Method for synthesis of 9-cis-beta-carotene and formulations thereof

A method for the synthesis of 9-cis β-carotene (9CBC) or a derivative thereof, said method comprising:

• (i) reducing 4-methyl-6-(2,6,6-trimethylcyclohex-1-en-1-yl)-5,6-dihydro-2H-pyran-2-one, herein identified compound 3, and opening the ring of the lactol obtained with complete retention of the double bond configuration, to thereby obtain (2Z,4E)-3-methyl-5-(2,6,6-trimethylcyclohex-1-en-1-yl)penta-2,4-dienal, herein identified compound 5;
• (ii) subjecting the (2Z,4E)-3-methyl-5-(2,6,6-trimethylcyclohex-1-en-1-yl)penta-2,4-dienal to Horner-Emmons reaction to obtain a 9-cis retinyl ester, herein identified compound 6;
• (iii) reducing the 9-cis retinyl ester to obtain 9-cis retinol, herein identified compound 7;
• and
• (iv) converting the 9-cis retinol to its triphenylphosphonium salt, herein identified compound 8, and subjecting said triphenylphosphonium salt to Wittig reaction with a compound of the formula A:
• wherein R2 is H or methyl;
• X is
• optionally substituted with one or more methyl groups;
• n is an integer of 0-16;
• and the asterisk represents the point of attachment to the cyclohexene ring, in the presence of a strong base, to thereby obtain said 9CBC or derivative thereof.