Palladium(II)-catalyzed carbonylation of 3-buten-1-ols and 3-butyn-1-ols: an efficient synthesis of .gamma.-butyrolactones
摘要:
Palladium(II)-catalyzed dicarbonylation of 3-buten-1-ols (1) in the presence of propylene oxide and ethyl orthoacetate in methanol-dichloromethane under carbon monoxide at atmospheric pressure afforded alpha-[(methoxycarbonyl)methyl]-gamma-butyrolactones (2) in good yields. This dicarbonylation reaction occurs via stereospecific cis addition. Under similar conditions, 4-(trimethylsilyl)-3-butyn-1-ols (4a and 4b) undergo dicarbonylation to provide cis-dicarbonylated alpha-methylene-gamma-butyrolactones (5a and 5b, respectively). 4-Alkyl-and 4-aryl-3-butyn-1-ols (4c-g), on the other hand, undergo trans alkoxycarbonylation across the triple bond and selectively furnish E tetrasubstituted alpha-methylene-gamma-butyrolactones (6).