[CH3:1][O:2][CH:3]([O:13][CH3:14])[CH2:4][CH:5]([CH3:12])[CH2:6][CH2:7][CH:8]=C(C)C.CC(=CCCC(CC=[O:25])C)C.O=[O+][O-].[BH4-].[Na+]>CO.CO.O>[CH3:1][O:2][CH:3]([O:13][CH3:14])[CH2:4][CH:5]([CH3:12])[CH2:6][CH2:7][CH2:8][OH:25]
A solution of citronellal dimethyl acetal [55.0 g, 275 mmole, prepared from racemic citronellal, according to the process described by V. R. Mamdapur et al. in Tetrahedron 20, 2601 (1964)] in methanol (550 ml) was treated at -75° with a stream of ozone for 3.5 h (4.5 g of O3 per hour, 328 mmole of O3). The excess of ozone was purged with argon, the solution was allowed to warm to 0° and then treated with a solution of NaBH4 (5.22 g, 137.5 mmole) in MeOH--H2O (1:1, 154 ml). After 2 h, the reaction mixture was concentrated at reduced pressure, then extracted with ether, and the organic phase was washed to neutrality, dried over MgSO4 and concentrated at reduced pressure. 60.2 g of the desired hexanol (ca. 85% pure) were thus obtained and this product was used as such in the next preparation step. An analytical sample, obtained by preparative GLC (gas-liquid chromatography) gave the following data:
読み込み中…
