An efficient, simple and relatively inexpensive method for the synthesis of coumarins in aqueous sodium bicarbonate at ambient temperature has been developed. It features an intramolecular Wittig reaction of substituted 2-formylphenyl 2-bromoacetate in saturated aqueous sodium bicarbonate. Its advantages include benign reaction conditions, easy work-up and good overall yield with short reaction time. Various substituted coumarins have been synthesized by utilizing this methodology.