BF 3 -Catalyzed Mukaiyama aldol reaction of acetaldehyde with 2-siloxy-1-propene.

The Mukaiyama aldol reaction is a powerful tool for the construction of the carbon-carbon bond and the formation of β-hydroxycarbonyl compounds. In this work, the mechanism of acetaldehyde and 2-siloxy-1-propene both in the absence and presence of the catalyst BF 3 was investigated based on density functional theory. The mechanism includes two major steps: the formation of the carbon-carbon bond and the removal of SiH 3 /BF 2 by water. The energy barrier of the carbon-carbon bond formation process in the presence of BF 3 is obviously lower, indicating that BF 3 is a good catalyst for this reaction. In terms of molecular configuration, the different tensions between the five-membered-ring and six-membered-ring can be considered as the possible reason for the catalytic effect of BF 3 . In terms of charge transfer, the charges of natural population analysis in the carbon atom of the carbonyl group in acetaldehyde becomes more positive, which is easier to attack by nucleophiles and promote the nucleophilic process.