439864-12-7Relevant articles and documents
Synthesis of 2-pyranylidene or (2-furyl)carbene-chromium complexes from conjugated enyne carbonyl compounds with Cr(CO)5(THF)
Miki, Koji,Yokoi, Tomomi,Nishino, Fumiaki,Ohe, Kouichi,Uemura, Sakae
, p. 228 - 234 (2002)
The reaction of Β-ethynyl α,β-unsaturated esters or amides with Cr(CO)5(L) (L = Et2O, THF), derived from chromium hexacarbonyl, gives 2-pyranylidene-chromium complexes in good yields. The conjugated ene-carbonyl-vinylidene complex is a key intermediate to these Fischer-type oxacarbene complexes. In contrast, β-ethynyl α,β-unsaturated ketones react with Cr(CO)5(THF) to give (2-furyl)carbene complexes via nucleophilic attack of the carbonyl oxygen atom to the intermediate π-alkyne-chromium complexes. Some chemical transformation, such as [4 + 2] type cyclization of 2-pyranylidene complexes with alkynes and aldehyde formation from (2-furyl)carbene complexes, has also been described.
