To study the oxidative degradation of p-carotene to vitamin A in the animal body, a number of possible intermediates have been prepared. Starting with 15,15′-dehydro-β-apo-12′-carotenal(C25) vinylogous series of polyene aldehydes and acetates with 25 to 40 carbon atoms have been synthesized by successive enol ether condensations. The synthetic β-apo-8′-carotenal(C30) and β-apo-8′-carotenal(C30) were