45 3h s ar u2014 ch 3 4 05 4 2 3h m h4 h5 5 02 5 4 1h m h3 5 31 1h m h2 6 09 s h11 u03b2 amp 6 25 d j 7 hz h1 u03b1 1h combined 7 36 2h t arh j 6 3 hz 7 79 2h t arh j 6 3 hz the synthetic intermediate p1 p2 diethyl methanediphosphonate bis tetra n butyl ammonium salt is prepared according to a previously reported method from the corresponding tetraethyl ester the 1 h nmr results cdcl 3 ppm include 0 84 24h t ch 3 1 05 6 h m ch 2 1 31 16 h m ch 2 1 52 16 h m ch 2 1 91 2h m p u2014 ch 2 u2014 p 3 25 16 h m ch 2 3 87 4 h m ch 2 31 p nmr results cdcl 3 15 99 s compound 10 or p1 5 o 1 2 3 triacetyl ribosyl p2 5 u2032 o 2 u2032 3 u2032 dibutyryl adenosyl p1 p2 diethyl methylenediphosphonate is prepared as discussed below see fig8 in brief 2 u2032 3 u2032 dibutyryl 5 u2032 o tosyl adenosine at least about 0 925 g 1 65 mmol and p1 p2 diethyl methanediphosphonate bis tetra n butyl ammonium salt at least about 1 135 g 1 59 mmol are heated in dmf 1 ml for 18 hours at 80 90 degrees centigrade under argon next 1 2 3 tri o acetyl 5 o tosyl ribofuranose 0 817g 1 9 mmol was added to the reaction mixture and the mixture.