Carbocyclic nucleosides containing bicyclic rings, oligonucleotides therefrom, process for their preparation, their use and intermediates

A compound of the formula I or Ia or their racemates ##STR47## in which A is --CH.sub.2 -- or --CH.sub.2 CH.sub.2 --, R.sub.1 is hydrogen or a protective group, R.sub.2 is hydrogen a protective group for alcohols or a radical forming a phosphorous-containing nucleotide bridge group of the formula:

• ##STR48## in which Y.sub.a is hydrogen, C.sub.1 -C.sub.12 alkyl, C.sub.6 -C.sub.12 aryl, C.sub.7 -C.sub.20 alkaryl, --OR.sub.b, --SR.sub.b, --NH.sub.2, primary amino, secondary amino, O.sup.- M.sup.+ or S.sup.- M.sup.+ ;
• X.sub.a is oxygen or sulfur;
• R.sub.a is hydrogen, M.sup.+, C.sub.1 -C.sub.12 alkyl, C.sub.2 -C.sub.12 alkenyl or C.sub.6 -C.sub.12 aryl, or the group R.sub.a O-- is N-heteroaryl-N-yl having 5 ring members and 1 to 3 N atoms;
• Rb is hydrogen, C.sub.1 -C.sub.12 alkyl or C.sub.6 -C.sub.12 -aryl;
• and M.sup.+ is Na.sup.+, K.sup.+, Li.sup.+, NH.sub.4.sup.+ or primary, secondary, tertiary or quaternary ammonium;
• where alkyl, aryl, aralkyl and alkaryl in Y.sub.a, R.sub.a and R.sub.b are unsubstituted or substituted by alkoxy, alkylthio, halogen, --CN, --NO.sub.2, phenyl, nitrophenyl or halophenyl;
• and B is pyrimidine radical having formula II or IIe;
• ##STR49## in which R.sub.4 is H, Cl, Br or OH or --O--alkyl having 1 to 12 C atoms, and R.sub.5, R.sub.6 and R.sub.7 independently of one another are H, OH, SH, NH.sub.2, NHNH.sub.2, NHOH, NHO alkyl having 1 to 12 C atoms, --N.dbd.CH--N(C.sub.1 -C.sub.12 alkyl).sub.2, F, Cl, Br, alkyl or hydroxyalkyl or aminoalkyl or alkoxy or alkylthio having 1 to 12 C atoms, the hydroxyl and amino groups being unsubstituted or substituted by a protective group, phenyl, benzyl, primary amino having 1 to 20 C atoms or secondary amino having 2 to 30 C atoms, and R.sub.11 is H or C.sub.1 -C.sub.4 alkyl.