Imperial College London

Professor Chris Braddock

Faculty of Natural SciencesDepartment of Chemistry

Professor of Organic Chemistry
 
 
 
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Contact

 

+44 (0)20 7594 5772c.braddock

 
 
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Location

 

601EMolecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Publication Type
Year
to

107 results found

Lo Q, Sale D, Braddock D, Davies Ret al., 2019, New insights into the reaction capabilities of ionic organic bases in cu-catalysed amination, European Journal of Organic Chemistry, Vol: 2019, Pages: 1944-1951, ISSN: 1099-0690

The application of ionic organic bases in the copper‐catalyzed amination reaction (Ullmann reaction) has been studied at room temperature, with sub‐mol‐% catalyst loadings, and with more challenging amines at elevated temperatures. The cation present in the base has been shown to have little effect on the reaction at standard catalyst and ancillary ligand loadings, whereas the choice of anion is crucial for good reactivity. A substrate scope carried out at room temperature with the best performing bases, TBAM and TBPM, showed both bases to be highly effective under these mild reaction conditions. Moreover, under sub‐mol % catalyst loadings and room temperature conditions, TBPM gave good to excellent yields for a number of different amines and functionalized aryl iodides (14 examples). However, reactions involving more challenging amines gave little or no yield. By using more forceful conditions (120 °C) moderate to excellent yields of cross‐coupled products containing more challenging amines was achievable using TBPM and to a lesser extent with TBAM. As part of this work a study on the stability of the organic bases at 120 °C was undertaken. TBAM is shown to decompose to give nBu3N and mono‐butylmalonate at higher temperatures, and this can be correlated to a decrease in performance in the coupling reaction. The phosphonium cations in TBPM did not undergo analogous reactivity but were shown instead to experience some degree of deprotonation at the α‐CH2 to generate phosphonium ylides. This however did not lead to a significantly degradation in the activity of the TBPM in the cross‐coupling reaction.

Journal article

Braddock DC, Lickiss PD, Rowley BC, Pugh D, Purnomo T, Santhakumar G, Fussell SJet al., 2018, Tetramethyl Orthosilicate (TMOS) as a Reagent for Direct Amidation of Carboxylic Acids, ORGANIC LETTERS, Vol: 20, Pages: 950-953, ISSN: 1523-7060

Journal article

Lo QA, Sale D, Braddock DC, Davies RPet al., 2018, Mechanistic and Performance Studies on the Ligand-Promoted Ullmann Amination Reaction, ACS CATALYSIS, Vol: 8, Pages: 101-109, ISSN: 2155-5435

Journal article

Bahou KA, Braddock DC, Meyer AG, Savage GPet al., 2017, Kinetic Benchmarking Reveals the Competence of Prenyl Groups in Ring-Closing Metathesis, ORGANIC LETTERS, Vol: 19, Pages: 5332-5335, ISSN: 1523-7060

Journal article

Clarke J, Bonney KJ, Yaqoob M, Solanki S, Rzepa HS, White AJP, Millan DS, Braddock DCet al., 2016, Epimeric Face-Selective Oxidations and Diastereodivergent Transannular Oxonium Ion Formation Fragmentations: Computational Modeling and Total Syntheses of 12-Epoxyobtusallene IV, 12-Epoxyobtusallene II, Obtusallene X, Marilzabicycloallene C, and Marilzabicycloallene D, Journal of Organic Chemistry, Vol: 81, Pages: 9539-9552, ISSN: 0022-3263

© 2016 American Chemical Society. The total syntheses of 12-epoxyobtusallene IV, 12-epoxyobtusallene II, obtusallene X, marilzabicycloallene C, and marilzabicycloallene D as halogenated C15-acetogenin 12-membered bicyclic and tricyclic ether bromoallene-containing marine metabolites from Laurencia species are described. Two enantiomerically pure C4-epimeric dioxabicyclo[8.2.1]tridecenes were synthesized by E-selective ring-closing metathesis where their absolute stereochemistry was previously set via catalytic asymmetric homoallylic epoxidation and elaborated via regioselective epoxide-ring opening and diastereoselective bromoetherification. Epimeric face-selective oxidation of their Δ12,13 olefins followed by bromoallene installation allowed access to the oppositely configured 12,13-epoxides of 12-epoxyobtusallene II and 12-epoxyobtusallene IV. Subsequent exploration of their putative biomimetic oxonium ion formation-fragmentations reactions revealed diastereodivergent pathways giving marilzabicycloallene C and obtusallene X, respectively. The original configurations of the substrates evidently control oxonium ion formation and their subsequent preferred mode of fragmentation by nucleophilic attack at C9 or C12. Quantum modeling of this stereoselectivity at the ωB97X-D/Def2-TZVPPD/SCRF = methanol level revealed that in addition to direction resulting from hydrogen bonding, the dipole moment of the ion-pair transition state is an important factor. Marilzabicycloallene D as a pentahalogenated 12-membered bicyclic ether bromoallene was synthesized by a face-selective chloronium ion initiated oxonium ion formation-fragmentation process followed by subsequent bromoallene installation.

