1,1'-(Chlorophenylmethylene)bis(4-methoxybenzene) → N2 (3-methoxyphenylacetyl)-5'-O-(4, 4'-dimethoxytrityl)-2'-deoxyguanosine

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Reaction Conditions

Reaction Steps

N2 -(3-Methoxyphenylacetyl)-2'-deoxyguanosine (2b) (2.08 g, 5 mmoles) was dried by coevaporation with dry pyridine (2×30 ml), dissolved in 40 ml of dry pyridine and ice cooled. To this solution, 4,4'-dimethoxytrityl chloride (2.2 g, 6.5 mmoles) was added. The reaction mixture was stirred at 5° C. for 20 hours. After removing the pyridine under reduced pressure, the resulting residue was taken up in 150 ml of methylene chloride and washed successively with 2×100 ml of 5% NaHCO3 and 1×100 ml of water. The organic layer was dried over anhydrous sodium sulfate and concentrated to near dryness. The product was purified on a silica gel column (2×40 cm) by gradient elution with 200 ml 0-6% methylene chloride-methanol. The desired fractions were collected, concentrated to about 30 ml and added dropwise to 200 ml cooled hexane (0° C.) to precipitate the product. The precipitated product was filtered, washed with hexane and air dried to yield 1.7 g (47%) of tritylated product (3b), as confirmed by spectroscopic and elemental analysis.

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