Synthesen in der Carotinoid‐Reihe. 15. Mitteilung Synthesen in der β‐Carotinal‐ und β‐Carotinal‐Reihe

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(C 25 ) 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(C 30 ) and β‐apo‐8′‐carotenal(C 30 ) were identical with the permanganate oxidation product of β‐carotene and its corresponding alcohol isolated by K ARRER .