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- A typical procedure is given: 5′-dimethoxyltrityl-D4T (5) (215 mg, 0.409 mmol) was dissolved in tetrachloromethane and methanol mixed solvent (1:1 v/v) (10ml). The reaction mixture was left in the ultrasonic bath on full power [30W] for 3 hrs at 25–40°C until the starting material spot disappeared (monitored by TLC). The solvent was removed by vacuum and the residue was purified by a simple filtration column on silica, eluted with 5% methanol in dichloromethane. The product was obtained as a white solid (84.6mg, 92%) dH (300MHz, DMSO) 1.73 (3H, s, 5-Me), 3.61 (2H, s, H5′), 4.78 (1H, s, OH), 5.04 (1H, t, H4′), 5.92 (1H, d, H2′), 6.40 (1H, d, H3′), 6.83 (1H, s, H1′), 7.66 (1H, s, H6), 11.32 (1H, s, NH); dC (300 MHz, DMSO) 13.59 (s, 5-Me), 63.64 (C5′), 88.69 (C4′), 90.25 (C1′), 110.36 (C5), 127.37 (C2′), 136.34 (C3′), 138.17 (C6), 152.18 (C2), 165.25 (C4); the product was also identified by TLC comparison with an authentic sample. In the Table ‘T’ stands for thymine.