Process for preparing 1(4-pentonoyl)-3,3-dimethylcyclohexane and intermediates used in a said process

A process for preparing the compound defined according to the structure:

• ##STR46## comprising the steps of:
• (i) reacting an alkyl acetate having the structure:
• ##STR47## with 1-acetyl-3,3-dimethylcyclohexane having the structure;
• ##STR48##
• wherein R.sub.2 is C.sub.1 -C.sub.5 alkyl thereby forming a diketone having the structure:
• ##STR49## at a temperature of from about 20.degree. C. up to about 50.degree. C. and a pressure of from about 0.7 atmospheres up to about 5 atmospheres in the presence of an alkali metal alkoxide catalyst or aluminum isopropylate catalyst, the mole ratio of said 1-acetyl-3,3-dimethylcyclohexane:alkyl acetate being between 1:1 and 1:2 and the mole ratio of alkali metal alkoxide or aluminum triisopropylate:1-acetyl-3,3-dimethylcylcohexane being between 0.5:1 and 1:0.5;
• (ii) reacting the diketone having the structure:
• ##STR50## with the allyl halide having the structure:
• ##STR51## wherein X is bromo or iodo therby forming the compound defined according to the structure:
• ##STR52## under reflux conditions at a pressure of from about 0.7 atmospheres up to about 10 atmospheres, the mole ratio of diketone:allyl halide being from 1:1 up to 1:2;
• (iii) performing a retro-Claisen reaction on the allyl diketone having the structure:
• ##STR53## in order to form the compound having the structure:
• ##STR54## by means of reacting the compound having the structure:
• ##STR55## with an alkali metal alkoxide or aluminum triisopropylate or in an aqueous alcoholic solution at a temperature of between 35.degree. C. and 50.degree. C.;
• and
• (iv) isolating the compound having the structure:
• ##STR56## from the reaction mass.