Reductive cross-aldol reaction using bromoaldehyde and an aldehyde mediated by germanium(II): one-pot, large-scale protocol.
[reaction: see text] The reaction of alpha-bromoaldehyde with aldehyde in the presence of GeCl(2)-dioxane gave the syn-selective cross-aldol equivalent. A catalytic amount of Bu(4)NBr 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.
Yasuda
Makoto
M
Department of Molecular Chemistry and Handai Frontier Research Center, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Tanaka
Shin-Ya
SY
Baba
Akio
A