Benzaldehyde → (1S,3S)-3-methyl-1-phenyl-hex-5-ene-1,3-diol

Participants

Reaction Conditions

Reaction Steps

Asymmetric tandem aldol-allylation reaction of benzaldehyde to give (1S,3S)-3-methyl-1-phenyl-hex-5-ene-1,3-diol: To a solution of (4R,5R)-2-allyl-2-isopropenyloxy-4,5-bis-(1-methoxy-1-methyl-ethyl)-[1,3,2]dioxasilolane (0.75 mmol) in benzene (0.3 mL) was added benzaldehyde (0.50 mmol). The mixture was heated to 40° C. (oil bath) and stirred at that temperature for 48 hours. The solution was cooled and 1 M HCl (10 mL) was added followed by ethyl acetate (10 mL). The mixture was stirred for 20 min. The layers were separated and the aqueous layer was extracted with ethyl acetate (10 mL). The combined organic layers were washed with saturated aqueous NaHC03 (10 mL) and brine (10 mL), dried (Na2SO4), filtered, and concentrated. Analysis of the residue by HPLC and 1H NMR revealed a 5.5:1 mixture of diastereomers and an enantiomeric excess for the major product of 68%. The residue was purified by chromatography on silica gel to give (1S,3S)-3-methyl-1-phenyl-hex-5-ene-1,3-diol in 70% yield and in 68% ee.

Provenance & Evidence