derivatives of 4 , 5 - dihydro - 4 - oxofuran - 2 - carboxylic acid characterized by having two substituents at position 5 and in addition being optionally further substituted at position 3 with a lower alkyl group , as well as esters therefor are disclosed . the foregoing compounds are useful hypolipidemic agents in a mammal . novel methods for the preparation of these compounds also are disclosed .