Vinyl Sulfoxides as Stereochemical Controllers in Intermolecular Pauson-Khand Reactions: Applications to the Enantioselective Synthesis of Natural Cyclopentanoids
作者:Marta Rodríguez Rivero、Inés Alonso、Juan C. Carretero
DOI:10.1002/chem.200400443
日期:2004.11.5
diastereoselectivity (de=86->96 %, (S,R(S)) diastereomer). Experimental studies suggest that the high reactivity exhibited by the vinyl sulfoxide 1 i relies on the ability of the amine group to act as a soft ligand on the alkyne dicobalt complex prior to the generation of the cobaltacycle intermediate. On the other hand, both theoretical and experimental studies show that the high stereoselectivity of the process is
描述了亚砜在不对称分子间Pauson-Khand反应中作为手性助剂的用途。在α,β-不饱和亚砜中筛选了硫原子上的各种取代基后,事实证明,现成的邻-(N,N-二甲基氨基)苯基乙烯基亚砜(1i)在氮气氛下可与取代的末端炔烃高度反应-氧化促进条件(CH3CN,0摄氏度)。另外,这些Pauson-Khand反应以完全的区域选择性和非常高的非对映选择性(de = 86-> 96%,(S,R(S))非对映异构体)发生。实验研究表明,乙烯基亚砜1 i表现出的高反应性取决于在生成钴环中间体之前,胺基团充当炔烃二钴配合物上的软配体的能力。另一方面,理论和实验研究均表明,该方法的高立体选择性是由于所得的5-亚磺酰基-2-环戊烯酮加合物在C5中心容易发生热力学差向异构。当考虑到已知的不对称分子间Pauson-Khand反应仅限于使用高反应性的双环烯烃,主要是降冰片烯和降冰片二烯时,该新颖的方法构成了具有未应