Oxidative Di- and Tricarbonylation

Oxidative Aikoxy- and Aminocarbonylation of Propai l Alcohols, Amines and Acetates, Ynois, and Ynones 

Under oxidative conditions, acyclic [75a,b] and cyclic [75c] 4-yn-l-ols react via a cyclization-methoxycarbonylation pathway to afford ( )-cyclic-P-alkoxyacrylates 2E-[(methoxycarbonyl)methylene]tetrahydrofurans in good yields under mild conditions (Equations 10.37 and 10.38). The stereochemical outcome is entirely consistent with a reaction initiated by intramolecular nucleophilic attack of the hydroxy group on the palladium-coordinated triple bond to generate a vinylpalladiumiodide intermediate that undergoes methoxycarbonylation to afford the P-alkoxyacrylate. The ketopyranose subunit can also be constructed via a palladium-catalyzed oxidative cyclocarbonylation of substituted 5-yn-l-ols, which occurs with excellent stereose- 

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