2,2,2-(N-phenyl)-ethynyl-adamantamine

A 250-mL three-necked round-bottom flask fitted with a soxhlet was purged with nitrogen and charged with 150mL dry toluene, 1g Adamantanone (6.65mMol), 0.65ml aniline (7.2mMol) and a trace of tosic acid (8mg) before heating under reflux until no hydrogen development could be observed in the thimble of the soxhlet. The clear colourless solution was allowed to cool to room to temperature . Separately, 0.65g (6.7mMol) trimethylsilylacetylene in 90mL dry THF was cooled to -78oC before the addition of 5.6ml of 1.6M BuLi (8.96mMol, 1.3eq, in hexane), then was allowed to reach room temperature to stir another two hours under nitrogen. By raising nitrogen pressure , the imine-solution was added dropwise by means of nitrogen to turn immediately into a Bordeaux-red solution which was allowed to boil under reflux for 67h to give a dark brown solution, passed through a Silica column (petrol/ethylacetate=2.5:1) and the collected fractions dried over K₂CO₃. Evaporation of the solvent afforded 2g of a brown oil of which after vacuum evaporation (2mm Hg) orange crystals could be collected, mp 59-65^oC. The crystals were recrystalised in an aequeous methanol solution to give white crystals, mp 73^oC. Part of the crystals (0.5g, 2mmol) were resolved in 20ml methanol and the trimethylsylyl-group hydrolised with 5 equivalents (10mmol, 0.56g) potassiumhydroxid under reflux during 15 minutes. The usual acid workup afforded a white compound, mp 108-110^oC, which after spectroscopic analysis was found to be 2,2,2-N-phenyl-ethynyl-adamantamin. MS, m/z=251 (M⁺), 236, 222, 208, 194, 180, 170, 159, 143, 130, 117, 105, 93, 77, 65; IR (nujol), 3395.8 (-NH), 3266.0 (-CC-H), 1598.1, 1466.4, 1377.2, 1305.8, 1258.7, 1180.1, 1139.9, 1099.9, 1068.9, 997.1, 927.9, 872.4, 747.7, 695.6 (cm^-1). TLC (ether/n-hexane/petrol=2:1:1), RF=0.8 Crystals suitable for X-ray analysis were grown in CHCl₃/pentan using the slow evaporation method.