Alexander McKillop

The use of phase-transfer catalysis for the synthesis of phenol ethers

Abstract A simple, rapid and efficient procedure has been developed for the preparation of ethers of both simple and highly hindered phenols. Based on the principle of phase-transfer catalysis, the method involves alkylation of the phenoxide ion with an alkyl halide or sulphate ester in a methylene chloride-water system at room temperature, using a quaternary ammonium salt as the effective reagent for transport of the phenoxide ion between the two phases. In contrast to certain other processes in which phase-transfer “catalysis” is involved, the present procedure is truly catalytic with respect to the quaternary ammonium salt when alkyl bromides or sulphates are employed as alkylating agents.

Further functional group oxidations using sodium perborate

Abstract Sodium perborate in acetic acid is an effective reagent for the oxidation of aromatic aldehydes to carboxylic acids, iodoarenes to (diacetoxyiodo)arenes, azines to N -oxides, and various types of sulphur heterocycles to S , S -dioxides. Nitriles are unaffected by the reagent in acetic acid, but undergo smooth hydration to amides when aqueous methanol is employed as solvent.

Efficicient, high yield, oxidation of thiols and selenols to disulphides and diselenides

Abstract Thiols and selenols are smoothly oxidised in high yield to disulphides and diselenides by sodium perborate at room temperature.

Sodium perborate - a cheap and effective reagent for the oxidation of anilines and sulphides

Abstract Sodium perborate in acetic acid is an effective reagent for the oxidation of anilines to the corresponding nitroarenes; it is also highly effective for the oxidation of sulphides to either sulphoxides or sulphones.

Palladium-catalysed cross-coupling reactions of arylboronic acids with π-deficient heteroaryl chlorides

Abstract The palladium-catalysed cross-coupling reactions of arylboronic acids with a variety of π-deficient heteroaryl chlorides proceed in high yield. [1,4-Bis(diphenylphosphino)butane]palladium(II) dichloride was found to be a very satisfactory catalyst for monocyclic heteroaryl chlorides, whereas tetrakis(triphenylphosphine)palladium(O) was found to be excellent for a range of chloroquinoline derivatives.

A study of the copper-catalysed direct arylation of β-dicarbonyl compounds with 2-bromobenzoic acids☆

Abstract The Cu-catalysed condensations of 2-bromobenzoic acids with β-dicarbonyl anions to give α-arylated-β-dicarbonyl compounds have been investigated in detail. Previously recommended experimental conditions for these reactions are shown to be in appropriate and the limited synthetic utility of these processes in the past is explained. Much superior conditions have now been developed by use of which a variety of β-dicarbonyl compounds can readily be arylated in good to excellent yield with A wide range of substituted 2-bromobenzoic acids and with certain other halo-aromatic acids. The scope and limitations of the synthetic method have been established, and a simple, high yield procedure for the preparation of homophthalic acids is described. It is shown that Cu(I) is almost certainly the effective catalyst, and information has been obtained on the probable mechanism of the substitution reaction by examination of steric and electronic effects in the halo-aromatic acids and by consideration of the structure and role of the β-dicarbonyl component.

Functional group oxidation using sodium perborate1

Abstract Sodium perborate in acetic acid is an effective reagent for the oxidation of anilines to nitroarenes and of sulphides to either sulphoxides or sulphones. It is also an excellent reagent for the oxidative deprotection of ketone dimethylhydrazones. Baeyer-Villiger oxidation of ketones can be carried out with sodium perborate in either trifluoroacetic acid or acetic acid/trifluoroacetic acid mixtures, and hydroquinones and certain highly substituted phenols are smoothly converted into quinones.

Thallium in organic synthesis. 68. A convenient synthesis of 2-phenylindoles from anilides

Abstract Thallation of anilides with TTFA in a mixture of TFA and ether gives ortho-thallated derivatives, which yield 2-acetamido-tolanes upon reaction with copper(I) phenylacetylide in acetonitrile. Treatment of the latter compounds with palladium(II) chloride results in ring closure to give 1-acyl-2-phenylindoles, from which 2-phenyl-indoles are obtained by alkaline hydrolysis.

Thallium in organic synthesis—XVI: Preparation of p-quinones by oxidation of phenols and hydroquinones with thallium(III) trifluoroacetate

Abstract Treatment of 2,6-disubstituted-4-t-butylphenols with thallium(III) trifluoroacetate in either trifluoroacetic acid or carbon tetrachloride as solvent results in loss of the 4-t-butyl substituent as isobutene and formation in high yield of the corresponding 2,6-disubstituted p-quinones. Possible mechanisms for this novel reaction, which probably proceeds via the intermediacy of a hydroquinone or hydroquinone mono-trifluoroacetate ester, are discussed. Consequent to these mechanistic considerations, thallium(III) trifluoroacetate is shown to be a highly efficient oxidant for the conversion ofhydroquinones and a variety of 2,4,6-trisubstituted phenols into the corresponding p-quinones.

Acetal and ketal deprotection using montmorillonite K10: The first synthesis of syn-4,8-dioxatricyclo[5.1.0.03,5]-2,6-octanedione

Abstract Montmorillonite K10 in dichloromethane at room temperature conveniently and efficiently converts acetals and ketals into the corresponding carbonyl compounds. The title dione (diepoxy-1,4-cyclohexanedione) has been prepared for the first time using this procedure.