Acetaldehyde → (-)-Ipsenol

Participants

Reaction Conditions

Reaction Steps

Isovaleraldehyde (2.15 g, 2.68 mL, 25 mmol) in ether (6 mL) was added dropwise to a rapidly stirred solution of B-isoprenyldiisopinocampheylborane, dIpc2BIpn, maintained at -78° C. Stirring was continued for 1 h, when the 11B NMR spectrum of an aliquot showed a peak at δ52 ppm corresponding to a borinate indicating completion of the reaction. The reaction mixture was warmed to 0° C. and acetaldehyde (2.1 mL, 37.5 mmol) was added when one equiv of α-pinene was eliminated. 11B NMR showed a peak at δ32 ppm corresponding to a boronate. THF was substituted with EE and 1.1 equiv. of diethanolamine (2.6 mL, 27.5 mmol) was added and stirred for 2 h. The precipitated boron components were filtered and the filtrate was concentrated and distilled (92°-94° C./19 mm Hg) to yield 2.3 g (60%) of (+)-ipsenol. [α]D =+17.3° (c 1, MeOH) which corresponds to 93.7% ee. The spectral properties were identical to the racemic mixture of Example 6.

Provenance & Evidence