Abstract
(+)-3-Ethylhept-3-on-2-al has been resolved by the fractional crystallisation of the brucine salt of its hydrogen phthalate, into the optically isomeric forms. The (-)-alcohol has been hydrogenated to (-)-3-ethyl-heptan-3-ol, which on oxidation have (+)-3-othylhoptan-3-one. These reactions constitute partial asymmetric synthesis; a new asymmetric centre is generated at O3, the two enantiomeric configuration being formed in unequal amounts, and the original asymmetric centre is rendered asymmetrical. A similar series of reaction has been carried with (+)-3-ethylhspt-3-en-2-ol. The stereochemistry of these hydrogenations is discussed. Addition of bromine to (+)-3ethylhert-3en-2-ol gave (+)-3:4-dibromo-3-ethylheptan-2-ol which on oxidation 3:4-dibromo-3-ethylheptan-2-one of low rotatory power. The following olefinic addition reactions have been carried out, with isolation of the products of reaction: addition of thiolacetic acid, benzyl meraptan, and bromine-sodium methoxide to (+)-3-othylhopt-3-on-2-ol; addition on bromine, thiolscatic acid, and thiophenol to 2-ethylhex-2-onal. Experimental evidence is presented that the aldehyde and alcohol are of one geometrical configuration only.