Reese C B, Skone P A
Nucleic Acids Res. 1985 Jul 25;13(14):5215-31. doi: 10.1093/nar/13.14.5215.
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)].
当2'-O-甲氧基四氢吡喃基-5'-O-(9-苯基呫吨-9-基)尿苷酰-(3'→5')-(2',3'-二-O-乙酰基尿苷) 2-氯苯酯(9)在室温下于二氯甲烷-丙-2-醇(85:15 v/v)中，在严格无水的条件下用溴化锌处理时，相应的5'-未封闭的二核苷磷酸酯(10)以86%的分离产率得到；然而，当未采取特殊预防措施以排除水分时，(10)的产率仅为72%。用质子酸(苯基磷酸二氢酯)从(10)上去除5'-O-(9-苯基呫吨-9-基)保护基的选择性和效率似乎要低得多。80%的乙酸促进从异构体完全保护的尿苷酰-(3'→5')-和尿苷酰-(2'→5')-尿苷衍生物[(11)和(21c)，分别]上去除甲氧基四氢吡喃基保护基，导致部分保护的二核苷磷酸酯[(14)和(15)]、2',3'-二-O-乙酰基尿苷(8)、5'-O-乙酰基尿苷2',3'-环磷酸酯(16)和5'-O-乙酰基尿苷2'(3')-磷酸酯[(18)和(17)]的几乎相同的混合物[分别为图1a和图1b]。
