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.

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

1. Introdution A 2. Early Developments B 2.1. First Reports B 2.2. Heterocycle Synthesis E 2.3. Nitroalkene Synthesis G 2.4. Synthesis of Dinitroamines G 2.5. Reactions with Preformed Imines H 2.6. Conjugate Addition Nitro-Mannich Reactions H 2.7. Reactions of Nitroesters I 3. Noncatayltic Reactions J 3.1. Base-Mediated Reactions J 3.2. Reactions of α-Amido Sulfones K 3.3. Auxiliary Controlled Stereoselective Reactions L 3.4. Reformatsky-Type Reactions M 3.5. Electrochemically Induced Nitro-Mannich Reactions N 4. Indirect Metal-Catalyzed Reactions N 4.1. Racemic Reactions N 4.2. Asymmetric Reactions N 5. Direct Metal-Catalyzed Reactions O 5.1. Racemic Reactions O 5.2. Asymmetric Reactions P 6. Organocatalytic Reactions T 6.1. Racemic Reactions T 6.2. Asymmetric Reactions U 6.2.1. Urea/Thiourea Catalysts U 6.2.2. Brønsted Acid Catalysts X 6.2.3. Phase-Transfer Catalysts Y 6.2.4. Brønsted-Base Catalysts Z 7. Reactions of Ketimines AA 7.1. Racemic Reactions AA 7.2. Auxiliary Controlled Reactions AB 7.3. Catalytic Enantioselective Reactions AB 8. Reactions of α-Nitroesters AC 9. Reactions of α-Nitrophosphonates AE 10. Conjugate Addition Nitro-Mannich Reactions AF 10.1. Organocatalytic Reactions of Carbon Nucleophiles AF 10.2. Reactions with Organometallic Nucleophiles AG 10.3. Aza-Morita−Baylis−Hillman Reactions AI 10.4. Synthesis of 3-Nitrochromene Derivatives AI 10.5. [3 + 2] Cycloadditions AJ 10.6. [2 + 2] Cycloadditions AL 11. Cascade Reactions AL 11.1. Nitro-Mannich/Lactamization Cascades AL 11.2. Other Cascade Reactions AO 12. Cross-Dehydrogenative Coupling Reactions AP 13. Miscellaneous Reactions AQ 13.1. Reactions of Isoquinolines AQ 13.2. Reactions of Trinitromethane AR 14. Applications to Synthesis AR 14.1. Peptide Synthesis AU 15. Summary AU Author Information AW Corresponding Author AW Notes AW Biographies AW Acknowledgments AX References AX

Nitro-Mannich reaction.

The catalytic hydrogenation of carboxylic acid derivatives represents an atom-efficient and clean reduction methodology in organic chemistry. More specifically, the selective hydrogenation of nitriles offers the possibility for a green synthesis of valuable primary amines. So far, this transformation lacks of useful, broadly applicable non-noble metal-based catalyst systems. In the present study, we describe a molecular-defined iron complex, which allows for the hydrogenation of aryl, alkyl, heterocyclic nitriles and dinitriles. By using an iron PNP pincer complex, we achieve very good functional group tolerance. Ester, ether, acetamido as well as amino substituents are not reduced in the presence of nitriles. Moreover, nitriles including an α,β-unsaturated double bond and halogenated derivatives are well tolerated in this reaction. Notably, our complex constitutes the first example of an homogeneous catalyst, which permits the selective hydrogenation of industrially important adipodinitrile to 1,6-hexamethylenediamine.

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Mild and selective hydrogenation of aromatic and aliphatic (di)nitriles with a well-defined iron pincer complex.

The catalytic hydrogenation of nitriles to primary amines represents an atom-efficient and environmentally benign reduction methodology in organic chemistry. This has been accomplished in recent years mainly with precious-metal-based catalysts, with a single exception. Here we report the first homogeneous Co-catalyzed hydrogenation of nitriles to primary amines. Several (hetero)aromatic, benzylic, and aliphatic nitriles undergo hydrogenation to the corresponding primary amines in good to excellent yields under the reaction conditions.

Selective Hydrogenation of Nitriles to Primary Amines Catalyzed by a Cobalt Pincer Complex.

This third review in a series involving reactions of hydrosilanes and transition metal complexes and characterization of the products covers the period 2009 thru 2013. After a brief discussion of other synthetic methods used for the formation of Si-TM complexes, Section 3 provides an extended discussion of the types of ligands and metal complexes used as reactants with hydrosilanes. The increase in use of pincer ligands in forming stable, isolable complexes is featured. Three tables list the complexes reported for primary, secondary, and tertiary silanes. Many reactions leading to SiTM complexes are initiated by loss of a ligand prior to oxidative addition of the hydrosilane or by a metathesis reaction. Structural data are tabulated for the isolated complexes and provide the Si-TM bond ranges for the elements in the “d” block. A major section on nonclassical (σ or agostic) complexes includes two general groupings with Si–H···TM and M–H···Si interactions. A section on solution processes identified by NMR s...

Reactions of Hydrosilanes with Transition Metal Complexes.

Highly deactivated aromatic compounds were smoothly monobrominated by treatment with N-bromosuccinimide (NBS) in concentrated H2SO4 medium affording the corresponding bromo derivatives in good yields. Mild reaction conditions and simple workup provides a practical and commercially viable route for the synthesis of bromo compounds of deactivated aromatics.

Bromination of deactivated aromatics: a simple and efficient method.

Rhenium(I) nitrosyl complexes bearing large bite angle diphosphines efficiently catalyze the hydrogenation of nitriles to the corresponding symmetrical secondary amines.

Homogeneous Hydrogenations of Nitriles Catalyzed by Rhenium Complexes

The reaction of [ReBr2(MeCN)(NO)(P∩P)] (P∩P = 1,1′-bisdiphenylphosphinoferrocene (dppfc) (1a), 1,1′-bisdiisopropylphosphinopherrocene (diprpfc) (1b), 2,2′-bis(diphenylphosphino)diphenyl ether (dpep...

Rhenium in homogeneous catalysis: [ReBrH(NO)(labile ligand)(large-bite-angle diphosphine)] complexes as highly active catalysts in olefin hydrogenations.

Shelf-available alkali metal tert-butoxides, hydrides and bis(trimethylsilyl)amides were shown to be highly efficient homogeneous precatalysts for the disproportionation of aldehydes to the corresponding carboxylic esters. Potassium compounds in combination with 18-crown-6 ether could drastically increase the rate of reaction in a few cases. Alternatively, efficient aldol condensations were found for aldehydes possessing an enolizable methylene group at the α-position to the aldehyde functionality. The active species involved in this esterification using any of these alkali metal catalysts is expected to be the metal alkoxide. Potassium compounds were found to be much more efficient when compared to analogous sodium compounds and kinetic studies revealed the rate-determining step to be a second order concerted hydride transfer from a potassium hemiacetal species to another molecule of aldehyde.

Kunjanpillai Rajesh

Papers

Bromination of deactivated aromatics: a simple and efficient method.

Homogeneous Hydrogenations of Nitriles Catalyzed by Rhenium Complexes

Rhenium in homogeneous catalysis: [ReBrH(NO)(labile ligand)(large-bite-angle diphosphine)] complexes as highly active catalysts in olefin hydrogenations.

Alkali Metal tert‐Butoxides, Hydrides and Bis(trimethylsilyl)amides as Efficient Homogeneous Catalysts for Claisen–Tishchenko Reaction

One-pot three component α-aminoalkylation of conjugated nitroalkenes and nitrodienes