypervalent iodine reagents,30 hypervalent iodine-mediated ring contraction reactions,21 application of hypervalent iodine in the synthesis of heterocycles,25,40 application of hypervalent iodine in the oxidation of phenolic compounds,32,34,50–53,60 oxidation of carbonyl compounds with organohypervalent iodine reagents,37 application of hypervalent iodine in (hetero)biaryl coupling reactions,31 phosphorolytic reactivity of o-iodosylcarboxylates,33 coordination of hypervalent iodine,19 transition metal catalyzed reactions of hypervalent iodine compounds,18 radical reactions of hypervalent iodine,35,39 stereoselective reactions of hypervalent iodine electrophiles,48 catalytic applications of organoiodine compounds,20,49 and synthetic applications of pentavalent iodine reagents.22,23,26,59 The main purpose of the present review is to summarize the data that appeared in the literature following publication of our previous reviews in 1996 and 2002. In addition, a brief introductory discussion of the most important earlier works is provided in each section. The review is organized according to the classes of organic polyvalent iodine compounds with emphasis on their synthetic application. Literature coverage is through July 2008.

Advances in Synthetic Applications of Hypervalent Iodine Compounds

Abstract: The preparation, structure, and chemistry of hypervalent iodine compounds are reviewed with emphasis on their synthetic application. Compounds of iodine possess reactivity similar to that of transition metals, but have the advantage of environmental sustainability and efficient utilization of natural resources. These compounds are widely used in organic synthesis as selective oxidants and environmentally friendly reagents. Synthetic uses of hypervalent iodine reagents in halogenation reactions, various oxidations, rearrangements, aminations, C–C bond-forming reactions, and transition metal-catalyzed reactions are summarized and discussed. Recent discovery of hypervalent catalytic systems and recyclable reagents, and the development of new enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important achievement in the field of hypervalent iodine chemistry. One of the goals of this Review is to attract the attention of the scientific community as to the benefits of...