Robin A. Fairhurst

Bis-trimethylsilylacetamide: A reagent for the control of Friedel-Crafts alkylation reactions using methyl chloromethoxyacetate

Abstract The Friedel-Crafts alkylation reactions of electron rich aromatic compounds using methyl α-chloro-α-methoxyacetate and Lewis acids leads predominantly to the formation of diarylacetic acid derivatives in which the second stage of the sequence is favoured by the presence of hydrogen chloride generated in the first step; effective control can be achieved in a number of cases by the addition of bis-trimethylsilylacetamide.

A new route to secondary amines from bis-(alkoxymethyl)-alkylamines - the activation of an aminomethyl group and protection of the product by the same functional group☆

Treatment of N,N-bis(alkoxymethyl)alkylamines with a variety of acidic reagents affords good yields of N-alkoxymethyl-N-alkylmethyleneiminium salts which react with trimethylsilyl enol ethers, and nucleophilic aromatic substrates to form protected secondary amines or tertiary amines by domino reactions; silyl ketene acetals afford tertiary amines only.

Mannich reactiohs of aryltrialkylstannunes in aprotic solvents

Abstract Aryltributyl- and aryltrimethyl-stannanes react with a range of N , N -dialkylmethylene-imonium salts to afford N , N -dialkylaminomethyl derivatives in good yields. The method can be used to obtain regloisomers that are not available using classical procedures. “In situ” reactions can also be carried out using alkoxydialkylaminomethanes (aminol ethers) and bis(dialkylamino)methanes (aminals) together with chlorotrimethyl- and trichloromethyl-silanes as the source of the electrophile. However, the “in situ” reactions do not afford good yields in the majority of cases, as a result of the inhibition of imonium salt formation by trialkylchlorostannane.

Mannich reactions of oxazolidines

Abstract 3-Methyl-1,3-oxazolidine and 3,4-dimethyl-5-phenyloxazolidine react with acidic reagents under aprotic conditions to afford reactive intermediates that interact with nucleophilic aromatic substrates and enolsilyl ethers to afford good yields of Mannich bases.

The effect of sulphur dioxide on the mannich reactions of phenols

Abstract Regioselectivity in the ortho -dialkylaminomethylation of phenols is greatest, for example in reactions of 2,5-dimethylphenol, when a mixture of the phenol and sulphur dioxide is allowed to stand for several hours before the addition of a bis-(dialkylamino)methane (aminal) or an alkoxydialkylaminomethane (aminol ether).