Thiophene derivatives R 0090 Synthesis of 4H-Indeno[1,2-b]thiophenes, 8H-Indeno[2,1-b]thiophenes and 8H-Indeno[2,1-b]furans Having Acrylic Acid Unit. -A new synthetic method for the preparation of the title fused indene derivatives via Friedel-Crafts cyclization of Baylis-Hillman adducts of hetarenobenzaldehydes is given. -(JEON, K.