Silver Ion-assisted Solvolysis of trans-2,2-Dibromo-1,3-dimethylcyclopropanecarboxylic Acid: Selective Formation of 4-Bromo-3,5-dimethyl-2(5H)-furanone.
作者:Leiv K. Sydnes、Rajesh Mungaroo、Berit A. Aanesen、Jacek Stawinski
DOI:10.3891/acta.chem.scand.52-1386
日期:——
The title compound has been solvolysed in 2,2,2-trifluoroethanol (IFE), isopropyl alcohol (IPA), 1,1,1,3,3,3-hexafluoro-2-propanol (HFP) and tert-butyl alcohol (TBA) in the presence of silver trifluoroacetate. The product distribution is sensitive to the solvent used. In TFE and IPA two major products were formed, the butenolide 4-bromo-3,5-dimethyl-2 (SH)-furanone and the corresponding (Z)-4-alkoxy-3-bromo-2-methyl-2-pentenoic acid, but, in addition, minor amounts of 2-alkoxy-3-bromo-2-methyl-3-pentenoic acid and 3-bromo-2-hydroxy-2-methyl-3-pentenoic acid were also obtained. In HFP and TEA the furanone was formed in better than 80% yield, the other products being 3-bromo-2-hydroxy-2-methyl-3-pentenoic acid and 3-bromo-2-methyl-2,4-pentadienoic acid. The outcome of the reactions is discussed on the basis of the nucleophilicity, the hydrogen-bonding ability and the polarity of the solvents.