Synthesis and Ritter reaction of endo-2-ethynyl-1,7,7-trimethyl- and exo-2-ethynyl-5,5,6-trimethylbicyclo[2.2.1]heptan-2-ols

endo-2-Ethynyl-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol and exo-2-ethynyl-5 ,5,6-trimethylbicyclo[2.2.1]heptan-2-ol were obtained by treatment of 1,7,7 -trimethylbicyclo[2.2.1]heptan-2-one and 5,5,6-trimethylbicyclo[2.2.1]hepta n-2-one, respectively, with lithium acetylide. The reaction of endo-2-ethyn yl-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol with acetonitrile in the presen ce of sulfuric acid (Ritter reaction) is accompanied by a series of skeleta l rearrangements resulting in formation of exo-2-acetylamino-4-ethynyl-1,7, 7-trimethylbicyclo[2,2.1]heptane with a small admixture of 4-acetyl-exo-2-a cetylamino-4-ethynyl-1,7,7-trimethylbicyclo[2.2.1]heptane. The Ritter react ion of exo-2-ethynyl-5,5,6-trimethylbicyclo[2.2.1]heptan-2-ol yields a 1:1 mixture of endo-6-acetyl-exo-2-acetyiamino-1,7,7-trimethylbicyclo[2.2,1]hep tane and 2-acetyl-exo-2-acetylamino-5,5,6-trimethylbicyclo[2.2.1]heptane.