The present invention provides a use of Iithium amide in liquid ammonia as a base to produce an enolate from at least one ester starting material in a crossed Claisen condensation reaction, wherein at least one ester starting material is a beta-hydroxy ester. Also provided is a method of producing lithium amide in situ for use in a crossed Claisen condensation reaction, wherein lithium is added to liquid ammonia, followed by an electron transfer agent, as well as a method of carrying out a crossed Claisen condensation reaction using an ester starting material and a beta-hydroxy ester, using lithium amide in liquid ammonia produced in situ.