A new type of nucleic acid analogs with polysiloxane backbones is reported in this paper. Four new organosilicon monomers containing nucleic acid bases or 5-fluorouracil

i.e.

γ-(N1-uracilyl) propylmethyldiethoxysilane (1)

γ-(N1-thyminyl) propylmethyldiethoxysilane (2)

γy-(N9-adenyl) propylmethyldiethoxysilane (4) anr-(N15-fluorouracilyl) propylmethyldiethoxysilane (3)

were prepared by the alkylation of γ-bromopropylmethyldiethoxysilane with uracil

thymine

adenine and 5-fluorouracil

respectively. The polymerization of these monomers

in-cluding the copolymerization of (1) with diacetoxydimethylsilane (5)

or 1

3-bis (acetoxy-1

1

3

3-tetramethyldisiloxane (6)

were carried out under different conditions. Thus

a variety of ho-mopolymers and copolymers were obtained with polysiloxane structure as the main chain and nucleic acid base as the pendant group. The monomers and polymers were structurally identi-fied by 1H-NMR

IR.UV and elemental analysis. The [n] and Mn of the polymers were also determined.