ORGANOLITHIUM COMPOUNDS AND ACETYLENES .7. EFFECT OF N,N,N',N'-TETRAMETHYLETHYLENEDIAMINE ON REACTIVITY AND PRODUCTS

The activating effect of N,N,N′,N′-tetramethylethylenediamine (TMEDA) on addition-metalation reactions of phenyllithium and n-butyllithium with diphenylacetylene (DPA) is reported. Phenyllithium and n-butyl-lithium react much more rapidly with DPA-in the presence of TMEDA-to give products arising from addition plus metalation. Whereas t-butyllithium and DPA in hydrocarbon solvent react to the extent of 50% after 72 hr, the addition of TMEDA causes quantitative conversion to an addition product in less than 20 min. No metalation of the addition product occurs. The stereochemistry of the addition products (6:1 cis: trans) was determined by the stereospecific conversion of the carboxylic acid derivative, having a phenyl group and a carboxyl cis, into an indone using sulfuric acid at 0°. © 1969, American Chemical Society. All rights reserved.