Patent GB-744887-A (GB)
Title: Polyene compounds and process for the manufacture thereof
IPC: C07F1/02
Filed: 1953-12-31
Abstract: The invention comprises polyene compounds of the general formul HO.CH(R).C(CH3):CH.C ­ C.CH:C(CH3).CH(R).OH  (I) wherein R represents an alkyl group or an ethinyl group either of which may contain an alkenyl or alkyl substituent which substituent may in turn contain an hydroxyl group or a cyclohexyl (including cyclohexenyl) group or both these groups or an etherified hydroxyl group or carbalkoxy group as substituents. Specified examples of R are (A) methyl, (B) 3-methyl - buten - (3) - inyl, (C) 5 - hydroxy - 3-methyl - penten - (3) inyl, (D) 3 - methyl - 5-[tetrahydropyranyl - (2) - oxy] - penten - (3)-inyl, (E) 3 - hydroxy - 3 - methyl - 5 - [2,6,6-trimethylcyclohexen - (1) - yl] - pentinyl, (F) ethinyl, (G) 6,6 - dicarbethoxy - 3 - methylhexen - (3) - inyl, (H) 3 - carbomethoxybuten-(2)-yl, or (J) 3-methyl-5-[2,6,6-trimethylcyclohexen-(1)-yl]-penten-(3)-ine-(1). The novel products are prepared by treating 2,7-dimethyloctadiene-(2,6)-ine-(4)-dial with an organometallic compound R-metal (X)n, where R is as defined above but may be modified by replacement of active hydrogen atoms by -metal (X)n and X and n represent halogen and 0 or 1 respectively, and hydrolysing the product by the action of water, weak acids or ammonium salt solutions.  Organo-magnesium halides, organo zinc halides or organo sodium or lithium compounds may be used.  The combination of the Grignard compounds with the C10 aldehyde may be effected in solvents such as ether or tetrahydrofurane. The reactions involving sodium or lithium acetylene compounds are preferably carried out in liquid ammonia.  The lithium condensation is preferred for condensing the C10 dialdehyde with acetylene and with 4-methylhexene - (3) - ine - (5) - 1,1 - dicarboxylic acid diethyl ester (G).  The latter is prepared by reacting 1-bromo-3-methylpenten-(2)-ine-(4) with sodium-malonic acid diethyl ester.  The zinc method is preferred for introducing a -bromo-acetic acid ester and vinylogues thereof such as g -bromo-tiglic acid ester (H).  The latter is formed by heating the tiglic acid ester with N-bromo-succinimide in carbon tetrachloride while exposing to light.  Starting materials for the acetylenic organo metallic compounds are obtained as follows: (a) methylbutenine by condensing acetylene with acetone and splitting-off water from the product; (b) 1-hydroxy-3-methylpenten-(2)-ine-(4) by condensation of acetylene with methyl vinyl ketone and subsequent allyl rearrangement by treatment with acid; (c) tetrahydropyranyl ether of (b) is formed by reacting with dihydropyrane in the presence of acid; (d) 3-hydroxy-3 - methyl - 5 - [2,6,61 - trimethylcyclohexene-(11)-yl]-pentine-(1) by reacting dihydro-b -ionone with acetylene in liquid ammonia by means of lithium acetylide; (e) the product of (d) may be dehydrated to give the corresponding pentenine.  Detailed examples are given of the preparation of the novel products of the formula (I) in which R represents the radicals A to H.  The product where R is A yields 3,8-dimethyldecadien - (3,7) - ine - (5) - dione-(2,9) when oxidized with manganese dioxide.  The product where R is B may be converted into crocetin dialdehyde by partial hydrogenation of the triple bonds, allyl rearrangement of the secondary hydroxyl group and oxidation of the primary hydroxy groups formed.  The product where R is E may be converted to b -carotene by partial hydrogenation, two allyl rearrangements and splitting-off water. The product where R is H may be converted into 8,81-dehydro-crocetin dimethyl ester by splitting-off water and the latter may be converted into trans-crocetin dimethyl ester by partial hydrogenation and isomerization.  A detailed example is given.  Specification 744,890 is referred to.