Diastereoselective Synthesis of Spirocyclopropane-Linked Pyrazolones from Azomethine Ylides via C(sp(3))-H Activation

作者：Yavari Issa; Naeimabadi Maryam; Sheykhahmadi Jamil; Bahemmat Samira; Halvagar Mohammad Reza

来源：ChemistrySelect, 2017, 2(35): 11370-11375.

DOI：10.1002/slct.201701906

<jats:title>Abstract</jats:title><jats:p>A novel synthesis of spirocyclopropane‐1,4′‐pyrazolin‐5′‐one derivatives <jats:italic>via</jats:italic> iodine‐mediated C(sp<jats:sup>3</jats:sup>)–H activation is described. Thus, a diastereoselective synthesis of spirocyclopropane‐linked pyrazolones from 4‐arylidene‐3‐methyl‐1‐phenylpyrazolin‐5‐ones and azomethine ylides, generated <jats:italic>in situ</jats:italic> from iodine‐catalyzed reaction of 2‐methylquinoline or acetophenones with pyridine in the presence of base, has been developed. These transformations proceeded <jats:italic>via</jats:italic> a cyclopropanation reaction followed by anti‐elimination of pyridine. Unequivocal evidence for the structures of spirocycles <jats:bold>rac‐anti‐5 a</jats:bold> and <jats:bold>rac‐anti‐12 a</jats:bold> were obtained from single‐crystal X‐ray analyses. These methods offer several advantages, such as being inexpensive, moderate to high yield, high atom economy, and ease of product isolation, which make them attractive processes for the synthesis of spirocyclopropane‐linked pyrazolones. The spirans reported in this work may deserve further attention not only from a synthetic but also from a pharmacological point of view.</jats:p>

• 出版日期2017-12-11