Reaction of certain geometrically defined 1,1-dioxy-4-alkyl- and -4,4-dialkyl-substituted buta-1,3-dienes with halogenated quinones does not involve Diels-Alder or Michael addition chemistry. Instead, rapid competitive oxidation of the dienes to give 2,4-dienoate esters was observed. This new reaction involves strong spatial association between diene and quinone, hydrogen being transferred specifically from the (4E)-alkyl group. Its scope is compared with addition of the same terminally substituted dienes towards the reactive non-quinonoid dienophile tetracyanoethylene.
Palladium-Catalyzed γ-Arylation of α,β-Unsaturated Esters from Silyl Ketene Acetals
作者:David S. Huang、John F Hartwig
DOI:10.1002/anie.201002328
日期:——
Smarty cat: A method for the palladium‐catalyzed γ‐arylation of α,β‐unsaturated estersviasilylketeneacetals in the absence of fluoride has been developed. The coupling proceeds with electron‐rich and electron‐poor aryl bromides and vinyl bromides in high yields with a high tolerance for other functional groups.
Reaction of certain geometrically defined 1,1-dioxy-4-alkyl- and -4,4-dialkyl-substituted buta-1,3-dienes with halogenated quinones does not involve Diels-Alder or Michael addition chemistry. Instead, rapid competitive oxidation of the dienes to give 2,4-dienoate esters was observed. This new reaction involves strong spatial association between diene and quinone, hydrogen being transferred specifically from the (4E)-alkyl group. Its scope is compared with addition of the same terminally substituted dienes towards the reactive non-quinonoid dienophile tetracyanoethylene.