Patent GB-1173063-A (GB)
Title: Novel Polyene Compounds and a process for the manufacture and conversion thereof
IPC: C07C403/00
Filed: 1967-02-14
Abstract: 1,173,063. Polyene compounds. ROCHE PRODUCTS Ltd. and B. C. L. WEEDON. 15 March, 1968 [14 Feb., 1967], No. 7095/67. Heading C2C. The invention comprises compounds of formula wherein the broken line represents an optional bond and R is a group of formula The compounds are prepared by reacting a phosphonium salt of formula wherein R<SP>1</SP> is an aryl group and A<SP>-</SP> is the anion of a mineral acid, with an aldehyde of formula wherein R<SP>2</SP> is a formyl group or a group of formula in the presence of a proton acceptor and converting any acyloxy or oxo group in the resulting compound of the formula into an hydroxy group by reduction or hydrolysis. In Examples: (1) 7,8,7<SP>1</SP>,8<SP>1</SP>-bisdehydro-zeaxanthin is prepared by reacting together 3-methylpent-2-en-4-yn-1-ol and 4,4-ethylenedioxy-2,2,6- trimethyl-cyclohexane in a Grignard reaction to give 5 - (4,4 - ethylenedioxy - 1 - hydroxy - 2,2,6 - trimethyl - cyclohexyl) - 3 - methyl - pent - 2 - en - 4-yn-1-ol which is reacted with acetic acid to yield a mixture of 5-(1-hydroxy-4-oxo.2,2,6- trimethyl - cyclohexyl) - 3 - methyl - pent - 2 - en - 4- yn - 1 - ol and 5 - (1 - hydroxy - 4 - oxo - 2,2,6 - trimethyl - cyclohexyl) - 1 - acetoxy - 3- methyl - pent - 2 - en - 4 - yne, the latter compound is treated with LiAlH4 to give 5-(1,4- dihydroxy - 2,2,6 - trimethyl - cyclohexyl) - 3 - methyl - pent - 2 - en - 4 - yn - 1 - ol, which is refluxed with acetic acid/acetic anhydride to give 5 - (4 - acetoxy 2,2,6 - trimethyl - cyclohex - 6 - enyl) - 1 - acetoxy - 3 - methyl - -pent 2 - en - 4 - yne, which is treated with methanolic KOH to yield 5-(4-hydroxy-2,2,6-trimethyl-cyclohex-6- enyl) - 3 - methyl - pent - 2 - en - 4 - yn - 1- ol, which is reacted with triphenyl-phosphine hydrobromide to give [5-(4-hydroxy-2,2,6-trimethyl - cyclohex - 6 - enyl) - 3 - methyl - pent - 2 - en - 4 - yn - 1 - yl] - triphenyl phosphonium bromide (compound X) which is reacted with 2,7 - dimethyl - octa - 2,4,6 - triene - 1,8 - dial to yield 13-(4-hydroxy-2,2,6-trimethyl-cyclohex - 6 - enyl) - 2,7,11 - trimethyl trideca- 2,4,6,8,10 - pentaen - 12 - yn - 1 - al which is further reacted with compound X to give 7,8, 7<SP>1</SP>,8<SP>1</SP>-bisdehydro-zeaxanthin; catalytic hydrogenation of the bisdehydro-zeaxanthin gives zeaxanthin: (2) alphaionone is added to a mixture of Li, liq. NH 3  and ferric nitrate through which acetylene has been passed and 5 - (2,2,6 - trimethyl - cyclohex - 5 - enyl) - 3 - methyl - pent - 4 - en - 1 - yn - 3 - ol is isolated and catalytically hydrogenated to give 5- (2,2,6 - trimethyl - cyclohex - 5 - enyl) - 3 - methyl - penta-1,4-dien-3-ol, which is reacted with triphenyl-phosphine hydrobromide to give [5- (2,2,6 - trimethyl - cyclohex - 5 - enyl) - 3 - methyl - penta - 2,4 - dien - 1 - yl] - triphenyl - phosphonium bromide, which is reacted with 2,7- dimethyl - octa - 2,4,6 - triene - 1,8 - dial to give 13 - (2,2,6 - trimethyl - cyclohex - 5 - enyl) - 2,7,11 - trimethyl - trideca - 2,4,6,8,10,12 - hexaen - 1-al (α-apo-12<SP>1</SP>-carotenal), which is reacted with compound X to give 7,8-dehydro-3-hydroxy-α- carotene: 7,8-dehydro-zeaxanthin, 7,8-dehydrolutein and 7,8-dehydro-3-hydroxy-#-carotene may be similarly prepared.