| 摘要 |
Optically active alcohols are prepared by hydrolysing the product obtained by reacting (a) a compound of formula RMgZR1, wherein R is a hydrocarbon residue having from 1 to 28 carbon atoms, R1 is a hydrocarbon residue having from 4 to 28 carbon atoms, at least one of which is asymmetric, and Z is -O- or -NR11, wherein R11 is R or R1, with (b) an unsymmetrically substituted carbonyl compound of the formula R111-CO-R1111, wherein R111 may be R or R1 and R1111 may be R111 or H, and R, R111 and R1111 must be different. Numerous examples of R, R1, R11, R111 and R1111 are listed. Reaction may take place at -50 DEG to +150 DEG C. at atmospheric pressure or above, e.g. under nitrogen, in absence of compounds containing reactive hydrogen atoms. The mole ratio of reactants is not critical. Optionally a solvent e.g. excess carbonyl compound, ethers, inert tertiary amines and inert hydrocarbons may be used. Up to two moles of associated magnesium halide may be present per mole of solvated RMgZR1. Hydrolysis of the reaction product may be achieved with an aqueous solution at pH 3-7, e.g. saturated ammonium chloride. The alcohol may be recovered by washing the solvent layer, distilling off the solvent and distilling or crystallizing the alcohol. Examples describe the reaction of ethylmagnesium - l - menthoxide with methyl isobutyl ketone to give laevorotatory 2,4-dimethyl-4-hexanol; the reaction product of methylmagnesium bromide and d-2-methylaminopropylbenzene with propiophenone to give methylethylphenyl carbinol enriched in d-isomer; ethyl magnesium d-2-octyloxide and acetophenone to give laevorotatory methylethylphenylcarbinol; phenylmagnesium d-2-octyloxide and methylethylketone to give laevorotatory methylethylphenyl carbinol; ethylmagnesium - l - borneoxide with acetophenone to give laevorotatory phenylmethylethyl carbinol; methylmagnesiumchlolesteroxide with benzaldehyde to give dextrorotatory phenylmethyl carbinol; phenylmagnesium - d-a - tocopheroxide with 3 - methylcyclohexanone to give dextrorotatory 3-methyl-1-phenylcyclohexanol; and benzylmagnesiumchlolesteroxide with dimethyl-(2-benzoyl) propylamine to give laevorotatory 1,2-diphenyl-3-methyl-4-dimethylamino-2 -butanol. Organomagnesium compounds RMgZR1 are prepared by reacting under anhydrous conditions a Grignard reagent RMgX, where R is as above and X is halogen with an optically active alcohol or amine R1ZH, where R1 and Z are as above. Alternatively, the Grignard reagent may be reacted with a compound Mg(ZR1)2. In an example, ethyl magnesium bromide is reacted with 1-menthol in dry ether to yield ether-solvated magnesium bromide-associated ethyl magnesium 1-menthoxide. |
