| 摘要 |
The invention comprises carotenoids (excepting capsorubin and capsanthin) and dehydrocarotenoids of formula (I) where R is a 1:2:2-trimethylcyclopentyl group which may contain a hydroxy or keto substituent in the 3- or 4-position and the broken line denotes optional bonds. A process for the manufacture of <FORM:0924255/IV(a)/1> <FORM:0924255/IV(a)/2> <FORM:0924255/IV(a)/3> compounds of formula (I) comprises condensing a polyen(yn)-al or -dial of formulae (II) or (III), in which any keto group in the cyclohexenyl radical may be protected by ketalisation, under alkaline conditions with 1-acetyl-1:2:2-trimethylcyclopentane or a 3-or 4-hydroxy or keto derivative thereof (in which the keto group may be protected by ketalisation); any triple bond in the product may be hydrogenated to a double bond (e.g. with Pd/Pb/CaCO3 catalyst) and any protecting group is then hydrolysed. The condensation may be carried out in presence of an alcoholic solution of alkali-metal hydroxide. In an example, 1-acetyl-1.2.2.-trimethyl-cyclopentane is condensed with crocetindial in an ethanolic solution of KOH to form 1.20-di-(11.21.21-trimethyl-cyclopentyl) 4.8.13.17- tetramethyleicosanonaene-(2.4.6. 8.10.12.14.16.18)-dione-(1.20). Other examples are given. These compounds are highly coloured and they may be used for colouring foodstuffs. Specification 924,257 is referred to. |