Journal article

Braddock DC, Mahtey A, Rzepa HS, White AJPet al., 2016, Stable bromoallene oxides, Chemical Communications, Vol: 52, Pages: 11219-11222, ISSN: 1364-548X

The first stable bromoallene oxides were obtained by the DMDO epoxidation of 1-bromo-1,3-di-tert-alkylallenes, producing the first crystalline allene oxide of any kind. The epoxidations are regioselective for the bromine-bearing Δ1,2 alkene, and also face selective producing single diastereomer E-olefin products.

Journal article

Sung S, Sale D, Braddock DC, Armstrong A, Brennan C, Davies RPet al., 2016, Mechanistic Studies on the Copper-Catalyzed N-Arylation of Alkylamines Promoted by Organic Soluble Ionic Bases, ACS CATALYSIS, Vol: 6, Pages: 3965-3974, ISSN: 2155-5435

Journal article

Campbell J, Burgal JDS, Szekely G, Davies RP, Braddock DC, Livingston Aet al., 2016, Hybrid polymer/MOF membranes for Organic Solvent Nanofiltration (OSN): Chemical modification and the quest for perfection, Journal of Membrane Science, Vol: 503, Pages: 166-176, ISSN: 0376-7388

© 2016 Elsevier B.V..One of the main challenges in the field of Organic Solvent Nanofiltration (OSN) is to improve the selectivity of membranes, allowing the separation of closely related solutes. This objective might be achieved by constructing membranes with uniform porous structures. Hybrid Polymer/Metal Organic Framework (MOF) membranes were prepared by in-situ growth (ISG) of HKUST-1 within the pores of polyimide membranes. To improve the performances of ISG membranes, chemical modification was performed. Aryl carboxylic acid moieties were introduced to polyimide P84 ultrafiltration membranes allowing coordination of the HKUST-1 directly on to the polymer. Chemically modified ISG membranes outperformed non-modified ISG membranes in both solute retentions and permeance. Retentions of polystyrene solute in acetone were used to calculate theoretical pore size distributions for each of the membranes tested. It was found that the chemically modified ISG membrane had he narrowest calculated pore size distribution.

Journal article

Sung S, Braddock DC, Armstrong A, Brennan C, Sale D, White AJP, Davies RPet al., 2015, Synthesis, Characterisation and Reactivity of Copper(I) Amide Complexes and Studies on Their Role in the Modified Ullmann Amination Reaction, CHEMISTRY-A EUROPEAN JOURNAL, Vol: 21, Pages: 7179-7192, ISSN: 0947-6539

Journal article

Campbell J, Davies RP, Braddock DC, Livingston AGet al., 2015, Improving the permeance of hybrid polymer/metal-organic framework (MOF) membranes for organic solvent nanofiltration (OSN) - development of MOF thin films via interfacial synthesis, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 3, Pages: 9668-9674, ISSN: 2050-7488

Journal article

Campbell J, Szekely G, Davies RP, Braddock DC, Livingston AGet al., 2014, Fabrication of hybrid polymer/metal organic framework membranes: mixed matrix membranes versus in situ growth, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 2, Pages: 9260-9271, ISSN: 2050-7488

Journal article

Kim M-S, Buisson LA, Heathcote DA, Hu H, Braddock DC, Barrett AGM, Ashton-Rickardt PG, Snyder JPet al., 2014, Approaches to design non-covalent inhibitors for human granzyme B (hGrB), ORGANIC & BIOMOLECULAR CHEMISTRY, Vol: 12, Pages: 8952-8965, ISSN: 1477-0520

Journal article

Braddock DC, Gao AX, White AJP, Whyte Met al., 2014, Studies towards the synthesis of halomon: asymmetric hexafunctionalisation of myrcene, CHEMICAL COMMUNICATIONS, Vol: 50, Pages: 13725-13728, ISSN: 1359-7345

Journal article

Braddock DC, Sbircea D-T, 2014, Proof-of-principle direct double cyclisation of a linear C-15-precursor to a dibrominated bicyclic medium-ring ether relevant to Laurencia species, CHEMICAL COMMUNICATIONS, Vol: 50, Pages: 12691-12693, ISSN: 1359-7345

Journal article

Armstrong A, Braddock DC, Jones AX, Clark Set al., 2013, Catalytic asymmetric bromolactonization reactions using (DHQD)(2)PHAL-benzoic acid combinations, TETRAHEDRON LETTERS, Vol: 54, Pages: 7004-7008, ISSN: 0040-4039

