1,3-Dipolar Cycloadditions of Diazoalkanes to Activated Sulfoxides: Influence of Lewis Acids
作者:José L. García Ruano、M. Teresa Peromingo、Marina Alonso、Alberto Fraile、M. Rosario Martín、Amelia Tito
DOI:10.1021/jo051574v
日期:2005.10.1
The reactions of diazomethane and diazoethane with (S)-3-p-tolylsulfinylfuran-2(5H)-one (3) and its 4-methyl derivative (4) have been studied. The sulfinyl group was able to completely control the π-facial selectivity of all these reactions, which decreased when the polarity of the solvent increased and could be inverted in the presence of Lewis acids, Yb(OTf)3 being the most efficient catalyst. This
研究了重氮甲烷和重氮乙烷与(S)-3-对甲苯基亚砜基呋喃-2(5 H)-one(3)及其4-甲基衍生物(4)的反应。亚磺酰基能够完全控制所有这些反应的π面选择性,当溶剂的极性增加时它会降低,并且在路易斯酸(Yb(OTf)3是最有效的催化剂)的存在下可以被反转。这种行为使得非对映异构吡唑啉的立体发散性合成几乎可以定量收率,de's高于98%。的内型/外型选择性也是在反应的完整3与重氮乙烷,而4提供了易于分离的非对映异构体的1:1混合物。立体因素说明内/外选择性,而也必须考虑静电相互作用来解释面部选择性。