Synthesis, X-ray Crystallography, and Computational Analysis of 1-Azafenestranes
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- 作者：Scott E. Denmark ; Justin I. Montgomery ; Laurenz A. Kramps
- 刊名：Journal of the American Chemical Society
- 出版年：2006
- 出版时间：September 6, 2006
- 年：2006
- 卷：128
- 期：35
- 页码：11620 - 11630
- 全文大小：456K
- 年卷期：v.128,no.35(September 6, 2006)
- ISSN：1520-5126
文摘
The tandem [4+2]/[3+2] cycloaddition of nitroalkenes has been employed in the synthesis of1-azafenestranes, molecules of theoretical interest because of planarizing distortion of their central carbonatoms. The synthesis of c,c,c,c-[5.5.5.5]-1-azafenestrane was completed in good yield from a substitutednitrocyclopentene, and its borane adduct was analyzed through X-ray crystallography, which showed amoderate distortion from ideal tetrahedral geometry. The syntheses of two members of the [4.5.5.5] familyof 1-azafenestranes are also reported, including one with a trans fusion at a bicyclic ring junction whichbrings about considerable planarization of one of the central angles (16.8
deviation from tetrahedralgeometry). While investigating the [4.5.5.5]-1-azafenestranes, a novel dyotropic rearrangement that convertsnitroso acetals into tetracyclic aminals was discovered. Through conformational analysis, a means to preventthis molecular reorganization was formulated and realized experimentally with the use of a bulky vinylether in the key [4+2] cycloaddition reaction. Finally, DFT calculations on relative strain energy for the1-azafenestranes, as well as their predicted central angles, are disclosed.
deviation from tetrahedralgeometry). While investigating the [4.5.5.5]-1-azafenestranes, a novel dyotropic rearrangement that convertsnitroso acetals into tetracyclic aminals was discovered. Through conformational analysis, a means to preventthis molecular reorganization was formulated and realized experimentally with the use of a bulky vinylether in the key [4+2] cycloaddition reaction. Finally, DFT calculations on relative strain energy for the1-azafenestranes, as well as their predicted central angles, are disclosed.