Method of making 2,7-dimethyl-2,4,6-octatrienedial and derivatives thereof

A method for making 2,7-dimethyl-2,4,6-octatrienedial comprising the steps of:

• a) forming a first reaction mixture of
• i) X--CH.sub.2 --CH.dbd.CH--CH.sub.2 --X where X is chlorine or bromine, and
• ii) at least two equivalents of P(OR).sub.3 where R is C.sub.1 -C.sub.4 alkyl;
• b) isolating 2-butenyl-1,4-bisphosphonic acid tetraalkyl ester from said first reaction mixture;
• c) forming a second reaction mixture at a temperature of about 0.degree. C. or above in an essentially water-free, nonpolar organic solvent of
• i) 2-butenyl-1,4-bisphosphonic acid tetraalkyl ester,
• ii) at least two equivalents of CH.sub.3 --CO--CH.dbd.Z where --CH.dbd.Z is, selected from the group consisting of --CH(OR').sub.2, where R' is C.sub.1 -C.sub.4 alkyl, and ##STR8## where n is an integer 2 or 3, and iii) at least two equivalents of a solid alkali metal hydroxide base;
• d) isolating ##STR9## from said second reaction mixture;
• e) forming a third reaction mixture ##STR10## and water acidified to a pH of less than 4 to convert --CH.dbd.Z to an unprotected aldehyde;
• and
• f) isolating 2,7-dimethyl-2,4,6-octatrienedial from said third reaction mixture.