Click Chemistry -- Publications
A rapid and convenient synthesis of amides from aromatic acids and aliphatic amines in dry …
PDF Downloads : Oriental Journal of Chemistry
The arynes 1a-1e were selected as substrates for our experiments. Aryne precursor 1a was selected as the simplest and most readily available aryne to study the scope of this chemistry. Aryne precursors 1b, 1d and 1e were selected to study the regioselectivity of the arylation procedure. The synthesis of silylaryl triflates 1a, 1b, 1c, and 1d has already been reported, and the precursor 1e can easily be prepared by a similar three-step procedure from the corresponding 2-bromo-4,6-dimethylphenol.
The direct and selective synthesis of phenols from aryl/heteroaryl halides and KOH has been achieved through the use of highly active monophosphine-based catalysts derived from Pd2dba3 and ligands L1 or L2 and the biphasic solvent system 1,4-dioxane/H2O. We have also demonstrated a one-pot method of phenol formation/alkylation for the preparation of alkyl aryl ethers from aryl halides. In many instances, this protocol overcomes limitations in existing Pd-catalyzed coupling reactions of aliphatic alcohols with aryl halides. Finally, we demonstrate that substituted benzofurans can be prepared efficiently via a Pd-catalyzed phenol formation/cyclization protocol starting from 2-chloroaryl alkynes.
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We have developed an efficient, mild, transition metal-free method for the N-arylation of amines, sulfonamides, and carbamates, and O-arylation of phenols and aromatic carboxylic acids. The regioselectivity of the methoxy-substituted silylaryl triflate 1b is excellent. With other silylaryl triflates, such as 1d and 1e, two isomers are obtained. Mono-arylated and diarylated amines can easily be obtained from primary amines by simply controlling the ratio of the reactants. A variety of functional groups are compatible with the reaction conditions, including nitro, hydroxyl, aldehyde, ketone, ester and amide groups, as well as double bonds and triple bonds. We have also shown that halides, which are not compatible with Pd-mediated arylation procedures, readily tolerate our reaction conditions. This chemistry nicely complements classical methods for the N-arylation of amines and sulfonamides, and the O-arylation of phenols and carboxylic acids.
Recently, silylaryl triflate 1a has been employed to generate benzyne under very mild reaction conditions, which can easily undergo a variety of synthetically useful nucleophilic and cycloaddition reactions. However, the arylation of amines, sulfonamides, phenols and carboxylic acids by arynes has not been widely studied due to the difficulty in generating arynes under convenient reaction conditions. Very recently, we reported that the reaction of a variety of amines, sulfonamides, carbamates, phenols and carboxylic acids with arynes generated from a variety of silylaryl triflates under very mild reaction conditions provides excellent yields of arylated products, while tolerating many functional groups. Herein, we wish to report the full details of this very efficient arylation procedure and our studies on the regioselectivity of addition to a number of unsymmetrical substituted silylaryl triflates.
Transition-Metal-Free O-, S-, and N-Arylation of …
Zargarani, Solventfree synthesis of trisubstituted thiophenes via thioClaisen rearrangement under microwave irradiation: A convenient route to sulfur containing triatyl amines J.
and N-Arylation of Alcohols, Thiols, Amides, Amines, ..
Transition Metal Catalyzed Synthesis of Aryl ..
Sulfides from Aryl Halides and Aromatic Thiols ..
The Selective Reaction of Aryl Halides with KOH: Synthesis of Phenols, Aromatic Ethers, and Benzofurans
Publications - Indian Institute of Technology Guwahati
937: Zhang, Y.-H.; Gao, Z.-X.; Zhong, C.-L.; Zhou, H.-B.; Chen, L.; Wu, W.-M.; Peng, X.-J.; Yao, Z.-J
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