Catalytic Ring Expansion of Vinyl Oxetanes: Asymmetric Synthesis of Dihydropyrans Using Chiral Counterion Catalysis
作者:Boying Guo、Gregg Schwarzwalder、Jon T. Njardarson
DOI:10.1002/anie.201201367
日期:2012.6.4
Acid Showdown! The first catalyticring expansion of vinyl oxetanes to 3,6‐dihydro‐2H‐pyrans is described. Copper(II) triflate emerged as the best catalyst for this new transformation, which has broad scope as demonstrated by the eighteen examples included. The symmetric vinyl oxetane substrate can be asymmetrically desymmetrized when using either chiral Lewis or Brønsted acids as catalysts.
Three‐Component Difunctionalization of Cyclohexenyl Triflates: Direct Access to Versatile Cyclohexenes via Cyclohexynes
作者:Seoyoung Cho、E. J. McLaren、Qiu Wang
DOI:10.1002/anie.202109482
日期:2021.12.6
dicarbofunctionalization, aminohalogenation and aminocarbonation of readily available cyclohexenyl triflates, via strained cyclic alkyne intermediates generated in situ. The importance and utility of this method is exemplified by the modularity of this approach and the ease in which even highly complex polycyclic scaffolds can be accessed in one step.
A Novel NaI-Promoted Ring Expansion of Cyclopropylidene Alcohols to Dihydropyrans
作者:Xian Huang、Weijun Fu、Ying Lin
DOI:10.1055/s-2007-968016
日期:2007.2
A novel and efficient approach to prepare dihydropyrans via the ringexpansion of cyclopropylidene alcohols in the presence of NaI in AcOH-MeCN was reported. The key feature in the transformation is the effect of the iodide anion.
报道了一种在 AcOH-MeCN 中在 NaI 存在下通过环丙叉醇的扩环来制备二氢吡喃的新型有效方法。转化的关键特征是碘阴离子的作用。
Chiral Hetero- and Carbocyclic Compounds from the Asymmetric Hydrogenation of Cyclic Alkenes
作者:J. Johan Verendel、Jia-Qi Li、Xu Quan、Byron Peters、Taigang Zhou、Odd R. Gautun、Thavendran Govender、Pher G. Andersson
DOI:10.1002/chem.201104073
日期:2012.5.21
Several types of chiral hetero‐ and carbocycliccompounds have been synthesized by using the asymmetrichydrogenation of cyclicalkenes. N,P‐Ligated iridium catalysts reduced six‐membered cyclicalkenes with various substituents and heterofunctionality in good to excellent enantioselectivity, whereas the reduction of five‐membered cyclicalkenes was generally less selective, giving modest enantiomeric