and γ-(silylpropyl)-tetrahydrofurans and tetrahydro-2-furanones containing alkyl and phenyl groups at the Si atom were obtained by the reactions of tetrahydrofuran (THF) and tetrahydro-2-furanone with vinyl- and allylsilanes in the presence of di(t-butyl) peroxide (DTBP). To reduce the amount of bis-products, the ratio [heterocycle]:[alkenylsilane]:[DTBP] = 80:4:1 was used.