Addition of arenesulphonyl iodides to substituted phenylacetylenes
- 1 January 1987
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 2,p. 103-107
- https://doi.org/10.1039/p29870000103
Abstract
The products of the addition of toluene-p-sulphonyl iodide to substituted phenylacetylenes (and styrenes) are studied. The regiospecificity and stereoselectivity of trans addition to acetylenes is inferred from 1H n.m.r. spectroscopy. The effect of substituents on the reactivity of substituted phenylacetylenes towards substituted benzenesulphonyl radicals generated by photolysis of sulphonyl iodides is studied. Phenylacetylenes with electron-donating substituents react faster. Relative reactivities yield good Hammet–Brown correlations showing the electrophilic character of sulphonyl radicals towards phenylacetylenes. The selectivity of the addition (measured by ρ) of different sulphonyl radicals towards the same set of acetylenes ranges from –0.53 to –0.93 and shows a tendency to be smaller for benzenesulphonyl iodides carrying electron-donating substituents. Results are discussed in terms of polar effects on the transition state and frontier molecular orbital theory.Keywords
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