Abstract: Polyene aldehydes of the general formula I ##STR1## where R is ##STR2## where R' is alkyl, aryl, aralkyl or cycloalkyl and, if desired, may be further substituted, and the radicals R" are each C.sub.1 -C.sub.4 -alkyl or together form --CH.sub.2 --CH.sub.2 -- or --CH.sub.2 --CH.sub.2 --CH.sub.2 -- bridges which, if desired, may be further substituted by C.sub.1 -C.sub.4 -alkyl, are prepared by catalytic oxidation of the corresponding polyene alcohol with oxygen or an oxygen-containing gas by a process wherein the oxidation is carried out in the presence of the catalyst system comprising 2,2,6,6-tetramethylpiperidine 1-oxide or 4-oxo-2,2,6,6-tetramethylpiperidine 1-oxide and copper(I) chloride.

Abstract: Alkyl .gamma.-halotiglates of the general formula I ##STR1## where X is Cl or Br and R.sup.2 is alkyl of 1 to 3 carbon atoms, having a high E isomer content, are prepared by a process in which(a) the corresponding 2-methyl-but-3-enoate of the general formula II ##STR2## is reacted with chlorine or bromine in the absence of a solvent and (b) the resulting 2-methyl-3,4-dihalobutyrate of the general formula III ##STR3## is dehydrohalogenated by reaction with a solution of an alkali metal hydroxide in an alcohol R.sup.2 OH, where R.sup.2 has the stated meaning, or in a mixture of water and an alcohol R.sup.2 OH, and the products are further processed to give O,O-dialkyl-.gamma.-phosphonotiglates of the general formula IV ##STR4## where R.sup.1 is alkyl of 1 to 4 carbon atoms and R.sup.2 is alkyl of 1 to 3 carbon atoms, preferably ethyl, by reaction with a trialkyl phosphite and thermal isomerization. The process gives C.sub.