The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Stephen P. Neary - One of the best experts on this subject based on the ideXlab platform.
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An investigation of Thiadiazolidines and related compounds for use as ligands in metal mediated catalysis
2011Co-Authors: Stephen P. NearyAbstract:This thesis describes the investigation of Thiadiazolidine 1-oxides and structurally related compounds as ligands in palladium catalysis. The introduction will provide background information on subjects related to the work of the main project. Palladium catalysed cross couplings, namely the Heck and Tsuji-Trost reactions, will feature prominently and will be discussed in basic detail. A general outline of different classes of ligands used in palladium catalysis will also be put forward. Extraneous factors which affect catalyst reactivity will also be discussed, including the use of microwave irradiation and the effect of additives. Special attention is paid towards sulfur containing ligands. As their use has been relatively limited this will also include other areas of catalysis. Investigations into the synthesis of esermethole prompt a general background of methods of synthesising oxindoles and also examples of previous syntheses of the compound. The second chapter begins by describing the initial exploratory work, the testing of a Thiadiazolidine 1-oxide compound as a ligand for the Heck reaction. Aryl iodides are successfully coupled to a range of styrenes and α,β-unsaturated esters in excellent yields under microwave conditions. Aryl bromides are also successfully coupled after some optimisation. In many cases the presence of tetrabutylammonium bromide is required to prevent shattering of the sealed microwave vial. A range of differently substituted Thiadiazolidine 1-oxides were synthesised in order to establish a pattern of reactivity based on steric and electronic factors. Structurally related chiral compounds were also synthesised, including the first reported enantiomerically pure thiadiazol-3-one 1-oxide and thiatriaza-indene 3-oxide systems chiral at the sulfur atom. The synthesis of oxindoles using palladium mediated and non-catalytic chemistry was also investigated. Investigations into the synthesis of esermethole were undertaken; the key stereoinducing reaction, the decarboxylative asymmetric allyic alkylation reaction, achieved a 46% ee. A formal synthesis of esermethole was outlined in 8 steps from commercially available material. The third chapter is the experimental section and is dedicated to the methods of synthesis and characterization of the compounds mentioned in the previous chapter. X-ray reports regarding the crystallographic representation of the structures presented in chapter two are provided in appendix A.
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Thiadiazolidine 1-oxide systems for phosphine-free palladium-mediated catalysis
Tetrahedron, 2010Co-Authors: Benjamin R. Buckley, Stephen P. NearyAbstract:Abstract We herein report several highly active catalyst systems with Thiadiazolidine 1-oxides as ligands for palladium in the Mizoroki–Heck reaction. Excellent yields of stilbenes derived from aryl iodides and bromides have been achieved using as little as 0.00002 mol % catalyst. The ligand/palladium system can be stored as a stock solution open to air at room temperature with no observable loss of activity for a period of several months.
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The First Thiadiazolidine 1‐Oxide System for Phosphine‐Free Palladium‐Mediated Catalysis
Advanced Synthesis & Catalysis, 2009Co-Authors: Benjamin R. Buckley, Stephen P. NearyAbstract:We herein report a highly active catalyst system using for the first time a Thiadiazolidine 1-oxide as a ligand for palladium in the Mizoroki–Heck reaction. Excellent yields of stilbenes derived from aryl iodides and bromides have been achieved using as little as 0.00002 mol% catalyst. The ligand/palladium system can be stored as a stock solution open to air at room temperature with no observable loss of activity for a period of several weeks/months.
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the first Thiadiazolidine 1 oxide system for phosphine free palladium mediated catalysis
Advanced Synthesis & Catalysis, 2009Co-Authors: Benjamin R. Buckley, Stephen P. NearyAbstract:We herein report a highly active catalyst system using for the first time a Thiadiazolidine 1-oxide as a ligand for palladium in the Mizoroki–Heck reaction. Excellent yields of stilbenes derived from aryl iodides and bromides have been achieved using as little as 0.00002 mol% catalyst. The ligand/palladium system can be stored as a stock solution open to air at room temperature with no observable loss of activity for a period of several weeks/months.
