A carboxylic acid ester activated in .alpha.-position by a keto, ester or nitrile group, i.e. of the formula ##STR1## where X is COOR.sup.4, COR.sup.5 or CN, and the several R's can have various meanings but only R.sup.1 and R.sup.2 can be hydrogen, is decarbalkoxylated by heating in the presence of a salt, e.g. sodium chloride, and a phosphorus-containing solvent such as a phospholine oxide, phospholane oxide or phosphetane oxide of the formulas ##STR2## wherein a-k and R can have varied definitions. Water is present either at the outset or end of the reaction before product separation. The reaction proceeds smoothly and in good yields.