transferred to a separating funnel and shaken well and the organic layer was recovered the aqueous layer was washed with 100 ml chloroform the organic layers were combined washed with 200 ml water dried over magnesium sulfate and filtered and the solvent was distilled off the residues were subjected to azeotropic distillation with toluene until the smell of pyridine disappeared and then the reaction solution was dissolved in 50 ml benzene subjected to a silica gel column 3 5 u00d7 50 cm and eluted with 0 to 12 5 ethyl acetate benzene solution 4000 ml product fractions were collected and the solvent was distilled off whereby caramel was obtained yield 3 80 g fw 635 1 5 99 mmol 80 1 h nmr cdcl 3 u03b4 8 76 1h s h2 8 36 1h d j 3 0 hz h8 7 2 8 1 ca 20h bz tr 6 66 1h dd j 21 7 j 2 7 hz h1 u2032 5 70 1h dd j 17 0 j 3 0 hz h3 u2032 5 28 1h ddd j 50 0 j 3 0 j 0 8 hz h2 u2032 4 42 1h m h4 u2032 3 62 1h dd j 10 4 j 5 2 hz h5 u2032 a 3 54 1h dd j 10 4 j 4 1 hz h5 u2032 b 6 chloro 9 5 o trityl 3 o benzoyl 2 deoxy 2 fluoro u03b2 d arabinofuranosyl 9 h purine 3 15 g 4 98 mmol was dissolved in 100 ml methanolic ammonia saturated at 0 u00b0 c and left in a sealed tube at 100 u00b0 c for 2 days after cooling the solvent was carefully distilled off and the residues were dissolved in 100 ml chloroform the insolubles were filtered off and the.