Kevin John Merchant - One of the best experts on this subject based on the ideXlab platform.
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Rapid and selective synthesis of substituted 1,2,5-Thiadiazolidine 1,1-dioxides
Synlett, 2006Co-Authors: Joanne Claire Hannam, Timothy Harrison, Felicity Heath, Andrew Madin, Kevin John MerchantAbstract:The reaction of N,N-dimethylsulfamoyl aziridines with primary amines gives direct access to substituted 1,2,5-Thiadiazolidines in a regioselective manner. Furthermore, the product from reaction with 4-methoxybenzyl amine can be subsequently manipulated to give the alternative nitrogen substitution pattern in a controlled fashion.
Joanne Claire Hannam - One of the best experts on this subject based on the ideXlab platform.
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Rapid and selective synthesis of substituted 1,2,5-Thiadiazolidine 1,1-dioxides
Synlett, 2006Co-Authors: Joanne Claire Hannam, Timothy Harrison, Felicity Heath, Andrew Madin, Kevin John MerchantAbstract:The reaction of N,N-dimethylsulfamoyl aziridines with primary amines gives direct access to substituted 1,2,5-Thiadiazolidines in a regioselective manner. Furthermore, the product from reaction with 4-methoxybenzyl amine can be subsequently manipulated to give the alternative nitrogen substitution pattern in a controlled fashion.
Romero Donna Lee - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of N-substituted 1,2,5-Thiadiazolidine and 1,2,6-thiadiazinane 1,1-dioxides from primary amines
Tetrahedron Letters, 2003Co-Authors: Paul D. Johnson, Sarah A. Jewell, Romero Donna LeeAbstract:Abstract Alkyl and aryl N -substituted 1,2,5-Thiadiazolidine and 1,2,6-thiadiazinane 1,1-dioxides 6 were synthesized in good yields from the reaction of sulfuryl chloride with 2-chloroethylamine or 3-chloropropylamine hydrochlorides, respectively, followed by treatment with a primary amine and triethylamine, and ring closure with K 2 CO 3 in DMSO.
Benjamin R. Buckley - One of the best experts on this subject based on the ideXlab platform.
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Thiadiazolidine 1-oxide systems for phosphine-free palladium-mediated catalysis
Tetrahedron, 2010Co-Authors: Benjamin R. Buckley, Stephen P. NearyAbstract:Abstract We herein report several highly active catalyst systems with Thiadiazolidine 1-oxides as ligands for palladium in the Mizoroki–Heck reaction. Excellent yields of stilbenes derived from aryl iodides and bromides have been achieved using as little as 0.00002 mol % catalyst. The ligand/palladium system can be stored as a stock solution open to air at room temperature with no observable loss of activity for a period of several months.
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The First Thiadiazolidine 1‐Oxide System for Phosphine‐Free Palladium‐Mediated Catalysis
Advanced Synthesis & Catalysis, 2009Co-Authors: Benjamin R. Buckley, Stephen P. NearyAbstract:We herein report a highly active catalyst system using for the first time a Thiadiazolidine 1-oxide as a ligand for palladium in the Mizoroki–Heck reaction. Excellent yields of stilbenes derived from aryl iodides and bromides have been achieved using as little as 0.00002 mol% catalyst. The ligand/palladium system can be stored as a stock solution open to air at room temperature with no observable loss of activity for a period of several weeks/months.
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the first Thiadiazolidine 1 oxide system for phosphine free palladium mediated catalysis
Advanced Synthesis & Catalysis, 2009Co-Authors: Benjamin R. Buckley, Stephen P. NearyAbstract:We herein report a highly active catalyst system using for the first time a Thiadiazolidine 1-oxide as a ligand for palladium in the Mizoroki–Heck reaction. Excellent yields of stilbenes derived from aryl iodides and bromides have been achieved using as little as 0.00002 mol% catalyst. The ligand/palladium system can be stored as a stock solution open to air at room temperature with no observable loss of activity for a period of several weeks/months.