Revisiting the reduction of di-tert-butyl ketone with alkali metals

The reduction of di-tert-butyl ketone (1) with alkali metals has been revisited. A novel product, 2,5,5-tri-tert-butyl-3-methyl-4,5-dihydrofuran (4), was isolated from the product mixture in very low yield. The formation of 4 requires the elimination of a methyl radical from the radical anion of 1 as key step. An alternative reaction mechanism, which involves the formation of the dianion of 1, was ruled out on the basis of the results of DFT calculations. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).