9- ethers ribonucleotides

Tipson devoted most of his years in Levene s laboratory accomplishing seminal work on the components of nucleic acids. To determine the ring forms of the ribose component of the ribonucleosides he applied Haworth s methylation technique and established the furanoid structure for the sugar in adenosine, guanosine, uridine, and thymidine. He showed that formation of a monotrityl ether is not a reliable proof for the presence of a primary alcohol group in a nucleoside, whereas a tosyl ester that is readily displaced by iodide affords clear evidence that the ester is at the 5-position of the pentofuranose. Acetonation of ribonucleosides was shown to give the 2, 3 -C -isopropyl-idene derivatives, which were to become extensively used in nucleoside and nucleotide chemistry, and were utilized by Tipson in the first chemical preparation of a ribonucleotide, inosinic acid. 

The genetic information of an organism is stored as a sequence of deoiy ribonucleotides strm tc ether in the DNA chain. For this information to be preserved and passed on to ftiture generations, a mechanism must exist for copying DNA. For the information to be used, a mechanism mu.st exist for decoding the DNA mess e and for implementing the instructions it contains. 

This ether is introduced by an acid catalyzed orthoester exchange process with an alcohol. It was developed for protection of the 2-hydroxyl in ribonucleotide synthesis. It is sufficiently stable to dichloroacetic acid, which is used for the cleavage of the dimethoxytrityl group. ... 

Protection of Hydroxyl Groups. Photolabile 2 -0-(o-nitrobenzyl) derivatives of various ribonucleotides as well as dinucleotides have been synthesized, and their subsequent photodeprotections, which yield the corresponding alcohols, examined (eq 11). Protection of the anomeric hydroxyl functionality of 2-deoxy-D-ribofuranose has been accomplished using o-NBA (eq 12). This protective group is quite stable to acidic conditions, and has proven invaluable in the synthesis of abasic oligonucleotides. Similar conditions are employed in the synthesis of bis(o-nitrobenzyl) ethers. ... 

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