DAST fluorination of 1-(5-O-trityl-3-deoxy-4-thio-β-d-threo-pentofuranosyl)uracil proceeds with retention of configuration, while the corresponding sulfoxide gives mainly the inverted product. The sulfone proceeds with elimination.
                                    1-(5-O-三苯甲基-3-脱氧-4-
硫代-β-D-苏式-
呋喃戊糖基)尿
嘧啶的
DAST氟化反应在保持构象不变的情况下进行,而相应的亚砜主要产生反式产物。砜则发生消除反应。