<p>A simple, cost-effective process for preparation of efavirenz of formula (I) comprising reacting a solution of 5-chloro-alpha-(cyclopropylethynyl)-2-amino-alpha-trifluoromethyl) benzene methanol of formula (II) in an organic solvent with triphosgene in the presence of an inorganic base at a temperature range -5° C. to 25° C., adding water and isolating compound of formula (I).</p>