Highly regioselective ring opening of epoxides and aziridines using (bromodimethyl)sulfonium bromide

DMSO-allyl bromide: a mild and efficient reagent for atom economic one-pot N-allylation and bromination of 2°-aryl amines, 2-aryl aminoamides, indoles and 7-aza indoles

A mixture DMSO-allyl bromide has been developed as a reagent for an atom economic one-pot N-allylation and aryl bromination under basic conditions. Utilizing this reagent, N-allylation-bromination of a number of 2°-aryl amines, aryl aminoamides, indoles, and 7-aza indoles has been achieved. The scope of the substrates and limitations, the synthetic utility of the products, and a plausible reaction mechanism have been proposed.

Ring-opening and cyclization of aziridines with aryl azides: metal-free synthesis of 6-(triflyloxy)quinolines

A metal-free synthesis of 6-(triflyloxy)quinolines has been developed via the ring-opening and cyclization of 2-aryl-1-tosylaziridines with 2-azidobenzaldehydes in the presence of TfOH.

Highly Functionalized Tricyclic Oxazinanones via Pairwise Oxidative Dearomatization and N-Hydroxycarbamate Dehydrogenation: Molecular Diversity Inspired by Tetrodotoxin

Benzenoids in principle represent attractive and abundant starting materials for the preparation of substituted cyclohexanes; however, the synthetic tools available for overcoming the considerable aromatic energies inherent to these building blocks limit the available product types. In this paper, we demonstrate access to heretofore unknown heterotricyclic structures by leveraging oxidative dearomatization of 2-hydroxymethyl phenols with concurrent N-hydroxycarbamate dehydrogenation using a common oxidant. The pairwise-generated, mutually reactive species then participate in a second stage acylnitroso Diels-Alder cycloaddition. The reaction chemistry of the derived [2.2.2]-oxazabicycles, bearing four orthogonal functional groups and three stereogenic centers, is shown to yield considerable diversity in downstream products. The methodology allows for the expeditious synthesis of a functionalized intermediate bearing structural and stereochemical features in common with the complex alkaloid tetrodotoxin.

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.

Intramolecular hydrogen bond in alkoxyamines. Influence on the C-ON bond homolysis

The C-ON bond homolysis in alkoxyamines can be influenced by the presence of an intramolecular hydrogen bond (IHB) between the alkyl and the nitroxyl fragments, which leads to an 8-fold decrease in the homolysis rate constant k(d). When the IHB is disrupted by the solvent or by substitution of the hydrogen involved in the IHB by a protecting group (OMe, OAc, OBz, OBn, or OTBDMS), a higher homolysis rate constant k(d) is observed, as expected from the correlations developed by Marque (Bertin, D.; Gigmes, D.; Marque, S.; Tordo, P. Macromolecules 2005, 38, 2638-2650). Results were confirmed by DFT calculations at the B3LYP/6-31G(d,p) level.

Three-component, one-pot synthesis of 3,4-dihydropyrimidin-2-(1H)-ones catalyzed by bromodimethylsulfonium bromide

An efficient synthesis of 3,4-dihydropyrimidin-2-(1H)-one derivatives by one-pot three-component condensation reaction between an alkyl or aryl aldehyde, a 1,3-dicarbonyl compound, and urea or thiourea in the presence of catalytic amount of bromodimethylsulfonium bromide has been developed. The condensation product was obtained in excellent yields in refluxing ethanol and easily separated from the reaction mixture and purified.

Regioselective Conversion of Unsymmetrical Terminal Epoxides into Vicinal Chlorohydrins Using Dimethoxyboron Chloride

A highly regioselective synthesis of chlorohydrins by chlorinative cleavage of unsymmetrical epoxides utilizing dimethoxyboron chloride is described. Except for styrene oxide, all the terminal epoxides were regioselectively cleaved following a predominantly SN2-type reaction pathway favouring the formation of primary chlorides. In the case of styrene oxide, a benzylic epoxide, (MeO)2BCl transfers the chlorine at the benzylic position, by following an apparent SN1-type mechanism.