Olefination and hydroxymethylation of aldehydes using Knochel's (dialkoxyboryl)methylcopper reagents

Article abstract of DOI:10.1016/0040-4020(95)00950-7

The in-situ preparation of [(Me₂C)₂O₂BCH₂]Cu(CN)ZnI (3) from Knochel's (dialkoxyboryl)-methylzinc reagent (2) and CuCN·2LiCl in THF, followed by its addition to aldehyde in the presence of boron trifluoride etherate yielded rather stable β-hydroxyalkylboronates (5). The thermal dehydroxyboronation or the alkaline hydrogen peroxide oxidation of 5 gave the corresponding alkenes (6) or 1,2-alkanediols (7) in high yields. The reaction provides a simple procedure for the olefination or the hydroxymethylation of aldehydes.