NOVELTY - A one pot catalytic decarboxylative acylation of amine (I) to obtain amide (IV) involves: a) heating mixture of amine (I) and malonic ester (II) in mole ratio of 1:10-20 for 0.5-3 hours at 100-130 degrees C to obtain intermediate (III), and cooling mixture; b) catalytic decarboxylation of (III) optionally in presence of alkali metal carbonate and polar organic solvent at 80-120 degrees C to obtain crude amide product; and c) evaporating organic solvent followed by dissolving in another organic solvent, washing with brine, drying and concentrating followed by washing with non-polar solvent, and drying.    USE - As one pot catalytic decarboxylative acylation process of amine to obtain amide (claimed) used in the preparation of pharmaceuticals, agrochemicals and polyamides.    ADVANTAGE - The method provides the product in high yield and purity. The yield of amides of formula (IV) is 57-98 (preferably 92-97)%. The method provides cost-effective, environment friendly and efficient one-pot method for acylation of aromatic/heteroaromatic primary/secondary amines using diethyl malonate (DEM). The method effectively uses non-toxic, non-corrosive, harmless reagents that contribute to improved yield of product. The method uses non-toxic, harmless, cheap and easily available acylating agent such as DEM. The method is short and simple.    DETAILED DESCRIPTION - A one pot catalytic decarboxylative acylation of amine of formula Ar-NH(R) (I) to obtain amide of formula Ar-N(R)-C(O)-CH2-R' (IV) in high yield and purity involves: a) heating the mixture of amine (I) and malonic ester of formula EtO-C(O)-CH(R')-COOEt (II) in mole ratio of 1:10-20 for a period of 0.5-3 hours at a temperature of 100-130 degrees C to obtain intermediate of formula (Ar-N(R)-C(O)-CH(R')-COOEt) (III) (in which Ar is alkylaryl or heteroaryl (all optionally substituted)), and cooling the reaction mixture; b) catalytic decarboxylation of the intermediate (III) as obtained in step (a) optionally in presence of alkali metal carbonate and a polar organic solvent at 80-120 degrees C until complete disappearance (1-3 hours) of the intermediate (III) to obtain crude amide product; and c) evaporating the organic solvent of step (b) followed by dissolving in another polar organic solvent, subsequently washing the organic layer with brine, drying and concentrating followed by washing with a non-polar solvent, filtering, drying to obtain the desired amide (IV) in good yield and purity.    R=H or alkyl, phenyl, alkylaryl or heteroaryl (all optionally substituted);    Ar=phenyl, alkylaryl or heteroaryl (all optionally substituted);    R'=H or alkyl, phenyl, alkylaryl or heteroaryl (all optionally substituted).