Synthesis of 1-(5,6-dihydro-2H-thiopyran-2-yl)uracil by a Pummerer-type thioglycosylation reaction: the regioselectivity of allylic substitution
作者:Yuichi Yoshimura、Yoshiko Yamazaki、Yukako Saito、Hiroki Takahata
DOI:10.1016/j.tet.2009.09.046
日期:2009.11
1-(5,6-Dihydro-2H-thiopyran-2-yl)uracil derivatives, a new 4′-thio-D4-nucleoside analogue, were synthesized by reacting 5,6-dihydro-2H-thiopyran sulfoxide and persilylated uracil in a Pummerer-type thioglycosylation reaction. The reaction of 5-alkyl substituted dihydrothiopyran sulfoxide 7 only gave 1-(dihydrothiopyran-2-yl)uracil 9. On the other hand, the reaction with a 5-siloxy substituted derivative
通过使5,6-二氢-2 H-硫代吡喃亚砜与过甲硅烷基化反应合成了一种新的4'-硫代-D4-核苷类似物1-(5,6-Dihydro-2 H -thiopyran-2-yl)尿嘧啶衍生物Pummerer型硫糖基化反应中的尿嘧啶。5-烷基取代的二氢噻喃亚砜7的反应仅得到1-(二氢硫吡喃-2-基)尿嘧啶9。在另一方面,具有5-甲硅烷氧基取代的衍生物的反应7导致的产品在任的α-或γ位的尿嘧啶部分的混合物。使用延长的反应时间导致4-取代的二氢噻喃衍生物10的排他性形成。。结果表明,α-和γ-加合物的形成过程中存在平衡,并且后者应比前者更具热力学稳定性。这一结论也得到了理论计算的支持。