Reactions of Ethyl and Phenyl Chloroformate with Adenosine Derivatives as an Entry to N6-Ureido-Linked Spin-Labeled Adenosine and Other Modified Adenosines

Article abstract of DOI:10.1021/jo00143a022

2',3',5'-O-Triacetyl-N⁶,N⁶-bis(phenoxycarbonyl)adenosine (10) reacted readlly with 4-amino-2,2,6,6-tetramethylpiperidinyl-1-oxy to afford an 87percent yield of ureido compound 16, which was then deacetylated to give spin-labeled adenosine derivative 19 in 56percent yield.Adenosine derivatives 24-27 were prepared from 10 in a similar manner.Treatment of 2',3'-O-isopropylideneadenosine (2) with phenyl chloroformate gave O^5',8-cycloadenosines 13 and 14; structure 13 was assigned on the basis of long-range selective proton-decoupled (LSPD) 13C NMR spectra.O^5',8-Cycloadenosine 8 was similarly prepared from 2 and ethyl chloroformate.Reaction of 2',3',5'-O-triacetyladenosine (9) with phenyl chloroformate in the presence of dimethylformamide afforded amidine derivative 12 (74percent).