Active metals prepared in liquid ammonia. Zinc and tin-promoted synthesis of β-hydroxyesters, homoallylic and homopropargylic alcohols

Article abstract of DOI:10.1016/0040-4020(96)00494-2

Active zinc and tin provider can be prepared by reduction of ZnCl₂ and SnCl₂ with sodium in tetrahydrofuran-liquid ammonia mixtures of various compositions. The activity of the reduced zinc depends on concentration of ammonia in the reactors medium Zinc(A) prepared in liquid ammonia (Method A) was much less active then zinc (B) prepared in THF containing 10-20 volume% of liquid ammonia (Method B). The X-ray powder difractiometry data suggested that zinc (H) was less crystalline then zinc (A). The Reformatsky and Barbier type reactions of carbonyl compounds with α-bromoesters, allylic and propargylic bromides in the presence of Zn or Sn prepared by method B gave the corresponding β-hydroxyesters, homollylic and homopropargylic alcohols in good to excellent yields.