Addition of Amines to Butadiene in Alkali metal-Hexamethylphosphoric Triamide Systems

Abstract

Addition of amines to butadiene in alkali metals or lithiumdiethylamide (LiNEt₂) -hexamethylphosphoric triamide (HMPA) systems was studied. In the case of dialkylamines in alkali metals-HMPA systems, the main products were dialkylamino-trans-2-butene and dialkylamino-2-vinyl-4-hexene.
When excess amounts of an amine was added, the product obtained was a 1 : 1 adduct of butadiene and the amine, which was a mixture of trans-isomer (8386%), cis-isomer (39%) and vinyl-isomer (812%).
The yield of dialkylamino-2-vinyl-4-hexenes increased with the ionic radii of alkali metals employed, that is, Li<Na<K.
When LiNEt₂ was used in place of Li, and a small ammount of HMPA was added to LiNEt₂, the trans-isomer of the 1 : 1 adduct was the main product.