2- Acetoxyethyl acetoxymethyl ether

Coupling of the bis(trimethylsilyl) derivative of 5-benzyluracil 789 with 2-acetoxyethyl acetoxymethyl ether (791) in presence of SnCU was complex. In addition to the expected N-1 substituted product 790, the N-3 substituted derivative 792 and disubstituted product 793 were also isolated. However, treatment of 789 with 783 in CH3CN in the absence of SnCU gave 790 as the only isolated product. Deblocking of 790 with NHs-MeOH gave the free nucleoside (88SC931). 

The same experimental procedure was used for further N-alkylation reactions of 2,4-bis(trimethylsilyloxo)thieno[3,2-d]pyrimidine-2,4-diones 271. Thus, reaction of 271 with 2-acetoxyethyl acetoxymethyl ether, 2-(acetoxymethoxy)propane-l,3-dibenzoate, and benzyloxymethyl acetate gave the respective 1- and 3-alkylated derivatives 274 and 275, 276 and 277, and 278 and 279 (90MI1 94JHC305 94MI2, 94MI3). ... 

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