| abstract |
Retinal is prepared by condensing a C 15 sulphide of formula: ##STR1## in which R 1 denotes aryl, aralkyl, pyridyl, 2-thiazolyl, 2-benzothiazolyl, 2-benzimidazolyl or 2-benzoxazolyl, with a haloacetal of formula: ##STR2## in which X denotes a halogen atom and R denotes an alkyl radical containing 1 to 4 carbon atoms, to give a C 20 sulphide acetal of formula: ##STR3## in which R 1 and R are defined as above, hydrolysing the said sulphide acetal to give a C 20 sulphide aldehyde of formula: ##STR4## in which R 1 is defined as above, desulphurizing the said sulphide aldehyde to give retinal, and isolating the retinal obtained. |