Prodeep Phukan

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

Bromination is one of the most important transformations in organic synthesis and can be carried out using bromine and many other bromo compounds. Use of molecular bromine in organic synthesis is well-known. However, due to the hazardous nature of bromine, enormous growth has been witnessed in the past several decades for the development of solid bromine carriers. This review outlines the use of bromine and different bromo-organic compounds in organic synthesis. The applications of bromine, a total of 107 bromo-organic compounds, 11 other brominating agents, and a few natural bromine sources were incorporated. The scope of these reagents for various organic transformations such as bromination, cohalogenation, oxidation, cyclization, ring-opening reactions, substitution, rearrangement, hydrolysis, catalysis, etc. has been described briefly to highlight important aspects of the bromo-organic compounds in organic synthesis.

CoFe2O4–ZnS nanocomposite: a magnetically recyclable photocatalyst

A new synthesis of a CoFe2O4–ZnS magnetic nanocomposite has been achieved and used as an efficient photocatalyst in the degradation of methyl orange in water under UV irradiation. The photocatalyst is magnetically recoverable from the reaction medium and suitable for multiple uses with sustained catalytic activity.

RECENT ADVANCES IN CLAY-CATALYZED ORGANIC TRANSFORMATIONS

(2000). RECENT ADVANCES IN CLAY-CATALYZED ORGANIC TRANSFORMATIONS. Organic Preparations and Procedures International: Vol. 32, No. 1, pp. 1-40.

Mukaiyama Aldol Reactions of Silyl Enolates Catalyzed by Iodine

Abstract Iodine catalyzed Mukaiyama aldol reaction of silyl enol ethers and silyl ketene acetal with aldehydes, ketones and acetals in good yield with preferential antiselectivity has been described.

EFFICIENT PROTOCOL FOR STEREOSELECTIVE EPOXIDATION OF CINNAMIC ESTERS USING TsNBr2

An efficient method has been developed for the synthesis of epoxide from cinnamic esters without any catalyst. The reaction was performed in CH3CN–water (4:1) using N,N-dibromo-p-toluenesulfonamide (TsNBr2) in alkaline conditions. This procedure can be utilized for stereoselective synthesis of epoxides from cinnamic esters in excellent yield in a shorter reaction time with exclusive formation of the trans-isomer. The method was further extended successfully for styrenes.

Formation of Cyclohepta[b]indole Scaffolds via Heck Cyclization: A Strategy for Structural Analogues of Ervatamine Group of Indole Alkaloid

Ervatamine, silicine, methuenine, etc., are naturally occurring alkaloids that exhibit antimicrobial, anticancer, and anti-HIV activities. Indole fused with a seven-membered carbocyclic ring is a commonly observed structural feature among this series of bioactive compounds. This work describes a strategic approach for the synthesis of cyclohepta[b]indole structural scaffolds. The synthetic strategy consists of a solvent-free Baylis-Hillman reaction of 2-bromobenzaldehydes, followed by iodine-catalyzed C-alkylation of indole with the Baylis-Hillman adducts. Finally, intramolecular Heck coupling reaction using Pd(OAc)2 as catalyst in the presence of benzyltrimethylammonium bromide under microwave condition produced the desired cyclohepta[b]indole derivatives.

Chemoselective Transfer Hydrogenation of Carbonyl Compounds Catalyzed by Macrocyclic Nickel (II)Complex

Abstract Macrocyclic Ni(II) complex, 1, catalyzes efficiently the chemoselective transfer reduction of carbonyl compounds in presence of propan-2-ol / KOH or HCO2H / HCO2NH4 as hydrogen donors to produce the corresponding alcohols in high yield.

A new ferrocene-based bulky pyridine as an efficient reusable homogeneous catalyst

An effective approach to reusing a homogeneous catalyst has been demonstrated. A ferrocene-based bulky pyridine has been synthesized and utilized as a homogeneous catalyst for the synthesis of benzoylfumarates as well as for acetylation. After the reaction, the catalyst was separated by simple precipitation and reused without appreciable loss of activity.

Three‐Component Synthesis of Homoallylic Carbamates

Abstract Scandium triflate catalyzed three component condensation of aldehyde, benzyl carbamate, and allyltrimethylsilane to afford the corresponding N‐Cbz protected homoallylic amine is described.

Rapid and Total Bromination of Aromatic Compounds Using TsNBr2 Without Any Catalyst

Abstract N,N-Dibromo-p-toluenesulfonamide (TsNBr2) has been found to be a new reagent for bromination of aromatic compounds. The reaction is extremely fast and goes into completion instantaneously at ambient temperature to produce exclusively the corresponding polybrominated product. This procedure is applicable to various phenols, anisole, and anilines to give corresponding polybrominated compound as a single product in excellent yield. GRAPHICAL ABSTRACT