Chemistry of electron‐rich conjugated polyenes (II)Synthesis of 1,1‐dimethoxy‐ and 1,1,4‐trialkoxy‐1,3‐butadienes and of 1,1,6,6‐tetramethoxy‐1,3,5‐hexatriene

Several poly‐unsaturated, conjugated ketene acetals (Table I) have been obtained by 1,2‐ or 1,4‐elimination of alcohol with potassium amide from unsaturated acetals or ortho‐esters having hydrogen in an allylic position. The products have properties similar to simple electron‐rich olefins as is apparent from their smooth addition reactions with alcohols.