Synthesis of a-Chloro-r-butyrolactones by the Ruthenium(II)-Catalyzed Reaction of Olefins with a-Polychloro Carboxylic Acids

Abstract

A variety of α-chloro-r-butyrolactones were prepared by the dichlorotris(triphenylphosphine)ruthenium(II)-catalyzed reaction of various olefins with a-polychloro carboxylic acids. Reactions of monoalkylethylenes with a-polychloro carboxylic acids such as trichloroacetic acid, dichloroacetic acid and 2, 2-dichloropropionic acid gave a-chloro-r-alkyl-r-butyrolactones in 50-84% yields (Table 2). In the reaction of cyclopentene, cyclohexene and cycloheptene with trichloroacetic acid, cis-fused r-butyrolactones were obtained in yields of 35, 22 and 32%, respectively (Table 3). Reactions of 1, 1-dialkylethylenes with a-polychloro carboxylic acids afforded isomeric mixtures of a pair of the expected and rearranged r-butyrolactones in combined yields of 42-67% (Table 3). The reaction of olefins such as 5-hexen-2-one and 3-butenoic acid gave the corresponding r-butyrolactones in somewhat low isolated yields (24 and 24%, respectively) (Table 5). No r-butyrolactones were obtained from the reaction of styrene and isoprene because of the prevailing cationic polymerization.