Acetaldehyde → (S)2-Methyl-6-methylenoct-7-en-4-ol

Temperature

0 °C

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 in THF/EE (1:2) at -100° C. Stirring was continued for 6 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 δ 32 ppm corresponding to a boronate. The solvents were removed in vacuo and EE (20 mL) was added, followed by 1.1 equiv. of diethanolamine (2.6 mL, 27.5 mmol). Stirring was continued for 2 h and the precipitated boron components were filtered and the filtrate concentrated. Distillation (92°-94° C./19 mm Hg) provided 2.3 g (60%) of (+)-ipsenol, [α]D =+18.5° which corresponds to 100% ee. The spectral properties were identical to the sample obtained from example 9.

1. customThe solvents were removed in vacuo and EE (20 mL)
2. additionwas added
3. stirringStirring
4. waitwas continued for 2 h
5. filtrationthe precipitated boron components were filtered
6. concentrationthe filtrate concentrated
7. distillationDistillation (92°-94° C./19 mm Hg)

ORD record

ord-1f6d21c8fa3f4b96844fa718dceffc0c

Source dataset

uspto-grants-1992_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05175378