Nucleophilic Addition of Benzenethiol to 1‘,2‘-Unsaturated Nucleosides: 1‘-C-Phenylthio-2‘-deoxynucleosides as Anomeric Radical Precursors
摘要:
The addition reaction of benzenethiol to the glycal portion of 1',2'-unsaturated uridine proceeds efficiently in the presence of Et3N. The mechanism involves nucleophilic attack of thiolate at the anomeric position in the rate-determining step, wherein conjugation between the nucleobase and the glycal portion is crucial. The derivative having a methyl group either at the 2'- or 6-position did not undergo this addition reaction, due to their sterically prohibited coplanarity. The 1',2'-unsaturated derivatives of thymine and adenine can also be used as substrates for this addition reaction. It was also shown that the resulting 1'-C-phenylthio-2'-deoxynucleosides serve as precursors for radical-mediated C-C bond formation at the anomeric position.
The addition reaction of benzenethiol to the glycal portion of 1',2'-unsaturated uridine proceeds efficiently in the presence of Et3N. The mechanism involves nucleophilic attack of thiolate at the anomeric position in the rate-determining step, wherein conjugation between the nucleobase and the glycal portion is crucial. The derivative having a methyl group either at the 2'- or 6-position did not undergo this addition reaction, due to their sterically prohibited coplanarity. The 1',2'-unsaturated derivatives of thymine and adenine can also be used as substrates for this addition reaction. It was also shown that the resulting 1'-C-phenylthio-2'-deoxynucleosides serve as precursors for radical-mediated C-C bond formation at the anomeric position.