Reductive cross-aldol reaction using bromoaldehyde and an aldehyde mediated by germanium(II): One-pot, large-scale protocol

摘要

The reaction of alpha-bromoaldehyde with aldehyde in the presence of GeCl2-dioxane gave the syn-selective cross-aldol equivalent. A catalytic amount of Bu4NBr improved the yield and selectivity. The initially formed aldol adduct (beta-germoxyaldehyde) did not suffer from over-reaction. This system enabled an intramolecular aldol reaction to give cyclic compounds effectively. One-pot synthetic methodology including bromination of aldehyde followed by cross-aldol reaction with the second aldehyde was successful on a large-scale.