Carbonylation of various organolithium reagents. A novel approach to heterocycles via intramolecular trapping of aromatic acyllithiums
Doubly lithiated N-pivaloylanilines react smoothly with carbon monoxide at 0 °C to give 3-tert-butyl-3-hydroxy-2,3-dihydroindol-2-ones in good yields. Similarly, carbonylation of doubly lithiated 4-pivaloylamino- and 2-pivaloylaminopyridines at 0 °C affords the corresponding 5-aza- and 7-aza-3-tert-butyl-3-hydroxy-2,3-dihydroindol-2-ones, respectively, in good yields. However, carbonylation of doubly lithiated N-pivaloyl-o-toluidines takes a different course due to direct intramolecular cyclisation of the dilithio reagents to afford 2-tert-butylindoles without uptake of carbon monoxide.