dieneiron tricarbonyl complex of the unstable 2-formylbutadiene was prepared from isoprene by two different ways and resolved via chiral semioxamazone formation. The complex reacts easily with Grignard or other carbanionic reagents leading to the corresponding alcohols from which the stable diene alcohols can now be obtained by decomplexation. The reaction of the aldehyde complex proceeds nearly diastereospecifically