One-pot stereoselective synthesis of perfluoroalkylated (E)-allylic alcohols mediated by Ti(OPr~i)_4 and Ph_3P~1

摘要

Synthesis of perfluoroalkylated (E)-allylic alcohols by the 'one-pot' reaction of equimolar amounts of aldehyde, 3-bromo-1,1,1-trifluoroacetone (or #alpha#-bromoalkyl perfluoroalkyl ketone), triphenylphosphine and titanium(IV) isopropoxide is described. The reductive olefination products were obtained in good yields exclusively in E-form. Thus this methodology provides a very convenient synthesis of perfluoroalkylated (E)-allylic alcohols and the widespread use of these allylic alcohols is quite important in organic synthesis. They are interesting fluorinated building blocks, not easily available by existing synthetic methods. A possible mechanism for the explanation of formation of reductive olefinic products and the stereochemical results is proposed.