A Lewis-acid-promoted approach to the synthesis of highly functionalized dihydrobenzofuranderivatives was developed. A diverse range of functional groups are tolerated in this type of reaction. The reaction mechanism investigation indicates that the highly reactive phenyl cation intermediate is probably involved in this process. The chirality of substrate is retained under the reaction conditions
(EN) Hypoglycemic 2,3-dihydro-5-benzo¨ADb¨BDfuranyl-2,3-dihydro-5-benzo¨ADb¨BDthienyl-, 3,4-dihydro(2H)-6-benzo-pyranyl- and 6-thiochromanyl-thiazolidine-2,4-diones and pharmaceutically acceptable salts thereof, method for their use in treatment of hyperglycemic animals and pharmaceutical compositions containing them.(FR) Thiazolidine-2,4-diones hypoglycémique de 2,3-dihydro-5-benzo¨ADb¨BDfuranyl-2,3-dihydro-5-benzo¨ADb¨BDthiényle, de 3,4-dihydro(2h)-6-benzo-pyranyle et de 6-thiochromanyle et sels acceptables pharmaceutiquement à partir desdits composés, ainsi que méthode d'utilisation desdits composés pour le traitement d'hyperglycémie chez les animaux et compositions pharmaceutiques contenant lesdits composés.