3,4-Dibromofuran-2(5H)-one (1a) and 3,4-dichlorofuran-2(5H)-one (1b) are attractive and versatile polyfunctional building blocks that can be selectively manipulated at their electrophilic C3 and C4 sites. In particular, compound 1a, the cyclic analogue of methyl (Z)-2,3-dibromopropenoate (2) (Figure [1] ), exhibits, similar to this dibromo ester 2, regioselectivity in palladium-catalyzed CC bond forming reactions, [1] which occur at the C4 site [2-9] even though the C3 site is ...
