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Leicestershire LEI 1 3TUThe potassium salts of indole, pyrrole, and 2.5-dimethylpyrrole were converted into N-alkyl derivatives in high yield in dimethyl sulphoxide by use of iodomethane, iodoethane, 1 -iodopropane, and benzyl bromide. Dehydrohalogenation occurred when 2-iodo-and 2-bromo-2-methylpropane were used ; when 2-iodopropane was employed alkylation and dehydrohalogenation were observed.WE required a high yield route to certain N-alkylpyrrole derivatives in connection with another study.l The alkylation of pyrrolylmagnesium bromide is complex; both 2-and 3-alkylpyrroles are formed and polyalkylation is observed when equivalent quantities of alkyl halide are used.2 The reactions of alkali metal salts of pyrroles3 and indole4 with alkyl halides are complex but alkylation at nitrogen is usually predominant in strongly ionising solvents. The use of dimethyl sulphoxide as a dipolar aprotic solvent is well known5 and excellent results have been obtained, for example in the methylation of phenols.6 Dimethyl sulphoxide has been used as a solvent for pyrrolylProfessor A. H. Jackson has recently informed us of his similar work on the N-alkylation of pyrroles and indoles in dimethyl sulphoxide using either potassium t-butoxide (D. J. Newman, MSc. Thesis, Liverpool, 1963) or sodium hydride (B. Naidoo and P. P. Lynch, Ph.D. Theses, Liverpool, 1969 and 1970, respectively) as the base,

Dinuclear alkynylcopper(I) ladderane complexes are prepared by a robust and simple protocol involving the reduction of Cu(2)(OH)(3)OAc or Cu(OAc)(2) by easily oxidised alcohols in the presence of terminal alkynes; they function as efficient catalysts in copper-catalysed alkyne-azide cycloaddition reactions as predicted by the Ahlquist-Fokin calculations. The same copper(I) catalysts are formed during reactions by using the Sharpless-Fokin protocol. The experimental results also provide evidence that sodium ascorbate functions as a base to deprotonate terminal alkynes and additionally give a convincing alternative explanation for the fact that the Cu(I)-catalysed reactions of certain 1,3-diazides with phenylacetylene give bis(triazoles) as the major products. The same dinuclear alkynylcopper(I) complexes also function as catalysts in cycloaddition reactions of azides with 1-iodoalkynes.

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