Journal article

Braddock DC, Marklew JS, Foote KM, White AJPet al., 2013, An Enantiospecific Polyene Cyclization Initiated by an Enantiomerically Pure Bromonium Ion, CHIRALITY, Vol: 25, Pages: 692-700, ISSN: 0899-0042

Journal article

Braddock DC, Clarke J, Rzepa HS, 2013, Epoxidation of bromoallenes connects red algae metabolites by an intersecting bromoallene oxide - Favorskii manifold, CHEMICAL COMMUNICATIONS, Vol: 49, Pages: 11176-11178, ISSN: 1359-7345

Journal article

Braddock DC, Roy D, Lenoir D, Moore E, Rzepa HS, Wu JI-C, Schleyer PVRet al., 2012, Verification of stereospecific dyotropic racemisation of enantiopure D and L-1,2-dibromo-1,2-diphenylethane in non-polar media, CHEMICAL COMMUNICATIONS, Vol: 48, Pages: 8943-8945, ISSN: 1359-7345

Journal article

Barrett TN, Braddock DC, Monta A, Webb MR, White AJPet al., 2011, Total Synthesis of the Marine Metabolite (+/-)-Polysiphenol via Highly Regioselective Intramolecular Oxidative Coupling, JOURNAL OF NATURAL PRODUCTS, Vol: 74, Pages: 1980-1984, ISSN: 0163-3864

Journal article

Bonney KJ, Braddock DC, White AJP, Yaqoob Met al., 2011, Intramolecular Bromonium Ion Assisted Epoxide Ring-Opening: Capture of the Oxonium Ion with an Added External Nucleophile, JOURNAL OF ORGANIC CHEMISTRY, Vol: 76, Pages: 97-104, ISSN: 0022-3263

Journal article

Braddock DC, Marklew JS, Thomas AJF, 2011, Enantiospecific bromonium ion generation and intramolecular capture: a model system for asymmetric bromonium ion-induced polyene cyclisations, CHEMICAL COMMUNICATIONS, Vol: 47, Pages: 9051-9053, ISSN: 1359-7345

Journal article

Braddock DC, Cailleau T, Cansell G, Hermitage SA, Pouwer RH, Redmond JM, White AJPet al., 2010, The reaction of aromatic dialdehydes with enantiopure 1,2-diamines: an expeditious route to enantiopure tricyclic amidines, TETRAHEDRON-ASYMMETRY, Vol: 21, Pages: 2911-2919, ISSN: 0957-4166

Journal article

Braddock DC, Pouwer RH, Burton JW, Broadwith Pet al., 2009, Clarification of the Stereochemical Course of Nucleophilic Substitution of Arylsulfonate-Based Nucleophile Assisting Leaving Groups, JOURNAL OF ORGANIC CHEMISTRY, Vol: 74, Pages: 6042-6049, ISSN: 0022-3263

Journal article

Braddock DC, Millan DS, Perez-Fuertes Y, Pouwer RH, Sheppard RN, Solanki S, White AJPet al., 2009, Bromonium Ion Induced Transannular Oxonium Ion Formation-Fragmentation in Model Obtusallene Systems and Structural Reassignment of Obtusallenes V-VII, JOURNAL OF ORGANIC CHEMISTRY, Vol: 74, Pages: 1835-1841, ISSN: 0022-3263

Journal article

Braddock DC, Hermitage SA, Kwok L, Pouwer R, Redmond JM, White AJPet al., 2009, The generation and trapping of enantiopure bromonium ions, CHEMICAL COMMUNICATIONS, Pages: 1082-1084, ISSN: 1359-7345

Journal article

Braddock DC, Rzepa HS, 2008, Structural reassignment of obtusallenes V, VI, and VII by GIAO-based density functional prediction, JOURNAL OF NATURAL PRODUCTS, Vol: 71, Pages: 728-730, ISSN: 0163-3864

Journal article

Braddock DC, Bhuva R, Perez-Fuertes Y, Pouwer R, Roberts CA, Ruggiero A, Stokes ESE, White AJPet al., 2008, The stereochemical course of bromoetherification of enynes, CHEMICAL COMMUNICATIONS, Pages: 1419-1421, ISSN: 1359-7345

Journal article

Ahmad SM, Braddock DC, Cansell G, Hermitage SA, Redmond JM, White AJPet al., 2007, Amidines as potent nucleophilic organocatalysts for the transfer of electrophilic bromine from N-bromosuccinimide to alkenes, TETRAHEDRON LETTERS, Vol: 48, Pages: 5948-5952, ISSN: 0040-4039

Journal article

Braddock DC, Tanaka K, Chadwick D, Bohm VPW, Roeper Met al., 2007, Vacuum-driven anionic ligand exchange in Buchmeiser-Hoveyda-Grubbs ruthenium(II) benzylidenes, TETRAHEDRON LETTERS, Vol: 48, Pages: 5301-5303, ISSN: 0040-4039

Journal article

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