A facile synthesis of 4-bromo-2H-chromenes and 2H-thiochromenes and of 1-bromo-3, 4- dihydronaphthalene from the corresponding ketones and PBr3 is described. In some instances, significant quantities of the phosphonic acids (3) are isolated. Conversion of the bromo compounds to the lithio derivatives provides access to a wide range of novel 4- substituted 2H-chromenes and 2H-thiochromenes.
