Synthesis of a Highly Strained Heterocycle Involving a Nitro Acetal to Aminal Rearrangement
S. E. Denmark*, J. I. Montgomery
University of Illinois, Urbana, USA
21 September 2005 (online)
The highly strained [22.214.171.124]-1-azafenestrane was efficiently prepared using tandem [4+2], [3+2] cycloadditions of nitroalkene as the key step, 2 to 1. A bonus uncovered in the route towards the target molecule involved a dyotropic rearrangement of a nitro acetal into a tetracyclic aminal, 3 to 4. X-ray structure crystallographic analysis of the azafenestrane indicates significant planarized distortion [N1-C1-C7 119.8(7)° and C4-C1-C10 120.7(8)°] of the central carbon atom. The degree of distortion agrees well with calculated values for the corresponding parent hydrocarbon (M. Thommen, R. Keese Synlett 1997, 231-240).