NOVELTY - Preparation (P1) of 2-amino-thiazole-5-carboxylic acid (2-chloro-6-methyl-phenyl)-amide compound (Ia) or its salt, involves: reacting thiazole-5-carboxylic acid compound (IIa) or its salt with magnesium (2-chloro-6-methylphenyl)amide bromide.    USE - For preparation of 2-amino-thiazole-5-carboxylic acid (2-chloro-6-methyl-phenyl)-amide compound or its salt useful for preparation of dasatinib (claimed) monohydrate used as cyclic protein tyrosine kinase inhibitor for the treatment of adults with chronic, accelerated, or myeloid or lymphoid blast phase Philadelphia chromosome-positive chronic myeloid leukemia.    ADVANTAGE - The process is improved process for the preparation of the compound (Ia) by directly reacting the compound (IIa) with activated derivative of 2-chloro-6-methylaniline produced in situ by treating 2-chloro-6-methylaniline with ethylmagnesium bromide. The process does not involve the use of a hazardous reagent such as oxalyl chloride, thionyl chloride, n-butyl lithium, or N- bromosuccinimide; provides an efficient, industrially preferable, and economic process for the preparation of compound (Ia) in good yield with excellent chemical purity and a reduced number of process steps; and avoids the excess usage of environmentally hazardous reagents and organic solvents, thereby promoting green chemistry and ensuring a cleaner surrounding by putting a reduced load on the environment.    DETAILED DESCRIPTION - Preparation (P1) of 2-amino-thiazole-5-carboxylic acid (2,6-dimethyl-phenyl)-amide compound of formula (Ia) or its salt, involves: reacting thiazole-5-carboxylic acid compound of formula (IIa) or its salt with magnesium (2-chloro-6-methylphenyl)amide bromide of formula (III).    R1 and R2=H, amino protecting group, 6-chloro-2-methyl-pyrimidin-4-yl or 6-(4-(2-hydroxyethyl)-1-piperazinyl)-2-methyl-4-pyrimidinyl;    R3=1-6C alkyl, 6-12C aryl, 7-12C arylalkyl or 7-12C alkylaryl.    INDEPENDENT CLAIMS are included for the following:    (1) purification (P2) of tert-butyl(5-((2-chloro-6-methylphenyl)carbamoyl)-1,3-thiazol-2-yl)carbamate of (Ib) or its salt, involving: a2) providing a mixture of compound (Ib) or its salt and aqueous methanol; and b2) isolating compound (Ib) or its salt; and    (2) preparation (P3) of dasatinib or its salt, solvate, or hydrate, involving: a3) reacting thiazole-5-carboxylic acid compound of formula (II'a) or its salt with the compound (III) to obtain the amide compound of formula (I'a); and b3) converting the compound (I'a) to dasatinib or its salt, solvate, or hydrate when R1 is not 6-(4-(2-hydroxyethyl)-1-piperazinyl)-2-methyl-4-pyrimidinyl.    R'1=H.