Backbone modified oligonucleotide analogues

An oligonucleotide analogue in which at least one of the subunits of the analogue have the structure:

• ##STR9## wherein B.sub.X is a variable base;
• Q is O;
• X is H;
• OH;
• C.sub.1 to C.sub.10 lower alkyl, substituted lower alkyl, alkaryl or aralkyl;
• F;
• Cl;
• Br;
• CN;
• CF.sub.3 ;
• OCF.sub.3 ;
• OCN;
• O-, S-, or N-alkyl;
• O-, S-, or N-alkenyl;
• SOCH.sub.3 ;
• SO.sub.2 CH.sub.3 ;
• ONO.sub.2 ;
• NO.sub.2 ;
• N.sub.3 ;
• NH.sub.2 ;
• heterocycloalkyl;
• heterocycloalkaryl;
• aminoalkylamino;
• polyalkylamino;
• or substituted silyl;
• L.sub.1, L.sub.2, L.sub.3, and L.sub.4 are selected such that:
• i. L.sub.1 and L.sub.4 are, independently, CH.sub.2, C.dbd.O, C.dbd.S, C-NH.sub.2, C-NHR.sub.3, C-OH, C-SH, C-O-R.sub.1 or C-S-R.sub.4 ;
• and
• L.sub.2 and L.sub.3 are, independently, CR.sub.1 R.sub.2, C.dbd.CR.sub.1 R.sub.2, C.dbd.NR.sub.3, P(O)R.sub.4, P(S)R.sub.4, C.dbd.O, C.dbd.S, O, S, SO, SO.sub.2, NR.sub.3 or SiR.sub.5 R.sub.6 ;
• or, together, form part of an alkene, alkyne, aromatic ring, carbocycle or heterocycle;
• or
• ii. L.sub.1, L.sub.2, L.sub.3 and L.sub.4, together, form a -CH.dbd.N-NH-CH.sub.2 - or -CH.sub.2 -O-N.dbd.CH- moiety;
• R.sub.1 and R.sub.2 are, independently, H;
• OH;
• SH;
• NH.sub.2 ;
• C.sub.1 to C.sub.10 alkyl, substituted alkyl, alkenyl, alkaryl or aralkyl;
• alkoxy;
• thioalkoxy;
• alkylamino;
• aralkylamino;
• substituted alkylamino;
• heterocycloalkyl;
• heterocycloalkylamino;
• aminoalkylamino;
• polyalkylamino;
• halo;
• formyl;
• keto;
• benzoxy;
• carboxamido;
• thiocarboxamido;
• ester;
• thioester;
• carboxamidine;
• carbamyl;
• ureido;
• or guanidino;
• R.sub.3 is H, OH, NH.sub.2, lower alkyl, substituted lower alkyl, alkoxy, lower alkenyl, aralkyl, alkylamino, aralkylamino, substituted alkylamino, heterocyclocalkyl, heterocycloalkylamino, aminoalkylamino, or polyalkylamino;
• R.sub.4 is OH, SH, NH.sub.2, O-alkyl, S-alkyl, NH-alkyl, O-alkylheterocyclo, S-alkylheterocyclo, N-alkylheterocyclo or a nitrogen-containing heterocycle;
• and
• R.sub.5 and R.sub.6 are, independently, C.sub.1 to C.sub.6 alkyl or alkoxy;
• provided that:
• if L.sub.1 is C.dbd.O or C.dbd.S then L.sub.2 is not NR.sub.3 ;
• if L.sub.4 is C.dbd.O or C.dbd.S then L.sub.3 is not NR.sub.3 ;
• if one of L.sub.2 or L.sub.3 is C.dbd.O or C.dbd.S then the other of L.sub.2 or L.sub.3 is not NR.sub.3 ;
• if L.sub.1 is CH.sub.2 and L.sub.2 is P(O)R.sub.4 and R.sub.4 is OH then L.sub.3 is not O;
• or if L.sub.1, L.sub.2 and L.sub.4 are CH.sub.2 and X is H or OH then L.sub.3 is not S, SO or SO.sub.2.