BINOL-Al catalyzed kinetic resolution of citronellal analogues: synthesis of a variety of fragrances

A chiral aluminum catalyst was used for the kinetic resolution of citronellal analogues. Racemic 3-alkylcitronellals gave optically active 5-alkylisopulegols with high enantioselectivity. Unreacted 3-alkylcitronellal analogues were obtained with low enantioselectivity. The two main diastereoisomers of the product were opposite to each other. The scents of 5-substituted isopulegols were evaluated. The chiral recognition of the catalysts and their effects on the kinetic resolutions are also discussed.

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