Cyclic 2-methyl-2,4-dialkoxy-3-buten-1-al-acetals, their preparation and use

摘要

New acetals, containing a 6-membered ring, of 2-methyl-2,4-dialkoxy-3-buten-1-al, are obtained by reacting the corresponding 2-methyl-2-alkoxy-3-butyn-1-al-acetals with a mixture of the appropriate alcohol and an alkali metal alcoholate of the said alcohol at from 100 DEG to 200 DEG C. The acetals are intermediates for the preparation of carotinoid-based physiologically safe food dyes.