| 摘要 |
1,145,213. Carotenoids. F. HOFFMANNLA ROCHE & CO. A.G. 27 Jan., 1967 [28 Jan., 1966], No. 4191/67. Heading C2C. [Also in Divisions A2 and A5] Novel carotenoids of the general formula in which R is hydrogen or C 1-4 alkyl and the broken line denotes an optional bond, except the all-ethylenic compound in which R is methyl, are claimed per se and a process for preparing these novel carotenoids and the allethylenic compound in which R is methyl is claimed in which 2,6,10,15,19,23-hexamethyltetracosa - 2,4,6,8,10,14,16,18,20,22 - decaen- 12 - yn - 1,24 - dial is condensed with at least two moles of a butan-2-one of the general formula Me 2 C(OR)COMe in the presence of an alkaline condensing agent and an inert solvent suitably at 40-60‹ C. and then optionally the triple-bond of the product is hydrogenated using palladium on calcium carbonate as catalyst deactivated with lead and quinoline and the cis-C 12-13 double bond is isomerized into a trans bond suitably with light in the presence of iodine. Intermediates.-The lithium salt of 5-(1- methoxy - 1<SP>1</SP> - methylethoxy) - 3 - methylpent- 3-en-1-yne is reacted with 3-ethoxy-2-methylaerolein in liquid ammonia to give 1-ethoxy-8- (1 - methoxy - 1 - methylethoxy) - 2,6 - dimethylocta-2,6-dien-4-yn-3-ol which is reacted with 2% sulphuric acid to yield 8-hydroxy-2,6-dimethylocta-2,6-dien-4-yn-1-al. Partial hydrogenation of this compound using a palladium on calcium carbonate catalyst deactivated with lead and quinoline, followed by cis to trans isomerization in the presence of iodine as catalyst, gives 8-hydroxy-2,6-dimethylocta-2,4,6-trien- 1-al which is reacted with phosphorus tribromide and N,N-dimethylformamide to afford 8- bromo - 2,6 - dimethylocta - 2,4,6 - trien - 1 - al. This compound is reacted with triphenyl phosphine to give 3,7-dimethyl-8-oxo-octa-2,4,6-trien- 1-yl-triphenyl phosphonium bromide, which is converted into the corresponding dimethyl acetal with methyl orthoformate and the product is reacted with 2,7-dimethylocta-2,6-dien- 4-yne-1,8-dial in the presence of sodium methoxide to give a tetramethyl acetal product which is hydrolysed with N-sulphuric acid to give 2,6,10,15,19,23 - hexamethyltetracosa - 2,4,6,8, 10,14,16,18,20,22 - decaen - 12 - yne - 1,24 - dial. The above novel carotenoids and 2,31- dimethoxy - 2,6,10,14,19,23,27,31 - octamethyldotriaconta - 4,6,8,10,12,14,16,18,20,22,24,26, 28-tridecaene-3,30-dione can be used to colour foodstuffs, e.g. confectionery, ice cream, marzipan, caramels, syrups, gelatine foods, yoghourt, puddings and soft drinks. |
