A Pd(II)-Catalyzed Ring-Expansion Reaction of Cyclic 2-Azidoalcohol Derivatives: Synthesis of Azaheterocycles
作者:Shunsuke Chiba、Yan-Jun Xu、Yi-Feng Wang
DOI:10.1021/ja9049564
日期:2009.9.16
A Pd(II)-catalyzed ring expansion-reaction of cyclic 2-azidoalcohol derivatives was found to proceed via an unprecedented C-C bond cleavage-C-N bond formation sequence, providing substituted azaheterocycles.
发现 Pd(II) 催化的环状 2-叠氮醇衍生物的扩环反应通过前所未有的 CC 键断裂-CN 键形成序列进行,提供取代的氮杂杂环。
Comparative reductive desymmetrization of 2,2-disubstituted-cycloalkane-1,3-diones
作者:Jeremy M. Carr、Timothy S. Snowden
DOI:10.1016/j.tet.2008.01.065
日期:2008.3
Reductive desymmetrization of 2-methyl-2-substituted-cycloalkane-1,3-diones can be effected using either NaBH(4) in DME or lithium tri-tert-butoxyaluminum hydride (LTBA) in THF at -60 degrees C. The former is a new approach that offers slightly greater diastereoselectivity in the reduction of 2,2-disubstituted-cyclopentane- 1,3-diones while LTBA is superior with 2,2-disubstituted-cyclohexane- 1,3-diones. Both conditions minimize subsequent reduction to diols thereby furnishing high yields of 1,3-ketols. Particularly rapid monoreductions are observed with 2-methyl-2-nitroethylcyclopentane-1,3-dione and 2-cyanoethyl-2-methylcyclopentane-1,3-dione when treated with NaBH(4) in DME at -60 degrees C. As expected, diastereoselectivity varies considerably with the substitution at C-2. (C) 2008 Elsevier Ltd. All rights reserved.