20120316366 | Method of Preparing 2,6,10-Trimethyl-1,1-Dialkoxy-3,5,9-Undecatriene Used as an Intermediate of Lycopene - The present invention describes a novel synthetic method for preparing the key intermediate 2,6,10-trimethyl-1,1-dialkoxy-3,5,9-undecatriene of lycopene. An existing synthetic method have some disadvantages that it is very difficult to gain the raw material dialkyl 4-methyl-5,5-diakoxy-1-pentene-1-phosphonate (10) because no effective synthetic method can be adopted, and furthermore the obtained target compound is composed of several cis/trans isomers. This invention relates to a process comprising a condensation step wherein a starting C10-phosphonate is changed to its carbanion completely at a temperature of −40˜30 under an atmosphere of a non-reactive gas in an organic solvent catalyzed by base, and then C4-dialkyl is added to undergo Wittig-Horner condensation. This invention affords all trans C14-acetal and this method is characterized with the advantages of simple procedure, easy access to raw material and low cost, which makes it has the value of industrial application. | 12-13-2012 |