Action of acid on oligoribonucleotide phosphotriester intermediates. Effect of released vicinal hydroxy functions.
When 2'-O-methoxytetrahydropyranyl-5'-O-(9-phenylxanthen-9-yl) uridylyl-(3'----5')-(2',3'-di-O-acetyluridine) 2-chlorophenyl ester (9) is treated with zinc bromide in dichloromethane-propan-2-ol (85:15 v/v) at room temperature, under stringently anhydrous conditions, the corresponding 5'-unblocked dinucleoside phosphate (10) is obtained in 86% isolated yield; however, when no special precautions are taken to exclude moisture, (10) is obtained in only 72% yield. The removal of the 5'-O-(9-phenylxanthen-9-yl) protecting group from (10) with a protic acid (phenyl dihydrogen phosphate) appears to be much less selective and efficient. 80% Acetic acid promoted removal of the methoxytetrahydropyranyl protecting group from the isomeric fully-protected uridylyl-(3'----5')- and uridylyl-(2'----5')-uridine derivatives [(11) and (21c), respectively] leads to virtually identical mixtures [Figures 1a and 1b, respectively] of the partially-protected dinucleoside phosphates [(14) and (15)], 2',3'-di-O-acetyluridine (8), 5'-O-acetyluridine 2',3'-cyclic phosphate (16), and 5'-O-acetyluridine 2'(3')-phosphates [(18) and (17)].
D000143:Acids; D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D015226:Dinucleoside Phosphates; D006863:Hydrogen-Ion Concentration; D009841:Oligonucleotides / Q000138:chemical synthesis*; D009843:Oligoribonucleotides / Q000138:chemical synthesis*; D011714:Pyrans
D000143:Acids; D015226:Dinucleoside Phosphates; D009841:Oligonucleotides; D009843:Oligoribonucleotides; D011714:Pyrans