Aza‐Henry Reaction with Nitrones, an Under‐Explored Transformation.

Nitromethylation of nitrones occurred efficiently in CH3NO2 in the presence of tetramethylammonium fluoride or triazabicyclodecene as promoters. The obtained adducts might be conveniently transformed into vicinal diamines. The process was extended to nitroethane and nitropropane affording mixtures of syn and anti stereoisomers with low diastereoselectivity. Comprehensive study of the addition of nitroalkanes to nitrones was conducted. The reaction proved efficient with TMAF or TBD as bases, in the presence of a large excess of R–NO2. Phase‐transfer catalysis gave also acceptable yields. Nitroethane or nitropropane afforded mixtures of isomerisable diastereomers. The reaction was applied to the synthesis of biologically relevant compounds. [ABSTRACT FROM AUTHOR]