NOVELTY - Improved transition metal-free synthesis of 2H-chromene compound involves adding 2 equivalent dry cesium fluoride to a flame-dried screw-capped test tube having a magnetic stirrer bar, evacuating and backfilling the screw-capped tube with argon, adding 2 equivalent ( alpha , beta )-unsaturated aldehyde (I) and acetonitrile to test tube, adding 1 equivalent aryne precursor (II), stirring at a temperature of 30-40 degrees C for 2-3 hours, and obtaining 2H-chromene compound (III).    USE - Improved transition metal-free synthesis of 2H-chromene compound e.g. 2-phenyl-2H-chromene, 2-(2-methoxyphenyl)-2H-chromene, 2-(3,4-dimethoxyphenyl)-2H-chromene, 2-(4-chlorophenyl)-2H-chromene, 2-(3-nitrophenyl)-2H-chromene, 2-(thiophen-2-yl)-2H-chromene, 6-(4-methoxyphenyl)-6H-(1,3)dioxolo(4,5-g)chromene, 2-(4-methoxyphenyl)-6,7-dimethyl-2H-chromene, 6,7-difluoro-2-(4-methoxyphenyl)-2H-chromene, 5-methoxy-2-(4-methoxyphenyl)-2H-chromene, 3-(4-methoxyphenyl)-3H-benzo(f)chromene, and 2-(4-methoxyphenyl)-7-methyl-2H-chromene (all claimed) used in pharmaceutical composition for treating diabetes mellitus, cancer, and inflammation. The pharmaceutical composition is in form of tablet, capsule, granule, suspension, injection, syrup or cream.    ADVANTAGE - The method enables improved transition metal-free synthesis of 2H-chromene compound with high yield, and reduced aryne precursor and cesium fluoride amount in ambient reaction conditions, by economical and fast process.    DETAILED DESCRIPTION - Improved transition metal-free synthesis of 2H-chromene compound involves adding 2 equivalent dry cesium fluoride to a flame-dried screw-capped test tube having a magnetic stirrer bar, evacuating and backfilling the screw-capped tube with argon, adding 2 equivalent ( alpha , beta )-unsaturated aldehyde of formula (I) and acetonitrile to test tube, adding 1 equivalent aryne precursor of formula (II), stirring at a temperature of 30-40 degrees C for 2-3 hours, and obtaining 2H-chromene compound of formula (III).    R1=H, halo, 1-6C alkyl, 1-4C alkoxy, fused aryl, aralkyl, naphthyl, or 1,3-dioxolane;and    R2=aryl, heteroaryl, or aralkyl (all optionally substituted by halo, 1-5C alkoxy, -NO2, or -CF3).