No abstract

Reaction of the anion derived from phosphine oxide 4 with saturated and unsaturated aldehydes provides diastereomeric mixtures of the adducts 5. After removal of the protecting group these can be separated and, upon reaction with base, afford the pure E‐and Z‐isomers of glyceryl enol ethers 7 in good yields.

ABSTRACT. A synthesis of racemic fecapentaene-12 and other glyceryl enol ethers has been developed based on the Horner-Wittig reaction. Coupling of the anion of the glyceryl substituted phosphine oxide2 with unsaturated aldehydes g-2 provided, after treatment with base, the silyl protected glyceryl enol ethers lLa-5, The silyl groups were easily removed and mixtures of E and Z isomers of glyceryl enol ethers 1La-Z were obtained. The isomers could be separated upon washing with ether/hexane.Recently four mutagenic compounds, fecapentaene-14 -1 and three stereoisomers of fecapentaene-12 were isolated from the feces of persons at high risk for colon ~ancerl-~.

Die zu Synthesezwecken notwendigen Titelcycloalkane (IV) werden ausgehend von den Cycloalkanonen (I) über ihre Mannichbasen (II) erhalten.

Abstract. Cycloalkanones can be converted to the corresponding 1,2-dimethylenecycloalkanes (I), in 10-50 o/A overall yield by a four-step sequence involving Mannich condensation, Wittig reaction and Hofmann degradation. The conformation of 1 is briefly discussed.