Oxidative heterocoupling of α-carbanions of lithium acylates with 1,2-dibromoethane

Abstract

The interaction of pairs of α-carbanions of lithium 2-methylpropanoate, butanoate, pentanoate, hexanoate, heptanoate and phenylacetate, generated from various CH-acids (A-H, B-H) under the action of lithium diisopropylamide in THF, with 1,2-dibromoethane leads to a mixture of products of oxidative homo[2,2,3,3-tetramethyl-, 2,3-diethyl-, 2,3-dipropyl-, 2,3-dibutyl-, 2,3-dipentyl- and 2,3 -diphenylsuccinic acids] and heterocoupling [2,2-dimethyl-3-ethyl-, 2-propyl-3-ethyl-, 2-butyl-3-ethyl-, 2-pentyl-3-ethyl-, 2-phenyl-3 -ethyl-, 2-butyl-3-propyl-, 2-pentyl-3-propyl-, 2-propyl-3-phenyl-, 2-butyl-3-pentyl-, 2-butyl-3-phenyl- and 2 -pentyl-3-phenylsuccinic acids] with a total yield of 83-99%. The selectivity of the formation of homo- and heterocoupling products depends on the structure of the coupled α-carbanions.