NOVELTY - Preparing pure strontium ranelate (I), comprises: (a) contacting malononitrile with 1,3-acetonedicarboxylic acid dialkyl ester (VIII) and sulfur to obtain dialkyl-5-amino-4-cyanothiophene-2-3-dicarboxylate (VI); (b) contacting (VI) with substituted haloacetamide (III) to obtain novel intermediate diamide diester (II); (c) hydrolyzing (II) with a base to obtain ranelic acid (VII); (d) contacting (VII) with alkali metal base to obtain alkali metal salt (VII A); and (e) contacting (VII A) with strontium source to obtain (I).    USE - The process is useful for preparing substantially pure strontium ranelate (claimed), which is useful for treating bone diseases, preferably postmenopausal osteoporosis to reduce the risk of vertebral and hip fractures. No biological data given.    ADVANTAGE - The process provides the strontium ranelate with high yield and purity in an environmental friendly manner.    DETAILED DESCRIPTION - Preparing a pure strontium ranelate (I) comprises: either (a) contacting malononitrile (NC-CH2-CN) (IX) with a 1,3-acetonedicarboxylic acid dialkyl ester compound of formula (VIII) and sulfur in presence of a base and a solvent to obtain dialkyl-5-amino-4-cyanothiophene-2-3-dicarboxylate compound of formula (VI), (b) contacting (VI) with a substituted haloacetamide of formula (X-CH2-C(=O-N(R1a)(R2a))) (III) in a solvent and in the presence of a base, a phase transfer catalyst in combination with alkali metal halides to obtain novel intermediate diamide diester of formula (II), (c) hydrolyzing optionally purified (II) with a base to obtain a ranelic acid compound of formula (VII), (d) optionally isolating and contacting (VII) with alkali metal base to obtain the corresponding alkali metal salt of compound of formula (VII A), and (e) contacting (VII A) with strontium source to obtain (I); or contacting (II) with strontium source to obtain (I).    R1, R2 = 1-8C-alkyl;    R1a, R2a = H, 1-6C-alkyl, carbocyclic, or heterocyclic; and    M = alkali metal comprising Li, Na or K.    An INDEPENDENT CLAIM is included for the diamide diester of formula (II).