Powdered KOH in DMSO: an efficient base for asymmetric cyclization via memory of chirality at ambient temperature
T Kawabata, K Moriyama, S Kawakami…
文献索引：Kawabata, Takeo; Moriyama, Katsuhiko; Kawakami, Shimpei; Tsubaki, Kazunori Journal of the American Chemical Society, 2008 , vol. 130, # 12 p. 4153 - 4157
Enolate chemistry has been extensively used for stereoselective CC bond formation, in which metal amide bases are frequently employed in strictly anhydrous solvents at low temperatures. However, we found that asymmetric intramolecular CC bond formation via axially chiral enolate intermediates proceeded in up to 99% ee at 20° C using powdered KOH in dry or wet DMSO as a base. The enantioselectivity was even higher than that of ...
