Synthesis of vitamin A, intermediates and conversion thereof to vitamin A

Claim 1

A process for synthesizing Vitamin A from beta-ionone by increasing the length of its conjugated aliphatic chain while still obtaining the trans form of Vitamin A, comprising: a. ethynylating beta-ionone to form ethynyl-beta-ionol, b. etherifying the hydroxyl group of said ionol at the tertiary carbon atom to form a compound having the general formula: ##SPC12## in which R is lower alkyl, lower alkenyl, phenyl, aralkyl, c. forming the cuprous acetylenyl derivative of a compound of Formula I, d. coupling said acetylenyl derivative to a reactant having the general formula: ##EQU3## in which R 1 is hydrogen or ##EQU4## R 2 being lower alkyl, phenyl, or aralkyl, and R 3 is halogen to form a compound having the general formula: ##SPC13## e. semi-hydrogenating the acetylenic bond of the compound of Formula III to form a compound having the general formula: ##SPC14## f. subjecting the compound of Formula IV to hydrolysis to convert the terminal ester group to a terminal hydroxyl group to form a compound having the general formula: ##SPC15## and, g. subjecting a compound of Formula V to the presence of a sufficiently strong basic medium to effect 1,4 elimination of ROH therefrom, formation of an additional double bond and conjugation of all five double bonds in the molecule in order to form Vitamin A.