Abstract: This invention provides a novel compound for .sup.35 S-labelling oligonucleotides. The compound is .sup.35 S-3H-1,2-benzodithiol-3-one-1,1 dioxide (1) ##STR1## wherein the asterisk indicates the position of the .sup.35 S. Also provided is a method of synthesizing this compound, comprising first contacting .sup.35 S-thiobenzoic acid (4) with thiosalicylic acid (5) in acid medium to yield the condensation product, .sup.35 S-3 H 1,2-benzodithiol-3-one (2). .sup.35 S-3 H 1,2-benzodithiol-3-one (2) is then oxidized with a suitable oxidating agent such as trifuoroacetic acid and hydrogen perioxide to yield the desired product, .sup.35 S-3H-1,2-benzodithiol-3-one-1,1 dioxide (1). Any oligonucleotide susceptible to oxidative sulfurized by 3H-1,2-benzodithiol-3-one-1,1 dioxide can be labeled by .sup.35 S-3H-1,2-benzodithiol-3-one-1,1 dioxide (1). Accordingly, this invention also provides novel methods for .sup.35 S-labelling oligonucleotides.

Abstract: The present invention comprises a method for quickly and efficiently detritylating oligonucleotides synthesized by standard chemical techniques. The method comprises contacting a 5'-DMT oligonucleotide with the H.sup.+ form of a "DOWEX," "AMBERLYST" or "AMBERLITE" ion-exchange resin for about 10 minutes to about 2 hours. The method is particularly advantageous when used in large scale synthesis. The method is quicker than the standard acetic acid method and eliminates much of the post-detritylation processing associated with the acetic acid method.

Abstract: The present invention provides new mononucleotide synthons useful in the synthesis of oligonucleotides having from one to all P-chiral centers that are predominantly and independently in the R or S configuration. The invention also provides methods of synthesizing these synthons, methods of synthesizing oligonucleotides having from one to all P-chiral centers predominantly and independently in the R or S configuration, and such oligonucleotides. Oligonucleotides synthesized with the novel synthons are useful for modulating nucleic acid expression, both in vitro and in vivo, as well as in traditional hybridization assays.

Abstract: The present invention comprises a novel method of incorporating a tritium label at one or more predetermined sites within an oligonucleotide. In particular, the method comprises contacting a nascent, support-bound oligonucleotide having a free 5' hydroxyl group with a suitable oxidizing agent to oxidize the alcohol to an aldehyde, followed by reducing the aldehyde thereby formed with a suitable tritium labeled reducing agent such as [.sup.3 H]NaBH.sub.4 to yield the 5' terminal alcohol with a 5' tritium label. Normal automated synthesis can then be continued to yield the oligonucleotide of desired length having the tritium label in the desired location. The oligonucleotides thereby produced have higher specific activity than those previously known in the art. According, in a second aspect, the present invention provides oligonucleotides having high specific activity.

Abstract: The present invention comprises a novel method of incorporating radiolabels and other type of labels at one or more predetermined sites within an oligonucleotide. In particular, the method comprises contacting a nascent, support-bound oligonucleotide having an unprotected 5' hydroxyl group with a suitable activating agent, followed by contacting the resulting activated nascent oligonucleotide with a labeled, Y-protected mononucleotide having an unprotected 3'-hydroxyl, thereby condensing the labeled mononucleotide and nascent oligonucleotide. Normal automated synthesis can then be continued to yield the oligonucleotide of desired length having the label in the desired location. This method advantageously yields oligonucleotides with high specific activity. The oligonucleotides thereby produced are useful for determining the pharmacokinetics and biodistribution of their non-radiolabeled counterparts, both in vitro and in vivo.