The Synthesis of 3-Amino-3-methylbicyclo[3.3.1]nonanes: endo-Selectivity in the Ritter Reaction of 1,3,5,7α-Tetramethylbicyclo[3.3.1]nonan-3-ol.

1,3,5,7α- and 1,3,5,7β-Tetramethylbicyclo[3.3.1]nonan-3-ols 3a and 3b were prepared from the corresponding ketones 2a and 2b. 7α-Methyl isomer 3a gave selectively endo-3α-N-formylaminobicyclononane 10 in the Ritter reaction with trimethylsilyl cyanide. 7β-Methyl epimer 3b suffered water elimination resulting in bicyclo[3.3.1]non-2-ene 12 under the same reaction conditions. The endo-amide structure was confirmed by X-ray analysis..